// Browser state: identity, pins, contacts and read markers in localStorage;
// sealed envelopes in IndexedDB, opened only on demand, so nothing at rest
// is plaintext (the seed excepted — it is the user's browser profile).

import { hex, unhex } from "./crypto.js";
import { b32decode, b32encode, identityFromSeed } from "./proto.js";

const KEY = "gsmol";

function load() {
  try {
    return JSON.parse(localStorage.getItem(KEY) || "{}");
  } catch {
    return {};
  }
}

function save(state) {
  localStorage.setItem(KEY, JSON.stringify(state));
}

function update(fn) {
  const state = load();
  const next = fn(state);
  save(next ?? state);
}

// --- identity ----------------------------------------------------------------

export function seed() {
  const raw = load().seed;
  return raw ? unhex(raw) : null;
}

export function identity() {
  const raw = seed();
  return raw ? identityFromSeed(raw) : null;
}

export function setIdentity(newSeed) {
  if (seed()) throw new Error("an identity already exists; rotate it instead");
  update(state => { state.seed = hex(newSeed); });
}

// Rotation (§7): the old seed is retained, since mail sealed to a superseded
// key is readable with nothing else.
export function rotateIdentity(newSeed) {
  const old = seed();
  if (!old) throw new Error("no identity to rotate");
  update(state => {
    state.retired = [...(state.retired || []), { seed: hex(old), at: Date.now() }];
    state.seed = hex(newSeed);
  });
}

// §7: seeds rotated away from are retained, since mail sealed to a superseded
// key is readable with nothing else.
export function identities() {
  const me = identity();
  if (!me) return [];
  const retired = (load().retired || []).map(({ seed: s }) => identityFromSeed(unhex(s)));
  return [me, ...retired];
}

// --- account and server pins ---------------------------------------------------

export function account() {
  const a = load().account;
  return a ? { ...a } : null;
}

export function setAccount(addr) {
  update(state => {
    state.account = { user: addr.user, host: addr.host, port: addr.port };
  });
}

export function serverPin(host) {
  const raw = (load().servers || {})[host];
  return raw ? b32decode(raw) : null;
}

export function pinServer(host, keyBytes) {
  update(state => {
    state.servers = { ...(state.servers || {}), [host]: b32encode(keyBytes) };
  });
}

export function unpinServer(host) {
  update(state => {
    delete (state.servers || {})[host];
  });
}

export function allPins() {
  return Object.entries(load().servers || {}).map(([host, key]) => ({ host, key }));
}

// --- contacts ------------------------------------------------------------------

export function contact(address) {
  const c = (load().contacts || {})[address];
  return c ? { key: b32decode(c.key), verified: c.verified } : null;
}

export function saveContact(address, keyBytes, verified) {
  update(state => {
    state.contacts = {
      ...(state.contacts || {}),
      [address]: { key: b32encode(keyBytes), verified, seenAt: Date.now() },
    };
  });
}

export function addressForKey(keyBytes) {
  return Object.entries(load().contacts || {})
    .find(([, c]) => c.key === b32encode(keyBytes))?.[0] ?? null;
}

export function allContacts() {
  return Object.entries(load().contacts || {})
    .map(([address, c]) => ({ address, key: c.key, verified: c.verified }));
}

// --- read markers ---------------------------------------------------------------

export function markRead(idHex) {
  update(state => {
    state.read = { ...(state.read || {}), [idHex]: true };
  });
}

export function isRead(idHex) {
  return Boolean((load().read || {})[idHex]);
}

// --- sealed mail (IndexedDB) ------------------------------------------------------

const DB_NAME = "gsmol", DB_VERSION = 1;

function openDb() {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open(DB_NAME, DB_VERSION);
    request.onupgradeneeded = () => {
      const db = request.result;
      for (const box of ["inbox", "sent"]) {
        if (!db.objectStoreNames.contains(box)) db.createObjectStore(box, { keyPath: "id" });
      }
    };
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

function tx(db, box, mode, fn) {
  return new Promise((resolve, reject) => {
    const request = fn(db.transaction(box, mode).objectStore(box));
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

export async function storeMessage(box, record) {
  const db = await openDb();
  await tx(db, box, "readwrite", store => store.put(record));
  db.close();
}

// Returns null when the id already exists, so fetch can leave server state alone.
export async function storeIfNew(box, record) {
  const db = await openDb();
  const existing = await tx(db, box, "readonly", store => store.get(record.id));
  if (existing) { db.close(); return null; }
  await tx(db, box, "readwrite", store => store.put(record));
  db.close();
  return record;
}

export async function listMessages(box) {
  const db = await openDb();
  const rows = await tx(db, box, "readonly", store => store.getAll());
  db.close();
  return rows.sort((a, b) => (a.receivedAt ?? a.sentAt) - (b.receivedAt ?? b.sentAt));
}

export async function getMessage(box, id) {
  const db = await openDb();
  const row = await tx(db, box, "readonly", store => store.get(id));
  db.close();
  return row ?? null;
}