/* ============================================================
   BAN YARO — Offline-Vektorkacheln
   Lädt einen Bereich aus der Remote-PMTiles (dach.pmtiles) als einzelne MVT-Tiles
   in IndexedDB und bedient MapLibre offline daraus über das `byt://`-Protokoll.
   Plan/Architektur: docs/OFFLINE_MAPS_PLAN.md
   ============================================================ */
window.MapOffline = (function () {
  'use strict';

  var DB_NAME = 'by-offline-tiles', STORE = 'tiles', META = 'meta', DB_VER = 1;
  var MAXZOOM = 14;                 // unsere pmtiles enden bei z14 (Overzoom darüber)
  var _db = null, _pm = null;
  // Hinweis: pmtiles.getZxy() liefert die Tiles BEREITS dekomprimiert (rohe MVT-Protobufs) →
  // wir speichern/servieren sie direkt, kein gunzip. Dadurch ist die IndexedDB-Größe ~2,5× die
  // komprimierte pmtiles-Extract-Größe (5 km ≈ ~16 MB statt 6,4 MB) — fürs Handy unkritisch.

  // ---- IndexedDB ----
  function _open() {
    if (_db) return Promise.resolve(_db);
    return new Promise(function (res, rej) {
      var r = indexedDB.open(DB_NAME, DB_VER);
      r.onupgradeneeded = function () {
        var d = r.result;
        if (!d.objectStoreNames.contains(STORE)) d.createObjectStore(STORE);
        if (!d.objectStoreNames.contains(META))  d.createObjectStore(META);
      };
      r.onsuccess = function () { _db = r.result; res(_db); };
      r.onerror   = function () { rej(r.error); };
    });
  }
  function _req(store, mode, make) {
    return _open().then(function (d) { return new Promise(function (res, rej) {
      var tx = d.transaction(store, mode), rq = make(tx.objectStore(store));
      tx.oncomplete = function () { res(rq ? rq.result : undefined); };
      tx.onerror    = function () { rej(tx.error); };
    }); });
  }
  var _get   = function (k)    { return _req(STORE, 'readonly',  function (os) { return os.get(k); }); };
  var _put   = function (k, v) { return _req(STORE, 'readwrite', function (os) { os.put(v, k); }); };
  var _count = function ()     { return _req(STORE, 'readonly',  function (os) { return os.count(); }); };

  // ---- Remote-PMTiles ----
  function _pmInst() { if (!_pm) _pm = new pmtiles.PMTiles(MapGLStyle.tilesUrl()); return _pm; }

  // MVT-Bytes (Uint8Array) für z/x/y — IndexedDB zuerst, sonst remote (online), sonst null.
  function tile(z, x, y) {
    return _get(z + '/' + x + '/' + y).then(function (hit) {
      if (hit) return hit instanceof Uint8Array ? hit : new Uint8Array(hit);
      return _pmInst().getZxy(z, x, y).then(function (r) {
        return (r && r.data) ? new Uint8Array(r.data) : null;   // getZxy ist bereits dekomprimiert
      }).catch(function () { return null; });   // offline + nicht gespeichert → leeres Tile
    });
  }

  // MapLibre-Protokolle registrieren (idempotent):
  //   byt://t/{z}/{x}/{y}          → Vektorkachel (MVT)
  //   byt://f/{fontstack}/{range}  → Glyph-PBF (fontstack ggf. URL-encodiert, je nach MapLibre-Version)
  function registerProtocol() {
    if (registerProtocol._done || typeof maplibregl === 'undefined') return;
    registerProtocol._done = true;
    maplibregl.addProtocol('byt', function (params) {
      var ret = function (u) {
        if (!u) return { data: new ArrayBuffer(0) };
        return { data: u.buffer.slice(u.byteOffset, u.byteOffset + u.byteLength) };
      };
      var t = /byt:\/\/t\/(\d+)\/(\d+)\/(\d+)/.exec(params.url);
      if (t) return tile(+t[1], +t[2], +t[3]).then(ret);
      var f = /byt:\/\/f\/([^/]+)\/(\d+-\d+)/.exec(params.url);
      if (f) return glyph(decodeURIComponent(f[1]), f[2]).then(ret);
      return Promise.resolve({ data: new ArrayBuffer(0) });
    });
  }

  // ---- Slippy-Tile-Mathe ----
  function _x(lon, z) { return Math.floor((lon + 180) / 360 * Math.pow(2, z)); }
  function _y(lat, z) {
    var r = lat * Math.PI / 180;
    return Math.floor((1 - Math.log(Math.tan(r) + 1 / Math.cos(r)) / Math.PI) / 2 * Math.pow(2, z));
  }
  function _tileList(lat, lon, radiusKm) {
    var dLat = radiusKm / 111, dLon = radiusKm / (111 * Math.cos(lat * Math.PI / 180));
    var w = lon - dLon, e = lon + dLon, s = lat - dLat, n = lat + dLat, list = [];
    for (var z = 0; z <= MAXZOOM; z++) {
      var x0 = _x(w, z), x1 = _x(e, z), y0 = _y(n, z), y1 = _y(s, z);
      for (var x = x0; x <= x1; x++) for (var y = y0; y <= y1; y++) list.push([z, x, y]);
    }
    return list;
  }

  // Glyphs (Open Sans Regular/Semibold, Latin + Latin-Extended) in IndexedDB persistieren
  // (Key-Präfix 'f/' im Tiles-Store, kein Schema-Bump) — überlebt App-Updates, anders als der
  // SW-Cache, der beim Update gepurged wird. Offline serviert übers byt://f/-Protokoll.
  // KRITISCH: ohne Glyphs lässt MapLibre offline die GANZE Kachel fallen (nicht nur die Labels) → leer.
  // 0-255 + 256-511 deckt DE/FR/PL/CZ/IT-Sonderzeichen ab.
  var FONTS = ['Open Sans Regular', 'Open Sans Semibold'], RANGES = ['0-255', '256-511'];
  function _glyphUrl(font, range) { return '/fonts/' + encodeURIComponent(font) + '/' + range + '.pbf'; }
  function _cacheGlyphs() {
    var bytes = 0, jobs = [];
    FONTS.forEach(function (f) { RANGES.forEach(function (rg) {
      jobs.push(fetch(_glyphUrl(f, rg))
        .then(function (r) { return r.ok ? r.arrayBuffer() : null; })
        .then(function (b) {
          if (!b) return;
          bytes += b.byteLength;
          return _put('f/' + f + '/' + rg, new Uint8Array(b));
        })
        .catch(function () {}));
    }); });
    return Promise.all(jobs).then(function () { return bytes; });
  }

  // Glyph-Bytes für fontstack/range — IndexedDB zuerst, sonst remote (online), sonst null.
  function glyph(font, range) {
    return _get('f/' + font + '/' + range).then(function (hit) {
      if (hit) return hit instanceof Uint8Array ? hit : new Uint8Array(hit);
      return fetch(_glyphUrl(font, range))
        .then(function (r) { return r.ok ? r.arrayBuffer() : null; })
        .then(function (b) { return b ? new Uint8Array(b) : null; })
        .catch(function () { return null; });
    });
  }

  // Bereich um lat/lon (radiusKm, Default 5) herunterladen + in IndexedDB ablegen.
  // onProgress({done,total,bytes}). Liefert {tiles,bytes}.
  function downloadAround(lat, lon, radiusKm, onProgress) {
    radiusKm = radiusKm || 5;
    var list = _tileList(lat, lon, radiusKm), total = list.length, done = 0, bytes = 0, stored = 0, i = 0, CONC = 6;
    function next() {
      if (i >= total) return Promise.resolve();
      var t = list[i++], key = t[0] + '/' + t[1] + '/' + t[2];
      return _pmInst().getZxy(t[0], t[1], t[2]).then(function (r) {
        if (r && r.data) { var u = new Uint8Array(r.data); bytes += u.byteLength; stored++; return _put(key, u); }
      }).catch(function () {}).then(function () {
        done++;
        if (onProgress && (done % 8 === 0 || done === total)) onProgress({ done: done, total: total, bytes: bytes });
        return next();
      });
    }
    var w = []; for (var k = 0; k < CONC; k++) w.push(next());
    return Promise.all(w)
      .then(function () { return _cacheGlyphs(); })   // Glyphs mitcachen (sonst offline kein Render)
      .then(function (gb) { bytes += gb; return _req(META, 'readwrite', function (os) {
        os.put({ lat: lat, lon: lon, radiusKm: radiusKm, tiles: stored, bytes: bytes, savedAt: Date.now() }, 'region');
      }); })
      .then(function () { return { tiles: stored, bytes: bytes }; });
  }

  function stats() {
    return _count().then(function (count) {
      return _req(META, 'readonly', function (os) { return os.get('region'); })
        .then(function (meta) { return { count: count, meta: meta || null }; });
    });
  }
  function hasRegion() { return stats().then(function (s) { return s.count > 0; }).catch(function () { return false; }); }
  function clear() {
    return _req(STORE, 'readwrite', function (os) { os.clear(); })
      .then(function () { return _req(META, 'readwrite', function (os) { os.clear(); }); });
  }

  return {
    registerProtocol: registerProtocol, downloadAround: downloadAround, tile: tile, glyph: glyph,
    stats: stats, hasRegion: hasRegion, clear: clear, MAXZOOM: MAXZOOM,
  };
})();