#include <Arduino.h>
#include "DataStore.h"
#include "Features.h"   // FEAT_JOYSTICK_ROTATION_SETTING (else `#if !FEAT_…` is always true)
#include <target.h>     // radio_driver — repeater-profile freq bounds (getFreqBounds)

#if defined(EXTRAFS) || defined(QSPIFLASH)
  #define MAX_BLOBRECS 100
#else
  #define MAX_BLOBRECS 20
#endif

DataStore::DataStore(FILESYSTEM& fs, mesh::RTCClock& clock) : _fs(&fs), _fsExtra(nullptr), _clock(&clock),
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
    identity_store(fs, "")
#elif defined(RP2040_PLATFORM)
    identity_store(fs, "/identity")
#else
    identity_store(fs, "/identity")
#endif
{
}

#if defined(EXTRAFS) || defined(QSPIFLASH)
DataStore::DataStore(FILESYSTEM& fs, FILESYSTEM& fsExtra, mesh::RTCClock& clock) : _fs(&fs), _fsExtra(&fsExtra), _clock(&clock),
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
    identity_store(fs, "")
#elif defined(RP2040_PLATFORM)
    identity_store(fs, "/identity")
#else
    identity_store(fs, "/identity")
#endif
{
}
#endif

static File openWrite(FILESYSTEM* fs, const char* filename) {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  fs->remove(filename);
  return fs->open(filename, FILE_O_WRITE);
#elif defined(RP2040_PLATFORM)
  return fs->open(filename, "w");
#else
  return fs->open(filename, "w", true);
#endif
}

// Atomically swap a fully-written temp file over its final path. LittleFS
// (nRF52/STM32) rename replaces an existing destination atomically, so a crash
// leaves either the old file or the new one intact — never a truncated mix.
// Other Arduino filesystems can't rename onto an existing file, so the
// destination is dropped first (a metadata-only window, vs. the record-by-record
// write window of a direct overwrite). Returns false if the swap fails.
static bool commitTempFile(FILESYSTEM* fs, const char* tmp, const char* final_path) {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  return fs->rename(tmp, final_path);
#else
  fs->remove(final_path);
  return fs->rename(tmp, final_path);
#endif
}

#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  static uint32_t _ContactsChannelsTotalBlocks = 0;
#endif

void DataStore::begin() {
#if defined(RP2040_PLATFORM)
  identity_store.begin();
#endif

#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  _ContactsChannelsTotalBlocks = _getContactsChannelsFS()->_getFS()->cfg->block_count;
  checkAdvBlobFile();
  #if defined(EXTRAFS) || defined(QSPIFLASH)
  migrateToSecondaryFS();
  #endif
#else
  // init 'blob store' support
  _fs->mkdir("/bl");
#endif
}

#if defined(ESP32)
  #include <SPIFFS.h>
  #include <nvs_flash.h>
#elif defined(RP2040_PLATFORM)
  #include <LittleFS.h>
#elif defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  #if defined(QSPIFLASH)
    #include <CustomLFS_QSPIFlash.h>
  #elif defined(EXTRAFS)
    #include <CustomLFS.h>
  #else 
    #include <InternalFileSystem.h>
  #endif
#endif

#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
int _countLfsBlock(void *p, lfs_block_t block){
      if (block > _ContactsChannelsTotalBlocks) {
        MESH_DEBUG_PRINTLN("ERROR: Block %d exceeds filesystem bounds - CORRUPTION DETECTED!", block);
        return LFS_ERR_CORRUPT;  // return error to abort lfs_traverse() gracefully
    }
  lfs_size_t *size = (lfs_size_t*) p;
  *size += 1;
    return 0;
}

lfs_ssize_t _getLfsUsedBlockCount(FILESYSTEM* fs) {
  lfs_size_t size = 0;
  int err = lfs_traverse(fs->_getFS(), _countLfsBlock, &size);
  if (err) {
    MESH_DEBUG_PRINTLN("ERROR: lfs_traverse() error: %d", err);
    return 0;
  }
  return size;
}
#endif

uint32_t DataStore::getStorageUsedKb() const {
#if defined(ESP32)
  return SPIFFS.usedBytes() / 1024;
#elif defined(RP2040_PLATFORM)
  FSInfo info;
  info.usedBytes = 0;
  _fs->info(info);
  return info.usedBytes / 1024;
#elif defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  const lfs_config* config = _getContactsChannelsFS()->_getFS()->cfg;
  int usedBlockCount = _getLfsUsedBlockCount(_getContactsChannelsFS());
  int usedBytes = config->block_size * usedBlockCount;
  return usedBytes / 1024;
#else
  return 0;
#endif
}

uint32_t DataStore::getStorageTotalKb() const {
#if defined(ESP32)
  return SPIFFS.totalBytes() / 1024;
#elif defined(RP2040_PLATFORM)
  FSInfo info;
  info.totalBytes = 0;
  _fs->info(info);
  return info.totalBytes / 1024;
#elif defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  const lfs_config* config = _getContactsChannelsFS()->_getFS()->cfg;
  int totalBytes = config->block_size * config->block_count;
  return totalBytes / 1024;
#else
  return 0;
#endif
}

File DataStore::openRead(const char* filename) {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  return _fs->open(filename, FILE_O_READ);
#elif defined(RP2040_PLATFORM)
  return _fs->open(filename, "r");
#else
  return _fs->open(filename, "r", false);
#endif
}

File DataStore::openRead(FILESYSTEM* fs, const char* filename) {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  return fs->open(filename, FILE_O_READ);
#elif defined(RP2040_PLATFORM)
  return fs->open(filename, "r");
#else
  return fs->open(filename, "r", false);
#endif
}

File DataStore::openWrite(const char* filename) {
  return ::openWrite(_fs, filename);
}

bool DataStore::commitFile(const char* tmp_path, const char* final_path) {
  return commitTempFile(_fs, tmp_path, final_path);
}

bool DataStore::removeFile(const char* filename) {
  return _fs->remove(filename);
}

bool DataStore::removeFile(FILESYSTEM* fs, const char* filename) {
  return fs->remove(filename);
}

bool DataStore::formatFileSystem() {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  if (_fsExtra == nullptr) {
    return _fs->format();
  } else {
    return _fs->format() && _fsExtra->format();
  }
#elif defined(RP2040_PLATFORM)
  return LittleFS.format();
#elif defined(ESP32)
  bool fs_success = ((fs::SPIFFSFS *)_fs)->format();
  esp_err_t nvs_err = nvs_flash_erase(); // no need to reinit, will be done by reboot
  return fs_success && (nvs_err == ESP_OK);
#else
  #error "need to implement format()"
#endif
}

bool DataStore::loadMainIdentity(mesh::LocalIdentity &identity) {
  return identity_store.load("_main", identity);
}

bool DataStore::saveMainIdentity(const mesh::LocalIdentity &identity) {
  return identity_store.save("_main", identity);
}

void DataStore::loadPrefs(NodePrefs& prefs, double& node_lat, double& node_lon) {
  if (_fs->exists("/new_prefs")) {
    loadPrefsInt("/new_prefs", prefs, node_lat, node_lon); // new filename
  } else if (_fs->exists("/node_prefs")) {
    loadPrefsInt("/node_prefs", prefs, node_lat, node_lon);
    savePrefs(prefs, node_lat, node_lon);                // save to new filename
    _fs->remove("/node_prefs"); // remove old
  }
}

void DataStore::loadPrefsInt(const char *filename, NodePrefs& _prefs, double& node_lat, double& node_lon) {
  // Set hardware defaults before reading — if the file is older and lacks these fields,
  // the compile-time values apply rather than the zero from memset in MyMesh::begin().
#ifdef DISPLAY_ROTATION
  _prefs.display_rotation = DISPLAY_ROTATION;
#endif
  // 0 is a valid SNR threshold, so the "off" state needs its own sentinel set
  // before reading — an older file lacking this field must read as disabled,
  // not as "filter everything below 0 dB".
  _prefs.repeat_min_snr = NodePrefs::REPEAT_SNR_DISABLED;
  File file = openRead(_fs, filename);
  if (!file) return;

  uint8_t pad[8];

  // Core fields — present in every saved file (written unconditionally since the beginning).
  file.read((uint8_t *)&_prefs.airtime_factor, sizeof(_prefs.airtime_factor));
  file.read((uint8_t *)_prefs.node_name, sizeof(_prefs.node_name));
  file.read(pad, 4);
  file.read((uint8_t *)&node_lat, sizeof(node_lat));
  file.read((uint8_t *)&node_lon, sizeof(node_lon));
  file.read((uint8_t *)&_prefs.freq, sizeof(_prefs.freq));
  file.read((uint8_t *)&_prefs.sf, sizeof(_prefs.sf));
  file.read((uint8_t *)&_prefs.cr, sizeof(_prefs.cr));
  file.read((uint8_t *)&_prefs.client_repeat, sizeof(_prefs.client_repeat));
  file.read((uint8_t *)&_prefs.manual_add_contacts, sizeof(_prefs.manual_add_contacts));
  file.read((uint8_t *)&_prefs.bw, sizeof(_prefs.bw));
  file.read((uint8_t *)&_prefs.tx_power_dbm, sizeof(_prefs.tx_power_dbm));
  file.read((uint8_t *)&_prefs.telemetry_mode_base, sizeof(_prefs.telemetry_mode_base));
  file.read((uint8_t *)&_prefs.telemetry_mode_loc, sizeof(_prefs.telemetry_mode_loc));
  file.read((uint8_t *)&_prefs.telemetry_mode_env, sizeof(_prefs.telemetry_mode_env));
  file.read((uint8_t *)&_prefs.rx_delay_base, sizeof(_prefs.rx_delay_base));
  file.read((uint8_t *)&_prefs.advert_loc_policy, sizeof(_prefs.advert_loc_policy));
  file.read((uint8_t *)&_prefs.multi_acks, sizeof(_prefs.multi_acks));
  file.read((uint8_t *)&_prefs.path_hash_mode, sizeof(_prefs.path_hash_mode));
  file.read(pad, 1);
  file.read((uint8_t *)&_prefs.ble_pin, sizeof(_prefs.ble_pin));
  file.read((uint8_t *)&_prefs.buzzer_quiet, sizeof(_prefs.buzzer_quiet));
  file.read((uint8_t *)&_prefs.gps_enabled, sizeof(_prefs.gps_enabled));
  file.read((uint8_t *)&_prefs.gps_interval, sizeof(_prefs.gps_interval));
  file.read((uint8_t *)&_prefs.autoadd_config, sizeof(_prefs.autoadd_config));
  file.read((uint8_t *)&_prefs.autoadd_max_hops, sizeof(_prefs.autoadd_max_hops));
  file.read((uint8_t *)&_prefs.rx_boosted_gain, sizeof(_prefs.rx_boosted_gain));
  file.read((uint8_t *)_prefs.default_scope_name, sizeof(_prefs.default_scope_name));
  file.read((uint8_t *)_prefs.default_scope_key, sizeof(_prefs.default_scope_key));
  file.read((uint8_t *)&_prefs.display_brightness, sizeof(_prefs.display_brightness));
  file.read((uint8_t *)&_prefs.auto_off_secs, sizeof(_prefs.auto_off_secs));
  file.read((uint8_t *)&_prefs.tz_offset_hours, sizeof(_prefs.tz_offset_hours));
  file.read((uint8_t *)&_prefs.low_batt_mv, sizeof(_prefs.low_batt_mv));
  file.read((uint8_t *)&_prefs.batt_display_mode, sizeof(_prefs.batt_display_mode));

  // Extension fields — append-only, newest at the bottom.
  // Each read is gated on file.available(); fields absent in older files stay at their
  // zero-initialised or hardware-default values set above.
  auto rd = [&](void* p, size_t n) {
    if (file.available() >= (int)n) file.read((uint8_t*)p, n);
  };

  rd(_prefs.custom_msgs,                sizeof(_prefs.custom_msgs));
  rd(&_prefs.ch_notif_override,         sizeof(_prefs.ch_notif_override));
  rd(&_prefs.ch_notif_muted,            sizeof(_prefs.ch_notif_muted));
  rd(&_prefs.dm_show_all,               sizeof(_prefs.dm_show_all));
  rd(&_prefs.room_fav_only,             sizeof(_prefs.room_fav_only));
  rd(&_prefs.buzzer_volume,             sizeof(_prefs.buzzer_volume));
  rd(&_prefs.ringtone_bpm_idx,          sizeof(_prefs.ringtone_bpm_idx));
  rd(&_prefs.ringtone_len,              sizeof(_prefs.ringtone_len));
  if (_prefs.ringtone_len > 32) _prefs.ringtone_len = 0;
  rd(_prefs.ringtone_notes,             sizeof(_prefs.ringtone_notes));
  rd(&_prefs.home_pages_mask,           sizeof(_prefs.home_pages_mask));
  rd(&_prefs.bot_enabled,               sizeof(_prefs.bot_enabled));
  rd(&_prefs.bot_channel_enabled,       sizeof(_prefs.bot_channel_enabled));
  rd(&_prefs.bot_channel_idx,           sizeof(_prefs.bot_channel_idx));
  rd(_prefs.bot_trigger,                sizeof(_prefs.bot_trigger));
  rd(_prefs.bot_reply_dm,               sizeof(_prefs.bot_reply_dm));
  rd(_prefs.bot_reply_ch,               sizeof(_prefs.bot_reply_ch));
  rd(&_prefs.clock_hide_seconds,        sizeof(_prefs.clock_hide_seconds));
  rd(&_prefs.buzzer_auto,               sizeof(_prefs.buzzer_auto));
  rd(_prefs.dm_notif,                   sizeof(_prefs.dm_notif));
  rd(_prefs.dashboard_fields,           sizeof(_prefs.dashboard_fields));
  rd(&_prefs.advert_auto_interval_sec,  sizeof(_prefs.advert_auto_interval_sec));
  rd(&_prefs.ringtone2_bpm_idx,         sizeof(_prefs.ringtone2_bpm_idx));
  rd(&_prefs.ringtone2_len,             sizeof(_prefs.ringtone2_len));
  if (_prefs.ringtone2_len > 32) _prefs.ringtone2_len = 0;
  rd(_prefs.ringtone2_notes,            sizeof(_prefs.ringtone2_notes));
  rd(&_prefs.notif_melody_dm,           sizeof(_prefs.notif_melody_dm));
  if (_prefs.notif_melody_dm > 3) _prefs.notif_melody_dm = 0;
  rd(&_prefs.notif_melody_ch,           sizeof(_prefs.notif_melody_ch));
  if (_prefs.notif_melody_ch > 3) _prefs.notif_melody_ch = 0;
  rd(&_prefs.ch_notif_melody_set,       sizeof(_prefs.ch_notif_melody_set));
  rd(&_prefs.ch_notif_melody_2,         sizeof(_prefs.ch_notif_melody_2));
  rd(_prefs.dm_melody,                  sizeof(_prefs.dm_melody));
  rd(&_prefs.auto_lock,                 sizeof(_prefs.auto_lock));
  rd(&_prefs.clock_12h,                 sizeof(_prefs.clock_12h));
  rd(&_prefs.use_lemon_font,            sizeof(_prefs.use_lemon_font));
  rd(&_prefs.display_rotation,          sizeof(_prefs.display_rotation));
  rd(_prefs.page_order,                 sizeof(_prefs.page_order));
  rd(&_prefs.joystick_rotation,         sizeof(_prefs.joystick_rotation));
#if !FEAT_JOYSTICK_ROTATION_SETTING
  // No UI to change it on this build, so force the default — this also corrects
  // a stale value migrated from another build (e.g. e-ink rotation=2). On builds
  // that DO expose the setting the stored value is kept; the old code clobbered
  // it unconditionally (FEAT_* was undefined here because Features.h wasn't
  // included → `#if !FEAT_…` was always true), so the setting never persisted.
  _prefs.joystick_rotation = 0;
#endif
  rd(&_prefs.eink_full_refresh_every,   sizeof(_prefs.eink_full_refresh_every));
  rd(&_prefs.page_order_set,            sizeof(_prefs.page_order_set));
  // Migration: pre-magic firmware wrote page_order without a flag. If we see a plausible
  // first entry from such a save, accept it once — savePrefs will then persist the magic.
  if (_prefs.page_order_set != NodePrefs::PAGE_ORDER_MAGIC
      && _prefs.page_order[0] >= 1 && _prefs.page_order[0] <= NodePrefs::HPB_COUNT) {
    _prefs.page_order_set = NodePrefs::PAGE_ORDER_MAGIC;
  }

  rd(_prefs.favourite_contacts, sizeof(_prefs.favourite_contacts));
  rd(&_prefs.trail_interval_idx,  sizeof(_prefs.trail_interval_idx));
  rd(&_prefs.trail_min_delta_idx, sizeof(_prefs.trail_min_delta_idx));
  rd(&_prefs.trail_units_idx,     sizeof(_prefs.trail_units_idx));
  rd(&_prefs.ch_fav_bitmask,      sizeof(_prefs.ch_fav_bitmask));
  rd(&_prefs.ch_fav_only,         sizeof(_prefs.ch_fav_only));
  rd(&_prefs.notif_melody_ad,     sizeof(_prefs.notif_melody_ad));
  rd(&_prefs.units_imperial,      sizeof(_prefs.units_imperial));
  rd(&_prefs.trail_show_pace,     sizeof(_prefs.trail_show_pace));
  rd(&_prefs.advert_sound_scope,  sizeof(_prefs.advert_sound_scope));
  rd(&_prefs.rx_powersave,        sizeof(_prefs.rx_powersave));
  rd(&_prefs.tx_apc,              sizeof(_prefs.tx_apc));
  rd(&_prefs.dm_resend_count,     sizeof(_prefs.dm_resend_count));
  rd(&_prefs.bot_commands_enabled, sizeof(_prefs.bot_commands_enabled));
  rd(&_prefs.bot_quiet_start,     sizeof(_prefs.bot_quiet_start));
  rd(&_prefs.bot_quiet_end,       sizeof(_prefs.bot_quiet_end));
  rd(_prefs.bot_trigger_ch,       sizeof(_prefs.bot_trigger_ch));
  rd(_prefs.user_radio_presets,   sizeof(_prefs.user_radio_presets));
  // → 0xC0DE000E: repeater forwarding-filter knobs. On a pre-E file the bytes here are
  // that file's own sentinel tail, so clamp every out-of-range value back to its
  // "off" default (same stray-byte handling as the fields below).
  rd(&_prefs.repeat_skip_adverts, sizeof(_prefs.repeat_skip_adverts));
  rd(&_prefs.repeat_max_hops,     sizeof(_prefs.repeat_max_hops));
  rd(&_prefs.repeat_delay_boost,  sizeof(_prefs.repeat_delay_boost));
  rd(&_prefs.repeat_min_snr,      sizeof(_prefs.repeat_min_snr));
  rd(&_prefs.repeat_suppress_dup, sizeof(_prefs.repeat_suppress_dup));
  if (_prefs.repeat_skip_adverts > 1) _prefs.repeat_skip_adverts = 0;
  if (_prefs.repeat_max_hops > 64)    _prefs.repeat_max_hops = 0;
  if (_prefs.repeat_delay_boost > 8)  _prefs.repeat_delay_boost = 0;
  if (_prefs.repeat_min_snr != NodePrefs::REPEAT_SNR_DISABLED &&
      (_prefs.repeat_min_snr < -20 || _prefs.repeat_min_snr > 10))
    _prefs.repeat_min_snr = NodePrefs::REPEAT_SNR_DISABLED;   // match the UI's -20..10 range
  if (_prefs.repeat_suppress_dup > 1) _prefs.repeat_suppress_dup = 0;
  rd(&_prefs.repeater_use_profile, sizeof(_prefs.repeater_use_profile));
  rd(&_prefs.repeater_freq,        sizeof(_prefs.repeater_freq));
  rd(&_prefs.repeater_bw,          sizeof(_prefs.repeater_bw));
  rd(&_prefs.repeater_sf,          sizeof(_prefs.repeater_sf));
  rd(&_prefs.repeater_cr,          sizeof(_prefs.repeater_cr));
  // → 0xC0DE0011: track_shared_loc. Pre-0x11 files leave a stray sentinel byte
  // here; clamp so upgraders fall back to "off".
  rd(&_prefs.track_shared_loc,     sizeof(_prefs.track_shared_loc));
  if (_prefs.track_shared_loc > 1) _prefs.track_shared_loc = 0;
  // → 0xC0DE0012: live location sharing. Pre-0x12 files leave stray bytes here;
  // clamp each field back to its default so upgraders start with sharing off.
  rd(&_prefs.loc_share_enabled,     sizeof(_prefs.loc_share_enabled));
  rd(&_prefs.loc_share_target_type, sizeof(_prefs.loc_share_target_type));
  rd(&_prefs.loc_share_channel_idx, sizeof(_prefs.loc_share_channel_idx));
  rd(_prefs.loc_share_dm_prefix,    sizeof(_prefs.loc_share_dm_prefix));
  rd(&_prefs.loc_share_move_idx,    sizeof(_prefs.loc_share_move_idx));
  rd(&_prefs.loc_share_interval_idx, sizeof(_prefs.loc_share_interval_idx));
  rd(&_prefs.loc_share_heartbeat_idx, sizeof(_prefs.loc_share_heartbeat_idx));
  if (_prefs.loc_share_enabled > 1)     _prefs.loc_share_enabled = 0;
  if (_prefs.loc_share_target_type > 1) _prefs.loc_share_target_type = 0;
  if (_prefs.loc_share_channel_idx >= MAX_GROUP_CHANNELS) _prefs.loc_share_channel_idx = 0;
  if (_prefs.loc_share_move_idx >= NodePrefs::LOC_SHARE_MOVE_COUNT)         _prefs.loc_share_move_idx = 1;
  if (_prefs.loc_share_interval_idx >= NodePrefs::LOC_SHARE_INTERVAL_COUNT) _prefs.loc_share_interval_idx = 1;
  if (_prefs.loc_share_heartbeat_idx >= NodePrefs::LOC_SHARE_HEARTBEAT_COUNT) _prefs.loc_share_heartbeat_idx = 0;
  // → 0xC0DE0013: locator + trail auto-pause. Pre-0x13 files leave stray bytes
  // here; clamp each back to its default so upgraders start with both off.
  rd(&_prefs.locator_enabled,    sizeof(_prefs.locator_enabled));
  rd(&_prefs.locator_has_target, sizeof(_prefs.locator_has_target));
  rd(&_prefs.locator_radius_idx, sizeof(_prefs.locator_radius_idx));
  rd(&_prefs.locator_mode,       sizeof(_prefs.locator_mode));
  rd(&_prefs.locator_lat_1e6,    sizeof(_prefs.locator_lat_1e6));
  rd(&_prefs.locator_lon_1e6,    sizeof(_prefs.locator_lon_1e6));
  rd(_prefs.locator_label,       sizeof(_prefs.locator_label));
  rd(&_prefs.trail_autopause_idx,  sizeof(_prefs.trail_autopause_idx));
  if (_prefs.locator_enabled > 1)    _prefs.locator_enabled = 0;
  if (_prefs.locator_has_target > 1) _prefs.locator_has_target = 0;
  if (_prefs.locator_radius_idx >= NodePrefs::LOCATOR_RADIUS_COUNT) _prefs.locator_radius_idx = 1;
  if (_prefs.locator_mode >= NodePrefs::LOCATOR_MODE_COUNT)         _prefs.locator_mode = 0;
  if (_prefs.trail_autopause_idx >= NodePrefs::TRAIL_AUTOPAUSE_COUNT)   _prefs.trail_autopause_idx = 0;
  _prefs.locator_label[sizeof(_prefs.locator_label) - 1] = '\0';
  // → 0xC0DE0014: locator proximity beeper.
  rd(&_prefs.locator_beeper, sizeof(_prefs.locator_beeper));
  if (_prefs.locator_beeper > 1) _prefs.locator_beeper = 0;
  // → 0xC0DE0015: locator can target a live contact (kind + pubkey prefix).
  rd(&_prefs.locator_target_kind, sizeof(_prefs.locator_target_kind));
  rd(_prefs.locator_key,          sizeof(_prefs.locator_key));
  if (_prefs.locator_target_kind > 1) _prefs.locator_target_kind = 0;
  // → 0xC0DE0016: GPS-averaging duration for waypoint marking.
  rd(&_prefs.gps_avg_idx, sizeof(_prefs.gps_avg_idx));
  if (_prefs.gps_avg_idx >= NodePrefs::GPS_AVG_COUNT) _prefs.gps_avg_idx = 0;
  // → 0xC0DE0017: one-shot alarm clock (local time-of-day + armed flag).
  rd(&_prefs.alarm_on,   sizeof(_prefs.alarm_on));
  rd(&_prefs.alarm_hour, sizeof(_prefs.alarm_hour));
  rd(&_prefs.alarm_min,  sizeof(_prefs.alarm_min));
  if (_prefs.alarm_on > 1)    _prefs.alarm_on = 0;
  if (_prefs.alarm_hour > 23) _prefs.alarm_hour = 0;
  if (_prefs.alarm_min > 59)  _prefs.alarm_min = 0;
  // Pre-0x10 files leave stray sentinel bytes here, same as a never-configured
  // device. Either way there's no valid saved profile, so default to a profile
  // in the same band as the companion's own network (_prefs.freq, already read
  // above) rather than "Current" — a repeater silently following the companion
  // onto whatever private network it later joins isn't the MeshCore community
  // norm; that stays opt-in. Band-matched rather than a flat frequency so the
  // default can't land outside what's legal where the companion is set up.
  if (_prefs.repeater_use_profile > 1) _prefs.repeater_use_profile = 0;
  float rpt_lo, rpt_hi; radio_driver.getFreqBounds(rpt_lo, rpt_hi);
  if (!isValidRepeaterProfile(_prefs.repeater_freq, _prefs.repeater_bw, _prefs.repeater_sf, _prefs.repeater_cr, rpt_lo, rpt_hi)) {
    seedDefaultRepeaterProfile(_prefs);
  }
  // → 0xC0DE000B: append bot_commands_enabled + quiet-hours. Older files leave
  // stray bytes here; clamp so upgraders fall back to off / no quiet hours.
  if (_prefs.bot_commands_enabled > 1)  _prefs.bot_commands_enabled = 0;
  if (_prefs.bot_quiet_start > 23)      _prefs.bot_quiet_start = 0;
  if (_prefs.bot_quiet_end   > 23)      _prefs.bot_quiet_end   = 0;
  // These fields were appended over successive schema bumps; an older file
  // can leave stray bytes here, so clamp out-of-range values back to defaults.
  // Values for notif_melody_ad: 0=built-in, 1=melody1, 2=melody2, 3=none.
  if (_prefs.notif_melody_ad > 3) _prefs.notif_melody_ad = 0;
  // A stale value >1 from an older multi-font build would read as "Lemon" (all
  // sites test != 0) until the user toggles Font; clamp it to default here.
  if (_prefs.use_lemon_font  > 1) _prefs.use_lemon_font  = 0;
  if (_prefs.units_imperial  > 1) _prefs.units_imperial  = 0;
  if (_prefs.trail_show_pace > 1) _prefs.trail_show_pace = 0;
  if (_prefs.advert_sound_scope > 1) _prefs.advert_sound_scope = ADVERT_SOUND_SCOPE_ALL;
  if (_prefs.rx_powersave    > 1) _prefs.rx_powersave    = 0;
  if (_prefs.tx_apc          > 1) _prefs.tx_apc          = 0;
  // An old (0xC0DE0009) file leaves the low byte of its sentinel here (0x09),
  // which is out of range — fall back to the default of 2 resends.
  if (_prefs.dm_resend_count > 5) _prefs.dm_resend_count = 2;

  // Schema sentinel: bumped on layout changes. Mismatch means an older file
  // (or a different schema); rd() already zero-inits any fields not present,
  // so we just log it — next savePrefs writes the current sentinel.
  uint32_t sentinel = 0;
  rd(&sentinel, sizeof(sentinel));
  if (sentinel != NodePrefs::SCHEMA_SENTINEL) {
    MESH_DEBUG_PRINTLN("prefs schema sentinel mismatch: got 0x%08X, expected 0x%08X — re-saving on next change",
                       (unsigned)sentinel, (unsigned)NodePrefs::SCHEMA_SENTINEL);
    // 0xC0DE0001 → 0xC0DE0002: FAVOURITES home page added. Only pre-0x0002 saves
    // lack the bit; turn it on once so those upgraders see the new page by
    // default. Must be gated to that transition — running it on every sentinel
    // mismatch (as it did) re-enabled Favourites on each firmware update,
    // clobbering a user who had deliberately hidden it.
    if (sentinel < 0xC0DE0002 && _prefs.home_pages_mask != 0) {
      _prefs.home_pages_mask |= NodePrefs::HP_FAVOURITES;
    }
    // 0xC0DE0017 → 0xC0DE0018: MAP home page moved into home_pages_mask (it was
    // always-on before, with no visibility toggle). Turn its bit on once for
    // pre-0x0018 saves so upgraders keep seeing the page; gated to this
    // transition so a user who later hides it isn't overridden on the next update.
    if (sentinel < 0xC0DE0018 && _prefs.home_pages_mask != 0) {
      _prefs.home_pages_mask |= NodePrefs::HP_MAP;
    }
    // 0xC0DE0003 → 0xC0DE0004: trail_units_idx added after trail_min_delta_idx.
    // On a 0xC0DE0003 file the sentinel bytes sit where trail_units_idx is now,
    // so rd() picks up 0x03 (low byte of the old sentinel) — reset just that
    // case to default 0. Newer mismatches (e.g. 0xC0DE0005 → 0xC0DE0006) had
    // the field saved correctly and must not be clobbered.
    if (sentinel == 0xC0DE0003) {
      _prefs.trail_units_idx = 0;
    }
    // → 0xC0DE0008: append advert_sound_scope after the existing 0xC0DE0007
    // tail (notif_melody_ad + units_imperial + trail_show_pace). Older files
    // leave stray/old bytes in these fields; they're clamped above, so
    // upgraders fall back to built-in advert sound + metric + speed + All.
    // → 0xC0DE0009: append tx_apc after rx_powersave. Clamped above, so
    // upgraders fall back to APC off (fixed tx power).
    // → 0xC0DE000C: split out a per-channel trigger (was shared with the DM
    // trigger). Pre-0x0C files have no bot_trigger_ch; seed it from bot_trigger
    // so an existing channel bot keeps reacting to the same word after upgrade.
    if (_prefs.bot_trigger_ch[0] == '\0')
      strncpy(_prefs.bot_trigger_ch, _prefs.bot_trigger, sizeof(_prefs.bot_trigger_ch) - 1);
    // → 0xC0DE000D: append user_radio_presets. No clamping needed — rd() already
    // zero-inits it on a pre-0x0D file, and name[0]=='\0' is exactly the "empty
    // slot" sentinel the UI already expects.
  }

  file.close();
}

void DataStore::savePrefs(const NodePrefs& _prefs, double node_lat, double node_lon) {
  // Atomic temp-then-rename (see commitTempFile) so an interrupted save can't
  // wipe settings; loadPrefs() still validates the tail sentinel on read.
  File file = ::openWrite(_fs, "/new_prefs.tmp");
  if (file) {
    uint8_t pad[8];
    memset(pad, 0, sizeof(pad));

    file.write((uint8_t *)&_prefs.airtime_factor, sizeof(float));
    file.write((uint8_t *)_prefs.node_name, sizeof(_prefs.node_name));
    file.write(pad, 4);
    file.write((uint8_t *)&node_lat, sizeof(node_lat));
    file.write((uint8_t *)&node_lon, sizeof(node_lon));
    file.write((uint8_t *)&_prefs.freq, sizeof(_prefs.freq));
    file.write((uint8_t *)&_prefs.sf, sizeof(_prefs.sf));
    file.write((uint8_t *)&_prefs.cr, sizeof(_prefs.cr));
    file.write((uint8_t *)&_prefs.client_repeat, sizeof(_prefs.client_repeat));
    file.write((uint8_t *)&_prefs.manual_add_contacts, sizeof(_prefs.manual_add_contacts));
    file.write((uint8_t *)&_prefs.bw, sizeof(_prefs.bw));
    file.write((uint8_t *)&_prefs.tx_power_dbm, sizeof(_prefs.tx_power_dbm));
    file.write((uint8_t *)&_prefs.telemetry_mode_base, sizeof(_prefs.telemetry_mode_base));
    file.write((uint8_t *)&_prefs.telemetry_mode_loc, sizeof(_prefs.telemetry_mode_loc));
    file.write((uint8_t *)&_prefs.telemetry_mode_env, sizeof(_prefs.telemetry_mode_env));
    file.write((uint8_t *)&_prefs.rx_delay_base, sizeof(_prefs.rx_delay_base));
    file.write((uint8_t *)&_prefs.advert_loc_policy, sizeof(_prefs.advert_loc_policy));
    file.write((uint8_t *)&_prefs.multi_acks, sizeof(_prefs.multi_acks));
    file.write((uint8_t *)&_prefs.path_hash_mode, sizeof(_prefs.path_hash_mode));
    file.write(pad, 1);
    file.write((uint8_t *)&_prefs.ble_pin, sizeof(_prefs.ble_pin));
    file.write((uint8_t *)&_prefs.buzzer_quiet, sizeof(_prefs.buzzer_quiet));
    file.write((uint8_t *)&_prefs.gps_enabled, sizeof(_prefs.gps_enabled));
    file.write((uint8_t *)&_prefs.gps_interval, sizeof(_prefs.gps_interval));
    file.write((uint8_t *)&_prefs.autoadd_config, sizeof(_prefs.autoadd_config));
    file.write((uint8_t *)&_prefs.autoadd_max_hops, sizeof(_prefs.autoadd_max_hops));
    file.write((uint8_t *)&_prefs.rx_boosted_gain, sizeof(_prefs.rx_boosted_gain));
    file.write((uint8_t *)_prefs.default_scope_name, sizeof(_prefs.default_scope_name));
    file.write((uint8_t *)_prefs.default_scope_key, sizeof(_prefs.default_scope_key));
    file.write((uint8_t *)&_prefs.display_brightness, sizeof(_prefs.display_brightness));
    file.write((uint8_t *)&_prefs.auto_off_secs, sizeof(_prefs.auto_off_secs));
    file.write((uint8_t *)&_prefs.tz_offset_hours, sizeof(_prefs.tz_offset_hours));
    file.write((uint8_t *)&_prefs.low_batt_mv, sizeof(_prefs.low_batt_mv));
    file.write((uint8_t *)&_prefs.batt_display_mode, sizeof(_prefs.batt_display_mode));
    file.write((uint8_t *)_prefs.custom_msgs, sizeof(_prefs.custom_msgs));
    file.write((uint8_t *)&_prefs.ch_notif_override, sizeof(_prefs.ch_notif_override));
    file.write((uint8_t *)&_prefs.ch_notif_muted, sizeof(_prefs.ch_notif_muted));
    file.write((uint8_t *)&_prefs.dm_show_all, sizeof(_prefs.dm_show_all));
    file.write((uint8_t *)&_prefs.room_fav_only, sizeof(_prefs.room_fav_only));
    file.write((uint8_t *)&_prefs.buzzer_volume, sizeof(_prefs.buzzer_volume));
    file.write((uint8_t *)&_prefs.ringtone_bpm_idx, sizeof(_prefs.ringtone_bpm_idx));
    file.write((uint8_t *)&_prefs.ringtone_len, sizeof(_prefs.ringtone_len));
    file.write((uint8_t *)_prefs.ringtone_notes, sizeof(_prefs.ringtone_notes));
    file.write((uint8_t *)&_prefs.home_pages_mask, sizeof(_prefs.home_pages_mask));
    file.write((uint8_t *)&_prefs.bot_enabled, sizeof(_prefs.bot_enabled));
    file.write((uint8_t *)&_prefs.bot_channel_enabled, sizeof(_prefs.bot_channel_enabled));
    file.write((uint8_t *)&_prefs.bot_channel_idx, sizeof(_prefs.bot_channel_idx));
    file.write((uint8_t *)_prefs.bot_trigger, sizeof(_prefs.bot_trigger));
    file.write((uint8_t *)_prefs.bot_reply_dm, sizeof(_prefs.bot_reply_dm));
    file.write((uint8_t *)_prefs.bot_reply_ch, sizeof(_prefs.bot_reply_ch));
    file.write((uint8_t *)&_prefs.clock_hide_seconds, sizeof(_prefs.clock_hide_seconds));
    file.write((uint8_t *)&_prefs.buzzer_auto, sizeof(_prefs.buzzer_auto));
    file.write((uint8_t *)_prefs.dm_notif, sizeof(_prefs.dm_notif));
    file.write((uint8_t *)_prefs.dashboard_fields, sizeof(_prefs.dashboard_fields));
    file.write((uint8_t *)&_prefs.advert_auto_interval_sec, sizeof(_prefs.advert_auto_interval_sec));
    file.write((uint8_t *)&_prefs.ringtone2_bpm_idx, sizeof(_prefs.ringtone2_bpm_idx));
    file.write((uint8_t *)&_prefs.ringtone2_len, sizeof(_prefs.ringtone2_len));
    file.write((uint8_t *)_prefs.ringtone2_notes, sizeof(_prefs.ringtone2_notes));
    file.write((uint8_t *)&_prefs.notif_melody_dm, sizeof(_prefs.notif_melody_dm));
    file.write((uint8_t *)&_prefs.notif_melody_ch, sizeof(_prefs.notif_melody_ch));
    file.write((uint8_t *)&_prefs.ch_notif_melody_set, sizeof(_prefs.ch_notif_melody_set));
    file.write((uint8_t *)&_prefs.ch_notif_melody_2, sizeof(_prefs.ch_notif_melody_2));
    file.write((uint8_t *)_prefs.dm_melody, sizeof(_prefs.dm_melody));
    file.write((uint8_t *)&_prefs.auto_lock, sizeof(_prefs.auto_lock));
    file.write((uint8_t *)&_prefs.clock_12h, sizeof(_prefs.clock_12h));
    file.write((uint8_t *)&_prefs.use_lemon_font, sizeof(_prefs.use_lemon_font));
    file.write((uint8_t *)&_prefs.display_rotation, sizeof(_prefs.display_rotation));
    file.write((uint8_t *)_prefs.page_order, sizeof(_prefs.page_order));
    file.write((uint8_t *)&_prefs.joystick_rotation, sizeof(_prefs.joystick_rotation));
    file.write((uint8_t *)&_prefs.eink_full_refresh_every, sizeof(_prefs.eink_full_refresh_every));
    file.write((uint8_t *)&_prefs.page_order_set, sizeof(_prefs.page_order_set));
    file.write((uint8_t *)_prefs.favourite_contacts, sizeof(_prefs.favourite_contacts));
    file.write((uint8_t *)&_prefs.trail_interval_idx,  sizeof(_prefs.trail_interval_idx));
    file.write((uint8_t *)&_prefs.trail_min_delta_idx, sizeof(_prefs.trail_min_delta_idx));
    file.write((uint8_t *)&_prefs.trail_units_idx,     sizeof(_prefs.trail_units_idx));
    file.write((uint8_t *)&_prefs.ch_fav_bitmask,      sizeof(_prefs.ch_fav_bitmask));
    file.write((uint8_t *)&_prefs.ch_fav_only,         sizeof(_prefs.ch_fav_only));
    file.write((uint8_t *)&_prefs.notif_melody_ad,     sizeof(_prefs.notif_melody_ad));
    file.write((uint8_t *)&_prefs.units_imperial,      sizeof(_prefs.units_imperial));
    file.write((uint8_t *)&_prefs.trail_show_pace,     sizeof(_prefs.trail_show_pace));
    file.write((uint8_t *)&_prefs.advert_sound_scope,  sizeof(_prefs.advert_sound_scope));
    file.write((uint8_t *)&_prefs.rx_powersave,        sizeof(_prefs.rx_powersave));
    file.write((uint8_t *)&_prefs.tx_apc,              sizeof(_prefs.tx_apc));
    file.write((uint8_t *)&_prefs.dm_resend_count,     sizeof(_prefs.dm_resend_count));
    file.write((uint8_t *)&_prefs.bot_commands_enabled, sizeof(_prefs.bot_commands_enabled));
    file.write((uint8_t *)&_prefs.bot_quiet_start,     sizeof(_prefs.bot_quiet_start));
    file.write((uint8_t *)&_prefs.bot_quiet_end,       sizeof(_prefs.bot_quiet_end));
    file.write((uint8_t *)_prefs.bot_trigger_ch,       sizeof(_prefs.bot_trigger_ch));
    file.write((uint8_t *)_prefs.user_radio_presets,   sizeof(_prefs.user_radio_presets));
    file.write((uint8_t *)&_prefs.repeat_skip_adverts,  sizeof(_prefs.repeat_skip_adverts));
    file.write((uint8_t *)&_prefs.repeat_max_hops,      sizeof(_prefs.repeat_max_hops));
    file.write((uint8_t *)&_prefs.repeat_delay_boost,   sizeof(_prefs.repeat_delay_boost));
    file.write((uint8_t *)&_prefs.repeat_min_snr,       sizeof(_prefs.repeat_min_snr));
    file.write((uint8_t *)&_prefs.repeat_suppress_dup,  sizeof(_prefs.repeat_suppress_dup));
    file.write((uint8_t *)&_prefs.repeater_use_profile, sizeof(_prefs.repeater_use_profile));
    file.write((uint8_t *)&_prefs.repeater_freq,        sizeof(_prefs.repeater_freq));
    file.write((uint8_t *)&_prefs.repeater_bw,          sizeof(_prefs.repeater_bw));
    file.write((uint8_t *)&_prefs.repeater_sf,          sizeof(_prefs.repeater_sf));
    file.write((uint8_t *)&_prefs.repeater_cr,          sizeof(_prefs.repeater_cr));
    file.write((uint8_t *)&_prefs.track_shared_loc,     sizeof(_prefs.track_shared_loc));
    file.write((uint8_t *)&_prefs.loc_share_enabled,     sizeof(_prefs.loc_share_enabled));
    file.write((uint8_t *)&_prefs.loc_share_target_type, sizeof(_prefs.loc_share_target_type));
    file.write((uint8_t *)&_prefs.loc_share_channel_idx, sizeof(_prefs.loc_share_channel_idx));
    file.write((uint8_t *)_prefs.loc_share_dm_prefix,    sizeof(_prefs.loc_share_dm_prefix));
    file.write((uint8_t *)&_prefs.loc_share_move_idx,    sizeof(_prefs.loc_share_move_idx));
    file.write((uint8_t *)&_prefs.loc_share_interval_idx, sizeof(_prefs.loc_share_interval_idx));
    file.write((uint8_t *)&_prefs.loc_share_heartbeat_idx, sizeof(_prefs.loc_share_heartbeat_idx));
    file.write((uint8_t *)&_prefs.locator_enabled,    sizeof(_prefs.locator_enabled));
    file.write((uint8_t *)&_prefs.locator_has_target, sizeof(_prefs.locator_has_target));
    file.write((uint8_t *)&_prefs.locator_radius_idx, sizeof(_prefs.locator_radius_idx));
    file.write((uint8_t *)&_prefs.locator_mode,       sizeof(_prefs.locator_mode));
    file.write((uint8_t *)&_prefs.locator_lat_1e6,    sizeof(_prefs.locator_lat_1e6));
    file.write((uint8_t *)&_prefs.locator_lon_1e6,    sizeof(_prefs.locator_lon_1e6));
    file.write((uint8_t *)_prefs.locator_label,       sizeof(_prefs.locator_label));
    file.write((uint8_t *)&_prefs.trail_autopause_idx,  sizeof(_prefs.trail_autopause_idx));
    file.write((uint8_t *)&_prefs.locator_beeper,     sizeof(_prefs.locator_beeper));
    file.write((uint8_t *)&_prefs.locator_target_kind, sizeof(_prefs.locator_target_kind));
    file.write((uint8_t *)_prefs.locator_key,         sizeof(_prefs.locator_key));
    file.write((uint8_t *)&_prefs.gps_avg_idx,        sizeof(_prefs.gps_avg_idx));
    file.write((uint8_t *)&_prefs.alarm_on,           sizeof(_prefs.alarm_on));
    file.write((uint8_t *)&_prefs.alarm_hour,         sizeof(_prefs.alarm_hour));
    file.write((uint8_t *)&_prefs.alarm_min,          sizeof(_prefs.alarm_min));

    // Tail sentinel — must be last. See NodePrefs::SCHEMA_SENTINEL. Its write is
    // the one we check: once the flash fills, writes return 0, so a good
    // sentinel write means the whole record fit. Only then swap it in.
    uint32_t sentinel = NodePrefs::SCHEMA_SENTINEL;
    bool ok = (file.write((uint8_t *)&sentinel, sizeof(sentinel)) == sizeof(sentinel));

    file.close();
    if (ok) {
      commitTempFile(_fs, "/new_prefs.tmp", "/new_prefs");
    } else {
      _fs->remove("/new_prefs.tmp");   // keep the previous good /new_prefs
    }
  }
}

void DataStore::saveRTCTime() {
  uint32_t t = _clock->getCurrentTime();
  if (t < 1000000000UL) return;  // don't save if time not yet synced
  File file = ::openWrite(_fs, "/rtc_save");
  if (file) {
    file.write((uint8_t *)&t, sizeof(t));
    file.close();
  }
}

void DataStore::restoreRTCTime() {
  File file = openRead(_fs, "/rtc_save");
  if (file) {
    uint32_t t = 0;
    file.read((uint8_t *)&t, sizeof(t));
    file.close();
    if (t > 1000000000UL) _clock->setCurrentTime(t);
  }
}

void DataStore::loadContacts(DataStoreHost* host) {
File file = openRead(_getContactsChannelsFS(), "/contacts3");
    if (file) {
      bool full = false;
      while (!full) {
        ContactInfo c;
        uint8_t pub_key[32];
        uint8_t unused;

        bool success = (file.read(pub_key, 32) == 32);
        success = success && (file.read((uint8_t *)&c.name, 32) == 32);
        success = success && (file.read(&c.type, 1) == 1);
        success = success && (file.read(&c.flags, 1) == 1);
        success = success && (file.read(&unused, 1) == 1);
        success = success && (file.read((uint8_t *)&c.sync_since, 4) == 4); // was 'reserved'
        success = success && (file.read((uint8_t *)&c.out_path_len, 1) == 1);
        success = success && (file.read((uint8_t *)&c.last_advert_timestamp, 4) == 4);
        success = success && (file.read(c.out_path, 64) == 64);
        success = success && (file.read((uint8_t *)&c.lastmod, 4) == 4);
        success = success && (file.read((uint8_t *)&c.gps_lat, 4) == 4);
        success = success && (file.read((uint8_t *)&c.gps_lon, 4) == 4);

        if (!success) break; // EOF

        c.id = mesh::Identity(pub_key);
        if (!host->onContactLoaded(c)) full = true;
      }
      file.close();
    }
}

void DataStore::saveContacts(DataStoreHost* host, bool (*filter)(const ContactInfo& c)) {
  FILESYSTEM* fs = _getContactsChannelsFS();
  // Write to a temp file, then atomically rename it over /contacts3 only once
  // every record has written cleanly. The old code truncated /contacts3 up
  // front and wrote in place, so a crash, reset or full flash mid-save wiped
  // the entire contact list. Now an interrupted save leaves the previous good
  // file untouched.
  File file = ::openWrite(fs, "/contacts3.tmp");
  if (!file) return;

  bool ok = true;
  uint32_t idx = 0;
  ContactInfo c;
  uint8_t unused = 0;

  while (host->getContactForSave(idx, c)) {
    if (filter && !filter(c)) {
      idx++;  // advance to next contact
      continue;
    }
    bool success = (file.write(c.id.pub_key, 32) == 32);
    success = success && (file.write((uint8_t *)&c.name, 32) == 32);
    success = success && (file.write(&c.type, 1) == 1);
    success = success && (file.write(&c.flags, 1) == 1);
    success = success && (file.write(&unused, 1) == 1);
    success = success && (file.write((uint8_t *)&c.sync_since, 4) == 4);
    success = success && (file.write((uint8_t *)&c.out_path_len, 1) == 1);
    success = success && (file.write((uint8_t *)&c.last_advert_timestamp, 4) == 4);
    success = success && (file.write(c.out_path, 64) == 64);
    success = success && (file.write((uint8_t *)&c.lastmod, 4) == 4);
    success = success && (file.write((uint8_t *)&c.gps_lat, 4) == 4);
    success = success && (file.write((uint8_t *)&c.gps_lon, 4) == 4);

    if (!success) { ok = false; break; } // write failed (e.g. flash full)

    idx++;  // advance to next contact
  }
  file.close();

  if (ok) {
    commitTempFile(fs, "/contacts3.tmp", "/contacts3");
  } else {
    fs->remove("/contacts3.tmp");   // keep the previous good /contacts3
  }
}

void DataStore::loadChannels(DataStoreHost* host) {
    FILESYSTEM* fs = _getContactsChannelsFS();
    File file = openRead(fs, "/channels3");
    if (file) {
      // /channels3: the leading 4-byte field's first byte is the channel's
      // original slot index (see saveChannels()) — load it back into that
      // exact slot. The old /channels2 format instead reassigned indices
      // 0,1,2… sequentially on every load, which silently shifted every
      // later channel down a slot once an earlier one was removed — anything
      // that remembers a channel by index (Live Share's target, the bot's
      // channel, per-channel melody) would then point at the wrong channel
      // after the next reboot.
      bool full = false;
      uint8_t skipped = 0;
      while (!full) {
        ChannelDetails ch;
        uint8_t hdr[4];

        bool success = (file.read(hdr, 4) == 4);
        success = success && (file.read((uint8_t *)ch.name, 32) == 32);
        success = success && (file.read((uint8_t *)ch.channel.secret, 32) == 32);

        if (!success) break; // EOF

        // Sanity check: an all-zero secret means the entry is uninitialised
        // or the file format was corrupted by a previous firmware (different
        // layout). Loading such a channel makes findChannelIdx() match the
        // wrong slot for incoming messages — drop it. The companion app can
        // re-sync the channel afterwards.
        bool secret_empty = true;
        for (int b = 0; b < 32; b++) {
          if (ch.channel.secret[b] != 0) { secret_empty = false; break; }
        }
        if (secret_empty) {
          skipped++;
          continue;
        }
        // Defensive: ensure name is null-terminated so callers can treat it
        // as a C string regardless of how the file was written.
        ch.name[31] = '\0';

        if (!host->onChannelLoaded(hdr[0], ch)) full = true;
      }
      file.close();
      if (skipped > 0) {
        MESH_DEBUG_PRINTLN("loadChannels: skipped %u corrupted/empty channel entr%s",
                           (unsigned)skipped, skipped == 1 ? "y" : "ies");
      }
      return;
    }

    // One-time migration from the old /channels2 format (sequential index,
    // reassigned on every load — the bug /channels3 above replaces). Loads
    // with that old semantics once, then resaves as /channels3 so this
    // fallback is never hit again on this device.
    file = openRead(fs, "/channels2");
    if (file) {
      bool full = false;
      uint8_t channel_idx = 0;
      while (!full) {
        ChannelDetails ch;
        uint8_t unused[4];

        bool success = (file.read(unused, 4) == 4);
        success = success && (file.read((uint8_t *)ch.name, 32) == 32);
        success = success && (file.read((uint8_t *)ch.channel.secret, 32) == 32);
        if (!success) break; // EOF

        bool secret_empty = true;
        for (int b = 0; b < 32; b++) if (ch.channel.secret[b] != 0) { secret_empty = false; break; }
        if (secret_empty) continue;
        ch.name[31] = '\0';

        if (host->onChannelLoaded(channel_idx, ch)) channel_idx++;
        else full = true;
      }
      file.close();
      saveChannels(host);   // write /channels3 so the migration runs only once
    }
}

void DataStore::saveChannels(DataStoreHost* host) {
  FILESYSTEM* fs = _getContactsChannelsFS();
  // Same atomic temp-then-rename pattern as saveContacts() — never truncate the
  // live /channels3 before the new copy is fully written.
  File file = ::openWrite(fs, "/channels3.tmp");
  if (!file) return;

  bool ok = true;
  uint8_t channel_idx = 0;
  ChannelDetails ch;

  while (host->getChannelForSave(channel_idx, ch)) {
    uint8_t idx = channel_idx++;
    // getChannelForSave() returns every slot up to MAX_GROUP_CHANNELS, so skip
    // the unused ones (all-zero secret) rather than writing all 40 — otherwise
    // the file is always ~2.7 KB and wears the flash needlessly. Unlike the old
    // /channels2 format, loadChannels() no longer compacts: the slot index
    // travels with the record (hdr[0] below) so a removed channel just leaves
    // a hole instead of shifting every later index down a slot.
    bool empty = true;
    for (int b = 0; b < 32; b++) if (ch.channel.secret[b]) { empty = false; break; }
    if (empty) continue;

    uint8_t hdr[4] = { idx, 0, 0, 0 };
    bool success = (file.write(hdr, 4) == 4);
    success = success && (file.write((uint8_t *)ch.name, 32) == 32);
    success = success && (file.write((uint8_t *)ch.channel.secret, 32) == 32);
    if (!success) { ok = false; break; } // write failed
  }
  file.close();

  if (ok) {
    commitTempFile(fs, "/channels3.tmp", "/channels3");
  } else {
    fs->remove("/channels3.tmp");   // keep the previous good /channels3
  }
}

#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)

#define MAX_ADVERT_PKT_LEN   (2 + 32 + PUB_KEY_SIZE + 4 + SIGNATURE_SIZE + MAX_ADVERT_DATA_SIZE)

struct BlobRec {
  uint32_t timestamp;
  uint8_t  key[7];
  uint8_t  len;
  uint8_t  data[MAX_ADVERT_PKT_LEN];
};

void DataStore::checkAdvBlobFile() {
  if (!_getContactsChannelsFS()->exists("/adv_blobs")) {
    File file = ::openWrite(_getContactsChannelsFS(), "/adv_blobs");
    if (file) {
      BlobRec zeroes;
      memset(&zeroes, 0, sizeof(zeroes));
      for (int i = 0; i < MAX_BLOBRECS; i++) {     // pre-allocate to fixed size
        file.write((uint8_t *) &zeroes, sizeof(zeroes));
      }
      file.close();
    }
  }
}

void DataStore::migrateToSecondaryFS() {
  // migrate old adv_blobs, contacts3 and channels2 files to secondary FS if they don't already exist
  if (!_fsExtra->exists("/adv_blobs")) {
    if (_fs->exists("/adv_blobs")) {
    File oldAdvBlobs = openRead(_fs, "/adv_blobs");
    File newAdvBlobs = ::openWrite(_fsExtra, "/adv_blobs");

    if (oldAdvBlobs && newAdvBlobs) {
      BlobRec rec;
      size_t count = 0;

      // Copy 20 BlobRecs from old to new
      while (count < 20 && oldAdvBlobs.read((uint8_t *)&rec, sizeof(rec)) == sizeof(rec)) {
        newAdvBlobs.seek(count * sizeof(BlobRec));
        newAdvBlobs.write((uint8_t *)&rec, sizeof(rec));
        count++;
      }
    }
    if (oldAdvBlobs) oldAdvBlobs.close();
    if (newAdvBlobs) newAdvBlobs.close();
    _fs->remove("/adv_blobs");
    }
  }
  if (!_fsExtra->exists("/contacts3")) {
    if (_fs->exists("/contacts3")) {
      File oldFile = openRead(_fs, "/contacts3");
      File newFile = ::openWrite(_fsExtra, "/contacts3");

      if (oldFile && newFile) {
        uint8_t buf[64];
        int n;
        while ((n = oldFile.read(buf, sizeof(buf))) > 0) {
          newFile.write(buf, n);
        }
      }
      if (oldFile) oldFile.close();
      if (newFile) newFile.close();
      _fs->remove("/contacts3");
    }
  }
  if (!_fsExtra->exists("/channels2")) {
    if (_fs->exists("/channels2")) {
      File oldFile = openRead(_fs, "/channels2");
      File newFile = ::openWrite(_fsExtra, "/channels2");

      if (oldFile && newFile) {
        uint8_t buf[64];
        int n;
        while ((n = oldFile.read(buf, sizeof(buf))) > 0) {
          newFile.write(buf, n);
        }
      }
      if (oldFile) oldFile.close();
      if (newFile) newFile.close();
      _fs->remove("/channels2");
    }
  }
  // cleanup nodes which have been testing the extra fs, copy _main.id and new_prefs back to primary
  if (_fsExtra->exists("/_main.id")) {
      if (_fs->exists("/_main.id")) {_fs->remove("/_main.id");}
      File oldFile = openRead(_fsExtra, "/_main.id");
      File newFile = ::openWrite(_fs, "/_main.id");

      if (oldFile && newFile) {
        uint8_t buf[64];
        int n;
        while ((n = oldFile.read(buf, sizeof(buf))) > 0) {
          newFile.write(buf, n);
        }
      }
      if (oldFile) oldFile.close();
      if (newFile) newFile.close();
      _fsExtra->remove("/_main.id");
  }
  if (_fsExtra->exists("/new_prefs")) {
    if (_fs->exists("/new_prefs")) {_fs->remove("/new_prefs");}
      File oldFile = openRead(_fsExtra, "/new_prefs");
      File newFile = ::openWrite(_fs, "/new_prefs");

      if (oldFile && newFile) {
        uint8_t buf[64];
        int n;
        while ((n = oldFile.read(buf, sizeof(buf))) > 0) {
          newFile.write(buf, n);
        }
      }
      if (oldFile) oldFile.close();
      if (newFile) newFile.close();
      _fsExtra->remove("/new_prefs");
  }
  // remove files from where they should not be anymore
  if (_fs->exists("/adv_blobs")) {
    _fs->remove("/adv_blobs");
  }
  if (_fs->exists("/contacts3")) {
    _fs->remove("/contacts3");
  }
  if (_fs->exists("/channels2")) {
    _fs->remove("/channels2");
  }
  if (_fsExtra->exists("/_main.id")) {
    _fsExtra->remove("/_main.id");
  }
  if (_fsExtra->exists("/new_prefs")) {
    _fsExtra->remove("/new_prefs");
  }
}

uint8_t DataStore::getBlobByKey(const uint8_t key[], int key_len, uint8_t dest_buf[]) {
  File file = openRead(_getContactsChannelsFS(), "/adv_blobs");
  uint8_t len = 0;  // 0 = not found
  if (file) {
    BlobRec tmp;
    while (file.read((uint8_t *) &tmp, sizeof(tmp)) == sizeof(tmp)) {
      if (memcmp(key, tmp.key, sizeof(tmp.key)) == 0) {  // only match by 7 byte prefix
        len = tmp.len;
        memcpy(dest_buf, tmp.data, len);
        break;
      }
    }
    file.close();
  }
  return len;
}

bool DataStore::putBlobByKey(const uint8_t key[], int key_len, const uint8_t src_buf[], uint8_t len) {
  if (len < PUB_KEY_SIZE+4+SIGNATURE_SIZE || len > MAX_ADVERT_PKT_LEN) return false;
  checkAdvBlobFile();
  File file = _getContactsChannelsFS()->open("/adv_blobs", FILE_O_WRITE);
  if (file) {
    uint32_t pos = 0, found_pos = 0;
    uint32_t min_timestamp = 0xFFFFFFFF;

    // search for matching key OR evict by oldest timestmap
    BlobRec tmp;
    file.seek(0);
    while (file.read((uint8_t *) &tmp, sizeof(tmp)) == sizeof(tmp)) {
      if (memcmp(key, tmp.key, sizeof(tmp.key)) == 0) {  // only match by 7 byte prefix
        found_pos = pos;
        break;
      }
      if (tmp.timestamp < min_timestamp) {
        min_timestamp = tmp.timestamp;
        found_pos = pos;
      }

      pos += sizeof(tmp);
    }

    memcpy(tmp.key, key, sizeof(tmp.key));  // just record 7 byte prefix of key
    memcpy(tmp.data, src_buf, len);
    tmp.len = len;
    tmp.timestamp = _clock->getCurrentTime();

    file.seek(found_pos);
    file.write((uint8_t *) &tmp, sizeof(tmp));

    file.close();
    return true;
  }
  return false; // error
}
bool DataStore::deleteBlobByKey(const uint8_t key[], int key_len) {
  return true; // this is just a stub on NRF52/STM32 platforms
}
#else
inline void makeBlobPath(const uint8_t key[], int key_len, char* path, size_t path_size) {
  char fname[18];
  if (key_len > 8) key_len = 8; // just use first 8 bytes (prefix)
  mesh::Utils::toHex(fname, key, key_len);
  sprintf(path, "/bl/%s", fname);
}

uint8_t DataStore::getBlobByKey(const uint8_t key[], int key_len, uint8_t dest_buf[]) {
  char path[64];
  makeBlobPath(key, key_len, path, sizeof(path));

  if (_fs->exists(path)) {
    File f = openRead(_fs, path);
    if (f) {
      int len = f.read(dest_buf, 255); // currently MAX 255 byte blob len supported!!
      f.close();
      return len;
    }
  }
  return 0; // not found
}

bool DataStore::putBlobByKey(const uint8_t key[], int key_len, const uint8_t src_buf[], uint8_t len) {
  char path[64];
  makeBlobPath(key, key_len, path, sizeof(path));

  File f = ::openWrite(_fs, path);
  if (f) {
    int n = f.write(src_buf, len);
    f.close();
    if (n == len) return true; // success!

    _fs->remove(path); // blob was only partially written!
  }
  return false; // error
}

bool DataStore::deleteBlobByKey(const uint8_t key[], int key_len) {
  char path[64];
  makeBlobPath(key, key_len, path, sizeof(path));

  _fs->remove(path);
  
  return true; // return true even if file did not exist
}
#endif