"""
MkDocs documentation management CLI.

This script provides a proper CLI interface to:
- Generate MkDocs Markdown files with mkdocstrings directives
- Build the documentation site
- Serve the documentation site locally

All operations are performed by calling MkDocs as a Python library
(no shell command invocation).

Requirements:
- mkdocs
- mkdocs-material
- mkdocstrings[python]

Usage:
    python manage_docs.py generate
    python manage_docs.py build
    python manage_docs.py serve
    python manage_docs.py build_mcp

Optional flags:
    --docs-dir PATH        Path to docs directory (default: ./docs)
    --package-root NAME    Root Python package name (default: mail_intake)
"""

from __future__ import annotations

import argparse
import json
import re
from pathlib import Path
from typing import Iterable

from mkdocs.commands import build as mkdocs_build
from mkdocs.commands import serve as mkdocs_serve
from mkdocs.config import load_config


PROJECT_ROOT = Path(__file__).resolve().parent
DEFAULT_DOCS_DIR = PROJECT_ROOT / "docs"
DEFAULT_PACKAGE_ROOT = "mail_intake"
MKDOCS_YML = PROJECT_ROOT / "mkdocs.yml"
DEFAULT_MCP_DIR = PROJECT_ROOT / "mcp"

MKDOCSTRINGS_DIRECTIVE = re.compile(r"^:::\s+([a-zA-Z0-9_.]+)", re.MULTILINE)


# -------------------------
# Existing functionality
# -------------------------

def generate_docs_from_nav(
    project_root: Path,
    docs_root: Path,
    package_root: str,
) -> None:
    """
    Create and populate MkDocs Markdown files with mkdocstrings directives.

    This function:
    - Walks the Python package structure
    - Mirrors it under the docs directory
    - Creates missing .md files
    - Creates index.md for packages (__init__.py)
    - Overwrites content with ::: package.module

    Examples:
        mail_intake/__init__.py           -> docs/mail_intake/index.md
        mail_intake/config.py             -> docs/mail_intake/config.md
        mail_intake/adapters/__init__.py  -> docs/mail_intake/adapters/index.md
        mail_intake/adapters/base.py      -> docs/mail_intake/adapters/base.md
    """

    package_dir = project_root / package_root
    if not package_dir.exists():
        raise FileNotFoundError(f"Package not found: {package_dir}")

    docs_root.mkdir(parents=True, exist_ok=True)

    for py_file in package_dir.rglob("*.py"):
        rel = py_file.relative_to(project_root)

        if py_file.name == "__init__.py":
            # Package → index.md
            module_path = ".".join(rel.parent.parts)
            md_path = docs_root / rel.parent / "index.md"
            title = rel.parent.name.replace("_", " ").title()
        else:
            # Regular module → <module>.md
            module_path = ".".join(rel.with_suffix("").parts)
            md_path = docs_root / rel.with_suffix(".md")
            title = md_path.stem.replace("_", " ").title()

        md_path.parent.mkdir(parents=True, exist_ok=True)

        content = f"""# {title}

::: {module_path}
"""

        md_path.write_text(content, encoding="utf-8")


def load_mkdocs_config():
    if not MKDOCS_YML.exists():
        raise FileNotFoundError("mkdocs.yml not found at project root")
    return load_config(str(MKDOCS_YML))


def cmd_generate(args: argparse.Namespace) -> None:
    generate_docs_from_nav(
        project_root=PROJECT_ROOT,
        docs_root=args.docs_dir,
        package_root=args.package_root,
    )


def cmd_build(_: argparse.Namespace) -> None:
    config = load_mkdocs_config()
    mkdocs_build.build(config)


def cmd_serve(_: argparse.Namespace) -> None:
    mkdocs_serve.serve(
        config_file=str(MKDOCS_YML)
    )


# -------------------------
# MCP generation
# -------------------------

def iter_markdown_files(docs_root: Path) -> Iterable[Path]:
    yield from docs_root.rglob("*.md")


def extract_modules(md_file: Path) -> list[str]:
    content = md_file.read_text(encoding="utf-8")
    return MKDOCSTRINGS_DIRECTIVE.findall(content)


def cmd_build_mcp(args: argparse.Namespace) -> None:
    docs_root = args.docs_dir
    mcp_root = args.mcp_dir

    modules_dir = mcp_root / "modules"
    modules_dir.mkdir(parents=True, exist_ok=True)

    nav = []
    modules = []

    for md in iter_markdown_files(docs_root):
        rel = md.relative_to(docs_root)

        module_refs = extract_modules(md)
        if not module_refs:
            continue

        nav.append({
            "page": str(rel),
            "modules": module_refs,
        })

        for module in module_refs:
            module_entry = {
                "module": module,
                "doc_page": str(rel),
            }
            modules.append(module_entry)

            out = modules_dir / f"{module}.json"
            out.parent.mkdir(parents=True, exist_ok=True)
            out.write_text(
                json.dumps(module_entry, indent=2),
                encoding="utf-8",
            )

    mcp_root.mkdir(parents=True, exist_ok=True)

    (mcp_root / "nav.json").write_text(
        json.dumps(nav, indent=2),
        encoding="utf-8",
    )

    (mcp_root / "index.json").write_text(
        json.dumps(
            {
                "project": "Aetoskia Mail Intake",
                "type": "docs-only",
                "modules_count": len(modules),
            },
            indent=2,
        ),
        encoding="utf-8",
    )

    print(f"MCP artifacts written to: {mcp_root}")


# -------------------------
# CLI
# -------------------------

def main() -> None:
    parser = argparse.ArgumentParser(
        prog="manage_docs.py",
        description="Manage MkDocs documentation and MCP exports for the project",
    )

    parser.add_argument(
        "--docs-dir",
        type=Path,
        default=DEFAULT_DOCS_DIR,
        help="Path to the docs directory",
    )

    parser.add_argument(
        "--package-root",
        default=DEFAULT_PACKAGE_ROOT,
        help="Root Python package name",
    )

    parser.add_argument(
        "--mcp-dir",
        type=Path,
        default=DEFAULT_MCP_DIR,
        help="Output directory for MCP artifacts",
    )

    subparsers = parser.add_subparsers(dest="command", required=True)

    subparsers.add_parser(
        "generate",
        help="Generate Markdown files with mkdocstrings directives",
    ).set_defaults(func=cmd_generate)

    subparsers.add_parser(
        "build",
        help="Build the MkDocs site",
    ).set_defaults(func=cmd_build)

    subparsers.add_parser(
        "serve",
        help="Serve the MkDocs site locally",
    ).set_defaults(func=cmd_serve)

    subparsers.add_parser(
        "build_mcp",
        help="Generate MCP artifacts (docs-only)",
    ).set_defaults(
        func=cmd_build_mcp
    )

    args = parser.parse_args()
    args.func(args)


if __name__ == "__main__":
    main()