import {
  Controller,
  Get,
  NotFoundException,
  Param,
  Res,
} from '@nestjs/common';
import type { Response } from 'express';
import { createReadStream, existsSync } from 'fs';
import { basename, extname, join } from 'path';
import { resolveWebsiteDocsRoot } from './website-docs.paths';

const ALLOWED_FILES = new Set([
  'index.html',
  'openapi.json',
  'AI_PROMPT.md',
  'Meshkee-Website-API.postman_collection.json',
  'Meshkee-Website-API.global.postman_environment.json',
]);

const CONTENT_TYPES: Record<string, string> = {
  '.html': 'text/html; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.md': 'text/markdown; charset=utf-8',
};

@Controller('docs/website')
export class WebsiteDocsController {
  private readonly root = resolveWebsiteDocsRoot();

  @Get()
  getIndex(@Res() res: Response) {
    return this.sendFile(res, 'index.html');
  }

  @Get(':fileName')
  getFile(@Param('fileName') fileName: string, @Res() res: Response) {
    const safe = basename(fileName);
    if (!ALLOWED_FILES.has(safe)) {
      throw new NotFoundException(`Unknown docs file: ${fileName}`);
    }
    return this.sendFile(res, safe);
  }

  private sendFile(res: Response, fileName: string) {
    const filePath = join(this.root, fileName);
    if (!existsSync(filePath)) {
      throw new NotFoundException(
        `Website docs not found on server (${fileName}). Deploy docs/website-api/ with the API.`,
      );
    }

    const type = CONTENT_TYPES[extname(fileName)] ?? 'application/octet-stream';
    res.setHeader('Content-Type', type);
    res.setHeader('Cache-Control', 'public, max-age=300');
    createReadStream(filePath).pipe(res);
  }
}