#!/usr/bin/env python3
"""Local tile server for HK aerial map. Translates /tiles/{z}/{x}/{y}.jpg -> tiles/18_{x}_{y}.jpg"""

import http.server
import socketserver
import os
import re
import webbrowser
import threading
from pathlib import Path

PORT = 8080
SCRIPT_DIR = Path(__file__).parent
TRANSPARENT_GIF = (
    b'GIF89a\x01\x00\x01\x00\x80\x00\x00\xff\xff\xff\x00\x00\x00'
    b'!\xf9\x04\x00\x00\x00\x00\x00,\x00\x00\x00\x00\x01\x00\x01'
    b'\x00\x00\x02\x02D\x01\x00;'
)

TILE_PATTERN = re.compile(
    r'^/(tiles(?:_annotated)?)/(\d+)/(\d+)/(\d+)\.(jpg|png|gif)$'
)


class Handler(http.server.SimpleHTTPRequestHandler):
    def do_GET(self):
        path = self.path.split('?')[0]
        m = TILE_PATTERN.match(path)
        if m:
            layer, z, x, y, ext = m.groups()
            # Tiles are stored as 18_x_y.jpg regardless of requested zoom
            flat = SCRIPT_DIR / layer / f'18_{x}_{y}.jpg'
            if flat.exists():
                data = flat.read_bytes()
                self.send_response(200)
                self.send_header('Content-Type', 'image/jpeg')
                self.send_header('Content-Length', len(data))
                self.send_header('Cache-Control', 'public, max-age=3600')
                self.end_headers()
                self.wfile.write(data)
            else:
                self.send_response(200)
                self.send_header('Content-Type', 'image/gif')
                self.send_header('Content-Length', len(TRANSPARENT_GIF))
                self.end_headers()
                self.wfile.write(TRANSPARENT_GIF)
            return

        super().do_GET()

    def log_message(self, fmt, *args):
        # Only log non-tile requests so output stays readable
        if not TILE_PATTERN.match(self.path.split('?')[0]):
            print(f'  {self.address_string()} {fmt % args}')


def main():
    os.chdir(SCRIPT_DIR)

    with socketserver.TCPServer(('', PORT), Handler) as httpd:
        httpd.allow_reuse_address = True
        url = f'http://localhost:{PORT}/map.html'
        print(f'HK Aerial Map  →  {url}')
        print('Press Ctrl+C to stop.\n')
        threading.Timer(0.4, webbrowser.open, args=(url,)).start()
        try:
            httpd.serve_forever()
        except KeyboardInterrupt:
            print('\nServer stopped.')


if __name__ == '__main__':
    main()