import { readFile, realpath, stat } from 'node:fs/promises';
import path from 'node:path';

const IMAGE_EXTENSIONS = new Set(['.png', '.jpg', '.jpeg', '.gif', '.webp', '.svg', '.bmp']);
const AUDIO_EXTENSIONS = new Set(['.mp3', '.wav', '.ogg', '.flac', '.m4a', '.aac']);
const MAX_IMAGE_BYTES = 8 * 1024 * 1024;
const MAX_AUDIO_BYTES = 16 * 1024 * 1024;
const MAX_MANIFEST_ITEMS = 100;

const MIME_BY_EXTENSION: Record<string, string> = {
  '.png': 'image/png', '.jpg': 'image/jpeg', '.jpeg': 'image/jpeg', '.gif': 'image/gif',
  '.webp': 'image/webp', '.svg': 'image/svg+xml', '.bmp': 'image/bmp',
  '.mp3': 'audio/mpeg', '.wav': 'audio/wav', '.ogg': 'audio/ogg', '.flac': 'audio/flac',
  '.m4a': 'audio/mp4', '.aac': 'audio/aac',
};

type PlanAsset = {
  id?: unknown; name?: unknown; category?: unknown; status?: unknown; purpose?: unknown;
  source?: unknown; license?: unknown; localPath?: unknown; previewPath?: unknown;
  coverPath?: unknown; manifestPaths?: unknown;
};

export type GameAssetCandidate = {
  id: string;
  name: string;
  category: string;
  status: string;
  purpose: string;
  source: string;
  license: string;
  localPath?: string;
  mediaKind: 'image' | 'audio' | 'bundle' | 'unavailable';
  previewDataUrl?: string;
  audioDataUrl?: string;
  manifest: string[];
  unavailableReason?: string;
};

function text(value: unknown): string {
  return typeof value === 'string' ? value.trim() : '';
}

function parseMarkdownCells(line: string): string[] | null {
  const trimmed = line.trim();
  if (!trimmed.includes('|')) return null;
  const withoutOuterPipes = trimmed.replace(/^\|/, '').replace(/\|$/, '');
  const cells = withoutOuterPipes.split('|').map((cell) => cell.trim());
  return cells.length >= 3 ? cells : null;
}

function isMarkdownSeparator(cells: string[]): boolean {
  return cells.every((cell) => /^:?-{3,}:?$/.test(cell.replace(/\s/g, '')));
}

function markdownAssetSlug(value: string): string {
  return value
    .toLowerCase()
    .replace(/[^a-z0-9\u4e00-\u9fff]+/gi, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 48);
}

function inferMarkdownAssetCategory(name: string, source: string, type = ''): string {
  const combined = `${name} ${source} ${type}`.toLowerCase();
  if (/音效|音频|音乐|🔊|sound|sfx|music/.test(combined)) return 'audio';
  if (/字体|界面|ui\b|font/.test(combined)) return 'ui';
  return 'visual';
}

function parseMarkdownAssetTables(content: string): PlanAsset[] {
  const assets: PlanAsset[] = [];
  const lines = content.split(/\r?\n/);

  for (let lineIndex = 0; lineIndex < lines.length; lineIndex += 1) {
    const headerCells = parseMarkdownCells(lines[lineIndex] ?? '');
    if (!headerCells) continue;
    const normalizedHeaders = headerCells.map((cell) => cell.replace(/[\s*_`]/g, '').toLowerCase());
    const nameIndex = normalizedHeaders.findIndex((cell) => /素材|资源|名称|asset|name/i.test(cell));
    const idIndex = normalizedHeaders.findIndex((cell) => /^id$|编号|标识|assetid/i.test(cell));
    const typeIndex = normalizedHeaders.findIndex((cell) => /类型|类别|type|category/i.test(cell));
    const sourceIndex = normalizedHeaders.findIndex((cell) => /来源|source/i.test(cell));
    const licenseIndex = normalizedHeaders.findIndex((cell) => /许可证|许可|授权|license/i.test(cell));
    const statusIndex = normalizedHeaders.findIndex((cell) => /状态|status/i.test(cell));
    const planIndex = normalizedHeaders.findIndex((cell) => /方案|计划|plan/i.test(cell));
    const hasSourceLicenseShape = nameIndex >= 0 && sourceIndex >= 0 && licenseIndex >= 0;
    const hasCandidateStatusShape = idIndex >= 0 && nameIndex >= 0 && statusIndex >= 0;
    if (!hasSourceLicenseShape && !hasCandidateStatusShape) continue;
    const lastRequiredIndex = hasSourceLicenseShape
      ? Math.max(nameIndex, sourceIndex, licenseIndex)
      : Math.max(idIndex, nameIndex, statusIndex);

    for (let rowIndex = lineIndex + 1; rowIndex < lines.length; rowIndex += 1) {
      const row = parseMarkdownCells(lines[rowIndex] ?? '');
      if (!row) break;
      if (isMarkdownSeparator(row)) continue;
      if (row.length <= lastRequiredIndex) continue;
      const rowId = idIndex >= 0 ? text(row[idIndex]) : '';
      const name = text(row[nameIndex]);
      if (!name) continue;
      const source = text(row[sourceIndex]);
      const license = text(row[licenseIndex]);
      const type = typeIndex >= 0 ? text(row[typeIndex]) : '';
      const status = statusIndex >= 0 ? text(row[statusIndex]) : '';
      const plan = planIndex >= 0 ? text(row[planIndex]) : '';
      const slug = markdownAssetSlug([name, source].filter(Boolean).join('-')) || `candidate-${assets.length + 1}`;
      assets.push({
        id: rowId || `asset-${slug}-${assets.length + 1}`,
        name,
        category: inferMarkdownAssetCategory(name, source, type),
        status: status || 'candidate',
        purpose: type || plan || name,
        source,
        license,
      });
    }
  }

  return assets;
}

function parsePlan(content: string): PlanAsset[] {
  for (const match of content.matchAll(/```(?:json)?\s*([\s\S]*?)```/gi)) {
    try {
      const value = JSON.parse(match[1] ?? '') as { assets?: unknown };
      if (Array.isArray(value.assets)) return value.assets as PlanAsset[];
    } catch {
      // Continue until the authoritative JSON block is found.
    }
  }
  return parseMarkdownAssetTables(content);
}

async function resolveInsideProject(projectPath: string, candidatePath: string): Promise<string | null> {
  if (!candidatePath || path.isAbsolute(candidatePath)) return null;
  const projectRealPath = await realpath(projectPath);
  const target = path.resolve(projectRealPath, candidatePath);
  const relative = path.relative(projectRealPath, target);
  if (!relative || relative.startsWith('..') || path.isAbsolute(relative)) return null;
  try {
    const targetRealPath = await realpath(target);
    const realRelative = path.relative(projectRealPath, targetRealPath);
    return !realRelative.startsWith('..') && !path.isAbsolute(realRelative) ? targetRealPath : null;
  } catch {
    return null;
  }
}

async function readMediaDataUrl(projectPath: string, candidatePath: string, maxBytes: number): Promise<string | null> {
  const resolved = await resolveInsideProject(projectPath, candidatePath);
  if (!resolved) return null;
  const fileStat = await stat(resolved);
  if (!fileStat.isFile() || fileStat.size > maxBytes) return null;
  const extension = path.extname(resolved).toLowerCase();
  const mime = MIME_BY_EXTENSION[extension];
  if (!mime) return null;
  return `data:${mime};base64,${(await readFile(resolved)).toString('base64')}`;
}

export async function loadGameAssetCandidates(projectPath: string): Promise<GameAssetCandidate[]> {
  const planContent = await readFile(path.join(projectPath, 'ASSET_PLAN.md'), 'utf8');
  return await Promise.all(parsePlan(planContent).map(async (asset, index) => {
    const id = text(asset.id) || `asset-${index + 1}`;
    const localPath = text(asset.localPath);
    const previewPath = text(asset.previewPath) || text(asset.coverPath) || localPath;
    const extension = path.extname(localPath || previewPath).toLowerCase();
    const category = text(asset.category) || 'other';
    const manifest = Array.isArray(asset.manifestPaths)
      ? asset.manifestPaths.map(text).filter(Boolean).slice(0, MAX_MANIFEST_ITEMS)
      : [];
    const common = {
      id,
      name: text(asset.name) || id,
      category,
      status: text(asset.status) || 'candidate',
      purpose: text(asset.purpose),
      source: text(asset.source),
      license: text(asset.license),
      ...(localPath ? { localPath } : {}),
      manifest,
    };

    if (IMAGE_EXTENSIONS.has(extension) || category === 'visual' || category === 'ui') {
      const previewDataUrl = await readMediaDataUrl(projectPath, previewPath, MAX_IMAGE_BYTES);
      return previewDataUrl
        ? { ...common, mediaKind: 'image' as const, previewDataUrl }
        : { ...common, mediaKind: 'unavailable' as const, unavailableReason: '候选素材还没有可预览的项目内图片' };
    }
    if (AUDIO_EXTENSIONS.has(extension) || category === 'audio') {
      const audioDataUrl = await readMediaDataUrl(projectPath, localPath, MAX_AUDIO_BYTES);
      return audioDataUrl
        ? { ...common, mediaKind: 'audio' as const, audioDataUrl }
        : { ...common, mediaKind: 'unavailable' as const, unavailableReason: '候选音频还没有保存到项目内，暂时无法试听' };
    }
    const previewDataUrl = previewPath ? await readMediaDataUrl(projectPath, previewPath, MAX_IMAGE_BYTES) : null;
    return {
      ...common,
      mediaKind: 'bundle' as const,
      ...(previewDataUrl ? { previewDataUrl } : {}),
      ...(!previewDataUrl && manifest.length === 0 ? { unavailableReason: '请让素材规划师补充封面或文件清单' } : {}),
    };
  }));
}