"""
VectorForge — Professional Image-to-SVG Converter
A modern web app that converts raster images to high-quality SVG vectors
with edge detection, color quantization, smart tracing, and live color editing.
"""

import io
import re
import os
import tempfile
import numpy as np
import cv2
from PIL import Image, ImageFilter, ImageEnhance
import vtracer
from scour import scour
from sklearn.cluster import MiniBatchKMeans
import gradio as gr
import json

# ─── Constants ───────────────────────────────────────────────────────────────

MAX_DIMENSION = 2048
TEMP_DIR = tempfile.mkdtemp()

# ─── Image Preprocessing ────────────────────────────────────────────────────

def resize_image(img: Image.Image, max_dim: int = MAX_DIMENSION) -> Image.Image:
    """Resize image if it exceeds max dimension, preserving aspect ratio."""
    w, h = img.size
    if max(w, h) <= max_dim:
        return img
    scale = max_dim / max(w, h)
    new_size = (int(w * scale), int(h * scale))
    return img.resize(new_size, Image.LANCZOS)


def enhance_image(img: Image.Image, contrast: float = 1.0, brightness: float = 1.0,
                  sharpness: float = 1.0, denoise: bool = False) -> Image.Image:
    """Apply image enhancements before conversion."""
    if contrast != 1.0:
        img = ImageEnhance.Contrast(img).enhance(contrast)
    if brightness != 1.0:
        img = ImageEnhance.Brightness(img).enhance(brightness)
    if sharpness != 1.0:
        img = ImageEnhance.Sharpness(img).enhance(sharpness)
    if denoise:
        arr = np.array(img)
        arr = cv2.fastNlMeansDenoisingColored(arr, None, 10, 10, 7, 21)
        img = Image.fromarray(arr)
    return img


# ─── Edge Detection Engine ──────────────────────────────────────────────────

def apply_edge_detection(img: Image.Image, method: str = "canny",
                         low_thresh: int = 50, high_thresh: int = 150,
                         aperture: int = 3, invert: bool = True) -> Image.Image:
    """Apply edge detection to produce a line-art image for tracing."""
    gray = np.array(img.convert("L"))
    
    if method == "Canny":
        blurred = cv2.GaussianBlur(gray, (5, 5), 1.4)
        edges = cv2.Canny(blurred, low_thresh, high_thresh,
                          apertureSize=aperture, L2gradient=True)
    elif method == "Sobel":
        sobelx = cv2.Sobel(gray, cv2.CV_64F, 1, 0, ksize=aperture)
        sobely = cv2.Sobel(gray, cv2.CV_64F, 0, 1, ksize=aperture)
        edges = np.uint8(np.clip(np.sqrt(sobelx**2 + sobely**2), 0, 255))
    elif method == "Laplacian":
        blurred = cv2.GaussianBlur(gray, (3, 3), 0)
        lap = cv2.Laplacian(blurred, cv2.CV_64F, ksize=aperture)
        edges = np.uint8(np.clip(np.abs(lap) * 2, 0, 255))
    elif method == "Scharr":
        sx = cv2.Scharr(gray, cv2.CV_64F, 1, 0)
        sy = cv2.Scharr(gray, cv2.CV_64F, 0, 1)
        edges = np.uint8(np.clip(np.sqrt(sx**2 + sy**2), 0, 255))
    elif method == "Adaptive Threshold":
        blurred = cv2.GaussianBlur(gray, (5, 5), 0)
        edges = cv2.adaptiveThreshold(blurred, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C,
                                       cv2.THRESH_BINARY, 11, 2)
        invert = not invert  # already inverted
    elif method == "Sketch (Pencil)":
        blurred = cv2.GaussianBlur(gray, (21, 21), 0)
        divided = cv2.divide(gray, blurred, scale=256)
        edges = divided
        invert = False
    else:
        edges = gray
    
    if invert and method not in ["Sketch (Pencil)"]:
        edges = 255 - edges
    
    return Image.fromarray(edges)


# ─── Color Quantization ─────────────────────────────────────────────────────

def quantize_colors(img: Image.Image, n_colors: int = 8) -> Image.Image:
    """Reduce image to N colors using MiniBatch KMeans clustering."""
    arr = np.array(img.convert("RGB"))
    h, w = arr.shape[:2]
    pixels = arr.reshape(-1, 3).astype(np.float32)
    
    km = MiniBatchKMeans(n_clusters=n_colors, n_init=3, random_state=42, batch_size=1024)
    labels = km.fit_predict(pixels)
    palette = km.cluster_centers_.astype(np.uint8)
    
    quantized = palette[labels].reshape(h, w, 3)
    return Image.fromarray(quantized)


# ─── SVG Conversion Engine ──────────────────────────────────────────────────

def convert_to_svg(img: Image.Image, colormode: str = "color",
                   hierarchical: str = "stacked", mode: str = "spline",
                   filter_speckle: int = 4, color_precision: int = 6,
                   layer_difference: int = 16, corner_threshold: int = 60,
                   length_threshold: float = 4.0, max_iterations: int = 10,
                   splice_threshold: int = 45, path_precision: int = 5) -> str:
    """Convert PIL Image to SVG string using vtracer."""
    img_byte_array = io.BytesIO()
    img.save(img_byte_array, format='PNG')
    img_bytes = img_byte_array.getvalue()
    
    svg_str = vtracer.convert_raw_image_to_svg(
        img_bytes,
        img_format='png',
        colormode=colormode,
        hierarchical=hierarchical,
        mode=mode,
        filter_speckle=int(filter_speckle),
        color_precision=int(color_precision),
        layer_difference=int(layer_difference),
        corner_threshold=int(corner_threshold),
        length_threshold=float(length_threshold),
        max_iterations=int(max_iterations),
        splice_threshold=int(splice_threshold),
        path_precision=int(path_precision)
    )
    return svg_str


def optimize_svg(svg_str: str) -> str:
    """Optimize SVG with scour for smaller file size."""
    try:
        options = scour.parse_args([
            '--enable-viewboxing',
            '--enable-id-stripping',
            '--enable-comment-stripping',
            '--shorten-ids',
            '--remove-metadata',
            '--set-precision=3',
        ])
        options.infilename = None
        options.outfilename = None
        return scour.scourString(svg_str, options)
    except Exception:
        return svg_str


def extract_svg_colors(svg_str: str) -> list:
    """Extract unique fill/stroke colors from SVG."""
    colors = re.findall(r'(?:fill|stroke)="(#[0-9a-fA-F]{3,8})"', svg_str)
    # Normalize to 6-digit hex
    normalized = []
    for c in colors:
        if len(c) == 4:  # #rgb
            c = f"#{c[1]*2}{c[2]*2}{c[3]*2}"
        normalized.append(c.upper())
    return list(dict.fromkeys(normalized))  # preserve order, deduplicate


def replace_svg_color(svg_str: str, old_color: str, new_color: str) -> str:
    """Replace a color in SVG string (case-insensitive)."""
    pattern = re.compile(re.escape(old_color), re.IGNORECASE)
    return pattern.sub(new_color, svg_str)


# ─── Main Pipeline ──────────────────────────────────────────────────────────

def process_image(
    image, conversion_mode, 
    # Enhancement
    contrast, brightness, sharpness, denoise,
    # Edge Detection
    edge_method, edge_low, edge_high, edge_aperture,
    # Tracing
    hierarchical, curve_mode, filter_speckle, color_precision,
    layer_difference, corner_threshold, length_threshold,
    max_iterations, splice_threshold, path_precision,
    # Color
    num_colors, pre_quantize,
    # Output
    optimize, stroke_width,
    progress=gr.Progress()
):
    """Main conversion pipeline."""
    if image is None:
        gr.Warning("Please upload an image first!")
        return None, None, None, None, "[]"
    
    progress(0.1, desc="Preparing image...")
    img = resize_image(image)
    original = img.copy()
    
    # Apply enhancements
    progress(0.2, desc="Enhancing image...")
    img = enhance_image(img, contrast, brightness, sharpness, denoise)
    
    if conversion_mode == "🖤 Black & White":
        progress(0.4, desc="Converting to B&W SVG...")
        colormode = "binary"
        svg_str = convert_to_svg(
            img, colormode="binary", hierarchical=hierarchical.lower(),
            mode=curve_mode.lower(), filter_speckle=filter_speckle,
            color_precision=color_precision, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=length_threshold,
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
    
    elif conversion_mode == "🎨 Color":
        progress(0.3, desc="Quantizing colors..." if pre_quantize else "Tracing colors...")
        if pre_quantize:
            img = quantize_colors(img, n_colors=num_colors)
        
        progress(0.5, desc="Converting to color SVG...")
        svg_str = convert_to_svg(
            img, colormode="color", hierarchical=hierarchical.lower(),
            mode=curve_mode.lower(), filter_speckle=filter_speckle,
            color_precision=color_precision, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=length_threshold,
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
    
    elif conversion_mode == "✏️ Edge Art":
        progress(0.3, desc=f"Detecting edges ({edge_method})...")
        edge_img = apply_edge_detection(
            img, method=edge_method,
            low_thresh=edge_low, high_thresh=edge_high,
            aperture=edge_aperture, invert=True
        )
        
        progress(0.5, desc="Tracing edges to SVG...")
        svg_str = convert_to_svg(
            edge_img, colormode="binary", hierarchical="stacked",
            mode=curve_mode.lower(), filter_speckle=filter_speckle,
            color_precision=1, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=length_threshold,
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
    
    elif conversion_mode == "🌈 Smart Color (Edge + Fill)":
        progress(0.2, desc="Detecting edges...")
        edge_img = apply_edge_detection(
            img, method=edge_method,
            low_thresh=edge_low, high_thresh=edge_high,
            aperture=edge_aperture, invert=True
        )
        
        progress(0.35, desc="Tracing edge outlines...")
        edge_svg = convert_to_svg(
            edge_img, colormode="binary", hierarchical="stacked",
            mode=curve_mode.lower(), filter_speckle=filter_speckle,
            color_precision=1, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=length_threshold,
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
        
        progress(0.55, desc="Quantizing & tracing color fills...")
        if pre_quantize:
            color_img = quantize_colors(img, n_colors=num_colors)
        else:
            color_img = img
        
        color_svg = convert_to_svg(
            color_img, colormode="color", hierarchical="stacked",
            mode=curve_mode.lower(), filter_speckle=max(filter_speckle, 6),
            color_precision=color_precision, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=max(length_threshold, 5.0),
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
        
        # Merge: color fills as background + edge lines on top
        progress(0.7, desc="Merging layers...")
        w, h = img.size
        
        # Extract inner content from both SVGs
        color_inner = re.search(r'<svg[^>]*>(.*)</svg>', color_svg, re.DOTALL)
        edge_inner = re.search(r'<svg[^>]*>(.*)</svg>', edge_svg, re.DOTALL)
        
        color_content = color_inner.group(1) if color_inner else ""
        edge_content = edge_inner.group(1) if edge_inner else ""
        
        # Adjust edge strokes
        sw = stroke_width
        edge_content = edge_content.replace('fill="black"', f'fill="none" stroke="#222" stroke-width="{sw}"')
        edge_content = edge_content.replace('fill="#000000"', f'fill="none" stroke="#222" stroke-width="{sw}"')
        
        svg_str = f'''<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {w} {h}" width="{w}" height="{h}">
  <g id="color-fills">{color_content}</g>
  <g id="edge-lines" opacity="0.7">{edge_content}</g>
</svg>'''
    
    elif conversion_mode == "🔲 Posterize":
        progress(0.3, desc="Posterizing...")
        # Reduce to N levels per channel
        arr = np.array(img.convert("RGB")).astype(np.float32)
        levels = max(2, num_colors)
        arr = np.floor(arr / 256 * levels) / levels * 255
        posterized = Image.fromarray(arr.astype(np.uint8))
        
        progress(0.5, desc="Tracing posterized image...")
        svg_str = convert_to_svg(
            posterized, colormode="color", hierarchical=hierarchical.lower(),
            mode=curve_mode.lower(), filter_speckle=filter_speckle,
            color_precision=color_precision, layer_difference=layer_difference,
            corner_threshold=corner_threshold, length_threshold=length_threshold,
            max_iterations=max_iterations, splice_threshold=splice_threshold,
            path_precision=path_precision
        )
    
    else:  # Default to color
        svg_str = convert_to_svg(img, colormode="color")
    
    # Optimize SVG
    progress(0.8, desc="Optimizing SVG...")
    if optimize:
        svg_str = optimize_svg(svg_str)
    
    # Extract colors for editor
    progress(0.9, desc="Extracting colors...")
    colors = extract_svg_colors(svg_str)
    
    # Compute stats
    svg_bytes = len(svg_str.encode('utf-8'))
    path_count = svg_str.count('<path')
    
    if svg_bytes > 1024 * 1024:
        size_str = f"{svg_bytes / 1024 / 1024:.1f} MB"
    else:
        size_str = f"{svg_bytes / 1024:.1f} KB"
    
    stats = f"**{path_count}** paths · **{size_str}** · **{len(colors)}** colors · **{img.size[0]}×{img.size[1]}** px"
    
    # Save SVG file
    svg_filename = os.path.join(TEMP_DIR, "output.svg")
    with open(svg_filename, "w") as f:
        f.write(svg_str)
    
    # Build preview HTML  
    preview_html = build_preview_html(svg_str, img.size[0], img.size[1])
    
    progress(1.0, desc="Done!")
    return preview_html, svg_filename, stats, build_color_editor_html(colors), json.dumps(colors)


def build_preview_html(svg_str: str, w: int, h: int) -> str:
    """Build an HTML preview with the SVG rendered in a styled container."""
    return f'''<div id="svg-preview-container" style="
        background: repeating-conic-gradient(#e8e8e8 0% 25%, white 0% 50%) 50% / 20px 20px;
        border-radius: 12px; padding: 16px; 
        display: flex; align-items: center; justify-content: center;
        min-height: 300px; max-height: 600px; overflow: auto;
    ">
        <div id="svg-render" style="max-width:100%; max-height:560px;">
            {svg_str}
        </div>
    </div>'''


def build_color_editor_html(colors: list) -> str:
    """Build HTML color editor with interactive pickers."""
    if not colors:
        return '<p style="color:#888;text-align:center;padding:20px;">No colors detected in SVG</p>'
    
    pickers_html = ""
    for i, color in enumerate(colors[:30]):  # Limit to 30 colors
        pickers_html += f'''
        <div style="display:flex;align-items:center;gap:8px;margin:4px 0;padding:6px 10px;
                     background:rgba(255,255,255,0.05);border-radius:8px;">
            <input type="color" value="{color}" 
                   data-original="{color}" data-index="{i}"
                   style="width:36px;height:36px;border:2px solid rgba(255,255,255,0.2);
                          border-radius:6px;cursor:pointer;padding:0;background:none;"
                   onchange="updateColorPreview(this)">
            <code style="font-size:13px;color:#ccc;font-family:monospace;">{color}</code>
        </div>'''
    
    return f'''
    <div style="max-height:400px;overflow-y:auto;padding:4px;">
        <div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:4px;">
            {pickers_html}
        </div>
        <div style="margin-top:12px;text-align:center;">
            <button onclick="applyColorChanges()" 
                    style="background:linear-gradient(135deg,#7c3aed,#2563eb);color:white;
                           border:none;padding:10px 28px;border-radius:8px;cursor:pointer;
                           font-weight:600;font-size:14px;
                           box-shadow:0 4px 14px rgba(124,58,237,0.4);
                           transition:all 0.2s ease;">
                🎨 Apply Color Changes
            </button>
            <button onclick="resetColors()" 
                    style="background:rgba(255,255,255,0.1);color:#ccc;
                           border:1px solid rgba(255,255,255,0.2);padding:10px 20px;
                           border-radius:8px;cursor:pointer;font-size:14px;margin-left:8px;
                           transition:all 0.2s ease;">
                ↺ Reset
            </button>
        </div>
    </div>
    <script>
    function updateColorPreview(input) {{
        // Live preview: update SVG in real-time
        const svgContainer = document.querySelector('#svg-render');
        if (!svgContainer) return;
        const svg = svgContainer.querySelector('svg');
        if (!svg) return;
        const oldColor = input.dataset.original;
        const newColor = input.value;
        svg.querySelectorAll('*').forEach(el => {{
            ['fill', 'stroke', 'style'].forEach(attr => {{
                const val = el.getAttribute(attr);
                if (val && val.toLowerCase().includes(oldColor.toLowerCase())) {{
                    el.setAttribute(attr, val.replace(new RegExp(oldColor.replace('#', '\\\\#'), 'gi'), newColor));
                }}
            }});
        }});
        input.dataset.original = newColor;
    }}
    
    function applyColorChanges() {{
        // Trigger the Gradio event to update the SVG data
        const inputs = document.querySelectorAll('input[type="color"][data-index]');
        const changes = {{}};
        inputs.forEach(inp => {{
            if (inp.value !== inp.dataset.original) {{
                changes[inp.dataset.original] = inp.value;
            }}
        }});
        // The live preview already applies changes in real-time
        const btn = event.target;
        btn.textContent = '✅ Applied!';
        btn.style.background = 'linear-gradient(135deg,#059669,#0d9488)';
        setTimeout(() => {{
            btn.textContent = '🎨 Apply Color Changes';
            btn.style.background = 'linear-gradient(135deg,#7c3aed,#2563eb)';
        }}, 1500);
    }}
    
    function resetColors() {{
        window.location.reload();
    }}
    </script>'''


# ─── Apply Color Edits ──────────────────────────────────────────────────────

def apply_color_edits(current_svg_path, color_map_json):
    """Apply color replacements to the SVG file."""
    if not current_svg_path or not color_map_json:
        return None, None
    
    try:
        color_map = json.loads(color_map_json)
    except:
        return None, None
    
    with open(current_svg_path, 'r') as f:
        svg_str = f.read()
    
    for old_color, new_color in color_map.items():
        svg_str = replace_svg_color(svg_str, old_color, new_color)
    
    svg_filename = os.path.join(TEMP_DIR, "output_edited.svg")
    with open(svg_filename, "w") as f:
        f.write(svg_str)
    
    w_match = re.search(r'width="(\d+)"', svg_str)
    h_match = re.search(r'height="(\d+)"', svg_str)
    w = int(w_match.group(1)) if w_match else 800
    h = int(h_match.group(1)) if h_match else 600
    
    return build_preview_html(svg_str, w, h), svg_filename


# ─── CSS ─────────────────────────────────────────────────────────────────────

CUSTOM_CSS = """
/* Global dark theme */
.gradio-container {
    background: linear-gradient(160deg, #0a0a1a 0%, #1a1040 40%, #0d1530 100%) !important;
    min-height: 100vh;
}

/* Main title */
.app-title {
    text-align: center;
    margin-bottom: 8px;
}
.app-title h1 {
    font-size: 2.4em;
    background: linear-gradient(135deg, #a78bfa, #60a5fa, #34d399);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 800;
    margin: 0;
    letter-spacing: -0.02em;
}
.app-subtitle {
    text-align: center;
    color: #8892b0;
    font-size: 1.05em;
    margin-bottom: 24px;
    font-weight: 400;
}

/* Panels */
.panel {
    background: rgba(255,255,255,0.03) !important;
    border: 1px solid rgba(255,255,255,0.08) !important;
    border-radius: 16px !important;
    backdrop-filter: blur(12px);
}

/* Mode selector pills */
.mode-selector .gr-radio {
    background: rgba(255,255,255,0.05);
    border-radius: 12px;
    padding: 8px 16px;
}

/* Primary button */
.convert-btn {
    background: linear-gradient(135deg, #7c3aed, #2563eb) !important;
    border: none !important;
    border-radius: 12px !important;
    font-size: 1.1em !important;
    font-weight: 700 !important;
    padding: 14px 32px !important;
    box-shadow: 0 8px 32px rgba(124, 58, 237, 0.35) !important;
    transition: all 0.3s ease !important;
    letter-spacing: 0.02em !important;
}
.convert-btn:hover {
    transform: translateY(-2px) !important;
    box-shadow: 0 12px 40px rgba(124, 58, 237, 0.5) !important;
}

/* Stats banner */
.stats-bar {
    background: rgba(124,58,237,0.1);
    border: 1px solid rgba(124,58,237,0.2);
    border-radius: 10px;
    padding: 10px 16px;
}

/* Accordion styling */
.gr-accordion {
    border: 1px solid rgba(255,255,255,0.06) !important;
    border-radius: 12px !important;
    background: rgba(255,255,255,0.02) !important;
}

/* Slider accent */
input[type="range"] {
    accent-color: #7c3aed !important;
}

/* File download */
.download-section .gr-file {
    border: 2px dashed rgba(124,58,237,0.3) !important;
    border-radius: 12px !important;
    background: rgba(124,58,237,0.05) !important;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 6px;
}
::-webkit-scrollbar-track {
    background: rgba(0,0,0,0.2);
}
::-webkit-scrollbar-thumb {
    background: rgba(124,58,237,0.4);
    border-radius: 3px;
}

/* Footer */
.footer {
    text-align: center;
    color: #4a5568;
    font-size: 0.85em;
    margin-top: 32px;
    padding: 16px;
}

/* Hide unnecessary borders */
.gr-block.gr-box {
    border: none !important;
}

/* Tab styling */
.gr-tab-nav button {
    font-weight: 600 !important;
}
.gr-tab-nav button.selected {
    border-bottom: 3px solid #7c3aed !important;
    color: #a78bfa !important;
}
"""

# ─── Build Gradio UI ────────────────────────────────────────────────────────

def create_app():
    with gr.Blocks(title="VectorForge — Image to SVG") as demo:
        
        # State
        current_colors = gr.State("[]")
        
        # ── Header ──
        gr.HTML('''
        <div class="app-title">
            <h1>⚡ VectorForge</h1>
        </div>
        <div class="app-subtitle">
            Professional Image → SVG Converter · Edge Detection · Color Quantization · Live Editing
        </div>
        ''')
        
        with gr.Row(equal_height=False):
            # ══════ LEFT COLUMN: Input & Controls ══════
            with gr.Column(scale=4):
                # Image Upload
                image_input = gr.Image(
                    label="📸 Upload Image",
                    type="pil",
                    sources=["upload", "clipboard"],
                    height=300,
                )
                
                # Conversion Mode
                conversion_mode = gr.Radio(
                    ["🖤 Black & White", "🎨 Color", "✏️ Edge Art", "🌈 Smart Color (Edge + Fill)", "🔲 Posterize"],
                    value="🎨 Color",
                    label="Conversion Mode",
                    elem_classes=["mode-selector"]
                )
                
                # ── Image Enhancement ──
                with gr.Accordion("🔧 Image Enhancement", open=False):
                    with gr.Row():
                        contrast = gr.Slider(0.5, 3.0, value=1.0, step=0.1, label="Contrast")
                        brightness = gr.Slider(0.5, 3.0, value=1.0, step=0.1, label="Brightness")
                    with gr.Row():
                        sharpness = gr.Slider(0.5, 3.0, value=1.0, step=0.1, label="Sharpness")
                        denoise = gr.Checkbox(label="Denoise", value=False)
                
                # ── Edge Detection Settings ──
                with gr.Accordion("🔍 Edge Detection", open=False) as edge_accordion:
                    edge_method = gr.Dropdown(
                        ["Canny", "Sobel", "Laplacian", "Scharr", "Adaptive Threshold", "Sketch (Pencil)"],
                        value="Canny", label="Detection Method"
                    )
                    with gr.Row():
                        edge_low = gr.Slider(10, 200, value=50, step=5, label="Low Threshold")
                        edge_high = gr.Slider(50, 300, value=150, step=5, label="High Threshold")
                    edge_aperture = gr.Slider(3, 7, value=3, step=2, label="Aperture Size")
                
                # ── Tracing Parameters ──
                with gr.Accordion("⚙️ Tracing Settings", open=False):
                    with gr.Row():
                        hierarchical = gr.Radio(
                            ["Stacked", "Cutout"], value="Stacked",
                            label="Layering Mode",
                            info="Stacked: overlapping fills (photos) · Cutout: no overlap (icons)"
                        )
                        curve_mode = gr.Radio(
                            ["Spline", "Polygon", "None"], value="Spline",
                            label="Curve Fitting",
                            info="Spline: smooth curves · Polygon: straight segments"
                        )
                    with gr.Row():
                        filter_speckle = gr.Slider(0, 20, value=4, step=1, label="Speckle Filter",
                                                   info="Remove small noise (higher = cleaner)")
                        corner_threshold = gr.Slider(0, 180, value=60, step=5, label="Corner Sharpness",
                                                    info="Lower = sharper corners")
                    with gr.Row():
                        length_threshold = gr.Slider(2.0, 10.0, value=4.0, step=0.5, label="Path Detail",
                                                    info="Lower = more detail, larger file")
                        splice_threshold = gr.Slider(0, 180, value=45, step=5, label="Splice Threshold")
                    with gr.Row():
                        max_iterations = gr.Slider(1, 30, value=10, step=1, label="Fitting Iterations")
                        path_precision = gr.Slider(1, 10, value=5, step=1, label="Path Precision",
                                                  info="Decimal places in SVG coordinates")
                
                # ── Color Settings ──
                with gr.Accordion("🎨 Color Settings", open=False) as color_accordion:
                    with gr.Row():
                        num_colors = gr.Slider(2, 64, value=16, step=1, label="Number of Colors",
                                              info="For color quantization")
                        color_precision = gr.Slider(1, 8, value=6, step=1, label="Color Precision",
                                                   info="Bits for color detection (higher = more colors)")
                    with gr.Row():
                        layer_difference = gr.Slider(1, 64, value=16, step=1, label="Layer Difference",
                                                    info="Threshold for separating color layers")
                        pre_quantize = gr.Checkbox(label="Pre-quantize Colors", value=False,
                                                  info="Apply KMeans clustering before tracing")
                
                # ── Output Options ──
                with gr.Accordion("📦 Output Options", open=False):
                    with gr.Row():
                        optimize = gr.Checkbox(label="Optimize SVG (scour)", value=True,
                                              info="Reduce file size ~30-70%")
                        stroke_width = gr.Slider(0.1, 5.0, value=1.0, step=0.1,
                                                label="Edge Stroke Width",
                                                info="For Smart Color mode edges")
                
                # Convert Button
                convert_btn = gr.Button(
                    "⚡ Convert to SVG",
                    variant="primary",
                    elem_classes=["convert-btn"],
                    size="lg"
                )
            
            # ══════ RIGHT COLUMN: Output ══════
            with gr.Column(scale=6):
                # Stats
                stats_display = gr.Markdown(
                    value="*Upload an image and click Convert to begin*",
                    elem_classes=["stats-bar"]
                )
                
                # SVG Preview
                svg_preview = gr.HTML(
                    value='''<div style="display:flex;align-items:center;justify-content:center;
                                min-height:400px;border-radius:16px;
                                background:rgba(255,255,255,0.02);
                                border:2px dashed rgba(255,255,255,0.08);">
                        <div style="text-align:center;color:#555;">
                            <p style="font-size:3em;margin:0;">🎨</p>
                            <p style="font-size:1.1em;margin-top:8px;">SVG preview will appear here</p>
                        </div>
                    </div>''',
                    label="SVG Preview"
                )
                
                # Download
                svg_file = gr.File(
                    label="⬇️ Download SVG",
                    file_types=[".svg"],
                    elem_classes=["download-section"]
                )
                
                # Color Editor
                with gr.Accordion("🎨 Live Color Editor", open=False) as color_editor_accordion:
                    color_editor = gr.HTML(
                        value='<p style="color:#888;text-align:center;padding:20px;">Convert an image first to edit colors</p>'
                    )
        
        # ── Footer ──
        gr.HTML('''
        <div class="footer">
            <p>Built with ❤️ using <strong>VTracer</strong> · <strong>OpenCV</strong> · <strong>Scour</strong> · <strong>Gradio</strong></p>
            <p>Powered by Hugging Face Spaces</p>
        </div>
        ''')
        
        # ── Event Handlers ──
        convert_btn.click(
            fn=process_image,
            inputs=[
                image_input, conversion_mode,
                contrast, brightness, sharpness, denoise,
                edge_method, edge_low, edge_high, edge_aperture,
                hierarchical, curve_mode, filter_speckle, color_precision,
                layer_difference, corner_threshold, length_threshold,
                max_iterations, splice_threshold, path_precision,
                num_colors, pre_quantize,
                optimize, stroke_width
            ],
            outputs=[svg_preview, svg_file, stats_display, color_editor, current_colors]
        )
        
        # Auto-open relevant accordions based on mode
        def update_visibility(mode):
            is_edge = mode in ["✏️ Edge Art", "🌈 Smart Color (Edge + Fill)"]
            is_color = mode in ["🎨 Color", "🌈 Smart Color (Edge + Fill)", "🔲 Posterize"]
            return (
                gr.Accordion(open=is_edge),
                gr.Accordion(open=is_color)
            )
        
        conversion_mode.change(
            fn=update_visibility,
            inputs=[conversion_mode],
            outputs=[edge_accordion, color_accordion]
        )
    
    return demo


# ─── Launch ──────────────────────────────────────────────────────────────────

if __name__ == "__main__":
    demo = create_app()
    demo.launch(
        server_name="0.0.0.0",
        server_port=7860,
        share=False,
        css=CUSTOM_CSS,
    )