# Font validation and preview functionality
import bpy
import os
import platform
from PIL import Image, ImageDraw, ImageFont

def test_font_mixed_case_support(font_path):
    """
    Test if a font properly supports mixed case rendering.
    Returns True if the font supports mixed case, False if it only renders uppercase.
    """
    try:
        # Test string with mixed case
        test_text = "AaBbCc"
        
        # Create a test image to render the font
        test_size = (200, 100)
        test_image = Image.new('RGBA', test_size, (0, 0, 0, 0))
        draw = ImageDraw.Draw(test_image)
        
        # Try to load the font
        try:
            font = ImageFont.truetype(font_path, 24)
        except (OSError, IOError):
            print(f"Text Texture Generator: Could not load font for testing: {font_path}")
            return False
        
        # Render the test text
        draw.text((10, 10), test_text, font=font, fill=(255, 255, 255, 255))
        
        # Get the rendered pixels
        pixels = list(test_image.getdata())
        
        # Create another image with uppercase version
        test_image_upper = Image.new('RGBA', test_size, (0, 0, 0, 0))
        draw_upper = ImageDraw.Draw(test_image_upper)
        draw_upper.text((10, 10), test_text.upper(), font=font, fill=(255, 255, 255, 255))
        
        pixels_upper = list(test_image_upper.getdata())
        
        # Compare the two renderings - if they're identical, the font only supports uppercase
        if pixels == pixels_upper:
            print(f"Text Texture Generator: Font only supports uppercase rendering: {os.path.basename(font_path)}")
            return False
        else:
            print(f"Text Texture Generator: Font supports mixed case rendering: {os.path.basename(font_path)}")
            return True
            
    except Exception as e:
        print(f"Text Texture Generator: Error testing font mixed case support: {str(e)}")
        return False

def get_validated_font(font_path, fallback_fonts=None):
    """
    Get a validated font that supports mixed case rendering.
    Returns the original font path if valid, otherwise returns a fallback font.
    """
    if not font_path or not os.path.exists(font_path):
        print(f"Text Texture Generator: Font file not found: {font_path}")
        return get_system_fallback_fonts()[0] if get_system_fallback_fonts() else None
    
    # Test if the font supports mixed case
    if test_font_mixed_case_support(font_path):
        return font_path
    else:
        print(f"Text Texture Generator: Font does not support mixed case, using fallback: {font_path}")
        
        # Try fallback fonts if provided
        if fallback_fonts:
            for fallback_font in fallback_fonts:
                if os.path.exists(fallback_font) and test_font_mixed_case_support(fallback_font):
                    print(f"Text Texture Generator: Using fallback font: {fallback_font}")
                    return fallback_font
        
        # Use system fallback fonts
        system_fallbacks = get_system_fallback_fonts()
        for fallback_font in system_fallbacks:
            if test_font_mixed_case_support(fallback_font):
                print(f"Text Texture Generator: Using system fallback font: {fallback_font}")
                return fallback_font
        
        # If no valid font found, return the original (better than nothing)
        print("Text Texture Generator: Warning - No valid mixed case font found, using original")
        return font_path

def get_system_fallback_fonts():
    """
    Get a list of system fallback fonts based on the operating system.
    Returns a list of font paths that are likely to be available.
    """
    system = platform.system()
    fallback_fonts = []
    
    if system == "Windows":
        windows_fonts = [
            "C:/Windows/Fonts/arial.ttf",
            "C:/Windows/Fonts/calibri.ttf",
            "C:/Windows/Fonts/verdana.ttf",
            "C:/Windows/Fonts/tahoma.ttf",
            "C:/Windows/Fonts/segoeui.ttf",
            "C:/Windows/Fonts/times.ttf"
        ]
        fallback_fonts.extend([f for f in windows_fonts if os.path.exists(f)])
        
    elif system == "Darwin":  # macOS
        macos_fonts = [
            "/System/Library/Fonts/Helvetica.ttc",
            "/System/Library/Fonts/Arial.ttf",
            "/System/Library/Fonts/Times.ttc",
            "/System/Library/Fonts/Verdana.ttf",
            "/Library/Fonts/Arial.ttf",
            "/System/Library/Fonts/Courier.dfont"
        ]
        fallback_fonts.extend([f for f in macos_fonts if os.path.exists(f)])
        
    elif system == "Linux":
        linux_fonts = [
            "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
            "/usr/share/fonts/truetype/liberation/LiberationSans-Regular.ttf",
            "/usr/share/fonts/truetype/ubuntu/Ubuntu-R.ttf",
            "/usr/share/fonts/truetype/noto/NotoSans-Regular.ttf",
            "/usr/share/fonts/TTF/arial.ttf",
            "/usr/share/fonts/truetype/ttf-bitstream-vera/Vera.ttf"
        ]
        fallback_fonts.extend([f for f in linux_fonts if os.path.exists(f)])
    
    # Also check common font directories
    common_directories = [
        "/usr/share/fonts",
        "/usr/local/share/fonts",
        os.path.expanduser("~/.fonts"),
        os.path.expanduser("~/Library/Fonts")
    ]
    
    for font_dir in common_directories:
        if os.path.exists(font_dir):
            for root, dirs, files in os.walk(font_dir):
                for file in files:
                    if file.lower().endswith(('.ttf', '.otf')):
                        font_path = os.path.join(root, file)
                        if font_path not in fallback_fonts:
                            fallback_fonts.append(font_path)
                        # Limit the number of fallback fonts to prevent excessive scanning
                        if len(fallback_fonts) >= 20:
                            break
                if len(fallback_fonts) >= 20:
                    break
    
    print(f"Text Texture Generator: Found {len(fallback_fonts)} system fallback fonts")
    for i, font in enumerate(fallback_fonts[:5]):  # Log first 5 fonts
        print(f"Text Texture Generator: Fallback font {i+1}: {font}")
    
    return fallback_fonts