import { Application, Router, Status, send } from "oak";
import { config } from "./config.ts";
import { logger } from "./logger.ts";
import { rateLimiter } from "./rateLimiter.ts";
import {
  ensureUploadDir,
  getUniqueFilename,
  listUploadedFiles,
  cleanupExpiredFiles,
  isAllowedFileType,
  getMimeType,
  isViewableInBrowser,
} from "./fileUtils.ts";
import { renderUploadPage, renderBrowsePage, renderGalleryPage, renderError } from "./views.ts";

const app = new Application();
const router = new Router();

// Temporary storage for chunked uploads
const chunkStorage = new Map<string, { chunks: Uint8Array[]; totalChunks: number }>();

function getClientIP(ctx: any): string {
  return ctx.request.ip || "unknown";
}

// Static file serving
router.get("/css/:filename", async (ctx) => {
  const filename = ctx.params.filename;
  try {
    await send(ctx, filename, {
      root: `${Deno.cwd()}/static/css`,
    });
  } catch {
    ctx.response.status = Status.NotFound;
  }
});

// Routes
router.get("/", async (ctx) => {
  logger.request("INFO", "Page visit", { page: "/", ip: getClientIP(ctx) });
  ctx.response.headers.set("Content-Type", "text/html");
  ctx.response.body = await renderUploadPage(false);
});

router.get("/chunked", async (ctx) => {
  logger.request("INFO", "Page visit", { page: "/chunked", ip: getClientIP(ctx) });
  ctx.response.headers.set("Content-Type", "text/html");
  ctx.response.body = await renderUploadPage(true);
});

router.get("/browse", async (ctx) => {
  logger.request("INFO", "Page visit", { page: "/browse", ip: getClientIP(ctx) });
  const files = await listUploadedFiles();
  ctx.response.headers.set("Content-Type", "text/html");
  ctx.response.body = await renderBrowsePage(files);
});

router.get("/gallery", async (ctx) => {
  logger.request("INFO", "Page visit", { page: "/gallery", ip: getClientIP(ctx) });
  const files = await listUploadedFiles();
  ctx.response.headers.set("Content-Type", "text/html");
  ctx.response.body = await renderGalleryPage(files);
});

router.post("/upload", async (ctx) => {
  const ip = getClientIP(ctx);

  if (rateLimiter.isRateLimited(ip)) {
    logger.security("WARN", "Upload rejected: rate limit", { ip });
    ctx.response.status = Status.TooManyRequests;
    ctx.response.body = { error: "Rate limit exceeded. Please try again later." };
    return;
  }

  try {
    const body = ctx.request.body;
    const formData = await body.formData();
    const uploadedFiles: string[] = [];

    const files = formData.getAll("files");

    if (files.length === 0) {
      ctx.response.status = Status.BadRequest;
      ctx.response.body = { error: "No files provided" };
      return;
    }

    for (const file of files) {
      if (!(file instanceof File)) {
        continue;
      }

      // Check file size
      if (file.size > config.maxFileSize) {
        const maxMB = Math.floor(config.maxFileSize / (1024 * 1024));
        logger.upload("WARN", "File size exceeded", { filename: file.name, size: file.size, maxSize: config.maxFileSize, ip });
        ctx.response.status = Status.BadRequest;
        ctx.response.body = { error: `File ${file.name} exceeds maximum size of ${maxMB}MB` };
        return;
      }

      // Check file type
      if (!isAllowedFileType(file.type)) {
        logger.upload("WARN", "File type not allowed", { filename: file.name, type: file.type, ip });
        ctx.response.status = Status.BadRequest;
        ctx.response.body = { error: `File type ${file.type} is not allowed` };
        return;
      }

      // Get unique filename
      const filename = await getUniqueFilename(file.name);
      const filepath = `${config.uploadDir}/${filename}`;

      // Save file
      const arrayBuffer = await file.arrayBuffer();
      await Deno.writeFile(filepath, new Uint8Array(arrayBuffer));

      uploadedFiles.push(filename);
      logger.upload("INFO", "File uploaded successfully", { filename, size: file.size, ip });
    }

    ctx.response.status = Status.OK;
    ctx.response.body = { files: uploadedFiles };
  } catch (error) {
    logger.upload("ERROR", "Upload failed", { error: String(error), ip });
    ctx.response.status = Status.InternalServerError;
    ctx.response.body = { error: "Upload failed" };
  }
});

router.post("/upload-chunk", async (ctx) => {
  const ip = getClientIP(ctx);

  try {
    const body = ctx.request.body;
    const formData = await body.formData();

    const chunk = formData.get("chunk");
    const filename = formData.get("filename") as string;
    const chunkIndex = parseInt(formData.get("chunkIndex") as string);
    const totalChunks = parseInt(formData.get("totalChunks") as string);

    if (!(chunk instanceof File) || !filename || isNaN(chunkIndex) || isNaN(totalChunks)) {
      ctx.response.status = Status.BadRequest;
      ctx.response.body = { error: "Invalid chunk data" };
      return;
    }

    const storageKey = `${ip}:${filename}`;

    // Only apply rate limiting to the first chunk of each file
    if (chunkIndex === 0) {
      if (rateLimiter.isRateLimited(ip)) {
        logger.security("WARN", "Chunked upload rejected: rate limit", { ip, filename });
        ctx.response.status = Status.TooManyRequests;
        ctx.response.body = { error: "Rate limit exceeded. Please try again later." };
        return;
      }
    }

    // Initialize storage for this file
    if (!chunkStorage.has(storageKey)) {
      chunkStorage.set(storageKey, { chunks: [], totalChunks });
    }

    const storage = chunkStorage.get(storageKey)!;

    // Store chunk
    const arrayBuffer = await chunk.arrayBuffer();
    storage.chunks[chunkIndex] = new Uint8Array(arrayBuffer);

    // Check if all chunks received
    if (storage.chunks.filter(c => c).length === totalChunks) {
      // Combine all chunks
      const totalSize = storage.chunks.reduce((sum, chunk) => sum + chunk.length, 0);

      // Check total file size
      if (totalSize > config.maxFileSize) {
        chunkStorage.delete(storageKey);
        const maxMB = Math.floor(config.maxFileSize / (1024 * 1024));
        logger.upload("WARN", "Chunked file size exceeded", { filename, size: totalSize, maxSize: config.maxFileSize, ip });
        ctx.response.status = Status.BadRequest;
        ctx.response.body = { error: `File exceeds maximum size of ${maxMB}MB` };
        return;
      }

      const completeFile = new Uint8Array(totalSize);
      let offset = 0;
      for (const chunk of storage.chunks) {
        completeFile.set(chunk, offset);
        offset += chunk.length;
      }

      // Get unique filename and save
      const uniqueFilename = await getUniqueFilename(filename);
      const filepath = `${config.uploadDir}/${uniqueFilename}`;
      await Deno.writeFile(filepath, completeFile);

      // Clean up
      chunkStorage.delete(storageKey);

      logger.upload("INFO", "Chunked file uploaded successfully", { filename: uniqueFilename, size: totalSize, chunks: totalChunks, ip });
    }

    ctx.response.status = Status.OK;
    ctx.response.body = { success: true, chunkIndex, totalChunks };
  } catch (error) {
    logger.upload("ERROR", "Chunk upload failed", { error: String(error), ip });
    ctx.response.status = Status.InternalServerError;
    ctx.response.body = { error: "Chunk upload failed" };
  }
});

router.get("/download/:filename+", async (ctx) => {
  const encodedFilename = ctx.params.filename;
  const ip = getClientIP(ctx);

  if (!encodedFilename) {
    ctx.response.status = Status.BadRequest;
    ctx.response.headers.set("Content-Type", "text/html");
    ctx.response.body = await renderError("Filename is required", 400);
    return;
  }

  // Decode the filename to handle special characters and spaces
  const filename = decodeURIComponent(encodedFilename);
  const filepath = `${config.uploadDir}/${filename}`;

  try {
    const fileInfo = await Deno.stat(filepath);

    if (!fileInfo.isFile) {
      logger.download("WARN", "File not found (not a file)", { filename, ip });
      ctx.response.status = Status.NotFound;
      ctx.response.headers.set("Content-Type", "text/html");
      ctx.response.body = await renderError("File not found", 404);
      return;
    }

    const file = await Deno.readFile(filepath);
    const mimeType = getMimeType(filename);
    const viewableInBrowser = isViewableInBrowser(mimeType);

    logger.download("INFO", viewableInBrowser ? "File viewed" : "File downloaded", { filename, mimeType, size: file.length, ip });

    ctx.response.headers.set("Content-Type", mimeType);

    // Properly encode filename for Content-Disposition header
    // Use RFC 5987 encoding for non-ASCII characters
    const asciiFilename = filename.replace(/[^\x00-\x7F]/g, "_"); // Fallback for old browsers
    const encodedFilename = encodeURIComponent(filename);

    if (viewableInBrowser) {
      ctx.response.headers.set("Content-Disposition", `inline; filename="${asciiFilename}"; filename*=UTF-8''${encodedFilename}`);
    } else {
      ctx.response.headers.set("Content-Disposition", `attachment; filename="${asciiFilename}"; filename*=UTF-8''${encodedFilename}`);
    }

    ctx.response.body = file;
  } catch (error) {
    if (error instanceof Deno.errors.NotFound) {
      logger.download("WARN", "File not found", { filename, ip });
      ctx.response.status = Status.NotFound;
      ctx.response.headers.set("Content-Type", "text/html");
      ctx.response.body = await renderError("File not found", 404);
    } else {
      logger.download("ERROR", "Download failed", { filename, error: String(error), ip });
      ctx.response.status = Status.InternalServerError;
      ctx.response.headers.set("Content-Type", "text/html");
      ctx.response.body = await renderError("Failed to download file", 500);
    }
  }
});

// Middleware
app.use(async (ctx, next) => {
  const start = Date.now();
  await next();
  const ms = Date.now() - start;
  logger.request("DEBUG", `${ctx.request.method} ${ctx.request.url.pathname}`, {
    duration: ms,
    status: ctx.response.status,
    ip: getClientIP(ctx)
  });
});

app.use(router.routes());
app.use(router.allowedMethods());

// Initialize
await ensureUploadDir();
cleanupExpiredFiles();

logger.server("INFO", "Server starting", { port: config.port });

app.addEventListener("listen", ({ hostname, port, secure }) => {
  logger.server("INFO", "Server started", {
    url: `${secure ? "https" : "http"}://${hostname ?? "localhost"}:${port}`,
  });
});

await app.listen({ port: config.port });