/**
 * WebDAV protocol handler
 * Implements RFC 4918 for network drive mounting
 */

import * as plugins from '../../plugins.js';
import type { IWebDAVConfig, IRequestContext } from '../../core/smartserve.interfaces.js';
import type {
  TWebDAVMethod,
  TWebDAVDepth,
  IWebDAVResource,
  IWebDAVLock,
  IWebDAVContext,
} from './webdav.types.js';
import {
  generateMultistatus,
  generateLockResponse,
  generateError,
  parsePropfindRequest,
} from './webdav.xml.js';
import { getMimeType } from '../../utils/utils.mime.js';
import { generateETag } from '../../utils/utils.etag.js';

/**
 * WebDAV handler for serving files with WebDAV protocol
 */
export class WebDAVHandler {
  private config: IWebDAVConfig;
  private locks: Map<string, IWebDAVLock> = new Map();

  constructor(config: IWebDAVConfig) {
    this.config = {
      locking: true,
      ...config,
    };
  }

  /**
   * Check if request is a WebDAV request
   */
  isWebDAVRequest(request: Request): boolean {
    const method = request.method.toUpperCase();
    const webdavMethods = ['PROPFIND', 'PROPPATCH', 'MKCOL', 'COPY', 'MOVE', 'LOCK', 'UNLOCK'];
    return webdavMethods.includes(method);
  }

  /**
   * Handle WebDAV request
   */
  async handle(request: Request): Promise<Response> {
    const method = request.method.toUpperCase() as TWebDAVMethod;
    const url = new URL(request.url);
    const path = decodeURIComponent(url.pathname);

    // Security check
    if (path.includes('..')) {
      return new Response('Forbidden', { status: 403 });
    }

    // Parse WebDAV context
    const context = this.parseContext(request);

    // Authentication
    if (this.config.auth) {
      const mockCtx = { headers: request.headers } as IRequestContext;
      const authenticated = await this.config.auth(mockCtx);
      if (!authenticated) {
        return new Response('Unauthorized', {
          status: 401,
          headers: { 'WWW-Authenticate': 'Basic realm="WebDAV"' },
        });
      }
    }

    try {
      switch (method) {
        case 'OPTIONS':
          return this.handleOptions();
        case 'PROPFIND':
          return await this.handlePropfind(request, path, context);
        case 'PROPPATCH':
          return await this.handleProppatch(request, path);
        case 'MKCOL':
          return await this.handleMkcol(path);
        case 'COPY':
          return await this.handleCopy(path, context);
        case 'MOVE':
          return await this.handleMove(path, context);
        case 'LOCK':
          return await this.handleLock(request, path, context);
        case 'UNLOCK':
          return await this.handleUnlock(path, context);
        case 'GET':
        case 'HEAD':
          return await this.handleGet(request, path, method === 'HEAD');
        case 'PUT':
          return await this.handlePut(request, path, context);
        case 'DELETE':
          return await this.handleDelete(path, context);
        default:
          return new Response('Method Not Allowed', { status: 405 });
      }
    } catch (error: any) {
      console.error('WebDAV error:', error);
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      return new Response('Internal Server Error', { status: 500 });
    }
  }

  /**
   * Parse WebDAV-specific headers into context
   */
  private parseContext(request: Request): IWebDAVContext {
    const depth = (request.headers.get('Depth') ?? '1') as TWebDAVDepth;
    const destination = request.headers.get('Destination') ?? undefined;
    const overwrite = request.headers.get('Overwrite') !== 'F';
    const lockToken = request.headers.get('Lock-Token')?.replace(/[<>]/g, '');
    const timeout = this.parseTimeout(request.headers.get('Timeout'));

    return {
      method: request.method.toUpperCase() as TWebDAVMethod,
      depth: depth === 'infinity' ? 'infinity' : depth === '0' ? '0' : '1',
      destination,
      overwrite,
      lockToken,
      timeout,
    };
  }

  /**
   * Parse timeout header
   */
  private parseTimeout(header: string | null): number {
    if (!header) return 3600; // 1 hour default
    const match = header.match(/Second-(\d+)/i);
    if (match) return parseInt(match[1], 10);
    if (header.toLowerCase() === 'infinite') return 0;
    return 3600;
  }

  /**
   * Resolve file path
   */
  private resolvePath(path: string): string {
    return plugins.path.join(this.config.root, path);
  }

  /**
   * Handle OPTIONS request
   */
  private handleOptions(): Response {
    return new Response(null, {
      status: 200,
      headers: {
        'Allow': 'OPTIONS, GET, HEAD, PUT, DELETE, PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK, UNLOCK',
        'DAV': '1, 2',
        'MS-Author-Via': 'DAV',
      },
    });
  }

  /**
   * Handle PROPFIND request
   */
  private async handlePropfind(
    request: Request,
    path: string,
    context: IWebDAVContext
  ): Promise<Response> {
    const filePath = this.resolvePath(path);

    // Parse request body
    const body = await request.text();
    const { allprop } = parsePropfindRequest(body);

    try {
      const stat = await plugins.fs.promises.stat(filePath);
      const resources: IWebDAVResource[] = [];

      // Add the requested resource
      resources.push(await this.statToResource(path, stat));

      // If directory and depth > 0, list children
      if (stat.isDirectory() && context.depth !== '0') {
        const entries = await plugins.fs.promises.readdir(filePath, { withFileTypes: true });

        for (const entry of entries) {
          const childPath = plugins.path.join(path, entry.name);
          const childFilePath = plugins.path.join(filePath, entry.name);
          const childStat = await plugins.fs.promises.stat(childFilePath);
          resources.push(await this.statToResource(childPath, childStat));

          // Handle infinite depth (recursive)
          if (context.depth === 'infinity' && entry.isDirectory()) {
            await this.collectResources(childPath, childFilePath, resources);
          }
        }
      }

      const xml = generateMultistatus(resources);
      return new Response(xml, {
        status: 207, // Multi-Status
        headers: {
          'Content-Type': 'application/xml; charset=utf-8',
        },
      });
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      throw error;
    }
  }

  /**
   * Recursively collect resources for infinite depth
   */
  private async collectResources(
    basePath: string,
    filePath: string,
    resources: IWebDAVResource[]
  ): Promise<void> {
    const entries = await plugins.fs.promises.readdir(filePath, { withFileTypes: true });

    for (const entry of entries) {
      const childPath = plugins.path.join(basePath, entry.name);
      const childFilePath = plugins.path.join(filePath, entry.name);
      const childStat = await plugins.fs.promises.stat(childFilePath);
      resources.push(await this.statToResource(childPath, childStat));

      if (entry.isDirectory()) {
        await this.collectResources(childPath, childFilePath, resources);
      }
    }
  }

  /**
   * Convert fs.Stats to WebDAV resource
   */
  private async statToResource(path: string, stat: plugins.fs.Stats): Promise<IWebDAVResource> {
    const isCollection = stat.isDirectory();
    const displayName = plugins.path.basename(path) || '/';

    return {
      href: encodeURI(path),
      isCollection,
      displayName,
      contentType: isCollection ? 'httpd/unix-directory' : getMimeType(path),
      contentLength: isCollection ? undefined : stat.size,
      lastModified: stat.mtime,
      creationDate: stat.birthtime,
      etag: generateETag(stat),
      properties: [],
    };
  }

  /**
   * Handle PROPPATCH request (property modification)
   */
  private async handleProppatch(request: Request, path: string): Promise<Response> {
    // For now, we don't support modifying properties
    // Return 403 Forbidden for property modification attempts
    const filePath = this.resolvePath(path);

    try {
      await plugins.fs.promises.access(filePath);
      return new Response(generateError(403, 'cannot-modify-protected-property'), {
        status: 403,
        headers: { 'Content-Type': 'application/xml; charset=utf-8' },
      });
    } catch {
      return new Response('Not Found', { status: 404 });
    }
  }

  /**
   * Handle MKCOL request (create directory)
   */
  private async handleMkcol(path: string): Promise<Response> {
    const filePath = this.resolvePath(path);

    try {
      // Check if parent exists
      const parent = plugins.path.dirname(filePath);
      await plugins.fs.promises.access(parent);

      // Check if already exists
      try {
        await plugins.fs.promises.access(filePath);
        return new Response('Method Not Allowed', { status: 405 }); // Already exists
      } catch {
        // Good, doesn't exist
      }

      await plugins.fs.promises.mkdir(filePath);
      return new Response(null, { status: 201 }); // Created
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Conflict', { status: 409 }); // Parent doesn't exist
      }
      throw error;
    }
  }

  /**
   * Handle COPY request
   */
  private async handleCopy(path: string, context: IWebDAVContext): Promise<Response> {
    if (!context.destination) {
      return new Response('Bad Request', { status: 400 });
    }

    const sourcePath = this.resolvePath(path);
    const destUrl = new URL(context.destination);
    const destPath = this.resolvePath(decodeURIComponent(destUrl.pathname));

    // Check if destination exists
    let destExists = false;
    try {
      await plugins.fs.promises.access(destPath);
      destExists = true;
      if (!context.overwrite) {
        return new Response('Precondition Failed', { status: 412 });
      }
    } catch {
      // Destination doesn't exist, that's fine
    }

    try {
      const stat = await plugins.fs.promises.stat(sourcePath);

      if (stat.isDirectory()) {
        await this.copyDirectory(sourcePath, destPath);
      } else {
        await plugins.fs.promises.copyFile(sourcePath, destPath);
      }

      return new Response(null, { status: destExists ? 204 : 201 });
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      throw error;
    }
  }

  /**
   * Recursively copy directory
   */
  private async copyDirectory(src: string, dest: string): Promise<void> {
    await plugins.fs.promises.mkdir(dest, { recursive: true });
    const entries = await plugins.fs.promises.readdir(src, { withFileTypes: true });

    for (const entry of entries) {
      const srcPath = plugins.path.join(src, entry.name);
      const destPath = plugins.path.join(dest, entry.name);

      if (entry.isDirectory()) {
        await this.copyDirectory(srcPath, destPath);
      } else {
        await plugins.fs.promises.copyFile(srcPath, destPath);
      }
    }
  }

  /**
   * Handle MOVE request
   */
  private async handleMove(path: string, context: IWebDAVContext): Promise<Response> {
    if (!context.destination) {
      return new Response('Bad Request', { status: 400 });
    }

    const sourcePath = this.resolvePath(path);
    const destUrl = new URL(context.destination);
    const destPath = this.resolvePath(decodeURIComponent(destUrl.pathname));

    // Check lock
    if (this.config.locking && this.isLocked(path) && !this.hasValidLock(path, context.lockToken)) {
      return new Response('Locked', { status: 423 });
    }

    // Check if destination exists
    let destExists = false;
    try {
      await plugins.fs.promises.access(destPath);
      destExists = true;
      if (!context.overwrite) {
        return new Response('Precondition Failed', { status: 412 });
      }
      // Remove existing destination
      await plugins.fs.promises.rm(destPath, { recursive: true, force: true });
    } catch {
      // Destination doesn't exist, that's fine
    }

    try {
      await plugins.fs.promises.rename(sourcePath, destPath);

      // Move lock if exists
      const lock = this.locks.get(path);
      if (lock) {
        this.locks.delete(path);
        lock.path = decodeURIComponent(destUrl.pathname);
        this.locks.set(lock.path, lock);
      }

      return new Response(null, { status: destExists ? 204 : 201 });
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      throw error;
    }
  }

  /**
   * Handle LOCK request
   */
  private async handleLock(
    request: Request,
    path: string,
    context: IWebDAVContext
  ): Promise<Response> {
    if (!this.config.locking) {
      return new Response('Method Not Allowed', { status: 405 });
    }

    const filePath = this.resolvePath(path);

    // Check if resource exists
    try {
      await plugins.fs.promises.access(filePath);
    } catch {
      return new Response('Not Found', { status: 404 });
    }

    // Check if already locked by someone else
    if (this.isLocked(path) && !this.hasValidLock(path, context.lockToken)) {
      return new Response('Locked', { status: 423 });
    }

    // Create lock
    const lock: IWebDAVLock = {
      token: `opaquelocktoken:${crypto.randomUUID()}`,
      owner: 'anonymous', // Could parse from request body
      depth: context.depth,
      timeout: context.timeout ?? 3600,
      scope: 'exclusive',
      type: 'write',
      path,
      created: new Date(),
    };

    this.locks.set(path, lock);

    // Set timeout to remove lock
    if (lock.timeout > 0) {
      setTimeout(() => {
        this.locks.delete(path);
      }, lock.timeout * 1000);
    }

    const xml = generateLockResponse(lock);
    return new Response(xml, {
      status: 200,
      headers: {
        'Content-Type': 'application/xml; charset=utf-8',
        'Lock-Token': `<${lock.token}>`,
      },
    });
  }

  /**
   * Handle UNLOCK request
   */
  private async handleUnlock(path: string, context: IWebDAVContext): Promise<Response> {
    if (!this.config.locking) {
      return new Response('Method Not Allowed', { status: 405 });
    }

    if (!context.lockToken) {
      return new Response('Bad Request', { status: 400 });
    }

    const lock = this.locks.get(path);
    if (!lock) {
      return new Response('Conflict', { status: 409 });
    }

    if (lock.token !== context.lockToken) {
      return new Response('Forbidden', { status: 403 });
    }

    this.locks.delete(path);
    return new Response(null, { status: 204 });
  }

  /**
   * Handle GET/HEAD request
   */
  private async handleGet(request: Request, path: string, headOnly: boolean): Promise<Response> {
    const filePath = this.resolvePath(path);

    try {
      const stat = await plugins.fs.promises.stat(filePath);

      if (stat.isDirectory()) {
        // Return directory listing as HTML (fallback)
        return new Response('This is a WebDAV directory', {
          status: 200,
          headers: { 'Content-Type': 'text/plain' },
        });
      }

      const headers = new Headers({
        'Content-Type': getMimeType(filePath),
        'Content-Length': stat.size.toString(),
        'Last-Modified': stat.mtime.toUTCString(),
        'ETag': `"${generateETag(stat)}"`,
      });

      if (headOnly) {
        return new Response(null, { status: 200, headers });
      }

      const stream = plugins.fs.createReadStream(filePath);
      const webStream = new ReadableStream({
        start(controller) {
          stream.on('data', (chunk: Buffer) => controller.enqueue(new Uint8Array(chunk)));
          stream.on('end', () => controller.close());
          stream.on('error', (err) => controller.error(err));
        },
        cancel() {
          stream.destroy();
        },
      });

      return new Response(webStream, { status: 200, headers });
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      throw error;
    }
  }

  /**
   * Handle PUT request (file upload)
   */
  private async handlePut(
    request: Request,
    path: string,
    context: IWebDAVContext
  ): Promise<Response> {
    const filePath = this.resolvePath(path);

    // Check lock
    if (this.config.locking && this.isLocked(path) && !this.hasValidLock(path, context.lockToken)) {
      return new Response('Locked', { status: 423 });
    }

    // Check if file exists
    let exists = false;
    try {
      await plugins.fs.promises.access(filePath);
      exists = true;
    } catch {
      // File doesn't exist, will create
    }

    // Ensure parent directory exists
    const parent = plugins.path.dirname(filePath);
    try {
      await plugins.fs.promises.mkdir(parent, { recursive: true });
    } catch {
      // Parent might already exist
    }

    // Write file
    const body = request.body;
    if (body) {
      const reader = body.getReader();
      const writeStream = plugins.fs.createWriteStream(filePath);

      try {
        while (true) {
          const { done, value } = await reader.read();
          if (done) break;
          writeStream.write(value);
        }
        writeStream.end();

        await new Promise<void>((resolve, reject) => {
          writeStream.on('finish', resolve);
          writeStream.on('error', reject);
        });
      } catch (error) {
        writeStream.destroy();
        throw error;
      }
    } else {
      // Empty file
      await plugins.fs.promises.writeFile(filePath, '');
    }

    return new Response(null, { status: exists ? 204 : 201 });
  }

  /**
   * Handle DELETE request
   */
  private async handleDelete(path: string, context: IWebDAVContext): Promise<Response> {
    const filePath = this.resolvePath(path);

    // Check lock
    if (this.config.locking && this.isLocked(path) && !this.hasValidLock(path, context.lockToken)) {
      return new Response('Locked', { status: 423 });
    }

    try {
      const stat = await plugins.fs.promises.stat(filePath);

      if (stat.isDirectory()) {
        await plugins.fs.promises.rm(filePath, { recursive: true });
      } else {
        await plugins.fs.promises.unlink(filePath);
      }

      // Remove lock if exists
      this.locks.delete(path);

      return new Response(null, { status: 204 });
    } catch (error: any) {
      if (error.code === 'ENOENT') {
        return new Response('Not Found', { status: 404 });
      }
      throw error;
    }
  }

  /**
   * Check if a path is locked
   */
  private isLocked(path: string): boolean {
    return this.locks.has(path);
  }

  /**
   * Check if token matches lock
   */
  private hasValidLock(path: string, token?: string): boolean {
    if (!token) return false;
    const lock = this.locks.get(path);
    return lock?.token === token;
  }
}