#!/usr/bin/env python3
"""
DomainFront Tunnel — Bypass DPI censorship via Google Apps Script.

Run a local HTTP proxy that tunnels all traffic through a Google Apps
Script relay fronted by www.google.com (TLS SNI shows www.google.com
while the encrypted Host header points at script.google.com).
"""

import argparse
import asyncio
import json
import logging
import os
import sys

# Project modules live under ./src — put that folder on sys.path so the
# historical flat imports ("from proxy_server import …") keep working.
_SRC_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "src")
if _SRC_DIR not in sys.path:
    sys.path.insert(0, _SRC_DIR)

from cert_installer import install_ca, is_ca_trusted
from constants import __version__
from lan_utils import log_lan_access
from google_ip_scanner import scan_sync
from logging_utils import configure as configure_logging, print_banner
from mitm import CA_CERT_FILE
from proxy_server import ProxyServer


def setup_logging(level_name: str):
    configure_logging(level_name)


_PLACEHOLDER_AUTH_KEYS = {
    "",
    "CHANGE_ME_TO_A_STRONG_SECRET",
    "your-secret-password-here",
}


def parse_args():
    parser = argparse.ArgumentParser(
        prog="domainfront-tunnel",
        description="Local HTTP proxy that relays traffic through Google Apps Script.",
    )
    parser.add_argument(
        "-c", "--config",
        default=os.environ.get("DFT_CONFIG", "config.json"),
        help="Path to config file (default: config.json, env: DFT_CONFIG)",
    )
    parser.add_argument(
        "-p", "--port",
        type=int,
        default=None,
        help="Override listen port (env: DFT_PORT)",
    )
    parser.add_argument(
        "--host",
        default=None,
        help="Override listen host (env: DFT_HOST)",
    )
    parser.add_argument(
        "--socks5-port",
        type=int,
        default=None,
        help="Override SOCKS5 listen port (env: DFT_SOCKS5_PORT)",
    )
    parser.add_argument(
        "--disable-socks5",
        action="store_true",
        help="Disable the built-in SOCKS5 listener.",
    )
    parser.add_argument(
        "--log-level",
        choices=["DEBUG", "INFO", "WARNING", "ERROR"],
        default=None,
        help="Override log level (env: DFT_LOG_LEVEL)",
    )
    parser.add_argument(
        "-v", "--version",
        action="version",
        version=f"%(prog)s {__version__}",
    )
    parser.add_argument(
        "--install-cert",
        action="store_true",
        help="Install the MITM CA certificate as a trusted root and exit.",
    )
    parser.add_argument(
        "--no-cert-check",
        action="store_true",
        help="Skip the certificate installation check on startup.",
    )
    parser.add_argument(
        "--scan",
        action="store_true",
        help="Scan Google IPs to find the fastest reachable one and exit.",
    )
    return parser.parse_args()


def main():
    args = parse_args()
    config_path = args.config

    try:
        with open(config_path) as f:
            config = json.load(f)
    except FileNotFoundError:
        print(f"Config not found: {config_path}")
        # Offer the interactive wizard if it's available and we're on a TTY.
        wizard = os.path.join(os.path.dirname(os.path.abspath(__file__)), "setup.py")
        if os.path.exists(wizard) and sys.stdin.isatty():
            try:
                answer = input("Run the interactive setup wizard now? [Y/n]: ").strip().lower()
            except EOFError:
                answer = "n"
            if answer in ("", "y", "yes"):
                import subprocess
                rc = subprocess.call([sys.executable, wizard])
                if rc != 0:
                    sys.exit(rc)
                try:
                    with open(config_path) as f:
                        config = json.load(f)
                except Exception as e:
                    print(f"Could not load config after setup: {e}")
                    sys.exit(1)
            else:
                print("Copy config.example.json to config.json and fill in your values,")
                print("or run: python setup.py")
                sys.exit(1)
        else:
            print("Run: python setup.py   (or copy config.example.json to config.json)")
            sys.exit(1)
    except json.JSONDecodeError as e:
        print(f"Invalid JSON in config: {e}")
        sys.exit(1)

    # Environment variable overrides
    if os.environ.get("DFT_AUTH_KEY"):
        config["auth_key"] = os.environ["DFT_AUTH_KEY"]
    if os.environ.get("DFT_SCRIPT_ID"):
        config["script_id"] = os.environ["DFT_SCRIPT_ID"]

    # CLI argument overrides
    if args.port is not None:
        config["listen_port"] = args.port
    elif os.environ.get("DFT_PORT"):
        config["listen_port"] = int(os.environ["DFT_PORT"])

    if args.host is not None:
        config["listen_host"] = args.host
    elif os.environ.get("DFT_HOST"):
        config["listen_host"] = os.environ["DFT_HOST"]

    if args.socks5_port is not None:
        config["socks5_port"] = args.socks5_port
    elif os.environ.get("DFT_SOCKS5_PORT"):
        config["socks5_port"] = int(os.environ["DFT_SOCKS5_PORT"])

    if args.disable_socks5:
        config["socks5_enabled"] = False

    if args.log_level is not None:
        config["log_level"] = args.log_level
    elif os.environ.get("DFT_LOG_LEVEL"):
        config["log_level"] = os.environ["DFT_LOG_LEVEL"]

    for key in ("auth_key",):
        if key not in config:
            print(f"Missing required config key: {key}")
            sys.exit(1)

    if config.get("auth_key", "") in _PLACEHOLDER_AUTH_KEYS:
        print(
            "Refusing to start: 'auth_key' is unset or uses a known placeholder.\n"
            "Pick a long random secret and set it in both config.json AND "
            "the AUTH_KEY constant inside Code.gs (they must match)."
        )
        sys.exit(1)

    # Always Apps Script mode — force-set for backward-compat configs.
    config["mode"] = "apps_script"
    sid = config.get("script_ids") or config.get("script_id")
    if not sid or (isinstance(sid, str) and sid == "YOUR_APPS_SCRIPT_DEPLOYMENT_ID"):
        print("Missing 'script_id' in config.")
        print("Deploy the Apps Script from Code.gs and paste the Deployment ID.")
        sys.exit(1)

    # ── Certificate installation ──────────────────────────────────────────
    if args.install_cert:
        setup_logging("INFO")
        _log = logging.getLogger("Main")
        _log.info("Installing CA certificate…")
        ok = install_ca(CA_CERT_FILE)
        sys.exit(0 if ok else 1)

    # ── Google IP Scanner ──────────────────────────────────────────────────
    if args.scan:
        setup_logging("INFO")
        front_domain = config.get("front_domain", "www.google.com")
        _log = logging.getLogger("Main")
        _log.info(f"Scanning Google IPs (fronting domain: {front_domain})")
        ok = scan_sync(front_domain)
        sys.exit(0 if ok else 1)

    setup_logging(config.get("log_level", "INFO"))
    log = logging.getLogger("Main")

    print_banner(__version__)
    log.info("DomainFront Tunnel starting (Apps Script relay)")

    log.info("Apps Script relay : SNI=%s → script.google.com",
             config.get("front_domain", "www.google.com"))
    script_ids = config.get("script_ids") or config.get("script_id")
    if isinstance(script_ids, list):
        log.info("Script IDs        : %d scripts (sticky per-host)", len(script_ids))
        for i, sid in enumerate(script_ids):
            log.info("  [%d] %s", i + 1, sid)
    else:
        log.info("Script ID         : %s", script_ids)

    # Ensure CA file exists before checking / installing it.
    # MITMCertManager generates ca/ca.crt on first instantiation.
    if not os.path.exists(CA_CERT_FILE):
        from mitm import MITMCertManager
        MITMCertManager()  # side-effect: creates ca/ca.crt + ca/ca.key

    # Auto-install MITM CA if not already trusted
    if not args.no_cert_check:
        if not is_ca_trusted(CA_CERT_FILE):
            log.warning("MITM CA is not trusted — attempting automatic installation…")
            ok = install_ca(CA_CERT_FILE)
            if ok:
                log.info("CA certificate installed. You may need to restart your browser.")
            else:
                log.error(
                    "Auto-install failed. Run with --install-cert (may need admin/sudo) "
                    "or manually install ca/ca.crt as a trusted root CA."
                )
        else:
            log.info("MITM CA is already trusted.")

    # ── LAN sharing configuration ────────────────────────────────────────
    lan_sharing = config.get("lan_sharing", False)
    if lan_sharing:
        # If LAN sharing is enabled and host is still localhost, change to all interfaces
        if config.get("listen_host", "127.0.0.1") == "127.0.0.1":
            config["listen_host"] = "0.0.0.0"
            log.info("LAN sharing enabled — listening on all interfaces")

    log.info("HTTP proxy         : %s:%d",
             config.get("listen_host", "127.0.0.1"),
             config.get("listen_port", 8080))
    if config.get("socks5_enabled", True):
        log.info("SOCKS5 proxy       : %s:%d",
                 config.get("socks5_host", config.get("listen_host", "127.0.0.1")),
                 config.get("socks5_port", 1080))

    # Log LAN access addresses if sharing is enabled
    if lan_sharing:
        socks_port = config.get("socks5_port", 1080) if config.get("socks5_enabled", True) else None
        log_lan_access(config.get("listen_port", 8080), socks_port)

    try:
        asyncio.run(_run(config))
    except KeyboardInterrupt:
        log.info("Stopped")


def _make_exception_handler(log):
    """Return an asyncio exception handler that silences Windows WinError 10054
    noise from connection cleanup (ConnectionResetError in
    _ProactorBasePipeTransport._call_connection_lost), which is harmless but
    verbose on Python/Windows when a remote host force-closes a socket."""
    def handler(loop, context):
        exc = context.get("exception")
        cb  = context.get("handle") or context.get("source_traceback", "")
        if (
            isinstance(exc, ConnectionResetError)
            and "_call_connection_lost" in str(cb)
        ):
            return  # suppress: benign Windows socket cleanup race
        log.error("[asyncio]  %s", context.get("message", context))
        if exc:
            loop.default_exception_handler(context)
    return handler


async def _run(config):
    loop = asyncio.get_running_loop()
    _log = logging.getLogger("asyncio")
    loop.set_exception_handler(_make_exception_handler(_log))
    server = ProxyServer(config)
    try:
        await server.start()
    finally:
        await server.stop()


if __name__ == "__main__":
    main()
