import os

SUPPORTED_COLORS = {"blue", "purple", "red", "orange", "green", "pink"}

COLOR_RGB_MAP = {
    "blue": (47, 108, 229),
    "purple": (138, 47, 229),
    "red": (229, 47, 47),
    "orange": (229, 138, 47),
    "green": (47, 229, 47),
    "pink": (229, 47, 168),
}

DEFAULT_COLOR = "blue"


def get_assets_dir():
    """Returns the absolute path to the assets directory"""
    current_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    return os.path.join(current_dir, "assets")

def get_valid_color(slide_colour: str) -> str:
    """
    Returns the validated color name. Falls back to DEFAULT_COLOR if unsupported.
    """
    color = slide_colour.lower()
    return color if color in SUPPORTED_COLORS else DEFAULT_COLOR

def get_color_rgb(slide_colour: str) -> tuple:
    """
    Returns the RGB color tuple based on the given slide color.
    """
    color = get_valid_color(slide_colour)
    return COLOR_RGB_MAP.get(color, COLOR_RGB_MAP[DEFAULT_COLOR])

def get_background_image_path(slide_colour: str, first_slide: bool = False) -> str:
    """
    Returns the path to the background image based on the slide color and type.
    """
    color = get_valid_color(slide_colour)
    suffix = "bg1" if first_slide else "bg2"
    assets_dir = get_assets_dir()
    image_path = os.path.join(assets_dir, f"{color}_{suffix}.png")
    
    if not os.path.exists(image_path):
        print(f"Warning: Background image not found at {image_path}")
        # Fallback to basic background if color-specific one doesn't exist
        image_path = os.path.join(assets_dir, f"{suffix}.png")
        if not os.path.exists(image_path):
            print(f"Warning: Fallback background image not found at {image_path}")
    
    return image_path

def get_code_rgb(slide_colour: str) -> tuple:
    """
    Returns the RGB color used for code syntax highlighting.
    """
    return get_color_rgb(slide_colour)

def get_title_rgb(slide_colour: str) -> tuple:
    """
    Returns the RGB color used for the topic title text.
    """
    return get_color_rgb(slide_colour)
    
def sanitize_filename(name: str, replacement: str = "_", max_length: int = 200) -> str:
    """
    Sanitize a string to be safe for use as a filesystem name.
    Focuses on replacing problematic special characters with a safe replacement.

    Behavior:
    - Normalize unicode (NFKC)
    - Remove control characters
    - Replace path separators and shell-sensitive punctuation with `replacement`
    - Replace whitespace sequences with `replacement`
    - Replace hyphens and dots with `replacement` (per config)
    - Collapse repeated replacement characters
    - Trim leading/trailing replacement characters
    - Truncate to `max_length` characters
    - Preserve non-Latin characters (Unicode) by default
    """
    if not name:
        return ""
    import re
    import unicodedata

    # Normalize
    s = unicodedata.normalize("NFKC", str(name))

    # Remove control chars (C0 controls)
    s = "".join(ch for ch in s if ord(ch) >= 32)

    # Replace a set of problematic punctuation with replacement
    # This includes path separators, shell-sensitive chars, punctuation and symbols.
    # Also replace hyphen and dot as requested.
        # Include '+' so languages like 'C++' are sanitized cleanly
    s = re.sub(r"[\\/\\:\\*\\?\"<>\\|,;@#%&\\$'`~()\[\]{}\\\\\+]", replacement, s)
    s = re.sub(r"[-\\.]", replacement, s)

    # Replace whitespace sequences with single replacement
    s = re.sub(r"\s+", replacement, s)

    # Collapse multiple replacements
    if replacement:
        esc = re.escape(replacement)
        s = re.sub(rf"{esc}+", replacement, s)

    # Trim leading/trailing replacements and spaces
    s = s.strip(replacement + " ")

    # Truncate
    if max_length and len(s) > max_length:
        s = s[:max_length].rstrip(replacement)

    # Avoid empty result
    if not s:
        return "topic"
    return s