import crypto from 'node:crypto';

const SUPPORTED_IMAGE_TYPES = new Set(['image/png', 'image/jpeg', 'image/webp']);
const ACTIVE_STATUSES = new Set(['queued', 'submitted', 'running', 'validating']);
const DEFAULT_MAX_RESULT_BYTES = 20 * 1024 * 1024;

function positiveInteger(value, fallback) {
  const number = Number(value);
  return Number.isFinite(number) && number > 0 ? Math.floor(number) : fallback;
}

function normalizeBaseUrl(value) {
  const url = new URL(String(value ?? '').trim());
  if (!['http:', 'https:'].includes(url.protocol) || url.username || url.password) {
    throw new Error('image_make base URL is invalid');
  }
  url.pathname = url.pathname.replace(/\/+$/, '');
  url.search = '';
  url.hash = '';
  return url.toString().replace(/\/$/, '');
}

function imageMagicMatches(buffer, mimeType) {
  if (mimeType === 'image/png') {
    return buffer.length >= 8 && buffer.subarray(0, 8).equals(Buffer.from('89504e470d0a1a0a', 'hex'));
  }
  if (mimeType === 'image/jpeg') {
    return buffer.length >= 3 && buffer[0] === 0xff && buffer[1] === 0xd8 && buffer[2] === 0xff;
  }
  if (mimeType === 'image/webp') {
    return buffer.length >= 12
      && buffer.subarray(0, 4).toString('ascii') === 'RIFF'
      && buffer.subarray(8, 12).toString('ascii') === 'WEBP';
  }
  return false;
}

async function safeJson(response) {
  try {
    return await response.json();
  } catch {
    return null;
  }
}

function createClientError(code, message, details = {}) {
  return Object.assign(new Error(message), { code, ...details });
}

export function createImageMakeClient({
  baseUrl,
  token,
  fetchImpl = globalThis.fetch,
  requestTimeoutMs = 15_000,
  generationTimeoutMs = 15 * 60_000,
  pollIntervalMs = 1_000,
  maxResultBytes = DEFAULT_MAX_RESULT_BYTES,
  sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms)),
} = {}) {
  if (typeof fetchImpl !== 'function') throw new Error('image_make fetch implementation is required');
  const normalizedBaseUrl = normalizeBaseUrl(baseUrl);
  const bearerToken = String(token ?? '').trim();
  if (!bearerToken) throw new Error('image_make token is required');
  const perRequestTimeout = positiveInteger(requestTimeoutMs, 15_000);
  const overallTimeout = positiveInteger(generationTimeoutMs, 15 * 60_000);
  const pollingDelay = positiveInteger(pollIntervalMs, 1_000);
  const resultLimit = positiveInteger(maxResultBytes, DEFAULT_MAX_RESULT_BYTES);

  async function request(pathname, init = {}, expectedStatuses = [200]) {
    const response = await fetchImpl(new URL(pathname, `${normalizedBaseUrl}/`), {
      ...init,
      headers: {
        accept: 'application/json',
        authorization: `Bearer ${bearerToken}`,
        ...(init.body ? { 'content-type': 'application/json' } : {}),
        ...(init.headers ?? {}),
      },
      signal: AbortSignal.timeout(perRequestTimeout),
    });
    if (!expectedStatuses.includes(response.status)) {
      const body = await safeJson(response);
      throw createClientError(
        'IMAGE_MAKE_HTTP_ERROR',
        body?.error_message_safe ?? body?.message ?? `image_make request failed (${response.status})`,
        { status: response.status },
      );
    }
    return response;
  }

  async function generateImage({
    prompt,
    negativePrompt = '',
    presetId,
    presetVersion = 1,
    width,
    height,
    consumerRef,
    idempotencyKey = `imgreq_${crypto.randomUUID()}`,
  } = {}) {
    const normalizedPrompt = String(prompt ?? '').trim();
    if (!normalizedPrompt) throw createClientError('INVALID_PROMPT', '图片描述不能为空');
    if (!presetId) throw createClientError('INVALID_PRESET', '图片 preset 不能为空');

    const createResponse = await request('/v1/generation-jobs', {
      method: 'POST',
      headers: { 'idempotency-key': idempotencyKey },
      body: JSON.stringify({
        idempotency_key: idempotencyKey,
        mode: 'text_to_image',
        prompt: normalizedPrompt,
        negative_prompt: String(negativePrompt ?? '').trim(),
        preset: { id: presetId, version: presetVersion },
        ...(width && height ? { width, height } : {}),
        count: 1,
        output_format: 'webp',
        consumer_ref: String(consumerRef ?? '').trim() || undefined,
      }),
    }, [200, 201]);
    const created = await safeJson(createResponse);
    const jobId = String(created?.job_id ?? '').trim();
    if (!jobId) throw createClientError('IMAGE_MAKE_INVALID_RESPONSE', 'image_make 未返回任务 ID');

    const deadline = Date.now() + overallTimeout;
    let job = created;
    if (!ACTIVE_STATUSES.has(String(job?.status ?? '')) && !job?.result && created?.status_url) {
      job = await safeJson(await request(created.status_url));
    }
    while (ACTIVE_STATUSES.has(String(job?.status ?? ''))) {
      if (Date.now() >= deadline) {
        throw createClientError('IMAGE_MAKE_TIMEOUT', '图片生成超时', { jobId });
      }
      await sleep(Math.min(pollingDelay, Math.max(1, deadline - Date.now())));
      job = await safeJson(await request(`/v1/generation-jobs/${encodeURIComponent(jobId)}`));
    }
    if (job?.status !== 'succeeded' || !job?.result?.download_url) {
      throw createClientError(
        'IMAGE_MAKE_JOB_FAILED',
        job?.error_message_safe ?? '图片生成失败',
        { jobId, jobStatus: job?.status ?? 'unknown' },
      );
    }

    const download = await request(job.result.download_url, {
      headers: { accept: 'image/png,image/jpeg,image/webp' },
    });
    const mimeType = String(download.headers.get('content-type') ?? '').split(';')[0].trim().toLowerCase();
    if (!SUPPORTED_IMAGE_TYPES.has(mimeType)) {
      throw createClientError('IMAGE_MAKE_INVALID_RESULT', 'image_make 返回了不支持的图片格式', { jobId });
    }
    const declaredSize = Number(download.headers.get('content-length') ?? 0);
    if (declaredSize > resultLimit) {
      throw createClientError('IMAGE_MAKE_RESULT_TOO_LARGE', 'image_make 图片超过大小限制', { jobId });
    }
    const buffer = Buffer.from(await download.arrayBuffer());
    if (!buffer.length || buffer.length > resultLimit || !imageMagicMatches(buffer, mimeType)) {
      throw createClientError('IMAGE_MAKE_INVALID_RESULT', 'image_make 图片内容校验失败', { jobId });
    }
    const sha256 = crypto.createHash('sha256').update(buffer).digest('hex');
    const expectedHashes = [job.result.sha256, download.headers.get('x-artifact-sha256')]
      .map((value) => String(value ?? '').trim().toLowerCase())
      .filter(Boolean);
    if (expectedHashes.some((value) => value !== sha256)) {
      throw createClientError('IMAGE_MAKE_CHECKSUM_MISMATCH', 'image_make 图片摘要校验失败', { jobId });
    }
    return {
      jobId,
      buffer,
      mimeType,
      sha256,
      width: Number(job.result.width ?? 0) || null,
      height: Number(job.result.height ?? 0) || null,
    };
  }

  async function acknowledge(jobId, consumerAssetRef) {
    await request(`/v1/generation-jobs/${encodeURIComponent(jobId)}/acknowledge`, {
      method: 'POST',
      body: JSON.stringify({ consumer_asset_ref: consumerAssetRef }),
    });
    return { ok: true };
  }

  return { baseUrl: normalizedBaseUrl, generateImage, acknowledge };
}

export function createImageMakeClientFromEnv(env = process.env, options = {}) {
  const baseUrl = String(env.IMAGE_MAKE_BASE_URL ?? '').trim();
  const token = String(env.IMAGE_MAKE_TOKEN ?? '').trim();
  if (!baseUrl || !token) return null;
  return createImageMakeClient({
    baseUrl,
    token,
    requestTimeoutMs: env.IMAGE_MAKE_REQUEST_TIMEOUT_MS,
    generationTimeoutMs: env.IMAGE_MAKE_GENERATION_TIMEOUT_MS,
    pollIntervalMs: env.IMAGE_MAKE_POLL_INTERVAL_MS,
    maxResultBytes: env.IMAGE_MAKE_MAX_RESULT_BYTES,
    ...options,
  });
}