#!/usr/bin/env python3
"""Simple static file server with /api proxy to backend."""
import os
import http.server
import socketserver
import urllib.request
import urllib.error
from pathlib import Path

PORT = 80
BACKEND = os.environ.get('BACKEND_URL', 'http://publish-backend:8080')
STATIC_DIR = '/app/dist'
UPLOADS_DIR = '/app/uploads'
STATIC_PATH = Path(STATIC_DIR)
UPLOADS_PATH = Path(UPLOADS_DIR)


class ProxyHTTPRequestHandler(http.server.SimpleHTTPRequestHandler):
    """Serve static files + proxy /api/ requests to backend."""

    def do_GET(self):
        if self.path.startswith('/api/') or self.path.startswith('/uploads/'):
            self.proxy_request()
        else:
            super().do_GET()

    def do_POST(self):
        if self.path.startswith('/api/'):
            self.proxy_request()
        else:
            self.send_error(404)

    def do_PUT(self):
        if self.path.startswith('/api/'):
            self.proxy_request()
        else:
            self.send_error(404)

    def do_DELETE(self):
        if self.path.startswith('/api/'):
            self.proxy_request()
        else:
            self.send_error(404)

    def proxy_request(self):
        """Forward request to backend and return response."""
        url = BACKEND + self.path
        content_length = int(self.headers.get('Content-Length', 0))
        body = self.rfile.read(content_length) if content_length else None

        headers = {}
        for key in ('Content-Type', 'Authorization', 'Accept', 'X-Requested-With'):
            if key in self.headers:
                headers[key] = self.headers[key]

        try:
            req = urllib.request.Request(url, data=body, headers=headers, method=self.command)
            with urllib.request.urlopen(req, timeout=30) as response:
                self.send_response(response.status)
                self.send_headers(response.headers)
                self.wfile.write(response.read())
        except urllib.error.HTTPError as e:
            self.send_response(e.code)
            self.send_header('Content-Type', 'application/json')
            self.end_headers()
            self.wfile.write(e.read())
        except Exception as e:
            self.send_response(502)
            self.send_header('Content-Type', 'application/json')
            self.end_headers()
            self.wfile.write(f'{{"error": "{e}"}}'.encode())

    def send_headers(self, headers):
        """Copy headers from backend response."""
        for key, value in headers.items():
            if key not in ('Transfer-Encoding', 'Connection'):
                self.send_header(key, value)
        self.end_headers()

    def translate_path(self, path):
        """Serve from /app/dist for frontend, /app/uploads for files."""
        if path.startswith('/uploads/'):
            return str(UPLOADS_PATH / path[9:])
        return str(STATIC_PATH / path.lstrip('/'))


class ReuseAddrTCPServer(socketserver.TCPServer):
    allow_reuse_address = True


if __name__ == '__main__':
    os.chdir('/app')
    with ReuseAddrTCPServer(('', PORT), ProxyHTTPRequestHandler) as httpd:
        print(f'Serving on port {PORT}, backend at {BACKEND}')
        httpd.serve_forever()