#!/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 re
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")

# Pattern to match markdown links to local files: [text](filename)
# Excludes URLs (http://, https://) and anchors (#)
LOCAL_LINK_PATTERN = re.compile(r"\[([^\]]+)\]\(([^)]+)\)")


def expand_file_references(content: str, skill_dir: Path) -> str:
    """Expand file references in skill content.

    Finds markdown links to local files and replaces them with the file content
    wrapped in reference tags.
    """
    lines = content.split("\n")
    result_lines: list[str] = []

    for line in lines:
        result_lines.append(line)
        matches = list(LOCAL_LINK_PATTERN.finditer(line))
        if not matches:
            continue

        # Check if any match is a local file reference
        for match in matches:
            link_path = match.group(2)

            # Skip URLs and anchors
            if link_path.startswith(("http://", "https://", "#", "/")):
                continue

            # Try to find the referenced file
            ref_file = skill_dir / link_path

            if ref_file.exists():
                ref_content = ref_file.read_text().strip()
                result_lines.append(f"<REFERENCE {ref_file.name}>")
                result_lines.append(ref_content)
                result_lines.append(f"<END REFERENCE {ref_file.name}>")
                result_lines.append("")
                break

    return "\n".join(result_lines)


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

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

    if not SKILLS_DIR.exists():
        return skills

    for skill_dir in sorted(SKILLS_DIR.iterdir()):
        if not skill_dir.is_dir():
            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
                # Remove frontmatter from content
                skill_content = skill_content[end_idx + 3 :].strip()

        # Expand file references in the skill content
        skill_content = expand_file_references(skill_content, skill_dir)

        skills.append((skill_name, skill_content))

    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 each skill
    skills = gather_skills()
    for skill_name, skill_content in skills:
        output_parts.append("")
        output_parts.append(f"# Skill: {skill_name}")
        output_parts.append("")
        output_parts.append(skill_content)
        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))