"""Initialize a new OpenEnv environment."""

from __future__ import annotations

import os
import random
import shutil
import subprocess
from importlib import resources
from pathlib import Path
from typing import Annotated, Dict, List, Optional, Tuple

import typer

from .._cli_utils import console

# Commands are registered in __main__.py


def _snake_to_pascal(snake_str: str) -> str:
    """Convert snake_case to PascalCase (e.g., 'my_env' -> 'MyEnv')."""
    return "".join(word.capitalize() for word in snake_str.split("_"))


def _get_env_prefix(env_name: str) -> str:
    """Extract the prefix for class names (e.g., 'my_env' -> 'My', 'test_env' -> 'Test')."""
    # Remove trailing '_env' if present
    if env_name.endswith("_env"):
        base = env_name[:-4]  # Remove '_env'
    else:
        base = env_name

    # If empty or just one part, use the whole thing
    if not base or "_" not in base:
        return base.capitalize() if base else env_name.capitalize()

    # PascalCase all parts except the last
    parts = base.split("_")
    return "".join(word.capitalize() for word in parts)


def _snake_to_camel(snake_str: str) -> str:
    """Convert snake_case to camelCase (e.g., 'my_env' -> 'myEnv')."""
    parts = snake_str.split("_")
    return parts[0] + "".join(word.capitalize() for word in parts[1:])


def _snake_to_title(snake_str: str) -> str:
    """Convert snake_case to Title Case (e.g., 'my_env' -> 'My Env')."""
    return " ".join(word.capitalize() for word in snake_str.split("_"))


def _validate_env_name(name: str) -> str:
    """Validate environment name (must be valid Python identifier in snake_case)."""
    if not name:
        raise typer.BadParameter("Environment name cannot be empty")

    # Check if it's a valid Python identifier
    if not name.isidentifier():
        raise typer.BadParameter(
            f"Environment name '{name}' is not a valid Python identifier. Use snake_case (e.g., 'my_env', 'game_env')."
        )

    # Check if it starts with a number
    if name[0].isdigit():
        raise typer.BadParameter(
            f"Environment name '{name}' cannot start with a number."
        )

    return name


def _get_random_hf_space_config() -> Dict[str, str]:
    """
    Get random Hugging Face Space configuration values.

    Returns:
        Dictionary with 'emoji', 'colorFrom', and 'colorTo' keys
    """
    # Valid emojis (emoji-only characters)
    emojis = [
        "🎮",
        "🎯",
        "🚀",
        "🌟",
        "🎨",
        "🎪",
        "🎭",
        "🎬",
        "🎤",
        "🎧",
        "🎵",
        "🎶",
        "🎸",
        "🎹",
        "🥁",
        "🎺",
        "🎻",
        "🎼",
        "🎯",
        "🎲",
        "🎳",
        "🎰",
        "🎴",
        "🃏",
        "🀄",
        "🎴",
        "🎨",
        "🖼️",
        "🎬",
        "🎭",
        "🎪",
        "🎤",
        "🎧",
        "🎵",
        "🎶",
        "🎸",
        "🎹",
        "🎺",
        "🎻",
        "🥁",
        "🎯",
        "🎲",
        "🎳",
        "🎰",
        "🏀",
        "⚽",
        "🏈",
        "⚾",
        "🎾",
        "🏐",
        "🏉",
        "🎱",
        "🏓",
        "🏸",
        "🥅",
        "🏒",
        "🏑",
        "🏏",
        "⛳",
        "🏹",
        "🎣",
        "🥊",
        "🥋",
        "🎽",
        "🏅",
        "🎖️",
        "🏆",
        "🥇",
        "🥈",
        "🥉",
        "🔊",
        "🔉",
        "🔈",
        "🔇",
        "📢",
        "📣",
        "📯",
        "🔔",
        "🔕",
        "📻",
        "📡",
        "💻",
        "🖥️",
        "🖨️",
        "⌨️",
        "🖱️",
        "🖲️",
        "🕹️",
        "🗜️",
        "💾",
        "💿",
        "📀",
        "📼",
        "📷",
        "📸",
        "📹",
        "🎥",
        "📽️",
        "🎞️",
        "📞",
        "☎️",
        "📟",
        "📠",
        "📺",
        "📻",
        "🎙️",
        "🎚️",
        "🎛️",
        "⏱️",
        "⏲️",
        "⏰",
        "🕰️",
        "⌚",
        "📱",
        "📲",
        "💻",
        "⌨️",
        "🖥️",
        "🖨️",
        "🖱️",
    ]

    # Valid colors from HF Spaces config reference
    colors = ["red", "yellow", "green", "blue", "indigo", "purple", "pink", "gray"]

    return {
        "emoji": random.choice(emojis),
        "colorFrom": random.choice(colors),
        "colorTo": random.choice(colors),
    }


def _create_template_replacements(env_name: str) -> Dict[str, str]:
    """
    Create comprehensive template replacement dictionary.

    Supports all naming conventions:
    - PascalCase for class names
    - camelCase for variable names
    - snake_case for module names, file paths
    """
    env_pascal = _snake_to_pascal(env_name)
    env_prefix = _get_env_prefix(env_name)
    env_camel = _snake_to_camel(env_name)
    env_title = _snake_to_title(env_name)

    # Get random HF Space config values
    hf_config = _get_random_hf_space_config()

    replacements = {
        # Template placeholders (MUST come first - full class names before partial)
        "__ENV_CLASS_NAME__Environment": f"{env_prefix}Environment",
        "__ENV_CLASS_NAME__Action": f"{env_prefix}Action",
        "__ENV_CLASS_NAME__Observation": f"{env_prefix}Observation",
        "__ENV_CLASS_NAME__Env": f"{env_prefix}Env",
        # Template placeholders (partial - must come after full replacements)
        "__ENV_NAME__": env_name,
        "__ENV_CLASS_NAME__": env_prefix,  # Use prefix, not full PascalCase
        "__ENV_TITLE_NAME__": env_title,
        "__ENV_CAMEL_NAME__": env_camel,
        # Hugging Face Space config placeholders
        "__HF_EMOJI__": hf_config["emoji"],
        "__HF_COLOR_FROM__": hf_config["colorFrom"],
        "__HF_COLOR_TO__": hf_config["colorTo"],
    }

    return replacements


def _replace_in_content(content: str, replacements: Dict[str, str]) -> str:
    """Replace all occurrences in content using case-sensitive replacements."""
    result = content
    # Sort by length (longest first) to avoid partial replacements
    for old, new in sorted(replacements.items(), key=lambda x: len(x[0]), reverse=True):
        result = result.replace(old, new)
    return result


def _should_rename_file(filename: str, env_name: str) -> Tuple[bool, str]:
    """
    Check if a file should be renamed and return the new name.

    Handles template placeholders in filenames like:
    - `__ENV_NAME___environment.py` → `<env_name>_environment.py`
    """
    # Check for template placeholder
    if "__ENV_NAME__" in filename:
        new_name = filename.replace("__ENV_NAME__", env_name)
        return True, new_name

    return False, filename


def _copy_and_template_file(
    src_path: Path,
    dest_path: Path,
    replacements: Dict[str, str],
) -> None:
    """Copy a file and apply template replacements."""
    dest_path.parent.mkdir(parents=True, exist_ok=True)

    try:
        # Read source file
        content = src_path.read_bytes()

        # Try to decode as text and apply replacements
        try:
            text = content.decode("utf-8")
            # Normalize line endings to LF before applying replacements
            text = text.replace("\r\n", "\n").replace("\r", "\n")
            text = _replace_in_content(text, replacements)
            dest_path.write_text(text, encoding="utf-8", newline="\n")
        except UnicodeDecodeError:
            # Binary file, just copy
            dest_path.write_bytes(content)
    except Exception as e:
        raise RuntimeError(
            f"Failed to copy template file {src_path} to {dest_path}: {e}"
        ) from e


def _copy_template_directory(
    template_pkg: str,
    template_dir: str,
    dest_dir: Path,
    replacements: Dict[str, str],
    env_name: str,
) -> List[Path]:
    """Recursively copy template directory and apply replacements."""
    created_files: List[Path] = []

    # Get the package path using importlib.resources but avoid importing the template package
    # We'll use the package's __file__ to get the directory path
    import importlib

    try:
        # Import the parent package (not the template package itself)
        if "." in template_pkg:
            parent_pkg = ".".join(template_pkg.split(".")[:-1])
            pkg = importlib.import_module(parent_pkg)
            template_path = Path(pkg.__file__).parent / template_pkg.split(".")[-1]
        else:
            pkg = importlib.import_module(template_pkg.split(".")[0])
            template_path = Path(pkg.__file__).parent / template_pkg.split(".")[-1]
    except Exception:
        # Fallback: try to use resources.files but handle import errors
        try:
            base = resources.files(template_pkg.split(".")[0])
            template_path = base.joinpath(*template_pkg.split(".")[1:])
            if not template_path.exists():
                raise FileNotFoundError(f"Template directory not found: {template_pkg}")
        except Exception as e:
            raise FileNotFoundError(
                f"Template directory not found: {template_pkg}"
            ) from e

    if template_dir:
        template_path = template_path / template_dir

    if not template_path.exists() or not template_path.is_dir():
        raise FileNotFoundError(
            f"Template directory not found: {template_pkg}.{template_dir}"
        )

    # Walk through all files in template directory using Path
    for item in template_path.rglob("*"):
        if item.is_file():
            rel_path = item.relative_to(template_path)
            dest_path = dest_dir / rel_path

            # Apply filename templating
            should_rename, new_name = _should_rename_file(dest_path.name, env_name)
            if should_rename:
                dest_path = dest_path.parent / new_name

            # Copy and apply replacements
            _copy_and_template_file(item, dest_path, replacements)
            created_files.append(dest_path)

    return created_files


def _generate_uv_lock(env_dir: Path) -> bool:
    """Generate uv.lock from pyproject.toml using uv."""
    pyproject_path = env_dir / "pyproject.toml"

    if not pyproject_path.exists():
        return False

    try:
        cmd = [
            "uv",
            "lock",
            "--directory",
            str(env_dir),
        ]

        result = subprocess.run(cmd, capture_output=True, text=True, check=True)

        if result.stdout:
            console.print(result.stdout)

        return True

    except subprocess.CalledProcessError as e:
        console.print(
            f"[yellow]Warning: Could not generate uv.lock: {e.stderr}[/yellow]"
        )
        return False
    except FileNotFoundError:
        console.print(
            "[yellow]Warning: 'uv' not found. Install it to generate uv.lock[/yellow]"
        )
        return False


def init(
    env_name: Annotated[
        str,
        typer.Argument(
            help="Name of the environment to create (snake_case, e.g., 'my_env')"
        ),
    ],
    output_dir: Annotated[
        Optional[str],
        typer.Option(
            "--output-dir",
            "-o",
            help="Output directory (defaults to current working directory)",
        ),
    ] = None,
) -> None:
    """
    Initialize a new OpenEnv environment.

    Creates a new directory with the environment name and generates all necessary
    files based on the OpenEnv template structure.

    Example:
        $ openenv init my_game_env
        $ openenv init my_env --output-dir /path/to/projects
    """
    # Validate environment name
    env_name = _validate_env_name(env_name)

    # Determine output directory
    base_dir = Path(output_dir).resolve() if output_dir else Path.cwd().resolve()
    env_dir = base_dir / env_name

    # Check if directory already exists
    if env_dir.exists():
        if env_dir.is_file():
            raise typer.BadParameter(f"Path '{env_dir}' exists and is a file")
        if any(env_dir.iterdir()):
            raise typer.BadParameter(
                f"Directory '{env_dir}' already exists and is not empty. "
                "Please choose a different name or remove the existing directory."
            )

    try:
        # Create template replacements
        replacements = _create_template_replacements(env_name)

        # Create environment directory
        env_dir.mkdir(parents=True, exist_ok=True)

        console.print(
            f"[bold cyan]Creating OpenEnv environment '{env_name}'...[/bold cyan]"
        )

        # Copy template files from template structure
        template_pkg = "openenv.cli.templates.openenv_env"
        created_files = _copy_template_directory(
            template_pkg,
            "",
            env_dir,
            replacements,
            env_name,
        )

        console.print(f"[bold green]✓[/bold green] Created {len(created_files)} files")

        # Generate uv.lock
        console.print("\n[bold]Generating uv.lock...[/bold]")
        if _generate_uv_lock(env_dir):
            console.print("[green]✓[/green] Generated uv.lock")
        else:
            console.print("[yellow]⚠[/yellow] Could not generate uv.lock automatically")
            console.print("    You can generate it manually with:")
            console.print(f"    cd {env_dir} && uv lock")

        console.print(
            f"\n[bold green]Environment created successfully at: {env_dir}[/bold green]"
        )
        console.print("\n[bold]Next steps:[/bold]")
        console.print(f"  cd {env_dir}")
        console.print(
            f"  # Edit your environment implementation in server/{env_name}_environment.py"
        )
        console.print("  # Edit your models in models.py")
        console.print("  # Install dependencies: uv sync")
        console.print("\n  # To integrate into OpenEnv repo:")
        console.print(f"  # 1. Copy this directory to <repo_root>/envs/{env_name}_env")
        console.print(
            f"  # 2. Build from repo root: docker build -t {env_name}_env:latest -f envs/{env_name}_env/server/Dockerfile ."
        )
        console.print(
            f"  # 3. Run your image: docker run -p 8000:8000 {env_name}_env:latest"
        )

    except Exception as e:
        # Cleanup on error
        if env_dir.exists() and env_dir.is_dir():
            try:
                shutil.rmtree(env_dir)
            except Exception:
                pass

        console.print(f"[bold red]Error:[/bold red] {e}")
        raise typer.Exit(1) from e