src/streamlit_app.py

import streamlit as st
import qrcode
from PIL import Image, ImageDraw, ImageFont
import io
import base64

# Page configuration
st.set_page_config(
    page_title="QR Code Generator",
    page_icon="📱",
    layout="wide",
    initial_sidebar_state="expanded"
)

# Custom CSS for beautiful styling
st.markdown("""
<style>
    .main-header {
        text-align: center;
        padding: 2rem 0;
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        border-radius: 10px;
        margin-bottom: 2rem;
    }
    
    .feature-box {
        background: #f8f9fa;
        padding: 1.5rem;
        border-radius: 10px;
        border-left: 4px solid #667eea;
        margin: 1rem 0;
    }
    
    .download-section {
        background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
        padding: 2rem;
        border-radius: 15px;
        text-align: center;
        margin: 2rem 0;
    }
    
    .sidebar-section {
        background: #ffffff;
        padding: 1rem;
        border-radius: 10px;
        margin: 1rem 0;
        box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    }
    
    .stDownloadButton > button {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        border: none;
        border-radius: 10px;
        padding: 0.5rem 2rem;
        font-weight: bold;
        width: 100%;
    }
</style>
""", unsafe_allow_html=True)

def hex_to_rgb(hex_color):
    """Convert hex color to RGB tuple"""
    hex_color = hex_color.lstrip('#')
    return tuple(int(hex_color[i:i+2], 16) for i in (0, 2, 4))

def create_gradient_image(size, start_color, end_color, direction='horizontal'):
    """Create a gradient image"""
    image = Image.new('RGB', size)
    draw = ImageDraw.Draw(image)
    
    if direction == 'horizontal':
        for x in range(size[0]):
            ratio = x / size[0]
            r = int(start_color[0] * (1 - ratio) + end_color[0] * ratio)
            g = int(start_color[1] * (1 - ratio) + end_color[1] * ratio)
            b = int(start_color[2] * (1 - ratio) + end_color[2] * ratio)
            draw.line([(x, 0), (x, size[1])], fill=(r, g, b))
    else:  # vertical
        for y in range(size[1]):
            ratio = y / size[1]
            r = int(start_color[0] * (1 - ratio) + end_color[0] * ratio)
            g = int(start_color[1] * (1 - ratio) + end_color[1] * ratio)
            b = int(start_color[2] * (1 - ratio) + end_color[2] * ratio)
            draw.line([(0, y), (size[0], y)], fill=(r, g, b))
    
    return image

def create_rounded_qr(qr_img, corner_radius=20):
    """Create rounded corners for QR code"""
    # Create mask for rounded corners
    size = qr_img.size
    mask = Image.new('L', size, 0)
    draw = ImageDraw.Draw(mask)
    draw.rounded_rectangle([(0, 0), size], corner_radius, fill=255)
    
    # Apply mask
    qr_rounded = Image.new('RGBA', size, (255, 255, 255, 0))
    qr_rounded.paste(qr_img, (0, 0))
    qr_rounded.putalpha(mask)
    
    return qr_rounded

def create_qr_code(data, fill_color, back_color, border, box_size, error_correction, style_type, gradient_end_color=None):
    """Generate QR code with custom styling"""
    
    # Error correction levels
    error_levels = {
        'L (~7%)': qrcode.constants.ERROR_CORRECT_L,
        'M (~15%)': qrcode.constants.ERROR_CORRECT_M,
        'Q (~25%)': qrcode.constants.ERROR_CORRECT_Q,
        'H (~30%)': qrcode.constants.ERROR_CORRECT_H
    }
    
    # Create QR code instance
    qr = qrcode.QRCode(
        version=1,
        error_correction=error_levels[error_correction],
        box_size=box_size,
        border=border,
    )
    
    qr.add_data(data)
    qr.make(fit=True)
    
    # Generate base QR code
    if style_type == "Gradient" and gradient_end_color:
        # Create gradient background
        img = qr.make_image(fill_color='black', back_color='white')
        
        # Create gradient
        start_rgb = hex_to_rgb(fill_color)
        end_rgb = hex_to_rgb(gradient_end_color)
        gradient = create_gradient_image(img.size, start_rgb, end_rgb, 'horizontal')
        
        # Apply gradient to QR code
        img_array = img.load()
        gradient_array = gradient.load()
        
        for x in range(img.size[0]):
            for y in range(img.size[1]):
                if img_array[x, y] == 0:  # Black pixel (QR code data)
                    img_array[x, y] = gradient_array[x, y]
                else:  # White pixel (background)
                    img_array[x, y] = hex_to_rgb(back_color)
    else:
        img = qr.make_image(fill_color=fill_color, back_color=back_color)
    
    # Apply style modifications
    if style_type == "Rounded":
        img = create_rounded_qr(img, corner_radius=box_size*2)
    elif style_type == "With Logo Space":
        # Create space in center for logo
        draw = ImageDraw.Draw(img)
        center_x, center_y = img.size[0] // 2, img.size[1] // 2
        logo_size = min(img.size) // 6
        draw.rectangle([
            center_x - logo_size//2, center_y - logo_size//2,
            center_x + logo_size//2, center_y + logo_size//2
        ], fill=back_color, outline=fill_color, width=2)
    
    return img

def get_qr_data_by_type(content_type):
    """Get QR data based on content type"""
    if content_type == "Text":
        return st.text_area("Enter your text:", height=100, placeholder="Hello World!")
    
    elif content_type == "URL":
        url = st.text_input("Enter URL:", placeholder="https://example.com")
        if url and not url.startswith(('http://', 'https://')):
            url = 'https://' + url
        return url
    
    elif content_type == "Email":
        email = st.text_input("Email address:", placeholder="contact@example.com")
        subject = st.text_input("Subject (optional):")
        body = st.text_area("Message (optional):", height=80)
        if email:
            params = []
            if subject:
                params.append(f"subject={subject}")
            if body:
                params.append(f"body={body}")
            return f"mailto:{email}{'?' + '&'.join(params) if params else ''}"
        return ""
    
    elif content_type == "Phone":
        phone = st.text_input("Phone number:", placeholder="+1234567890")
        return f"tel:{phone}" if phone else ""
    
    elif content_type == "SMS":
        phone = st.text_input("Phone number:", placeholder="+1234567890")
        message = st.text_area("Message:", height=80, placeholder="Hello!")
        if phone:
            return f"sms:{phone}{'?body=' + message if message else ''}"
        return ""
    
    elif content_type == "WiFi":
        ssid = st.text_input("Network Name (SSID):", placeholder="MyWiFi")
        password = st.text_input("Password:", type="password")
        security = st.selectbox("Security Type", ["WPA", "WEP", "nopass"])
        hidden = st.checkbox("Hidden Network")
        if ssid:
            return f"WIFI:T:{security};S:{ssid};P:{password};H:{'true' if hidden else 'false'};;"
        return ""
    
    elif content_type == "vCard":
        name = st.text_input("Full Name:", placeholder="John Doe")
        phone = st.text_input("Phone:", placeholder="+1234567890")
        email = st.text_input("Email:", placeholder="john@example.com")
        organization = st.text_input("Organization (optional):", placeholder="Company Inc.")
        
        if name:
            vcard = f"BEGIN:VCARD\nVERSION:3.0\nFN:{name}\n"
            if phone:
                vcard += f"TEL:{phone}\n"
            if email:
                vcard += f"EMAIL:{email}\n"
            if organization:
                vcard += f"ORG:{organization}\n"
            vcard += "END:VCARD"
            return vcard
        return ""

# Main header
st.markdown("""
<div class="main-header">
    <h1>🎨 Beautiful QR Code Generator</h1>
    <p>Create stunning, customizable QR codes with advanced styling options</p>
</div>
""", unsafe_allow_html=True)

# Sidebar for customization
with st.sidebar:
    st.markdown("## 🎛️ Customization Panel")
    
    # QR Code Content
    st.markdown('<div class="sidebar-section">', unsafe_allow_html=True)
    st.markdown("### 📝 Content")
    
    content_type = st.selectbox(
        "Content Type",
        ["Text", "URL", "Email", "Phone", "SMS", "WiFi", "vCard"]
    )
    
    qr_data = get_qr_data_by_type(content_type)
    st.markdown('</div>', unsafe_allow_html=True)
    
    # Style Settings
    st.markdown('<div class="sidebar-section">', unsafe_allow_html=True)
    st.markdown("### 🎨 Style Settings")
    
    style_type = st.selectbox(
        "QR Style",
        ["Standard", "Rounded", "Gradient", "With Logo Space"]
    )
    
    col1, col2 = st.columns(2)
    with col1:
        fill_color = st.color_picker("Foreground Color", "#000000")
    with col2:
        back_color = st.color_picker("Background Color", "#FFFFFF")
    
    gradient_end_color = None
    if style_type == "Gradient":
        gradient_end_color = st.color_picker("Gradient End Color", "#333333")
    
    st.markdown('</div>', unsafe_allow_html=True)
    
    # Advanced Settings
    st.markdown('<div class="sidebar-section">', unsafe_allow_html=True)
    st.markdown("### ⚙️ Advanced Settings")
    
    box_size = st.slider("Module Size", 5, 20, 10, help="Size of each QR code square")
    border = st.slider("Border Width", 1, 10, 4, help="White border around QR code")
    error_correction = st.selectbox(
        "Error Correction Level",
        ["L (~7%)", "M (~15%)", "Q (~25%)", "H (~30%)"],
        index=1,
        help="Higher levels = more damage resistance but larger code"
    )
    
    st.markdown('</div>', unsafe_allow_html=True)

# Main content area
col1, col2 = st.columns([2, 1])

with col1:
    if qr_data:
        try:
            # Generate QR code
            with st.spinner("🎨 Generating your beautiful QR code..."):
                qr_img = create_qr_code(
                    qr_data, fill_color, back_color, border, 
                    box_size, error_correction, style_type, gradient_end_color
                )
            
            # Display QR code
            st.markdown("### 📱 Your QR Code")
            st.image(qr_img, caption="Generated QR Code", use_container_width=True)
            
            # Convert to bytes for download
            img_buffer = io.BytesIO()
            qr_img.save(img_buffer, format="PNG")
            img_bytes = img_buffer.getvalue()
            
            # Download section
            st.markdown("""
            <div class="download-section">
                <h3>🚀 Ready to Download!</h3>
                <p>Your QR code is ready. Click below to download it as PNG.</p>
            </div>
            """, unsafe_allow_html=True)
            
            # Download button
            filename = f"qrcode_{content_type.lower()}_{style_type.lower().replace(' ', '_')}.png"
            st.download_button(
                label="📥 Download QR Code",
                data=img_bytes,
                file_name=filename,
                mime="image/png",
                use_container_width=True
            )
            
            # QR Code Info
            st.info(f"""
            **QR Code Details:**
            - Content Type: {content_type}
            - Style: {style_type}
            - Size: {qr_img.size[0]}x{qr_img.size[1]} pixels
            - Error Correction: {error_correction}
            """)
            
        except Exception as e:
            st.error(f"❌ Error generating QR code: {str(e)}")
            st.info("💡 Try adjusting your content or settings")
    else:
        # Welcome message with example
        st.markdown("""
        ### 👋 Welcome to QR Code Generator!
        
        👈 **Get started by entering content in the sidebar**
        
        #### 🌟 What you can create:
        - **Text QR codes** for messages
        - **URL QR codes** for websites  
        - **Contact QR codes** (vCard format)
        - **WiFi QR codes** for easy connection
        - **Email & SMS QR codes**
        
        #### 🎨 Styling options:
        - Custom colors
        - Rounded corners
        - Gradient effects
        - Logo space preparation
        """)

with col2:
    st.markdown("### ✨ Features")
    
    features = [
        "🎨 Multiple visual styles",
        "🌈 Custom colors & gradients", 
        "📱 Various content types",
        "⚙️ Advanced settings",
        "📥 Instant PNG download",
        "🔧 Error correction levels",
        "📇 vCard contact support",
        "📶 WiFi QR codes"
    ]
    
    for feature in features:
        st.markdown(f'<div class="feature-box">{feature}</div>', unsafe_allow_html=True)
    
    st.markdown("### 💡 Pro Tips")
    st.success("""
    **🎯 Best Practices:**
    - Use high contrast colors
    - Test with your phone camera
    - Higher error correction for outdoor use
    - Larger module size for distant scanning
    - Keep URLs short for simpler codes
    """)
    
    st.markdown("### 📊 Error Correction Guide")
    st.info("""
    - **L (7%)**: Good for clean environments
    - **M (15%)**: Standard recommendation  
    - **Q (25%)**: Better for rough handling
    - **H (30%)**: Best for outdoor/damaged codes
    """)

# Footer
st.markdown("---")
st.markdown("""
<div style="text-align: center; color: #666; padding: 2rem;">
    <p>🚀 Built with Streamlit | 💝 Made for QR code enthusiasts</p>
    <p><small>💡 Tip: Bookmark this page for quick QR code generation!</small></p>
</div>
""", unsafe_allow_html=True)