const endpoint = process.env.APPWRITE_SELF_HOSTED_URL || 'https://app.friborg.uk/v1'
const projectId = process.env.APPWRITE_SELF_HOSTED_PROJECT_ID || 'freecastle'

export const BUILDPULSE_DATABASE_ID = process.env.BUILDPULSE_APPWRITE_DATABASE_ID || process.env.APPWRITE_SELF_HOSTED_DATABASE_ID || 'freecastle'
export const BUILDPULSE_COLLECTION_ID = process.env.BUILDPULSE_APPWRITE_COLLECTION_ID || 'runtime'
export const BUILDPULSE_DOCUMENT_ID = process.env.BUILDPULSE_APPWRITE_DOCUMENT_ID || 'buildpulse_state'
export const BUILDPULSE_DOCUMENT_KEY = process.env.BUILDPULSE_APPWRITE_DOCUMENT_KEY || 'buildpulse_state'

const baseHeaders = {
  'Content-Type': 'application/json',
  'X-Appwrite-Project': projectId,
}

const REQUEST_TIMEOUT_MS = Number(process.env.BUILDPULSE_APPWRITE_TIMEOUT_MS || 4500)
const documentUrl = `${endpoint}/databases/${BUILDPULSE_DATABASE_ID}/collections/${BUILDPULSE_COLLECTION_ID}/documents/${BUILDPULSE_DOCUMENT_ID}`
const collectionUrl = `${endpoint}/databases/${BUILDPULSE_DATABASE_ID}/collections/${BUILDPULSE_COLLECTION_ID}/documents`

async function appwriteFetch(url, init = {}) {
  const controller = new AbortController()
  const timeout = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS)

  let response
  try {
    response = await fetch(url, {
      ...init,
      signal: init.signal || controller.signal,
      headers: {
        ...baseHeaders,
        ...(init.headers || {}),
      },
    })
  } catch (error) {
    if (error?.name === 'AbortError') {
      const timeoutError = new Error(`Appwrite request timed out after ${REQUEST_TIMEOUT_MS}ms`)
      timeoutError.status = 504
      throw timeoutError
    }
    throw error
  } finally {
    clearTimeout(timeout)
  }

  if (response.status === 204) return null

  const text = await response.text()
  const payload = text ? JSON.parse(text) : null

  if (!response.ok) {
    const error = new Error(payload?.message || `Appwrite request failed with ${response.status}`)
    error.status = response.status
    error.payload = payload
    throw error
  }

  return payload
}

export async function fetchStoredAppState() {
  try {
    const document = await appwriteFetch(documentUrl)
    return document?.value ? JSON.parse(document.value) : null
  } catch (error) {
    if (error?.status === 404) return null
    throw error
  }
}

export async function persistAppState(state) {
  const body = {
    data: {
      key: BUILDPULSE_DOCUMENT_KEY,
      value: JSON.stringify(state),
      updatedAt: new Date().toISOString(),
    },
  }

  try {
    return await appwriteFetch(documentUrl, {
      method: 'PATCH',
      body: JSON.stringify(body),
    })
  } catch (error) {
    if (error?.status !== 404) throw error
  }

  return appwriteFetch(collectionUrl, {
    method: 'POST',
    body: JSON.stringify({
      documentId: BUILDPULSE_DOCUMENT_ID,
      ...body,
    }),
  })
}

export async function checkBackendHealth() {
  const document = await appwriteFetch(documentUrl).catch((error) => {
    if (error?.status === 404) return null
    throw error
  })

  return {
    ok: true,
    backend: 'appwrite',
    endpoint,
    databaseId: BUILDPULSE_DATABASE_ID,
    collectionId: BUILDPULSE_COLLECTION_ID,
    documentPresent: Boolean(document),
  }
}