import type {
  AsEntriesResponse,
  CdnSourcesResponse,
  DomainEntriesResponse,
  IpRangeEntriesResponse,
  JobRow,
  ModuleType,
  RevisionPrefix,
  RevisionPrefixesResponse,
} from '@/types/api'

export const TOKEN_STORAGE_KEY = 'evobgp_api_token'

/** Локальный demo-токен (operator) при включённом demo-seed — см. docs/access.md */
export const DEV_API_TOKEN = 'dev'

export type Problem = {
  type?: string
  title?: string
  status?: number
  detail?: string
}

/** Убирает пробелы и опциональный префикс Bearer (UI часто вставляет «Bearer dev»). */
export function normalizeApiToken(raw: string): string {
  let t = raw.trim()
  if (/^bearer\s+/i.test(t)) {
    t = t.replace(/^bearer\s+/i, '').trim()
  }
  return t
}

function getToken(): string | null {
  if (typeof window === 'undefined') return null
  const raw = window.localStorage.getItem(TOKEN_STORAGE_KEY)
  if (!raw) return null
  const normalized = normalizeApiToken(raw)
  return normalized || null
}

export function setToken(token: string | null): void {
  if (typeof window === 'undefined') return
  if (!token) {
    window.localStorage.removeItem(TOKEN_STORAGE_KEY)
    return
  }
  const normalized = normalizeApiToken(token)
  if (normalized) window.localStorage.setItem(TOKEN_STORAGE_KEY, normalized)
  else window.localStorage.removeItem(TOKEN_STORAGE_KEY)
}

function mergeHeaders(init?: RequestInit, extraHeaders?: Record<string, string>): Headers {
  const h = new Headers(init?.headers)
  if (!h.has('Accept')) h.set('Accept', 'application/json')
  const t = getToken()
  if (t && !h.has('Authorization')) h.set('Authorization', `Bearer ${t}`)
  if (extraHeaders) {
    for (const [k, v] of Object.entries(extraHeaders)) {
      if (!h.has(k)) h.set(k, v)
    }
  }
  return h
}

/**
 * Idempotency keys: `crypto.randomUUID()` exists only in secure contexts (HTTPS / localhost).
 * Over plain HTTP to a LAN IP it is often undefined — use getRandomValues or a fallback.
 */
function newIdempotencyKey(): string {
  const c = typeof globalThis !== 'undefined' ? globalThis.crypto : undefined
  if (c?.randomUUID) return c.randomUUID()
  if (c?.getRandomValues) {
    const buf = new Uint8Array(16)
    c.getRandomValues(buf)
    buf[6] = (buf[6]! & 0x0f) | 0x40
    buf[8] = (buf[8]! & 0x3f) | 0x80
    const hex = [...buf].map((b) => b.toString(16).padStart(2, '0')).join('')
    return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`
  }
  return `idem-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 14)}`
}

export class ApiError extends Error {
  constructor(
    public readonly status: number,
    message: string,
    public readonly problem?: Problem,
  ) {
    super(message)
  }
}

export async function apiFetch(path: string, init?: RequestInit): Promise<Response> {
  if (typeof window === 'undefined') throw new Error('API is only available in the browser')
  return fetch(path, { ...init, headers: mergeHeaders(init) })
}

/** GET / DELETE без тела */
export async function apiJSON<T>(path: string, init?: RequestInit): Promise<T> {
  const res = await apiFetch(path, init)
  return parseResponse<T>(res)
}

/** POST / PATCH / PUT с JSON-телом и автоматическим Idempotency-Key */
export async function apiMutate<T = void>(
  path: string,
  method: 'POST' | 'PATCH' | 'PUT' | 'DELETE',
  body?: unknown,
  opts?: { idempotent?: boolean },
): Promise<T> {
  const headers: Record<string, string> = {}
  if (body !== undefined) headers['Content-Type'] = 'application/json'
  if (opts?.idempotent !== false) {
    headers['Idempotency-Key'] = newIdempotencyKey()
  }
  const res = await fetch(path, {
    method,
    headers: mergeHeaders({ headers }, headers),
    body: body !== undefined ? JSON.stringify(body) : undefined,
  })
  return parseResponse<T>(res)
}

async function parseResponse<T>(res: Response): Promise<T> {
  if (res.status === 204 || res.status === 205) return undefined as T
  const text = await res.text()
  if (!res.ok) {
    let problem: Problem | undefined
    let detail = `HTTP ${res.status}`
    try {
      problem = JSON.parse(text) as Problem
      detail = problem.detail ?? problem.title ?? detail
    } catch {
      if (text) detail = text
    }
    throw new ApiError(res.status, detail, problem)
  }
  if (!text) return undefined as T
  return JSON.parse(text) as T
}

const terminalJobStatuses = new Set(['succeeded', 'failed', 'cancelled'])

/** Ожидает завершения фоновой задачи (poll GET /v1/jobs/{id}). */
export async function waitForJob(
  jobId: string,
  opts?: { pollMs?: number; timeoutMs?: number },
): Promise<JobRow> {
  const pollMs = opts?.pollMs ?? 400
  const timeoutMs = opts?.timeoutMs ?? 120000
  const deadline = Date.now() + timeoutMs
  while (Date.now() < deadline) {
    const j = await apiJSON<JobRow>(`/v1/jobs/${jobId}`)
    if (terminalJobStatuses.has(j.status)) return j
    await new Promise((r) => setTimeout(r, pollMs))
  }
  throw new Error(`Таймаут ожидания задачи ${jobId}`)
}

export async function apiPageAll<T>(path: string, limit = 500): Promise<T[]> {
  const items: T[] = []
  let cursor: string | null = null
  while (true) {
    const [basePath, rawQuery = ''] = path.split('?')
    const query = new URLSearchParams(rawQuery)
    if (!query.has('limit')) query.set('limit', String(limit))
    if (cursor) query.set('cursor', cursor)
    else query.delete('cursor')
    const page = await apiJSON<{ items?: T[]; next_cursor?: string | null; has_more?: boolean }>(
      `${basePath}?${query.toString()}`,
    )
    items.push(...(page.items ?? []))
    if (!page.has_more || !page.next_cursor) break
    cursor = page.next_cursor
  }
  return items
}

export async function fetchRevisionPrefixesAll(revisionId: string): Promise<RevisionPrefix[]> {
  const items = await apiPageAll<RevisionPrefix>(`/v1/revisions/${revisionId}/prefixes`)
  return items
}

export async function fetchRevisionPrefixesResponse(
  revisionId: string,
  cursor?: string | null,
  limit = 500,
): Promise<RevisionPrefixesResponse> {
  const query = new URLSearchParams({ limit: String(limit) })
  if (cursor) query.set('cursor', cursor)
  return apiJSON<RevisionPrefixesResponse>(`/v1/revisions/${revisionId}/prefixes?${query.toString()}`)
}

export async function fetchModuleSourceCatalog(moduleId: string, moduleType: ModuleType) {
  if (moduleType === 'DOMAINS') {
    const entries = await apiPageAll<DomainEntriesResponse['items'][number]>(
      `/v1/modules/${moduleId}/domain-entries`,
    )
    return { domains: entries }
  }
  if (moduleType === 'AS_PREFIXES') {
    const entries = await apiPageAll<AsEntriesResponse['items'][number]>(
      `/v1/modules/${moduleId}/as-entries`,
    )
    return { asns: entries }
  }
  if (moduleType === 'CDN_CIDRS') {
    const entries = await apiPageAll<CdnSourcesResponse['items'][number]>(
      `/v1/modules/${moduleId}/cdn-sources`,
    )
    return { cdnSources: entries }
  }
  if (moduleType === 'IP_RANGES') {
    const entries = await apiPageAll<IpRangeEntriesResponse['items'][number]>(
      `/v1/modules/${moduleId}/ip-range-entries`,
    )
    return { ipRanges: entries }
  }
  return {}
}