#!/usr/bin/env python3
"""Classify git changes as user-facing or workflow-only.

Determines whether changes between two git refs (e.g., last tag and HEAD)
affect the GRM tool itself (user-facing) or only the CI/CD infrastructure
(workflow-only).  This is used by:

- **release.py** — skips release when only workflow files changed
- **CI workflow** — skips molecule tests and release dry-run when only
  workflow files changed

Classification strategy (safe-by-default):

  Any file that is NOT in the explicit workflow-only allowlist is treated
  as user-facing.  This ensures new file types default to requiring a
  release rather than silently skipping it.

  Workflow-only paths (infrastructure → no release needed):
    - .gitea/workflows/**          — Gitea Actions workflows
    - scripts/**                   — All scripts (CI/CD, dev tools, setup)
    - src/gitea_runner_manager/__init__.py — Version file (release artifact)
    - src/gitea_runner_manager/api_clients.py — Gitea API client (CI/CD only, not used by CLI)
    - docs/**                      — Documentation
    - tests/**                     — Test files
    - hooks/**                     — Git hooks
    - AGENTS.md                    — Agent conventions
    - REVIEW_CHECKLIST.md          — Review checklist
    - README.md                    — README (lean, links to wiki)
    - CHANGELOG.md                 — Changelog (generated)
    - TROUBLESHOOTING.md           — Troubleshooting guide
    - cliff.toml                   — git-cliff config
    - Makefile                     — Build automation
    - .pre-commit-config.yaml      — Pre-commit config
    - .ansible-lint                — Ansible lint config
    - .env.example                 — Environment template
    - .gitignore                   — Git ignore rules
    - .ruff.toml                   — Ruff config (if separate)
    - .github/**                   — GitHub config (if present)

  Everything else is user-facing (tool changes → release needed),
  including but not limited to:
    - src/gitea_runner_manager/*.py — Python CLI source (except __init__.py)
    - ansible/**                   — Ansible role
    - pyproject.toml               — Package metadata
    - Any new file type not in the allowlist

Usage:
  python3 scripts/ci/classify_changes.py [--base <ref>] [--head <ref>]
  python3 scripts/ci/classify_changes.py --base v0.3.0 --head HEAD
"""

from __future__ import annotations

import subprocess  # nosec B404
import sys

import click

from gitea_runner_manager.i18n import _

# Explicit allowlist of workflow-only path patterns.
# Anything NOT matching these is treated as user-facing (safe default).
WORKFLOW_ONLY_PATTERNS = frozenset(
    [
        # CI/CD infrastructure
        ".gitea/",
        # All scripts are infrastructure (CI/CD, dev tools, setup)
        # User-facing code lives in src/gitea_runner_manager/
        "scripts/",
        # Version file — only contains __version__, not user-facing code.
        # Version bumps are a release artifact, not a feature.
        "src/gitea_runner_manager/__init__.py",
        # Gitea API client — used only by CI/CD scripts, not by the GRM CLI.
        "src/gitea_runner_manager/api_clients.py",
        # Documentation
        "docs/",
        "AGENTS.md",
        "REVIEW_CHECKLIST.md",
        "README.md",
        "CHANGELOG.md",
        "TROUBLESHOOTING.md",
        # Tests
        "tests/",
        # Config / build automation
        "cliff.toml",
        "Makefile",
        ".pre-commit-config.yaml",
        ".ansible-lint",
        ".env.example",
        ".gitignore",
        ".ruff.toml",
        # Hooks
        "hooks/",
        # GitHub (if ever added)
        ".github/",
    ]
)


def run_git(args: list[str]) -> str:
    """Run a git command and return stdout."""
    result = subprocess.run(  # nosec B603
        args,
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode != 0:
        raise click.ClickException(
            _("git command failed ({cmd}): {stderr}", cmd=" ".join(args), stderr=result.stderr.strip())
        )
    return result.stdout.strip()


def get_changed_files(base: str, head: str) -> list[str]:
    """Get list of files changed between base and head refs."""
    output = run_git(["git", "diff", "--name-only", base, head])
    if not output:
        return []
    return output.split("\n")


def is_workflow_only(file_path: str) -> bool:
    """Check if a file path is workflow-only (infrastructure, not the tool itself).

    Uses an explicit allowlist — anything not in the list is treated as
    user-facing (safe default that prevents accidental release skips).
    """
    return any(file_path.startswith(pattern) or file_path == pattern for pattern in WORKFLOW_ONLY_PATTERNS)


def is_user_facing(file_path: str) -> bool:
    """Check if a file path is user-facing (affects the GRM tool).

    Inverse of is_workflow_only — anything not explicitly workflow-only
    is treated as user-facing.
    """
    return not is_workflow_only(file_path)


def classify_changes(files: list[str]) -> dict[str, list[str]]:
    """Classify changed files into user-facing and workflow-only.

    Returns a dict with keys "user_facing" and "workflow_only".
    """
    user_facing: list[str] = []
    workflow_only: list[str] = []
    for f in files:
        if is_user_facing(f):
            user_facing.append(f)
        else:
            workflow_only.append(f)
    return {"user_facing": user_facing, "workflow_only": workflow_only}


def has_user_facing_changes(base: str, head: str) -> bool:
    """Check if any user-facing files changed between base and head.

    Imported by ``scripts/ci/release.py`` to decide whether a release
    is needed. This is a cross-CI import that requires ``PYTHONPATH=.``.
    """
    files = get_changed_files(base, head)
    return any(is_user_facing(f) for f in files)


def get_latest_tag() -> str:
    """Get the latest git tag, or empty string if none exists."""
    result = subprocess.run(  # nosec B603 B607
        ["git", "describe", "--tags", "--abbrev=0"],
        capture_output=True,
        text=True,
        check=False,
    )
    if result.returncode != 0:
        return ""
    return result.stdout.strip()


def _write_github_output(key: str, value: str) -> None:
    """Append a key=value line to the $GITHUB_OUTPUT file."""
    import os

    gh_output = os.environ.get("GITHUB_OUTPUT")
    if not gh_output:
        raise click.ClickException("GITHUB_OUTPUT environment variable is not set")
    with open(gh_output, "a") as f:  # noqa: PTH123
        f.write(f"{key}={value}\n")


@click.command()
@click.option("--base", default=None, help="Base ref (default: latest tag).")
@click.option("--head", default="HEAD", help="Head ref (default: HEAD).")
@click.option("--quiet", is_flag=True, default=False, help="Only output true/false.")
@click.option(
    "--check",
    type=click.Choice(["all", "ansible", "user-facing"]),
    default="all",
    help="Check specific category: all (default), ansible, or user-facing.",
)
@click.option(
    "--github-output",
    "github_output",
    is_flag=True,
    default=False,
    help="Write results to $GITHUB_OUTPUT file (for CI workflow steps).",
)
def main(base: str | None, head: str, quiet: bool, check: str, github_output: bool) -> None:
    if base is None:
        base = get_latest_tag()
        if not base:
            if github_output:
                _write_github_output("ansible-changed", "true")
                _write_github_output("user-facing-changed", "true")
                click.echo("No tags found — treating all changes as user-facing.")
                return
            if quiet:
                click.echo("true")
            else:
                click.echo(_("No tags found — treating all changes as user-facing."))
            return

    files = get_changed_files(base, head)
    if not files:
        if github_output:
            _write_github_output("ansible-changed", "false")
            _write_github_output("user-facing-changed", "false")
            click.echo(f"No changes between {base} and {head}.")
            return
        if quiet:
            click.echo("false")
        else:
            click.echo(_("No changes between {base} and {head}.", base=base, head=head))
        return

    if github_output:
        ansible_files = [f for f in files if f.startswith("ansible/") or f == ".ansible-lint"]
        user_files = [f for f in files if is_user_facing(f)]
        _write_github_output("ansible-changed", "true" if ansible_files else "false")
        _write_github_output("user-facing-changed", "true" if user_files else "false")
        click.echo(f"Ansible files changed: {bool(ansible_files)}")
        click.echo(f"User-facing files changed: {bool(user_files)}")
        return

    if check == "ansible":
        # Check only for Ansible-related file changes
        ansible_files = [f for f in files if f.startswith("ansible/") or f == ".ansible-lint"]
        has_ansible = bool(ansible_files)
        if quiet:
            click.echo("true" if has_ansible else "false")
            return
        click.echo(_("\nAnsible files changed ({count}):", count=len(ansible_files)))
        for f in ansible_files:
            click.echo(f"  {f}")
        click.echo(_("\nResult: {status}", status="Ansible changes detected" if has_ansible else "No Ansible changes"))
        return

    if check == "user-facing":
        # Check only for user-facing file changes (inverse of workflow-only)
        user_files = [f for f in files if is_user_facing(f)]
        has_user = bool(user_files)
        if quiet:
            click.echo("true" if has_user else "false")
            return
        click.echo(_("\nUser-facing files changed ({count}):", count=len(user_files)))
        for f in user_files:
            click.echo(f"  {f}")
        click.echo(
            _("\nResult: {status}", status="User-facing changes detected" if has_user else "No user-facing changes")
        )
        return

    result = classify_changes(files)
    has_user = bool(result["user_facing"])

    if quiet:
        click.echo("true" if has_user else "false")
        return

    click.echo(_("Comparing {base}..{head} ({count} files changed)", base=base, head=head, count=len(files)))
    click.echo(_("\nUser-facing changes ({count}):", count=len(result["user_facing"])))
    for f in result["user_facing"]:
        click.echo(f"  {f}")
    click.echo(_("\nWorkflow-only changes ({count}):", count=len(result["workflow_only"])))
    for f in result["workflow_only"]:
        click.echo(f"  {f}")
    if has_user:
        status = "USER-FACING changes detected — release needed"
    else:
        status = "Workflow-only changes — no release needed"
    click.echo(_("\nResult: {status}", status=status))

    if not has_user:
        sys.exit(2)  # Exit code 2 = workflow-only (used by CI to skip release)


if __name__ == "__main__":  # pragma: no cover
    main()