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

Necessary until copilot can handle skills.
"""

from pathlib import Path
import sys

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

AGENTS_FILE = Path("AGENTS.md")
OUTPUT_FILE = Path(".github/copilot-instructions.md")
INTEGRATION_SKILL_FILE = Path(".claude/skills/ha-integration-knowledge/SKILL.md")
INTEGRATION_PATH_SPECIFIC_OUTPUT_FILE = Path(
    ".github/instructions/integrations.instructions.md"
)

COPILOT_SPECIFIC_INSTRUCTIONS = """
# Copilot code review instructions

- Start review comments with a short, one-sentence summary of the suggested fix.
- Do not comment on code style, formatting or linting issues.
- A Pull Request with a dependency version bump should only contain changes required for the version bump. If the PR includes other changes, request that they are removed from the PR.
"""

INTEGRATION_PATH_SPECIFIC_INSTRUCTIONS = """---
applyTo: "homeassistant/components/**, tests/components/**"
excludeAgent: "cloud-agent"
---
"""


def _strip_frontmatter(text: str) -> str:
    """Strip YAML frontmatter from the start of a markdown document."""
    if not text.startswith("---\n"):
        return text

    end = text.find("\n---\n", 4)
    if end == -1:
        return text

    return text[end + len("\n---\n") :].lstrip("\n")


def generate_integration_path_specific_instructions() -> str:
    """Generate instructions for integration paths."""
    if not INTEGRATION_SKILL_FILE.exists():
        print(f"Error: {INTEGRATION_SKILL_FILE} not found")
        sys.exit(1)

    skill_content = _strip_frontmatter(INTEGRATION_SKILL_FILE.read_text())

    return (
        INTEGRATION_PATH_SPECIFIC_INSTRUCTIONS
        + "\n"
        + GENERATED_MESSAGE
        + "\n"
        + skill_content
    )


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, COPILOT_SPECIFIC_INSTRUCTIONS]

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

    return "\n".join(output_parts)


def check_file(path: Path, expected_content: str):
    """Check if the file exists and has the expected content."""
    if not path.exists():
        print(f"Error: {path} does not exist")
        sys.exit(1)

    existing = path.read_text()
    if existing != expected_content:
        print(f"Error: {path} is out of date")
        print("Please run: python -m script.gen_copilot_instructions")
        sys.exit(1)

    print(f"{path} is up to date")


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

    main_content = generate_output()
    integration_path_specific_content = (
        generate_integration_path_specific_instructions()
    )

    if validate:
        check_file(OUTPUT_FILE, main_content)
        check_file(
            INTEGRATION_PATH_SPECIFIC_OUTPUT_FILE, integration_path_specific_content
        )
        return 0

    OUTPUT_FILE.write_text(main_content)
    print(f"Generated {OUTPUT_FILE}")

    INTEGRATION_PATH_SPECIFIC_OUTPUT_FILE.write_text(integration_path_specific_content)
    print(f"Generated {INTEGRATION_PATH_SPECIFIC_OUTPUT_FILE}")
    return 0


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