#!/usr/bin/env python3
"""SessionStart hook — verify AirContext/ presence and surface a friendly notice.

Stage-2 implementation. For now we:
  - look for AirContext/ in cwd
  - if absent or invalid, set state.config_missing=true so UserPromptSubmit can block
  - emit a SessionStart additionalContext message describing AirContext status
"""
from __future__ import annotations
import json
import os
import sys
from pathlib import Path

_HERE = Path(__file__).resolve().parent
sys.path.insert(0, str(_HERE))

from core.config_loader import validate_config  # noqa: E402
from core.state import StateFile  # noqa: E402


def _find_project_root(stdin_payload: dict) -> Path:
    cwd = stdin_payload.get("cwd") or os.environ.get("CLAUDE_PROJECT_DIR") or os.getcwd()
    return Path(cwd)


def main() -> int:
    raw = sys.stdin.read() or "{}"
    try:
        payload = json.loads(raw)
    except json.JSONDecodeError:
        payload = {}

    project = _find_project_root(payload)
    air = project / "AirContext"

    # Project hasn't opted in — stay completely silent so AirContext doesn't
    # pollute every Claude Code session globally.
    if not air.exists():
        return 0

    config = air / "config.yaml"
    state = StateFile(air / "state.json")

    sid = payload.get("session_id")
    if sid:
        state.update(last_session_id=sid)

    if not config.exists():
        state.update(config_missing=True)
        print(json.dumps({
            "hookSpecificOutput": {
                "hookEventName": "SessionStart",
                "additionalContext": (
                    "AirContext: AirContext/ exists but config.yaml is missing. "
                    "Run `/aircontext-init` to (re)install templates."
                )
            }
        }))
        return 0

    err = validate_config(config)
    if err:
        state.update(config_missing=True)
        print(json.dumps({
            "hookSpecificOutput": {
                "hookEventName": "SessionStart",
                "additionalContext": f"AirContext config invalid: {err}"
            }
        }))
        return 0

    state.update(config_missing=False)
    # Healthy — stay silent to keep prompt clean.
    return 0


if __name__ == "__main__":
    sys.exit(main())