import http from 'node:http'
import { randomUUID } from 'node:crypto'

/**
 * Nachgebautes Appwrite fuer Tests: nur der REST-Ausschnitt, den `appwriteAdmin.js` und
 * `appwriteStaff.js` nutzen (Dokumente einer Sammlung, `/account` per JWT). Laeuft auf
 * 127.0.0.1 mit einem vom Betriebssystem vergebenen Port; `endpoint` endet auf `/v1`,
 * genau wie `config.appwrite.endpoint`.
 *
 * @param {object} [options]
 * @param {Record<string, object[]>} [options.seed]
 *   Anfangsbestand je Sammlung (Sammlungsname -> Dokumente). Jedes Dokument darf `$id`
 *   mitbringen (sonst wird eins erzeugt); `$createdAt`/`$updatedAt` werden sonst mit dem
 *   Startzeitpunkt gefuellt.
 * @returns {Promise<{
 *   endpoint: string,
 *   all: (collection: string) => object[],
 *   get: (collection: string, id: string) => (object|undefined),
 *   calls: Array<{method: string, path: string, query: Record<string, string>, headers: Record<string, string>, body: any}>,
 *   failNext: (spec: {method: string, pathIncludes: string, status: number}) => void,
 *   close: () => Promise<void>,
 * }>} `all`/`get` lesen den LIVE-Stand (nach create/patch/delete ueber HTTP). Die
 *   Datenbank-ID im Pfad wird nicht geprueft - jede wird akzeptiert.
 *   `failNext({method, pathIncludes, status})` laesst GENAU die naechste Anfrage, deren Methode
 *   passt und deren Pfad `pathIncludes` enthaelt, mit diesem Status und einer generischen
 *   JSON-Fehlermeldung scheitern (danach wieder normales Verhalten).
 */
export async function startFakeAppwrite(options = {}) {
  const calls = []
  const pendingFailures = []
  // Optionale Unique-Indizes wie in Appwrite/MariaDB: { websiteProjects: ['repoFullName', 'subdomain'] }.
  // Strings vergleichen ohne Gross-/Kleinschreibung, null/undefined kollidieren nie, '' schon.
  const uniqueAttrs = options.unique || {}
  let beforeCreate = null
  /** @type {Map<string, Map<string, object>>} Sammlungsname -> (Dokument-ID -> Dokument). */
  const store = new Map()

  function collectionOf(name) {
    let map = store.get(name)
    if (!map) {
      map = new Map()
      store.set(name, map)
    }
    return map
  }

  function all(col) {
    return [...collectionOf(col).values()]
  }

  function get(col, id) {
    return collectionOf(col).get(id)
  }

  function send(res, status, body) {
    if (body === undefined) {
      res.writeHead(status)
      res.end()
      return
    }
    const text = JSON.stringify(body)
    res.writeHead(status, {
      'Content-Type': 'application/json',
      'Content-Length': Buffer.byteLength(text),
    })
    res.end(text)
  }

  function parseQueries(searchParams) {
    return searchParams
      .getAll('queries[]')
      .map((s) => {
        try {
          return JSON.parse(s)
        } catch {
          return null
        }
      })
      .filter(Boolean)
  }

  /* ------------------------------------------------------------- Routen --- */

  function handleAccount(match, searchParams, body, headers, res) {
    if (headers['x-appwrite-jwt'] === 'jwt-admin') {
      return send(res, 200, { $id: 'staff1', labels: ['admin'] })
    }
    send(res, 401, { message: 'Unauthorized' })
  }

  function handleListDocuments(match, searchParams, body, headers, res) {
    const docs = [...collectionOf(match[2]).values()]
    const queries = parseQueries(searchParams)

    let result = docs.filter((doc) =>
      queries.every((q) => {
        if (q.method === 'equal') return q.values.includes(doc[q.attribute])
        if (q.method === 'greaterThan') return doc[q.attribute] > q.values[0]
        return true
      })
    )

    const orderAsc = queries.find((q) => q.method === 'orderAsc')
    const orderDesc = queries.find((q) => q.method === 'orderDesc')
    const sortAttr = orderAsc?.attribute || orderDesc?.attribute
    if (sortAttr) {
      const dir = orderAsc ? 1 : -1
      result = [...result].sort((a, b) => {
        if (a[sortAttr] === b[sortAttr]) return 0
        return a[sortAttr] > b[sortAttr] ? dir : -dir
      })
    }

    const total = result.length
    const limit = queries.find((q) => q.method === 'limit')
    if (limit) result = result.slice(0, Number(limit.values[0]))

    send(res, 200, { total, documents: result })
  }

  function uniqueConflict(col, data, ownId) {
    for (const attr of uniqueAttrs[col] || []) {
      const value = data?.[attr]
      if (value === null || value === undefined) continue
      const norm = (v) => (typeof v === 'string' ? v.toLowerCase() : v)
      for (const doc of collectionOf(col).values()) {
        if (doc.$id !== ownId && doc[attr] !== null && doc[attr] !== undefined && norm(doc[attr]) === norm(value)) return true
      }
    }
    return false
  }

  async function handleCreateDocument(match, searchParams, body, headers, res) {
    if (beforeCreate) await beforeCreate(match[2], body?.data || {})
    const map = collectionOf(match[2])
    const documentId = body?.documentId || randomUUID()
    if (map.has(documentId) || uniqueConflict(match[2], body?.data, documentId)) {
      return send(res, 409, { message: 'Document with the requested ID already exists.', type: 'document_already_exists' })
    }
    const now = new Date().toISOString()
    const doc = { $id: documentId, $createdAt: now, $updatedAt: now, ...(body?.data || {}) }
    map.set(documentId, doc)
    send(res, 201, doc)
  }

  function handleGetDocument(match, searchParams, body, headers, res) {
    const doc = collectionOf(match[2]).get(match[3])
    if (!doc) return send(res, 404, { message: 'Document not found' })
    send(res, 200, doc)
  }

  function handlePatchDocument(match, searchParams, body, headers, res) {
    const doc = collectionOf(match[2]).get(match[3])
    if (!doc) return send(res, 404, { message: 'Document not found' })
    if (uniqueConflict(match[2], body?.data, doc.$id)) {
      return send(res, 409, { message: 'Document with the requested ID already exists.', type: 'document_already_exists' })
    }
    Object.assign(doc, body?.data || {})
    doc.$updatedAt = new Date().toISOString()
    send(res, 200, doc)
  }

  function handleDeleteDocument(match, searchParams, body, headers, res) {
    const map = collectionOf(match[2])
    if (!map.has(match[3])) return send(res, 404, { message: 'Document not found' })
    map.delete(match[3])
    send(res, 204)
  }

  const ROUTES = [
    { method: 'GET', re: /^\/v1\/account$/, handler: handleAccount },
    {
      method: 'GET',
      re: /^\/v1\/databases\/([^/]+)\/collections\/([^/]+)\/documents$/,
      handler: handleListDocuments,
    },
    {
      method: 'POST',
      re: /^\/v1\/databases\/([^/]+)\/collections\/([^/]+)\/documents$/,
      handler: handleCreateDocument,
    },
    {
      method: 'GET',
      re: /^\/v1\/databases\/([^/]+)\/collections\/([^/]+)\/documents\/([^/]+)$/,
      handler: handleGetDocument,
    },
    {
      method: 'PATCH',
      re: /^\/v1\/databases\/([^/]+)\/collections\/([^/]+)\/documents\/([^/]+)$/,
      handler: handlePatchDocument,
    },
    {
      method: 'DELETE',
      re: /^\/v1\/databases\/([^/]+)\/collections\/([^/]+)\/documents\/([^/]+)$/,
      handler: handleDeleteDocument,
    },
  ]

  /* --------------------------------------------------------- Server --- */

  const sockets = new Set()
  const server = http.createServer((req, res) => {
    const chunks = []
    req.on('data', (c) => chunks.push(c))
    req.on('end', () => {
      const raw = Buffer.concat(chunks).toString('utf8')
      const url = new URL(req.url, 'http://fake-appwrite.local')
      let parsedBody = null
      if (raw) {
        try {
          parsedBody = JSON.parse(raw)
        } catch {
          parsedBody = null
        }
      }
      calls.push({
        method: req.method,
        path: url.pathname,
        query: Object.fromEntries(url.searchParams),
        headers: { ...req.headers },
        body: parsedBody,
      })

      const failIdx = pendingFailures.findIndex(
        (f) => f.method === req.method && url.pathname.includes(f.pathIncludes)
      )
      if (failIdx !== -1) {
        const [f] = pendingFailures.splice(failIdx, 1)
        return send(res, f.status, { message: `fakeAppwrite: erzwungener Fehler (${f.status})` })
      }

      const route = ROUTES.find((r) => r.method === req.method && r.re.test(url.pathname))
      if (!route) return send(res, 404, { message: 'Not Found' })
      const match = route.re.exec(url.pathname)
      Promise.resolve()
        .then(() => route.handler(match, url.searchParams, parsedBody, req.headers, res))
        .catch((err) => send(res, 500, { message: err?.message || 'fakeAppwrite: interner Fehler' }))
    })
  })

  server.on('connection', (socket) => {
    sockets.add(socket)
    socket.on('close', () => sockets.delete(socket))
  })

  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve))
  const { port } = server.address()
  const endpoint = `http://127.0.0.1:${port}/v1`

  /* --------------------------------------------------------- Seeding --- */

  const seededAt = new Date().toISOString()
  for (const [col, docs] of Object.entries(options.seed || {})) {
    const map = collectionOf(col)
    for (const doc of docs || []) {
      const { $id, $createdAt, $updatedAt, ...fields } = doc
      const id = $id || randomUUID()
      map.set(id, { $id: id, $createdAt: $createdAt || seededAt, $updatedAt: $updatedAt || seededAt, ...fields })
    }
  }

  function failNext({ method, pathIncludes, status }) {
    pendingFailures.push({ method, pathIncludes, status })
  }

  /** fn(collection, data) laeuft vor jeder Anlage (z. B. um einen gleichzeitigen Schreiber nachzustellen). */
  function setBeforeCreate(fn) {
    beforeCreate = fn || null
  }

  /** Dokument direkt in den Speicher legen (ohne HTTP), z. B. aus einem setBeforeCreate-Haken. */
  function insert(col, doc) {
    const now = new Date().toISOString()
    const id = doc.$id || randomUUID()
    const full = { $createdAt: now, $updatedAt: now, ...doc, $id: id }
    collectionOf(col).set(id, full)
    return full
  }

  function close() {
    for (const socket of sockets) socket.destroy()
    return new Promise((resolve) => server.close(() => resolve()))
  }

  return { endpoint, all, get, calls, failNext, setBeforeCreate, insert, close }
}