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

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")
PR_TEMPLATE_FILE = Path(".github/PULL_REQUEST_TEMPLATE.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.
- When reviewing changes under `homeassistant/components/` or `tests/components/`, use the `ha-integration-knowledge` skill as the primary reference.
- Flag comments that over-explain straightforward code, narrate the obvious, or read like AI commentary (multi-sentence justifications for a single line).
- 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.
- Check that the PR description is complete and filled in according to the PR template included below. Every section and checklist item from the template must be present, except the `## Breaking change` section which is optional. No content from the template should be missing, except for HTML comments and Markdown link reference definitions (lines of the form `[name]: url`), which do not render and cannot be verified from the description. Even unchecked checkboxes or empty sections must be present. This is a hard requirement.

## Pull Request template

The PR description must follow this template (from `.github/PULL_REQUEST_TEMPLATE.md`):

```markdown
{pr_template}
```
"""


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)

    if not PR_TEMPLATE_FILE.exists():
        print(f"Error: {PR_TEMPLATE_FILE} not found")
        sys.exit(1)

    copilot_instructions = COPILOT_SPECIFIC_INSTRUCTIONS.replace(
        "{pr_template}", PR_TEMPLATE_FILE.read_text().strip()
    )

    output_parts: list[str] = [GENERATED_MESSAGE, copilot_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()

    if validate:
        check_file(OUTPUT_FILE, main_content)
        return 0

    OUTPUT_FILE.write_text(main_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))