import argparse
import json
import re
import tomllib
from dataclasses import dataclass
from pathlib import Path

from clan_cli.cmd import run_no_stdout
from clan_cli.errors import ClanCmdError, ClanError
from clan_cli.nix import nix_eval

from . import API


@dataclass
class Frontmatter:
    description: str
    categories: list[str] | None = None


def extract_frontmatter(readme_content: str, err_scope: str) -> tuple[Frontmatter, str]:
    """
    Extracts TOML frontmatter from a README file content.

    Parameters:
    - readme_content (str): The content of the README file as a string.

    Returns:
    - str: The extracted frontmatter as a string.
    - str: The content of the README file without the frontmatter.

    Raises:
    - ValueError: If the README does not contain valid frontmatter.
    """
    # Pattern to match YAML frontmatter enclosed by triple-dashed lines
    frontmatter_pattern = r"^---\s+(.*?)\s+---\s?+(.*)$"

    # Search for the frontmatter using the pattern
    match = re.search(frontmatter_pattern, readme_content, re.DOTALL)

    # If a match is found, return the frontmatter content
    match = re.search(frontmatter_pattern, readme_content, re.DOTALL)

    # If a match is found, parse the TOML frontmatter and return both parts
    if match:
        frontmatter_raw, remaining_content = match.groups()
        try:
            # Parse the TOML frontmatter
            frontmatter_parsed = tomllib.loads(frontmatter_raw)
        except tomllib.TOMLDecodeError as e:
            raise ClanError(
                f"Error parsing TOML frontmatter: {e}",
                description=f"Invalid TOML frontmatter. {err_scope}",
                location="extract_frontmatter",
            )

        return Frontmatter(**frontmatter_parsed), remaining_content

    # If no frontmatter is found, raise an error
    raise ClanError(
        "Invalid README: Frontmatter not found.",
        location="extract_frontmatter",
        description=f"{err_scope} does not contain valid frontmatter.",
    )


def get_roles(module_path: str) -> None | list[str]:
    roles_dir = Path(module_path) / "roles"
    if not roles_dir.exists() or not roles_dir.is_dir():
        return None

    return [
        role.stem  # filename without .nix extension
        for role in roles_dir.iterdir()
        if role.is_file() and role.suffix == ".nix"
    ]


@dataclass
class ModuleInfo:
    description: str
    categories: list[str] | None
    roles: list[str] | None


def get_modules(base_path: str) -> dict[str, str]:
    cmd = nix_eval(
        [
            f"{base_path}#clanInternals.clanModules",
            "--json",
        ]
    )
    try:
        proc = run_no_stdout(cmd)
        res = proc.stdout.strip()
    except ClanCmdError:
        raise ClanError(
            "clanInternals might not have clanModules attributes",
            location=f"list_modules {base_path}",
            description="Evaluation failed on clanInternals.clanModules attribute",
        )
    modules: dict[str, str] = json.loads(res)
    return modules


@API.register
def list_modules(base_path: str) -> list[str]:
    """
    Show information about a module
    """
    modules = get_modules(base_path)
    return [m for m in modules.keys()]


@API.register
def show_module_info(base_path: str, module_name: str) -> ModuleInfo:
    """
    Show information about a module
    """
    modules = get_modules(base_path)
    module_path = modules.get(module_name, None)
    if not module_path:
        raise ClanError(
            "Module not found",
            location=f"show_module_info {module_name}",
            description="Module does not exist",
        )
    module_readme = Path(module_path) / "README.md"
    if not module_readme.exists():
        raise ClanError(
            "Module not found",
            location=f"show_module_info {module_name}",
            description="Module does not exist or doesn't have any README.md file",
        )
    with open(module_readme) as f:
        readme = f.read()
        frontmatter, readme_content = extract_frontmatter(
            readme, f"{module_path}/README.md"
        )

    return ModuleInfo(
        description=frontmatter.description,
        categories=frontmatter.categories,
        roles=get_roles(module_path),
    )


def command(args: argparse.Namespace) -> None:
    res = show_module_info(args.flake, args.module_name)
    print(res)