#!/usr/bin/env python3
"""Small user-session daemon for Android-triggered Trainlog sync requests."""

from __future__ import annotations

import argparse
import json
import os
import re
import signal
import subprocess
import sys
import tempfile
import time
import uuid
from datetime import datetime, timezone
from pathlib import Path


STOP = False
REQUEST_NAME = "trainlog-sync-request-v1.json"
REQUEST_ID = re.compile(r"sr_[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}")


def request_stop(
    _signum: int,
    _frame: object,
) -> None:
    global STOP
    STOP = True


def append_log(
    text: str,
) -> None:
    state_home = Path.home() / ".local" / "state" / "trainlog"
    state_home.mkdir(
        parents=True,
        exist_ok=True,
    )

    with (
        state_home / "syncd.log"
    ).open(
        "a",
        encoding="utf-8",
    ) as handle:
        handle.write(
            time.strftime(
                "%Y-%m-%d %H:%M:%S "
            )
        )

        handle.write(text.rstrip())
        handle.write("\n")


def default_database() -> Path:
    data_home = Path(os.environ.get("XDG_DATA_HOME", Path.home() / ".local/share"))
    return data_home / "trainlog/trainlog.db"


def atomic_json(path: Path, value: dict) -> None:
    raw = (json.dumps(value, sort_keys=True, separators=(",", ":")) + "\n").encode()
    path.parent.mkdir(parents=True, exist_ok=True, mode=0o700)
    descriptor, temporary = tempfile.mkstemp(prefix=".sync-run-", dir=path.parent)
    try:
        os.fchmod(descriptor, 0o600)
        with os.fdopen(descriptor, "wb") as stream:
            stream.write(raw)
            stream.flush()
            os.fsync(stream.fileno())
        os.replace(temporary, path)
    finally:
        try:
            os.unlink(temporary)
        except FileNotFoundError:
            pass


def load_generation_config(path: Path) -> dict:
    value = json.loads(path.read_text(encoding="utf-8"))
    if (
        not isinstance(value, dict)
        or value.get("format") != "trainlog-sync-orchestrator-config"
        or value.get("enabled") is not True
        or value.get("mode") not in ("mtp", "auto")
    ):
        raise RuntimeError("trusted full-generation MTP configuration is invalid")
    return value


def request_id(path: Path) -> str | None:
    try:
        value = json.loads(path.read_text(encoding="utf-8"))
    except (OSError, UnicodeError, json.JSONDecodeError):
        return None
    if not isinstance(value, dict):
        return None
    candidate = value.get("request_id")
    if (
        set(value) == {"format", "version", "request_id", "requested_at"}
        and value.get("format") == "trainlog-sync-request"
        and type(value.get("version")) is int
        and value.get("version") == 1
        and isinstance(candidate, str)
        and REQUEST_ID.fullmatch(candidate)
    ):
        return candidate
    return None


def run_full_generation(args: argparse.Namespace, config_path: Path) -> int:
    config = load_generation_config(config_path)
    root = Path(config["transport_root"])
    expected_peer = config["expected_peer_id"]
    adapter = args.mtp_adapter
    pull = subprocess.run(
        [str(adapter), "pull", expected_peer, str(root)],
        capture_output=True,
        text=True,
        check=False,
    )
    if pull.returncode != 0:
        return 3
    correlated_request = request_id(root / REQUEST_NAME)
    if correlated_request is None:
        return 3
    if args.state.is_file():
        try:
            previous = json.loads(args.state.read_text(encoding="utf-8"))
            if previous.get("request_id") == correlated_request:
                return 3
        except (OSError, UnicodeError, json.JSONDecodeError):
            pass
    run_id = "sy_" + str(uuid.uuid4())
    now = datetime.now(timezone.utc).isoformat()
    atomic_json(
        args.state,
        {
            "format": "trainlog-sync-run-report",
            "version": 1,
            "run_id": run_id,
            "request_id": correlated_request,
            "trigger": args.trigger,
            "requested_mode": "full_generation_v1",
            "effective_mode": "full_generation_v1",
            "phase": "requested",
            "progress_revision": 1,
            "result": "running",
            "started_at": now,
            "updated_at": now,
        },
    )
    result = subprocess.run(
        [
            sys.executable,
            str(args.orchestrator),
            "--database",
            str(args.database),
            "--state",
            str(args.state),
            "--config",
            str(config_path),
            "--run-id",
            run_id,
            "--request-id",
            correlated_request,
        ],
        capture_output=True,
        text=True,
        check=False,
    )
    append_log(result.stdout if result.returncode == 0 else result.stderr or result.stdout)
    return result.returncode


def main() -> int:
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "--sync-once",
        required=True,
        type=Path,
    )

    parser.add_argument("--trigger", choices=("android", "daemon"), default="android")
    parser.add_argument(
        "--generation-config",
        type=Path,
        default=os.environ.get("TRAINLOG_SYNC_GENERATION_CONFIG"),
    )
    parser.add_argument(
        "--orchestrator",
        type=Path,
        default=Path(__file__).with_name("sync_orchestrator.py"),
    )
    parser.add_argument("--database", type=Path, default=default_database())
    parser.add_argument("--state", type=Path)
    parser.add_argument(
        "--mtp-adapter",
        type=Path,
        default=Path(os.environ.get("TRAINLOG_SYNC_MTP_ADAPTER", "")),
    )

    parser.add_argument(
        "--interval",
        type=float,
        default=3.0,
    )

    args = parser.parse_args()

    if args.state is None:
        # The Web adapter owns .sync-run.json. The daemon keeps independent
        # durable request replay evidence while sharing the database lock.
        args.state = Path(str(args.database) + ".syncd-run.json")

    if not args.sync_once.exists():
        raise SystemExit(
            f"sync executable missing: {args.sync_once}"
        )

    if args.generation_config is not None:
        if not args.orchestrator.is_file() or not args.mtp_adapter.is_file():
            raise SystemExit("full-generation runtime is incomplete")

    signal.signal(
        signal.SIGTERM,
        request_stop,
    )

    signal.signal(
        signal.SIGINT,
        request_stop,
    )

    append_log(
        "trainlog-syncd started"
    )

    while not STOP:
        if args.generation_config is not None:
            code = run_full_generation(args, args.generation_config)
            result = subprocess.CompletedProcess([], code, "", "")
        else:
            result = subprocess.run(
                [
                    str(args.sync_once),
                    "--request-only",
                    "--trigger",
                    args.trigger,
                ],
                capture_output=True,
                text=True,
                check=False,
            )

        if result.returncode == 0:
            append_log(
                result.stdout
            )
        elif result.returncode not in (
            3,
        ):
            detail = (
                result.stderr.strip()
                or result.stdout.strip()
                or f"exit={result.returncode}"
            )

            append_log(
                detail
            )

        deadline = (
            time.monotonic()
            + max(
                args.interval,
                1.0,
            )
        )

        while (
            not STOP
            and time.monotonic()
            < deadline
        ):
            time.sleep(0.2)

    append_log(
        "trainlog-syncd stopped"
    )

    return 0


if __name__ == "__main__":
    raise SystemExit(main())