"""
src/main.py
-----------
Entry point for the Fox CARLA ADAS simulation pipeline.

This file is now a thin CLI wrapper around the PipelineManager.
It parses arguments, builds a PipelineContext, and executes the
stage sequence: Simulation → Shenron → MCAP.

Usage
-----
    python src/main.py --scenario braking
    python src/main.py --scenario cutin --frames 120
    python src/main.py --list-scenarios
    python src/main.py --only-mcap --session data/braking_20260423_093000
    python src/main.py --skip-shenron

This file never changes when new scenarios are added.
All scenario logic lives in scenarios/<name>.py.
"""

import sys
import os
from pathlib import Path
import argparse

# Add project root to sys.path
sys.path.append(str(Path(__file__).resolve().parents[1]))

import config
from scenario_loader import list_scenarios


# -----------------------------------------------------------------------
# CLI
# -----------------------------------------------------------------------

def parse_args():
    parser = argparse.ArgumentParser(
        description="CARLA ADAS Simulation — stage-based pipeline runner"
    )
    parser.add_argument(
        "--scenario", "-s",
        type=str,
        default=getattr(config, "DEFAULT_SCENARIO", "braking"),
        help="Scenario name to run (e.g. braking, cutin, obstacle)"
    )
    parser.add_argument(
        "--frames", "-f",
        type=int,
        default=None,
        help="Override config.MAX_FRAMES for this run"
    )
    parser.add_argument(
        "--spawn-point", "-p",
        type=int,
        default=None,
        help="Index of the spawn point to use for ego vehicle"
    )
    parser.add_argument(
        "--no-record",
        action="store_true",
        help="Disable image and metadata recording for faster iteration"
    )
    parser.add_argument(
        "--weather", "-w",
        type=str,
        default=None,
        help="Weather preset (ClearNoon, Rain, etc.). "
             "If omitted, scenario or config default is used."
    )
    parser.add_argument(
        "--params",
        type=str,
        default=None,
        help="Scenario parameters as key=val pairs, "
             "e.g. 'BRAKE_FRAME=100,SPEED=50'"
    )
    parser.add_argument(
        "--list-scenarios", "-l",
        action="store_true",
        help="Print available scenarios and exit"
    )

    # --- Pipeline Stage Control ---
    parser.add_argument(
        "--skip-sim",
        action="store_true",
        help="Skip the simulation stage (requires --session)"
    )
    parser.add_argument(
        "--skip-shenron",
        action="store_true",
        help="Skip the Shenron radar synthesis stage"
    )
    parser.add_argument(
        "--skip-mcap",
        action="store_true",
        help="Skip the MCAP conversion stage"
    )
    parser.add_argument(
        "--only-mcap",
        action="store_true",
        help="Run only the MCAP stage (requires --session)"
    )
    parser.add_argument(
        "--only-shenron",
        action="store_true",
        help="Run only the Shenron stage (requires --session)"
    )
    parser.add_argument(
        "--session",
        type=str,
        default=None,
        help="Path to an existing session folder. Required when "
             "skipping the simulation stage."
    )

    return parser.parse_args()


# -----------------------------------------------------------------------
# Main
# -----------------------------------------------------------------------

def main():
    args = parse_args()

    # ------------------------------------------------------------------
    # 0. Clean up stale stop flags
    # ------------------------------------------------------------------
    flag_path = os.path.join(os.path.dirname(__file__), "..", "tmp", "stop.flag")
    if os.path.exists(flag_path):
        try:
            os.remove(flag_path)
            print("[INFO] Cleaned up stale stop.flag")
        except Exception:
            pass

    if args.list_scenarios:
        print("Available scenarios:")
        for s in list_scenarios():
            print(f"  - {s}")
        return

    # ------------------------------------------------------------------
    # 1. Build PipelineContext
    # ------------------------------------------------------------------
    from pipeline.base import PipelineContext

    ctx = PipelineContext(
        scenario_name=args.scenario,
        args=args,
    )

    # Populate session_path if provided via CLI (for --skip-sim modes)
    if args.session:
        session = Path(args.session)
        if session.exists():
            ctx.session_path = session
            print(f"[INFO] Using existing session: {session}")
        else:
            print(f"[ERROR] Session path does not exist: {args.session}")
            return

    # Determine which stages to skip
    if args.only_mcap:
        ctx.skip_stages = ["simulation", "shenron"]
    elif args.only_shenron:
        ctx.skip_stages = ["simulation", "mcap"]
    else:
        if args.skip_sim:
            ctx.skip_stages.append("simulation")
        if args.skip_shenron:
            ctx.skip_stages.append("shenron")
        if args.skip_mcap:
            ctx.skip_stages.append("mcap")

    # Validate: if sim is skipped, session_path must be provided
    if "simulation" in ctx.skip_stages and ctx.session_path is None:
        print("[ERROR] --session is required when skipping the simulation "
              "stage (--skip-sim, --only-mcap, --only-shenron).")
        return

    # ------------------------------------------------------------------
    # 2. Build & Execute Pipeline
    # ------------------------------------------------------------------
    from pipeline.manager import PipelineManager
    from pipeline.stages.sim_stage import SimulationStage
    from pipeline.stages.shenron_stage import ShenronStage
    from pipeline.stages.mcap_stage import McapStage
    from pipeline.stages.video_stage import VideoStage

    manager = PipelineManager([
        SimulationStage(),
        ShenronStage(),
        McapStage(),
        VideoStage(),
    ])

    manager.execute(ctx)

    print("[INFO] Done")


if __name__ == "__main__":
    main()