import { Router, Request, Response } from "express";
import rateLimit from "express-rate-limit";
import { renderPdf } from "../services/browser.js";
import { markdownToHtml, wrapHtml } from "../services/markdown.js";
import logger from "../services/logger.js";
import { sanitizeFilename } from "../utils/sanitize.js";
import { validatePdfOptions } from "../utils/pdf-options.js";

const router = Router();

const WATERMARK_SVG = `<svg xmlns='http://www.w3.org/2000/svg' width='400' height='200'><text transform='rotate(-35 200 100)' x='50%' y='50%' font-family='sans-serif' font-size='22' font-weight='bold' fill='rgba(52,211,153,0.22)' text-anchor='middle' dominant-baseline='middle'>DEMO — docfast.dev</text></svg>`;
const WATERMARK_BG = `data:image/svg+xml,${encodeURIComponent(WATERMARK_SVG)}`;
const WATERMARK_HTML = `
<div style="position:fixed;top:0;left:0;width:100%;height:100%;z-index:999999;pointer-events:none;background-image:url(&quot;${WATERMARK_BG}&quot;);background-repeat:repeat;background-size:400px 200px;"></div>
<div style="position:fixed;bottom:0;left:0;right:0;background:rgba(52,211,153,0.92);color:#0b0d11;text-align:center;padding:8px;font-family:sans-serif;font-size:12px;font-weight:bold;z-index:999999;letter-spacing:0.3px;">Generated by DocFast — docfast.dev | Upgrade to Pro for clean PDFs</div>`;

function injectWatermark(html: string): string {
  if (html.includes("</body>")) {
    return html.replace("</body>", WATERMARK_HTML + "</body>");
  }
  return html + WATERMARK_HTML;
}

// 5 requests per hour per IP
const demoLimiter = rateLimit({
  windowMs: 60 * 60 * 1000,
  max: 5,
  message: { error: "Demo limit reached (5/hour). Get a Pro API key at https://docfast.dev for unlimited access." },
  standardHeaders: true,
  legacyHeaders: false,
  keyGenerator: (req) => req.ip || req.socket.remoteAddress || "unknown",
});

router.use(demoLimiter);

interface DemoBody {
  html?: string;
  markdown?: string;
  css?: string;
  format?: string;
  landscape?: boolean;
  margin?: { top?: string; right?: string; bottom?: string; left?: string };
  printBackground?: boolean;
  filename?: string;
}

/**
 * @openapi
 * /v1/demo/html:
 *   post:
 *     tags: [Demo]
 *     summary: Convert HTML to PDF (demo)
 *     description: |
 *       Public endpoint — no API key required. Rate limited to 5 requests per hour per IP.
 *       Output PDFs include a DocFast watermark. Upgrade to Pro for clean output.
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             allOf:
 *               - type: object
 *                 required: [html]
 *                 properties:
 *                   html:
 *                     type: string
 *                     description: HTML content to convert
 *                     example: '<h1>Hello World</h1><p>My first PDF</p>'
 *                   css:
 *                     type: string
 *                     description: Optional CSS to inject (used when html is a fragment)
 *               - $ref: '#/components/schemas/PdfOptions'
 *     responses:
 *       200:
 *         description: Watermarked PDF document
 *         content:
 *           application/pdf:
 *             schema:
 *               type: string
 *               format: binary
 *       400:
 *         description: Missing html field
 *         content:
 *           application/json:
 *             schema:
 *               $ref: '#/components/schemas/Error'
 *       415:
 *         description: Unsupported Content-Type
 *       429:
 *         description: Demo rate limit exceeded (5/hour)
 *         content:
 *           application/json:
 *             schema:
 *               $ref: '#/components/schemas/Error'
 *       503:
 *         description: Server busy
 *       504:
 *         description: PDF generation timed out
 */
router.post("/html", async (req: Request, res: Response) => {
  let slotAcquired = false;
  try {
    const ct = req.headers["content-type"] || "";
    if (!ct.includes("application/json")) {
      res.status(415).json({ error: "Unsupported Content-Type. Use application/json." });
      return;
    }

    const body: DemoBody = typeof req.body === "string" ? { html: req.body } : req.body;
    if (!body.html) {
      res.status(400).json({ error: "Missing 'html' field" });
      return;
    }

    const validation = validatePdfOptions(body);
    if (!validation.valid) {
      res.status(400).json({ error: validation.error });
      return;
    }

    if (req.acquirePdfSlot) {
      await req.acquirePdfSlot();
      slotAcquired = true;
    }

    const fullHtml = body.html.includes("<html")
      ? injectWatermark(body.html)
      : injectWatermark(wrapHtml(body.html, body.css));

    const defaultOpts = {
      format: "A4" as const,
      landscape: false,
      printBackground: true,
      margin: { top: "0", right: "0", bottom: "0", left: "0" },
    };
    const { pdf, durationMs } = await renderPdf(fullHtml, {
      ...defaultOpts,
      ...validation.sanitized,
    });

    const filename = sanitizeFilename(body.filename || "demo.pdf");
    res.setHeader("Content-Type", "application/pdf");
    res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
    res.setHeader("Content-Length", pdf.length);
    res.setHeader("X-Render-Time", String(durationMs));
    res.send(pdf);
  } catch (err: any) {
    if (err.message === "QUEUE_FULL") {
      res.status(503).json({ error: "Server busy. Please try again in a moment." });
    } else if (err.message === "PDF_TIMEOUT") {
      res.status(504).json({ error: "PDF generation timed out." });
    } else {
      logger.error({ err }, "Demo HTML conversion failed");
      res.status(500).json({ error: "PDF generation failed." });
    }
  } finally {
    if (slotAcquired && req.releasePdfSlot) req.releasePdfSlot();
  }
});

/**
 * @openapi
 * /v1/demo/markdown:
 *   post:
 *     tags: [Demo]
 *     summary: Convert Markdown to PDF (demo)
 *     description: |
 *       Public endpoint — no API key required. Rate limited to 5 requests per hour per IP.
 *       Markdown is converted to HTML then rendered to PDF with a DocFast watermark.
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             allOf:
 *               - type: object
 *                 required: [markdown]
 *                 properties:
 *                   markdown:
 *                     type: string
 *                     description: Markdown content to convert
 *                     example: '# Hello World\n\nThis is **bold** and *italic*.'
 *                   css:
 *                     type: string
 *                     description: Optional CSS to inject
 *               - $ref: '#/components/schemas/PdfOptions'
 *     responses:
 *       200:
 *         description: Watermarked PDF document
 *         content:
 *           application/pdf:
 *             schema:
 *               type: string
 *               format: binary
 *       400:
 *         description: Missing markdown field
 *       415:
 *         description: Unsupported Content-Type
 *       429:
 *         description: Demo rate limit exceeded (5/hour)
 *       503:
 *         description: Server busy
 *       504:
 *         description: PDF generation timed out
 */
router.post("/markdown", async (req: Request, res: Response) => {
  let slotAcquired = false;
  try {
    const ct = req.headers["content-type"] || "";
    if (!ct.includes("application/json")) {
      res.status(415).json({ error: "Unsupported Content-Type. Use application/json." });
      return;
    }

    const body: DemoBody = typeof req.body === "string" ? { markdown: req.body } : req.body;
    if (!body.markdown) {
      res.status(400).json({ error: "Missing 'markdown' field" });
      return;
    }

    const validation = validatePdfOptions(body);
    if (!validation.valid) {
      res.status(400).json({ error: validation.error });
      return;
    }

    if (req.acquirePdfSlot) {
      await req.acquirePdfSlot();
      slotAcquired = true;
    }

    const htmlContent = markdownToHtml(body.markdown);
    const fullHtml = injectWatermark(wrapHtml(htmlContent, body.css));

    const defaultOpts = {
      format: "A4" as const,
      landscape: false,
      printBackground: true,
      margin: { top: "0", right: "0", bottom: "0", left: "0" },
    };
    const { pdf, durationMs } = await renderPdf(fullHtml, {
      ...defaultOpts,
      ...validation.sanitized,
    });

    const filename = sanitizeFilename(body.filename || "demo.pdf");
    res.setHeader("Content-Type", "application/pdf");
    res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
    res.setHeader("Content-Length", pdf.length);
    res.setHeader("X-Render-Time", String(durationMs));
    res.send(pdf);
  } catch (err: any) {
    if (err.message === "QUEUE_FULL") {
      res.status(503).json({ error: "Server busy. Please try again in a moment." });
    } else if (err.message === "PDF_TIMEOUT") {
      res.status(504).json({ error: "PDF generation timed out." });
    } else {
      logger.error({ err }, "Demo markdown conversion failed");
      res.status(500).json({ error: "PDF generation failed." });
    }
  } finally {
    if (slotAcquired && req.releasePdfSlot) req.releasePdfSlot();
  }
});

export { router as demoRouter };