import crypto from 'node:crypto';

const PURPOSES = {
  inline_image: { presetId: 'memind_square_illustration', filename: 'inline-image.webp', envPrefix: 'INLINE_IMAGE' },
  hero: { presetId: 'memind_dark_hero', filename: 'hero.webp', envPrefix: 'HERO' },
  card_cover: { presetId: 'memind_card_cover', filename: 'card-cover.webp', envPrefix: 'CARD_COVER' },
  feed_cover: { presetId: 'memind_feed_cover_source', filename: 'feed-cover.webp', envPrefix: 'FEED_COVER' },
};

function htmlSrcForWorkspaceAsset(workspaceRelativePath) {
  const normalized = String(workspaceRelativePath ?? '').trim().replace(/\\/g, '/').replace(/^\/+/, '');
  if (!normalized.startsWith('public/')) return null;
  return normalized.slice('public/'.length) || null;
}

const IMAGE_MAKE_IDEMPOTENCY_KEY_MAX_LENGTH = 128;
const WECHAT_PAGE_THUMBNAIL_KEY_PATTERN = /^wechat-[a-zA-Z0-9._-]+-page-\d+-thumbnail$/;

function boundedIdempotencyKey(base, suffix = '') {
  const normalizedBase = String(base ?? '').trim();
  const normalizedSuffix = String(suffix ?? '');
  return `${normalizedBase.slice(0, Math.max(0, IMAGE_MAKE_IDEMPOTENCY_KEY_MAX_LENGTH - normalizedSuffix.length))}${normalizedSuffix}`;
}

function resolveImageMakeIdempotencyKey({ idempotencyKey, purpose, prompt, negativePrompt }) {
  const normalized = String(idempotencyKey ?? '').trim();
  if (!normalized) return `imgreq_${crypto.randomUUID()}`;
  if (purpose !== 'hero' || !WECHAT_PAGE_THUMBNAIL_KEY_PATTERN.test(normalized)) {
    return normalized;
  }
  const promptHash = crypto
    .createHash('sha256')
    .update([purpose, String(prompt ?? '').trim(), String(negativePrompt ?? '').trim()].join('\0'))
    .digest('hex')
    .slice(0, 12);
  return boundedIdempotencyKey(normalized, `-p-${promptHash}`);
}

function resolvePurposeDimensions(spec, env, logger) {
  const widthKey = `IMAGE_MAKE_${spec.envPrefix}_WIDTH`;
  const heightKey = `IMAGE_MAKE_${spec.envPrefix}_HEIGHT`;
  const rawWidth = String(env?.[widthKey] ?? '').trim();
  const rawHeight = String(env?.[heightKey] ?? '').trim();
  if (!rawWidth && !rawHeight) return {};
  const width = Number(rawWidth);
  const height = Number(rawHeight);
  const valid = Number.isInteger(width) && width >= 64 && width <= 4096
    && Number.isInteger(height) && height >= 64 && height <= 4096;
  if (!valid) {
    logger.warn?.(`[image_make] ignoring invalid ${widthKey}/${heightKey} override`);
    return {};
  }
  return { width, height };
}

export function createMindSpaceImageGenerationService({
  configService,
  assetService,
  imageMakeClient,
  imageReviewService,
  env = process.env,
  logger = console,
} = {}) {
  async function generate({
    userId,
    purpose,
    prompt,
    negativePrompt = '',
    consumerRef = '',
    idempotencyKey,
  } = {}) {
    const spec = PURPOSES[purpose];
    if (!spec) {
      return { ok: false, fallback: true, code: 'unsupported_purpose', message: '不支持的图片生成用途' };
    }
    if (!configService?.resolveImageGenerationPurpose) {
      return { ok: false, fallback: true, code: 'gateway_unavailable', message: '图片生成能力未启用' };
    }
    const gate = await configService.resolveImageGenerationPurpose(purpose);
    if (!gate.ok) return { ...gate, fallback: true };
    if (!imageMakeClient || !assetService?.createChatAsset) {
      return { ok: false, fallback: true, code: 'runtime_unavailable', message: '图片生成服务未配置' };
    }

    try {
      const dimensions = resolvePurposeDimensions(spec, env, logger);
      const configuredAttempts = Number(env.IMAGE_MAKE_SEMANTIC_REVIEW_MAX_ATTEMPTS ?? 3);
      const maxAttempts = Number.isFinite(configuredAttempts)
        ? Math.max(1, Math.min(3, Math.floor(configuredAttempts)))
        : 3;
      const baseIdempotencyKey = resolveImageMakeIdempotencyKey({
        idempotencyKey,
        purpose,
        prompt,
        negativePrompt,
      });
      let generated = null;
      let acceptedReview = null;
      let retryFeedback = '';

      for (let attempt = 1; attempt <= maxAttempts; attempt += 1) {
        const attemptPrompt = retryFeedback
          ? `${String(prompt).slice(0, 1100)}\n\n必须修正上次错误：${retryFeedback.slice(0, 400)}。画面必须以原始要求的主体和场景为核心。`
          : prompt;
        const attemptKey = attempt === 1
          ? baseIdempotencyKey
          : boundedIdempotencyKey(baseIdempotencyKey, `-review-${attempt}`);
        generated = await imageMakeClient.generateImage({
          prompt: attemptPrompt,
          negativePrompt,
          presetId: gate.presetId ?? spec.presetId,
          ...dimensions,
          consumerRef,
          idempotencyKey: attemptKey,
        });
        const review = await imageReviewService?.review?.({
          buffer: generated.buffer,
          mimeType: generated.mimeType,
          purpose,
          prompt,
        });
        if (!review?.ok) {
          throw Object.assign(new Error('图片语义审核暂不可用'), {
            code: review?.code ?? 'IMAGE_REVIEW_UNAVAILABLE',
          });
        }
        if (review.pass) {
          acceptedReview = review;
          break;
        }
        retryFeedback = [
          review.reason,
          review.observedSubjects?.length ? `错误主体：${review.observedSubjects.join('、')}` : '',
          review.missingRequiredElements?.length
            ? `缺失元素：${review.missingRequiredElements.join('、')}`
            : '',
        ].filter(Boolean).join('；');
        logger.warn?.(
          `[image-review] rejected ${purpose} attempt ${attempt}/${maxAttempts}: ${review.relevanceScore}`,
        );
      }

      if (!generated || !acceptedReview) {
        throw Object.assign(new Error('生成图片与页面内容不符'), {
          code: 'IMAGE_SEMANTIC_MISMATCH',
        });
      }
      const storedAsset = await assetService.createChatAsset(userId, {
        categoryCode: 'public',
        buffer: generated.buffer,
        filename: spec.filename,
        displayName: spec.filename,
        sourceType: 'image_make',
      });
      const htmlSrc = htmlSrcForWorkspaceAsset(storedAsset?.workspaceRelativePath);
      if (!htmlSrc) {
        throw Object.assign(new Error('generated asset has no public HTML source path'), {
          code: 'IMAGE_ASSET_PATH_UNAVAILABLE',
        });
      }
      const asset = { ...storedAsset, htmlSrc };
      await imageMakeClient.acknowledge(generated.jobId, asset.id).catch((error) => {
        logger.warn?.('[image_make] acknowledge failed; TTL cleanup will apply:', error?.message ?? error);
      });
      return {
        ok: true,
        purpose,
        jobId: generated.jobId,
        asset,
        source: {
          mimeType: generated.mimeType,
          width: generated.width,
          height: generated.height,
          sha256: generated.sha256,
        },
        review: {
          relevanceScore: acceptedReview.relevanceScore,
          minimumScore: acceptedReview.minimumScore,
          verdict: acceptedReview.verdict ?? 'pass',
        },
      };
    } catch (error) {
      logger.warn?.('[image_make] generation failed; existing flow remains active:', error?.message ?? error);
      return {
        ok: false,
        fallback: true,
        code: error?.code ?? 'image_make_unavailable',
        message: error?.code === 'IMAGE_SEMANTIC_MISMATCH'
          ? '生成图片与页面内容不符，已阻止使用'
          : '图片生成暂不可用，已保留原有流程',
      };
    }
  }

  return { purposes: Object.keys(PURPOSES), generate };
}