"""
DungeonMaster AI - Input Validators

Utilities for validating user input and game data.
"""

import re
from typing import Any


class ValidationError(Exception):
    """Custom exception for validation errors."""

    def __init__(self, message: str, field: str | None = None):
        self.message = message
        self.field = field
        super().__init__(self.message)


def validate_dice_notation(notation: str) -> bool:
    """
    Validate dice notation format.

    Valid formats:
    - d20, D20
    - 2d6, 2D6
    - 1d8+5, 1d8-2
    - 4d6kh3 (keep highest 3)
    - 2d20kl1 (keep lowest 1, disadvantage)

    Args:
        notation: The dice notation string

    Returns:
        True if valid, False otherwise
    """
    # Pattern for standard dice notation with optional modifiers and keep syntax
    pattern = r"^(\d+)?[dD](\d+)(kh\d+|kl\d+)?([+-]\d+)?$"
    return bool(re.match(pattern, notation.strip()))


def validate_character_name(name: str) -> tuple[bool, str]:
    """
    Validate a character name.

    Args:
        name: The proposed character name

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    if not name or not name.strip():
        return False, "Character name cannot be empty"

    name = name.strip()

    if len(name) < 2:
        return False, "Character name must be at least 2 characters"

    if len(name) > 50:
        return False, "Character name must be 50 characters or less"

    # Allow letters, spaces, apostrophes, and hyphens
    if not re.match(r"^[a-zA-Z][a-zA-Z\s'\-]*$", name):
        return False, "Character name must start with a letter and contain only letters, spaces, apostrophes, and hyphens"

    return True, ""


def validate_ability_score(score: int, method: str = "standard") -> tuple[bool, str]:
    """
    Validate an ability score.

    Args:
        score: The ability score value
        method: The generation method ("standard", "point_buy", "rolled")

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    if not isinstance(score, int):
        return False, "Ability score must be an integer"

    if method == "point_buy":
        if score < 8 or score > 15:
            return False, "Point buy scores must be between 8 and 15"
    elif method == "standard":
        valid_scores = [8, 10, 12, 13, 14, 15]
        if score not in valid_scores:
            return False, f"Standard array scores must be one of {valid_scores}"
    else:  # rolled or other
        if score < 3 or score > 18:
            return False, "Rolled scores must be between 3 and 18"

    return True, ""


def validate_level(level: int) -> tuple[bool, str]:
    """
    Validate a character level.

    Args:
        level: The character level

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    if not isinstance(level, int):
        return False, "Level must be an integer"

    if level < 1 or level > 20:
        return False, "Level must be between 1 and 20"

    return True, ""


def validate_hp(
    current: int, maximum: int, allow_negative: bool = False
) -> tuple[bool, str]:
    """
    Validate HP values.

    Args:
        current: Current HP
        maximum: Maximum HP
        allow_negative: Whether to allow negative current HP (for massive damage)

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    if not isinstance(current, int) or not isinstance(maximum, int):
        return False, "HP values must be integers"

    if maximum < 1:
        return False, "Maximum HP must be at least 1"

    if not allow_negative and current < 0:
        return False, "Current HP cannot be negative"

    if allow_negative and current < -maximum:
        return False, "Current HP cannot be less than negative maximum HP"

    return True, ""


def validate_player_input(
    message: str, max_length: int = 1000
) -> tuple[bool, str, str]:
    """
    Validate and sanitize player input.

    Args:
        message: The player's input message
        max_length: Maximum allowed length

    Returns:
        Tuple of (is_valid, sanitized_message, error_message)
    """
    if not message:
        return False, "", "Please enter an action or message"

    # Strip and normalize whitespace
    sanitized = " ".join(message.split())

    if len(sanitized) > max_length:
        return False, "", f"Message is too long (max {max_length} characters)"

    # Check for potentially problematic content
    # (In a real app, might want more sophisticated content filtering)
    if sanitized.count("```") > 4:
        return False, sanitized, "Message contains too many code blocks"

    return True, sanitized, ""


def validate_session_data(data: dict[str, Any]) -> tuple[bool, str]:
    """
    Validate session/save data structure.

    Args:
        data: The session data dictionary

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    required_fields = ["session_id", "started_at", "system"]

    for field in required_fields:
        if field not in data:
            return False, f"Missing required field: {field}"

    if data.get("system") not in ["dnd5e", "pathfinder2e", "call_of_cthulhu", "fate"]:
        return False, "Invalid game system"

    if "party" in data and not isinstance(data["party"], list):
        return False, "Party must be a list"

    if "game_state" in data:
        state = data["game_state"]
        if "in_combat" in state and not isinstance(state["in_combat"], bool):
            return False, "in_combat must be a boolean"

    return True, ""


def validate_adventure_data(data: dict[str, Any]) -> tuple[bool, str]:
    """
    Validate adventure JSON structure.

    Args:
        data: The adventure data dictionary

    Returns:
        Tuple of (is_valid, error_message or empty string)
    """
    if "metadata" not in data:
        return False, "Adventure must have metadata"

    metadata = data["metadata"]
    required_metadata = ["name", "description", "difficulty"]
    for field in required_metadata:
        if field not in metadata:
            return False, f"Metadata missing required field: {field}"

    if "starting_scene" not in data:
        return False, "Adventure must have a starting_scene"

    if "scenes" not in data or not isinstance(data["scenes"], list):
        return False, "Adventure must have a scenes array"

    if len(data["scenes"]) == 0:
        return False, "Adventure must have at least one scene"

    # Validate scene references
    scene_ids = {scene.get("scene_id") for scene in data["scenes"]}
    starting_id = data["starting_scene"].get("scene_id")
    if starting_id not in scene_ids:
        return False, f"Starting scene '{starting_id}' not found in scenes"

    return True, ""


def sanitize_for_tts(text: str) -> str:
    """
    Sanitize text for text-to-speech processing.

    Removes or converts elements that might cause TTS issues.

    Args:
        text: The raw text

    Returns:
        Sanitized text suitable for TTS
    """
    # Remove markdown formatting
    text = re.sub(r"\*\*(.+?)\*\*", r"\1", text)  # Bold
    text = re.sub(r"\*(.+?)\*", r"\1", text)  # Italic
    text = re.sub(r"~~(.+?)~~", r"\1", text)  # Strikethrough
    text = re.sub(r"`(.+?)`", r"\1", text)  # Inline code
    text = re.sub(r"```[\s\S]*?```", "", text)  # Code blocks
    text = re.sub(r"^#{1,6}\s+", "", text, flags=re.MULTILINE)  # Headers

    # Remove links, keep text
    text = re.sub(r"\[(.+?)\]\(.+?\)", r"\1", text)

    # Remove emojis (basic pattern)
    text = re.sub(
        r"[\U0001F600-\U0001F64F\U0001F300-\U0001F5FF\U0001F680-\U0001F6FF\U0001F1E0-\U0001F1FF]",
        "",
        text,
    )

    # Normalize whitespace
    text = " ".join(text.split())

    return text.strip()