#!/usr/bin/env python3
"""Generate .github/copilot-instructions.md from AGENTS.md and skills.

Necessary until copilot can handle skills.
"""

from __future__ import annotations

from pathlib import Path
import sys

GENERATED_MESSAGE = (
    f"<!-- Automatically generated by {Path(__file__).name}, do not edit -->\n\n"
)

SKILLS_DIR = Path(".claude/skills")
AGENTS_FILE = Path("AGENTS.md")
OUTPUT_FILE = Path(".github/copilot-instructions.md")

EXCLUDED_SKILLS = {"github-pr-reviewer"}


def gather_skills() -> list[tuple[str, Path]]:
    """Gather all skills from the skills directory.

    Returns a list of tuples (skill_name, skill_file_path).
    """
    skills: list[tuple[str, Path]] = []

    if not SKILLS_DIR.exists():
        return skills

    for skill_dir in sorted(SKILLS_DIR.iterdir()):
        if not skill_dir.is_dir():
            continue

        if skill_dir.name in EXCLUDED_SKILLS:
            continue

        skill_file = skill_dir / "SKILL.md"
        if not skill_file.exists():
            continue

        skill_content = skill_file.read_text()

        # Extract skill name from frontmatter if present
        skill_name = skill_dir.name
        if skill_content.startswith("---"):
            # Parse YAML frontmatter
            end_idx = skill_content.find("---", 3)
            if end_idx != -1:
                frontmatter = skill_content[3:end_idx]
                for line in frontmatter.split("\n"):
                    if line.startswith("name:"):
                        skill_name = line[5:].strip()
                        break

        skills.append((skill_name, skill_file))

    return skills


def generate_output() -> str:
    """Generate the copilot-instructions.md content."""
    if not AGENTS_FILE.exists():
        print(f"Error: {AGENTS_FILE} not found")
        sys.exit(1)

    output_parts: list[str] = [GENERATED_MESSAGE]

    # Add AGENTS.md content
    agents_content = AGENTS_FILE.read_text()
    output_parts.append(agents_content.strip())
    output_parts.append("")

    # Add skills section as a bullet list of name: path
    skills = gather_skills()
    if skills:
        output_parts.append("")
        output_parts.append("# Skills")
        output_parts.append("")
        for skill_name, skill_file in skills:
            output_parts.append(f"- {skill_name}: {skill_file}")
        output_parts.append("")

    return "\n".join(output_parts)


def main(validate: bool = False) -> int:
    """Run the script."""
    if not Path("homeassistant").is_dir():
        print("Run this from HA root dir")
        return 1

    content = generate_output()

    if validate:
        if not OUTPUT_FILE.exists():
            print(f"Error: {OUTPUT_FILE} does not exist")
            return 1

        existing = OUTPUT_FILE.read_text()
        if existing != content:
            print(f"Error: {OUTPUT_FILE} is out of date")
            print("Please run: python -m script.gen_copilot_instructions")
            return 1

        print(f"{OUTPUT_FILE} is up to date")
        return 0

    OUTPUT_FILE.write_text(content)
    print(f"Generated {OUTPUT_FILE}")
    return 0


if __name__ == "__main__":
    _validate = len(sys.argv) > 1 and sys.argv[1] == "validate"
    sys.exit(main(_validate))