#include <Arduino.h>
#include <string.h>
#include "DataStore.h"
#if defined(ESP32)
#include <SD.h>
#include "helpers/esp32/WdtHeavyGuard.h"   // suspend core-0 idle WDT during the (SPIFFS-GC-prone) contact write
#endif

#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

const char* DataStore::_rp(const char* name) {
  if (!_root[0]) return name;            // default: filesystem root, zero change
  snprintf(_rpbuf, sizeof(_rpbuf), "%s%s", _root, name);
  return _rpbuf;
}

File DataStore::openWrite(FILESYSTEM* fs, const char* filename) {
#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  fs->remove(_rp(filename));
  return fs->open(_rp(filename), FILE_O_WRITE);
#elif defined(RP2040_PLATFORM)
  return fs->open(_rp(filename), "w");
#else
  return fs->open(_rp(filename), "w", true);
#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");
  #if defined(ESP32)
  // One-time migration: when a secondary FS is active (an SD card is present)
  // but contacts/channels still live on the primary FS from an earlier build,
  // copy them onto the card ONCE and delete the primary copies. This preserves
  // the user's contact list while getting the frequently-rewritten files off a
  // small/near-full SPIFFS — whose garbage collection can otherwise stall the
  // loop task for seconds during saveContacts and trip the task watchdog
  // (the beta_25 reboot loop). Identity + prefs stay on _fs and never move.
  // No-op once the card already holds the files, and a safe no-op on boards
  // whose primary-FS metadata can't confirm the source exists (e.g. P4 FFat).
  if (_fsExtra) {
    static const char* const kMoveFiles[] = { "/contacts3", "/channels2" };
    for (const char* nm : kMoveFiles) {
      if (_fsExtra->exists(nm)) continue;       // already on the card
      if (!_fs->exists(nm))     continue;       // nothing to move
      File in  = openRead(_fs, nm);
      File out = openWrite(_fsExtra, nm);
      bool ok = in && out;
      if (ok) {
        uint8_t buf[256];
        int n;
        while ((n = in.read(buf, sizeof(buf))) > 0) {
          if (out.write(buf, (size_t)n) != (size_t)n) { ok = false; break; }
        }
      }
      if (in)  in.close();
      if (out) out.close();
      if (ok)  _fs->remove(nm);                            // reclaim SPIFFS space
      else if (_fsExtra->exists(nm)) _fsExtra->remove(nm); // don't leave a partial copy
    }
  }
  #endif
#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(_rp(filename), FILE_O_READ);
#elif defined(RP2040_PLATFORM)
  return _fs->open(_rp(filename), "r");
#else
  return _fs->open(_rp(filename), "r", false);
#endif
}

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

bool DataStore::removeFile(const char* filename) {
  return _fs->remove(_rp(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)
  // Only the internal store is SPIFFS. When useSdStorage() is active, _fs points
  // at the SD (SDFS) singleton — NOT a SPIFFSFS — so casting it and calling
  // format() dereferences garbage and crashes. That crash aborted the factory
  // reset before NVS was erased or the device restarted (everything came back).
  // On SD the data dir (_root) is wiped by the caller, so here we only format
  // SPIFFS when it's genuinely the active store.
  bool fs_success = true;
  if (_root[0] == '\0') 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(_rp("/new_prefs"))) {
    loadPrefsInt("/new_prefs", prefs, node_lat, node_lon); // new filename
  } else if (_fs->exists(_rp("/new_prefs.tmp"))) {
    // Main file gone but a staged copy exists: a reboot landed between the temp
    // write and the swap (or the swap was torn). Recover from it — this is the
    // "device booted with the default name once" failure mode.
    MESH_DEBUG_PRINTLN("DataStore: /new_prefs missing, recovering from .tmp");
    loadPrefsInt("/new_prefs.tmp", prefs, node_lat, node_lon);
    savePrefs(prefs, node_lat, node_lon);                // re-establish the main file
  } else if (_fs->exists(_rp("/node_prefs"))) {
    loadPrefsInt("/node_prefs", prefs, node_lat, node_lon);
    savePrefs(prefs, node_lat, node_lon);                // save to new filename
    _fs->remove(_rp("/node_prefs")); // remove old
  } else {
    MESH_DEBUG_PRINTLN("DataStore: no prefs file found — using defaults");
  }
}

namespace {

void default_rx_boosted_gain_pref(uint8_t& out) {
#if defined(USE_SX1262) || defined(USE_SX1268) || defined(USE_LR1121) || defined(SX126X_RX_BOOSTED_GAIN)
  #ifdef SX126X_RX_BOOSTED_GAIN
  out = (SX126X_RX_BOOSTED_GAIN != 0) ? 1 : 0;
  #else
  out = 1;
  #endif
#else
  out = 0;
#endif
}

// After multi_acks (byte offset 78): upstream meshcore-dev layout is 15 bytes tail; legacy Meshcomod
// used 13 bytes (path_hash, autoadd_max, ble_pin..autoadd without reserved pad or trailing rx_boost).
void load_prefs_tail_meshcomod_legacy(NodePrefs& p, const uint8_t* tail) {
  p.path_hash_mode = tail[0];
  p.autoadd_max_hops = tail[1];
  memcpy(&p.ble_pin, tail + 2, 4);
  p.buzzer_quiet = tail[6];
  p.gps_enabled = tail[7];
  memcpy(&p.gps_interval, tail + 8, 4);
  p.autoadd_config = tail[12];
  default_rx_boosted_gain_pref(p.rx_boosted_gain);
}

void load_prefs_tail_upstream(NodePrefs& p, const uint8_t* tail, size_t n) {
  p.path_hash_mode = tail[0];
  // tail[1] reserved
  memcpy(&p.ble_pin, tail + 2, 4);
  p.buzzer_quiet = tail[6];
  p.gps_enabled = tail[7];
  memcpy(&p.gps_interval, tail + 8, 4);
  p.autoadd_config = tail[12];
  p.autoadd_max_hops = tail[13];
  if (n >= 15) {
    p.rx_boosted_gain = tail[14] ? 1 : 0;
  } else {
    default_rx_boosted_gain_pref(p.rx_boosted_gain);
  }
}

}  // namespace

void DataStore::loadPrefsInt(const char *filename, NodePrefs& _prefs, double& node_lat, double& node_lon) {
  File file = openRead(_fs, filename);
  if (file) {
    uint8_t pad[8];

    file.read((uint8_t *)&_prefs.airtime_factor, sizeof(float));                           // 0
    file.read((uint8_t *)_prefs.node_name, sizeof(_prefs.node_name));                      // 4
    file.read(pad, 4);                                                                     // 36
    file.read((uint8_t *)&node_lat, sizeof(node_lat));                                     // 40
    file.read((uint8_t *)&node_lon, sizeof(node_lon));                                     // 48
    file.read((uint8_t *)&_prefs.freq, sizeof(_prefs.freq));                               // 56
    file.read((uint8_t *)&_prefs.sf, sizeof(_prefs.sf));                                   // 60
    file.read((uint8_t *)&_prefs.cr, sizeof(_prefs.cr));                                   // 61
    file.read((uint8_t *)&_prefs.client_repeat, sizeof(_prefs.client_repeat));             // 62
    file.read((uint8_t *)&_prefs.manual_add_contacts, sizeof(_prefs.manual_add_contacts)); // 63
    file.read((uint8_t *)&_prefs.bw, sizeof(_prefs.bw));                                   // 64
    file.read((uint8_t *)&_prefs.tx_power_dbm, sizeof(_prefs.tx_power_dbm));               // 68
    file.read((uint8_t *)&_prefs.telemetry_mode_base, sizeof(_prefs.telemetry_mode_base)); // 69
    file.read((uint8_t *)&_prefs.telemetry_mode_loc, sizeof(_prefs.telemetry_mode_loc));   // 70
    file.read((uint8_t *)&_prefs.telemetry_mode_env, sizeof(_prefs.telemetry_mode_env));   // 71
    file.read((uint8_t *)&_prefs.rx_delay_base, sizeof(_prefs.rx_delay_base));             // 72
    file.read((uint8_t *)&_prefs.advert_loc_policy, sizeof(_prefs.advert_loc_policy));     // 76
    file.read((uint8_t *)&_prefs.multi_acks, sizeof(_prefs.multi_acks));                   // 77
    uint8_t tail[15];
    size_t n = file.read(tail, sizeof(tail));
    bool migrated_legacy = false;
    if (n == 13) {
      load_prefs_tail_meshcomod_legacy(_prefs, tail);
      migrated_legacy = true;
    } else if (n >= 14) {
      load_prefs_tail_upstream(_prefs, tail, n);
    }
    memset(_prefs.default_scope_name, 0, sizeof(_prefs.default_scope_name));
    memset(_prefs.default_scope_key, 0, sizeof(_prefs.default_scope_key));
    file.read((uint8_t *)_prefs.default_scope_name, sizeof(_prefs.default_scope_name));    // 90
    file.read((uint8_t *)_prefs.default_scope_key, sizeof(_prefs.default_scope_key));      // 121

    file.close();

    if (migrated_legacy) {
      savePrefs(_prefs, node_lat, node_lon);
    }
  }
}

bool DataStore::savePrefs(const NodePrefs& _prefs, double node_lat, double node_lon) {
  // Write to a temp file first and swap it in afterwards: a reboot / power cut
  // mid-write can then never destroy the only copy (the loader recovers from
  // whichever file survived). SPIFFS has no atomic rename-over, so the swap is
  // remove+rename — the loader handles the tiny between-steps window too.
  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));                           // 0
    file.write((uint8_t *)_prefs.node_name, sizeof(_prefs.node_name));                      // 4
    file.write(pad, 4);                                                                     // 36
    file.write((uint8_t *)&node_lat, sizeof(node_lat));                                     // 40
    file.write((uint8_t *)&node_lon, sizeof(node_lon));                                     // 48
    file.write((uint8_t *)&_prefs.freq, sizeof(_prefs.freq));                               // 56
    file.write((uint8_t *)&_prefs.sf, sizeof(_prefs.sf));                                   // 60
    file.write((uint8_t *)&_prefs.cr, sizeof(_prefs.cr));                                   // 61
    file.write((uint8_t *)&_prefs.client_repeat, sizeof(_prefs.client_repeat));             // 62
    file.write((uint8_t *)&_prefs.manual_add_contacts, sizeof(_prefs.manual_add_contacts)); // 63
    file.write((uint8_t *)&_prefs.bw, sizeof(_prefs.bw));                                   // 64
    file.write((uint8_t *)&_prefs.tx_power_dbm, sizeof(_prefs.tx_power_dbm));               // 68
    file.write((uint8_t *)&_prefs.telemetry_mode_base, sizeof(_prefs.telemetry_mode_base)); // 69
    file.write((uint8_t *)&_prefs.telemetry_mode_loc, sizeof(_prefs.telemetry_mode_loc));   // 70
    file.write((uint8_t *)&_prefs.telemetry_mode_env, sizeof(_prefs.telemetry_mode_env));   // 71
    file.write((uint8_t *)&_prefs.rx_delay_base, sizeof(_prefs.rx_delay_base));             // 72
    file.write((uint8_t *)&_prefs.advert_loc_policy, sizeof(_prefs.advert_loc_policy));     // 76
    file.write((uint8_t *)&_prefs.multi_acks, sizeof(_prefs.multi_acks));                   // 77
    file.write((uint8_t *)&_prefs.path_hash_mode, sizeof(_prefs.path_hash_mode));            // 78
    file.write(pad, 1);                                                                     // 79 reserved (upstream layout)
    file.write((uint8_t *)&_prefs.ble_pin, sizeof(_prefs.ble_pin));                         // 80
    file.write((uint8_t *)&_prefs.buzzer_quiet, sizeof(_prefs.buzzer_quiet));               // 84
    file.write((uint8_t *)&_prefs.gps_enabled, sizeof(_prefs.gps_enabled));                 // 85
    // gps_interval (4B) — was MISSING here; the loader (load_prefs_tail_*) reads
    // it at tail[8..11], so omitting it shifted autoadd_config/max_hops/rx_boost
    // and the scope fields by 4 bytes on every load (auto-add types read garbage
    // -> appeared to reset on reboot). Writing it realigns save with load.
    file.write((uint8_t *)&_prefs.gps_interval, sizeof(_prefs.gps_interval));               // 86
    file.write((uint8_t *)&_prefs.autoadd_config, sizeof(_prefs.autoadd_config));           // 90
    file.write((uint8_t *)&_prefs.autoadd_max_hops, sizeof(_prefs.autoadd_max_hops));       // 91
    file.write((uint8_t *)&_prefs.rx_boosted_gain, sizeof(_prefs.rx_boosted_gain));         // 92
    file.write((uint8_t *)_prefs.default_scope_name, sizeof(_prefs.default_scope_name));    // 93
    size_t last = file.write((uint8_t *)_prefs.default_scope_key, sizeof(_prefs.default_scope_key)); // 125

    file.close();
    if (last != sizeof(_prefs.default_scope_key)) {
      _fs->remove(_rp("/new_prefs.tmp"));   // short write (storage full?) — keep the old main file
      return false;
    }
    _fs->remove(_rp("/new_prefs"));
    return _fs->rename(_rp("/new_prefs.tmp"), _rp("/new_prefs"));
  }
  return false;
}

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)) {
#if defined(ESP32)
  // A full/fragmenting contacts write on SPIFFS can trigger a multi-second GC
  // pass that disables the flash cache and starves core 0's idle task, tripping
  // the task watchdog (the beta_25 reboot loop, confirmed by coredump: loopTask
  // stuck in spiffs_gc_clean under this exact call). Suspend that watchdog for
  // the write so a bounded-but-slow pass stalls the UI instead of rebooting. The
  // ref-count is shared with the UI history/backup guards, so a backup import
  // that calls saveContacts stays balanced. On SD-routed devices this is cheap
  // (FAT has no such GC); it matters most for card-less SPIFFS devices.
  WdtHeavyGuard _wdt;
#endif
  File file = openWrite(_getContactsChannelsFS(), "/contacts3");
  if (file) {
    uint32_t idx = 0;
    ContactInfo c;
    uint8_t unused = 0;

    // Field-by-field writes cost ~12 FS calls per contact — ~7000 tiny writes at
    // ~570 contacts measured 2.6-3.0 s on SD, freezing the loop/UI for the whole
    // save (issue #82). Pack the SAME 152-byte records into a heap chunk and
    // flush in ~5 KB slabs instead: identical file bytes, ~20 large writes, tens
    // of ms. Falls back to the original per-field path if the alloc fails.
    static const size_t REC = 152;           // 32+32+1+1+1+4+1+4+64+4+4+4
    static const size_t CHUNK_RECS = 32;
    uint8_t* buf = (uint8_t*)malloc(REC * CHUNK_RECS);
    if (buf) {
      size_t fill = 0;
      bool ok = true;
      while (ok && host->getContactForSave(idx, c)) {
        if (filter && !filter(c)) {
          idx++;  // advance to next contact
          continue;
        }
        uint8_t* p = buf + fill;
        memcpy(p, c.id.pub_key, 32);                       p += 32;
        memcpy(p, (uint8_t *)&c.name, 32);                 p += 32;
        *p++ = c.type;
        *p++ = c.flags;
        *p++ = unused;
        memcpy(p, (uint8_t *)&c.sync_since, 4);            p += 4;
        memcpy(p, (uint8_t *)&c.out_path_len, 1);          p += 1;
        memcpy(p, (uint8_t *)&c.last_advert_timestamp, 4); p += 4;
        memcpy(p, c.out_path, 64);                         p += 64;
        memcpy(p, (uint8_t *)&c.lastmod, 4);               p += 4;
        memcpy(p, (uint8_t *)&c.gps_lat, 4);               p += 4;
        memcpy(p, (uint8_t *)&c.gps_lon, 4);               p += 4;
        fill += REC;
        if (fill == REC * CHUNK_RECS) {
          ok = (file.write(buf, fill) == fill);
          fill = 0;
        }
        idx++;  // advance to next contact
      }
      if (ok && fill > 0) file.write(buf, fill);
      free(buf);
    } else {
      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) break; // write failed

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

void DataStore::loadChannels(DataStoreHost* host) {
    File file = openRead(_getContactsChannelsFS(), "/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

        if (host->onChannelLoaded(channel_idx, ch)) {
          channel_idx++;
        } else {
          full = true;
        }
      }
      file.close();
    }
}

void DataStore::saveChannels(DataStoreHost* host) {
  File file = openWrite(_getContactsChannelsFS(), "/channels2");
  if (file) {
    uint8_t channel_idx = 0;
    ChannelDetails ch;
    uint8_t unused[4];
    memset(unused, 0, 4);

    while (host->getChannelForSave(channel_idx, ch)) {
      bool success = (file.write(unused, 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) break; // write failed
      channel_idx++;
    }
    file.close();
  }
}

#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(_rp(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(_rp(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(_rp(path));

  return true; // return true even if file did not exist
}
#endif

#if defined(ESP32)
// Redirect all data storage to the SD card under /meshcomod (identity, prefs,
// contacts, channels, blobs). The SD card must already be mounted by the caller.
// Creates the folders, repoints _fs + the identity store, and sets the path
// prefix so every subsequent read/write/exists/remove lands under /meshcomod.
bool DataStore::useSdStorage() {
  if (!SD.exists("/meshcomod"))          SD.mkdir("/meshcomod");
  if (!SD.exists("/meshcomod/bl"))       SD.mkdir("/meshcomod/bl");
  if (!SD.exists("/meshcomod/identity")) SD.mkdir("/meshcomod/identity");
  strncpy(_root, "/meshcomod", sizeof(_root) - 1);
  _root[sizeof(_root) - 1] = '\0';
  _fs = &SD;
  _fsExtra = nullptr;
  identity_store.use(SD, "/meshcomod/identity");
  return true;
}
#endif