import http from 'node:http'

/**
 * Appwrite-Nachbau für Tests: die REST-Pfade, die server/services/appwriteAdmin.js benutzt, im
 * Speicher. Mit schema = { collection: ['attr', ...] } lehnt er unbekannte Attribute ab wie
 * Appwrite ("Invalid document structure: Unknown attribute"). Dokument-IDs prüft er wie Appwrite
 * (höchstens 36 Zeichen aus a-z, A-Z, 0-9, Punkt, Bindestrich, Unterstrich, kein Sonderzeichen am
 * Anfang). failNext({ collection?, method?, status, message?, after? }) lässt die nächste passende Anfrage
 * mit diesem Status scheitern (Fehlerpfade wie "Appwrite nicht erreichbar" oder "Collection fehlt");
 * after = Zahl passender Anfragen, die vorher noch durchgehen (z. B. erst die zweite PATCH scheitert).
 */
export async function startAppwriteMock({ schema = {} } = {}) {
  const collections = new Map()
  let sequence = 0
  let pendingFailure = null

  // Wie Appwrite (Validator UID): 'unique()' ist erlaubt, sonst [A-Za-z0-9][A-Za-z0-9._-]{0,35}
  const validDocumentId = (id) => id === 'unique()' || (typeof id === 'string' && /^[A-Za-z0-9][A-Za-z0-9._-]{0,35}$/.test(id))
  const invalidDocumentId = [
    400,
    {
      message: 'Invalid `documentId` param: UID must contain at most 36 chars. Valid chars are a-z, A-Z, 0-9, period, hyphen, and underscore. Can\'t start with a special char',
      code: 400,
      type: 'general_argument_invalid',
    },
  ]

  const docs = (collection) => {
    if (!collections.has(collection)) collections.set(collection, new Map())
    return collections.get(collection)
  }

  const stamp = (doc, collection) => {
    const now = new Date().toISOString()
    return { $createdAt: now, $updatedAt: now, $collectionId: collection, ...doc, $seq: (sequence += 1) }
  }

  const seed = (collection, doc) => {
    if (!doc?.$id) throw new Error('seed: $id fehlt')
    docs(collection).set(doc.$id, stamp(doc, collection))
  }

  const unknownAttribute = (collection, data) => {
    const allowed = schema[collection]
    if (!allowed) return null
    return Object.keys(data).find((key) => !key.startsWith('$') && !allowed.includes(key)) || null
  }

  const matches = (doc, query) => {
    const value = doc[query.attribute]
    switch (query.method) {
      case 'equal':
        return query.values.includes(value)
      case 'greaterThan':
        return value > query.values[0]
      case 'lessThan':
        return value < query.values[0]
      default:
        return true
    }
  }

  const list = (collection, rawQueries) => {
    const queries = rawQueries.map((q) => JSON.parse(q))
    const unsupported = queries.find((q) => !['equal', 'greaterThan', 'lessThan', 'orderAsc', 'orderDesc', 'limit'].includes(q.method))
    if (unsupported) return [400, { message: `Query ${unsupported.method} wird nicht nachgebaut`, code: 400 }]
    let result = [...docs(collection).values()].filter((doc) => queries.every((q) => matches(doc, q)))
    for (const q of queries.filter((q) => q.method === 'orderAsc' || q.method === 'orderDesc')) {
      const dir = q.method === 'orderAsc' ? 1 : -1
      result.sort((a, b) => {
        const x = a[q.attribute]
        const y = b[q.attribute]
        if (x === y) return (a.$seq - b.$seq) * dir
        return (x > y ? 1 : -1) * dir
      })
    }
    const limit = queries.find((q) => q.method === 'limit')
    if (limit) result = result.slice(0, limit.values[0])
    return [200, { total: result.length, documents: result.map(publicDoc) }]
  }

  const publicDoc = ({ $seq, ...doc }) => doc

  const readBody = (req) =>
    new Promise((resolve) => {
      let raw = ''
      req.on('data', (chunk) => (raw += chunk))
      req.on('end', () => resolve(raw ? JSON.parse(raw) : {}))
    })

  const handle = async (req) => {
    const url = new URL(req.url, 'http://127.0.0.1')
    const docPath = url.pathname.match(/^\/v1\/databases\/[^/]+\/collections\/([^/]+)\/documents(?:\/([^/]+))?$/)
    const userPath = url.pathname.match(/^\/v1\/users\/([^/]+)$/)
    if (userPath && req.method === 'GET') return [200, { $id: userPath[1], passwordUpdate: '' }]
    // GET /v1/account (requireAppwriteStaff, Ticketsystem-JWT): jwt-admin = Mitarbeiter mit Label admin,
    // jwt-kunde = angemeldet ohne Label, alles andere 401 wie Appwrite bei einem ungueltigen JWT
    if (url.pathname === '/v1/account' && req.method === 'GET') {
      const jwt = req.headers['x-appwrite-jwt']
      if (jwt === 'jwt-admin') return [200, { $id: 'u_admin', email: 'kenso@webklar.com', labels: ['admin'] }]
      if (jwt === 'jwt-kunde') return [200, { $id: 'u_admin', email: 'kenso@webklar.com', labels: [] }]
      return [401, { message: 'User (role: guests) missing scope (account)', code: 401, type: 'general_unauthorized_scope' }]
    }
    if (!docPath) return [404, { message: 'Route not found', code: 404 }]

    const [, collection, id] = docPath
    const store = docs(collection)
    const notFound = [404, { message: 'Document with the requested ID could not be found.', code: 404, type: 'document_not_found' }]

    // Eingeplanter Fehler (failNext): genau eine passende Anfrage scheitert
    if (
      pendingFailure &&
      (!pendingFailure.collection || pendingFailure.collection === collection) &&
      (!pendingFailure.method || pendingFailure.method === req.method)
    ) {
      if (pendingFailure.after > 0) {
        pendingFailure.after -= 1
      } else {
        const { status, message } = pendingFailure
        pendingFailure = null
        return [status, { message: message || `Nachbau: eingeplanter Fehler ${status}`, code: status, type: 'general_server_error' }]
      }
    }

    if (!id && req.method === 'GET') return list(collection, url.searchParams.getAll('queries[]'))
    if (!id && req.method === 'POST') {
      const { documentId, data = {} } = await readBody(req)
      if (!validDocumentId(documentId)) return invalidDocumentId
      if (store.has(documentId)) {
        return [409, { message: 'Document with the requested ID already exists.', code: 409, type: 'document_already_exists' }]
      }
      const bad = unknownAttribute(collection, data)
      if (bad) return [400, { message: `Invalid document structure: Unknown attribute: "${bad}"`, code: 400 }]
      const doc = stamp({ ...data, $id: documentId }, collection)
      store.set(documentId, doc)
      return [201, publicDoc(doc)]
    }
    if (id && req.method === 'GET') return store.has(id) ? [200, publicDoc(store.get(id))] : notFound
    if (id && req.method === 'PATCH') {
      if (!store.has(id)) return notFound
      const { data = {} } = await readBody(req)
      const bad = unknownAttribute(collection, data)
      if (bad) return [400, { message: `Invalid document structure: Unknown attribute: "${bad}"`, code: 400 }]
      const doc = { ...store.get(id), ...data, $updatedAt: new Date().toISOString() }
      store.set(id, doc)
      return [200, publicDoc(doc)]
    }
    if (id && req.method === 'DELETE') {
      if (!store.delete(id)) return notFound
      return [204, null]
    }
    return [405, { message: 'Method not allowed', code: 405 }]
  }

  const server = http.createServer(async (req, res) => {
    try {
      const [status, body] = await handle(req)
      res.writeHead(status, { 'Content-Type': 'application/json' })
      res.end(body === null ? '' : JSON.stringify(body))
    } catch (err) {
      res.writeHead(500, { 'Content-Type': 'application/json' })
      res.end(JSON.stringify({ message: err.message, code: 500 }))
    }
  })
  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve))

  return {
    url: `http://127.0.0.1:${server.address().port}/v1`,
    docs: (collection) => new Map([...docs(collection)].map(([id, doc]) => [id, publicDoc(doc)])),
    seed,
    /** Naechste passende Dokument-Anfrage scheitert mit status (einmalig); after passende Anfragen gehen vorher durch. */
    failNext: ({ collection = null, method = null, status = 500, message = '', after = 0 }) => {
      pendingFailure = { collection, method, status, message, after }
    },
    close: () => new Promise((resolve) => server.close(resolve)),
  }
}