#!/usr/bin/env python3
"""Compile hooks.template.json + prompt .md files into hooks.json.

Usage:
    python3 hooks/scripts/compile-hooks.py           # Generate hooks.json
    python3 hooks/scripts/compile-hooks.py --check    # Verify hooks.json is up to date
"""

import json
import sys
from pathlib import Path

HOOKS_DIR = Path(__file__).resolve().parent.parent
TEMPLATE = HOOKS_DIR / "hooks.template.json"
OUTPUT = HOOKS_DIR / "hooks.json"
PROMPTS_DIR = HOOKS_DIR / "prompts"


def load_prompt(filename: str) -> str:
    """Load a prompt .md file and return its content as a string."""
    path = PROMPTS_DIR / filename
    if not path.exists():
        print(f"ERROR: Prompt file not found: {path}", file=sys.stderr)
        sys.exit(1)
    content = path.read_text(encoding="utf-8")
    if not content.strip():
        print(f"ERROR: Prompt file is empty: {path}", file=sys.stderr)
        sys.exit(1)
    return content.rstrip("\n")


def resolve_prompts(obj):
    """Recursively walk JSON and replace prompt_file with inline prompt."""
    if isinstance(obj, dict):
        if "prompt_file" in obj:
            if obj.get("type") != "prompt":
                print(
                    f"ERROR: prompt_file used on non-prompt hook type: {obj.get('type')}",
                    file=sys.stderr,
                )
                sys.exit(1)
            filename = obj.pop("prompt_file")
            obj["prompt"] = load_prompt(filename)
        return {k: resolve_prompts(v) for k, v in obj.items()}
    if isinstance(obj, list):
        return [resolve_prompts(item) for item in obj]
    return obj


def compile_hooks() -> str:
    """Read template, resolve prompts, return JSON string."""
    if not TEMPLATE.exists():
        print(f"ERROR: Template not found: {TEMPLATE}", file=sys.stderr)
        sys.exit(1)
    template = json.loads(TEMPLATE.read_text(encoding="utf-8"))
    resolved = resolve_prompts(template)
    # Strip any top-level keys except "hooks" — Claude Code requires only "hooks"
    invalid_keys = [k for k in resolved if k != "hooks"]
    for k in invalid_keys:
        print(f"WARNING: Stripping invalid top-level key '{k}' from output", file=sys.stderr)
        del resolved[k]
    return json.dumps(resolved, indent=2, ensure_ascii=False) + "\n"


def main():
    check_mode = "--check" in sys.argv
    compiled = compile_hooks()

    if check_mode:
        if not OUTPUT.exists():
            print(f"ERROR: {OUTPUT} does not exist", file=sys.stderr)
            sys.exit(1)
        current = OUTPUT.read_text(encoding="utf-8")
        if current == compiled:
            print("OK: hooks.json is up to date")
            sys.exit(0)
        else:
            print(
                "DRIFT DETECTED: hooks.json does not match compiled output.\n"
                "Run: python3 hooks/scripts/compile-hooks.py",
                file=sys.stderr,
            )
            sys.exit(1)

    OUTPUT.write_text(compiled, encoding="utf-8")
    print(f"Compiled {OUTPUT.relative_to(HOOKS_DIR.parent)}")


if __name__ == "__main__":
    main()