/**
 * Persistent multi-host peer roster (PearDock-style).
 *
 *   ~/.config/peardata/cache/peers.json
 *
 * Migrates legacy bookmarks.json on first load.
 */
import fs from 'fs'
import path from 'path'
import { getPeardataCacheDir, getPeardataHome } from './paths.js'
import { atomicWriteJson } from './jsonCache.js'

export const PEERS_CACHE_VERSION = 1
export const ACTIVE_PEER_LS_KEY = 'peardata_active_peer_id'
export const PEERS_LS_KEY = 'peardata.cache.peers'

/**
 * @typedef {{
 *   publicKeyHex: string,
 *   alias: string,
 *   invite: string|null,
 *   capability: string|null,
 *   adminSeed: string|null,
 *   lastConnectedAt: number|null,
 *   autoConnect: boolean,
 *   createdAt: number,
 * }} PeerEntry
 */

export function getPeersCachePath() {
  return path.join(getPeardataCacheDir(), 'peers.json')
}

/**
 * @param {unknown} raw
 * @returns {string|null}
 */
export function normalizeAdminSeed(raw) {
  if (raw == null || raw === '') return null
  const seed = String(raw).trim().toLowerCase()
  return /^[0-9a-f]{64}$/.test(seed) ? seed : null
}

/**
 * @param {object} value
 * @returns {PeerEntry|null}
 */
export function normalizePeerEntry(value) {
  if (!value) return null
  const publicKeyHex = String(value.publicKeyHex || value.id || '')
    .trim()
    .toLowerCase()
  if (!/^[0-9a-f]{64}$/.test(publicKeyHex)) return null
  let capability = value.capability || null
  let invite = value.invite || value.inviteToken || null
  if (!capability && invite && String(invite).includes('.')) {
    // pd1 invites stay as invite; HMAC grants look like a.b
    if (!String(invite).startsWith('pd1.')) {
      capability = invite
      invite = null
    }
  }
  return {
    publicKeyHex,
    alias: value.alias ? String(value.alias).slice(0, 64) : '',
    invite: invite || null,
    capability: capability || null,
    adminSeed: normalizeAdminSeed(value.adminSeed),
    lastConnectedAt: value.lastConnectedAt || null,
    autoConnect: value.autoConnect !== false,
    createdAt: value.createdAt || Date.now(),
  }
}

/**
 * @returns {Record<string, PeerEntry>}
 */
export function loadPeers() {
  const file = getPeersCachePath()
  try {
    if (fs.existsSync(file)) {
      const raw = JSON.parse(fs.readFileSync(file, 'utf8'))
      return parsePeersPayload(raw)
    }
  } catch (err) {
    console.warn('[WARN] peerCache: read failed', err?.message || err)
  }

  // Migrate legacy bookmarks.json
  const migrated = migrateBookmarks()
  if (Object.keys(migrated).length) {
    savePeers(migrated)
    return migrated
  }

  try {
    if (typeof localStorage !== 'undefined') {
      const mir = localStorage.getItem(PEERS_LS_KEY)
      if (mir) return parsePeersPayload(JSON.parse(mir))
    }
  } catch {
    // ignore
  }
  return {}
}

/**
 * @param {unknown} raw
 * @returns {Record<string, PeerEntry>}
 */
export function parsePeersPayload(raw) {
  if (!raw || typeof raw !== 'object') return {}
  const source =
    raw.peers && typeof raw.peers === 'object' && !Array.isArray(raw.peers)
      ? raw.peers
      : Array.isArray(raw.bookmarks)
        ? Object.fromEntries(
            raw.bookmarks.map((b) => [String(b.publicKeyHex || '').toLowerCase(), b])
          )
        : raw
  /** @type {Record<string, PeerEntry>} */
  const out = {}
  for (const [key, value] of Object.entries(source)) {
    if (key === 'version' || key === 'updatedAt' || key === 'peers' || key === 'activePeerId') {
      continue
    }
    const entry = normalizePeerEntry(value)
    if (!entry) continue
    out[entry.publicKeyHex] = entry
  }
  return out
}

/**
 * @returns {Record<string, PeerEntry>}
 */
function migrateBookmarks() {
  const candidates = [
    path.join(getPeardataHome(), 'bookmarks.json'),
    path.join(getPeardataCacheDir(), 'bookmarks.json'),
  ]
  for (const file of candidates) {
    try {
      if (!fs.existsSync(file)) continue
      const raw = JSON.parse(fs.readFileSync(file, 'utf8'))
      const list = Array.isArray(raw?.bookmarks) ? raw.bookmarks : []
      /** @type {Record<string, PeerEntry>} */
      const out = {}
      for (const b of list) {
        const entry = normalizePeerEntry(b)
        if (entry) out[entry.publicKeyHex] = entry
      }
      if (Object.keys(out).length) return out
    } catch {
      // try next
    }
  }
  return {}
}

/**
 * @param {Record<string, PeerEntry|object>} peersMap
 * @param {{ activePeerId?: string|null }} [opts]
 */
export function savePeers(peersMap, opts = {}) {
  /** @type {Record<string, PeerEntry>} */
  const peers = {}
  for (const value of Object.values(peersMap || {})) {
    const entry = normalizePeerEntry(value)
    if (!entry) continue
    peers[entry.publicKeyHex] = entry
  }

  // Wipe protection: refuse empty write unless intentional clear
  if (!Object.keys(peers).length && opts.activePeerId !== null && Object.keys(loadPeers()).length) {
    if (!opts.force) {
      console.warn('[WARN] peerCache: refused empty wipe')
      return false
    }
  }

  let activePeerId =
    opts.activePeerId !== undefined ? opts.activePeerId : getLastActivePeerId()
  if (activePeerId) activePeerId = String(activePeerId).toLowerCase()
  if (activePeerId && !peers[activePeerId]) activePeerId = null

  const payload = {
    version: PEERS_CACHE_VERSION,
    updatedAt: new Date().toISOString(),
    peers,
  }
  if (activePeerId) payload.activePeerId = activePeerId

  try {
    atomicWriteJson(getPeersCachePath(), payload)
  } catch (err) {
    console.warn('[WARN] peerCache: write failed', err?.message || err)
    return false
  }

  try {
    if (typeof localStorage !== 'undefined') {
      localStorage.setItem(PEERS_LS_KEY, JSON.stringify(payload))
      if (activePeerId) localStorage.setItem(ACTIVE_PEER_LS_KEY, activePeerId)
      else localStorage.removeItem(ACTIVE_PEER_LS_KEY)
    }
  } catch {
    // ignore
  }
  return true
}

/**
 * @returns {string|null}
 */
export function getLastActivePeerId() {
  try {
    const file = getPeersCachePath()
    if (fs.existsSync(file)) {
      const raw = JSON.parse(fs.readFileSync(file, 'utf8'))
      const id = raw?.activePeerId
      if (id && /^[0-9a-f]{64}$/i.test(id)) return String(id).toLowerCase()
    }
  } catch {
    // ignore
  }
  try {
    if (typeof localStorage !== 'undefined') {
      const id = localStorage.getItem(ACTIVE_PEER_LS_KEY)
      if (id && /^[0-9a-f]{64}$/i.test(id)) return String(id).toLowerCase()
    }
  } catch {
    // ignore
  }
  return null
}

/**
 * @param {string|null} id
 */
export function setLastActivePeerId(id) {
  const next = id && /^[0-9a-f]{64}$/i.test(id) ? String(id).toLowerCase() : null
  const peers = loadPeers()
  savePeers(peers, { activePeerId: next, force: true })
}

/**
 * @param {Partial<PeerEntry> & { publicKeyHex: string }} peer
 * @param {{ makeActive?: boolean }} [opts]
 */
export function upsertPeer(peer, opts = {}) {
  const entry = normalizePeerEntry(peer)
  if (!entry) return loadPeers()
  const peers = loadPeers()
  const prev = peers[entry.publicKeyHex]
  peers[entry.publicKeyHex] = {
    ...entry,
    alias: peer.alias != null ? entry.alias : prev?.alias || entry.alias,
    invite: entry.invite || prev?.invite || null,
    capability: entry.capability || prev?.capability || null,
    adminSeed: entry.adminSeed || prev?.adminSeed || null,
    lastConnectedAt: peer.lastConnectedAt ?? Date.now(),
    createdAt: prev?.createdAt || entry.createdAt,
    autoConnect: peer.autoConnect != null ? entry.autoConnect : prev?.autoConnect !== false,
  }
  const active =
    opts.makeActive !== false ? entry.publicKeyHex : getLastActivePeerId()
  savePeers(peers, { activePeerId: active })
  return peers
}

/**
 * @param {string} publicKeyHex
 * @param {string} alias
 */
export function setPeerAlias(publicKeyHex, alias) {
  const id = String(publicKeyHex || '').toLowerCase()
  const peers = loadPeers()
  if (!peers[id]) return peers
  peers[id].alias = String(alias || '').slice(0, 64)
  savePeers(peers)
  return peers
}

/**
 * @param {string} publicKeyHex
 */
export function removePeer(publicKeyHex) {
  const id = String(publicKeyHex || '').toLowerCase()
  const peers = loadPeers()
  delete peers[id]
  const active = getLastActivePeerId()
  savePeers(peers, {
    activePeerId: active === id ? null : active,
    force: true,
  })
  return peers
}

/**
 * Bookmark-shaped list for UI compatibility.
 * @returns {Array<PeerEntry & { id: string }>}
 */
export function listPeersAsBookmarks() {
  return Object.values(loadPeers())
    .map((p) => ({ ...p, id: p.publicKeyHex }))
    .sort((a, b) => (b.lastConnectedAt || 0) - (a.lastConnectedAt || 0))
}