"""
FastAPI Backend for HTML to PDF Conversion
Runs alongside Streamlit on port 7860
"""
from fastapi import FastAPI, UploadFile, File, Form, HTTPException
from fastapi.responses import Response, JSONResponse
from fastapi.middleware.cors import CORSMiddleware
import subprocess
import os
import tempfile
import shutil
import re
import mimetypes
from typing import List, Optional
from pathlib import Path

app = FastAPI(
    title="HTML to PDF API",
    description="Convert HTML to PDF with image support and page breaks",
    version="1.0.0"
)

# Add CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

def detect_aspect_ratio(html_content):
    """Detect aspect ratio from HTML content"""
    viewport_match = re.search(r'<meta[^>]*viewport[^>]*content=["\']([^"\']*)["\']', html_content, re.IGNORECASE)
    if viewport_match:
        viewport = viewport_match.group(1).lower()
        if 'orientation=portrait' in viewport:
            return "9:16"
        elif 'orientation=landscape' in viewport:
            return "16:9"
    
    aspect_match = re.search(r'aspect-ratio\s*:\s*(\d+)\s*/\s*(\d+)', html_content, re.IGNORECASE)
    if aspect_match:
        width = int(aspect_match.group(1))
        height = int(aspect_match.group(2))
        ratio = width / height
        if ratio > 1.5:
            return "16:9"
        elif ratio < 0.7:
            return "9:16"
        else:
            return "1:1"
    
    if any(keyword in html_content.lower() for keyword in ['reveal.js', 'impress.js', 'slide', 'presentation']):
        return "16:9"
    
    return "9:16"

def normalize_image_paths(html_content):
    """Replace complex image paths with just filenames"""
    replacements = {}
    
    # Pattern for img src - capture full path and extract filename
    def replace_img_src(match):
        prefix = match.group(1)
        quote = match.group(2)
        full_path = match.group(3)
        # Extract just the filename from the full path
        filename = os.path.basename(full_path)
        
        replacements[f"img: {full_path}"] = filename
        return f'{prefix}{quote}{filename}{quote}'
    
    html_content = re.sub(
        r'(<img[^>]*\s+src\s*=\s*)(["\'])([^"\']+\.(jpg|jpeg|png|gif|svg|webp|bmp|JPG|JPEG|PNG|GIF|SVG|WEBP|BMP))(\2)',
        replace_img_src,
        html_content,
        flags=re.IGNORECASE
    )
    
    # Pattern for background-image
    def replace_bg_image(match):
        prefix = match.group(1)
        quote = match.group(2)
        full_path = match.group(3)
        suffix = match.group(5)
        # Extract just the filename from the full path
        filename = os.path.basename(full_path)
        
        replacements[f"bg: {full_path}"] = filename
        return f'{prefix}{quote}{filename}{quote}{suffix}'
    
    html_content = re.sub(
        r'(background-image\s*:\s*url\s*\()(["\']?)([^)"\'/]+\.(jpg|jpeg|png|gif|svg|webp|bmp|JPG|JPEG|PNG|GIF|SVG|WEBP|BMP))(\2)(\))',
        replace_bg_image,
        html_content,
        flags=re.IGNORECASE
    )
    
    # Pattern for CSS url()
    def replace_url(match):
        prefix = match.group(1)
        quote = match.group(2)
        full_path = match.group(3)
        suffix = match.group(5)
        # Extract just the filename from the full path
        filename = os.path.basename(full_path)
        
        replacements[f"url: {full_path}"] = filename
        return f'{prefix}{quote}{filename}{quote}{suffix}'
    
    html_content = re.sub(
        r'(url\s*\()(["\']?)([^)"\'/]+\.(jpg|jpeg|png|gif|svg|webp|bmp|JPG|JPEG|PNG|GIF|SVG|WEBP|BMP))(\2)(\))',
        replace_url,
        html_content,
        flags=re.IGNORECASE
    )
    
    return html_content, replacements

def inject_page_breaks(html_content: str, aspect_ratio: str):
    """Automatically inject page breaks and page sizing CSS"""
    
    if aspect_ratio == "16:9":
        page_size = "288mm 162mm"
    elif aspect_ratio == "1:1":
        page_size = "210mm 210mm"
    else:
        page_size = "162mm 288mm"
    
    page_css = f"""
    <style id="auto-page-breaks">
        @page {{
            size: {page_size};
            margin: 0;
        }}
        
        html, body {{
            margin: 0 !important;
            padding: 0 !important;
            width: 100% !important;
            height: 100% !important;
        }}
        
        .page, .slide, section.page, article.page, div[class*="page"], div[class*="slide"] {{
            width: 100% !important;
            min-height: 100vh !important;
            page-break-after: always !important;
            break-after: page !important;
            page-break-inside: avoid !important;
            break-inside: avoid !important;
            position: relative !important;
            box-sizing: border-box !important;
        }}
        
        .page:last-child, .slide:last-child,
        section.page:last-child, article.page:last-child {{
            page-break-after: auto !important;
            break-after: auto !important;
        }}
        
        body > section:not(.no-page-break),
        body > article:not(.no-page-break),
        body > div:not(.no-page-break) {{
            page-break-after: always !important;
            break-after: page !important;
            min-height: 100vh;
            box-sizing: border-box !important;
            position: relative !important;
        }}
        
        body > section:last-child,
        body > article:last-child,
        body > div:last-child {{
            page-break-after: auto !important;
        }}
        
        .page-break, .page-break-after {{
            page-break-after: always !important;
            break-after: page !important;
        }}
        
        .page-break-before {{
            page-break-before: always !important;
            break-before: page !important;
        }}
        
        .no-page-break, .keep-together {{
            page-break-inside: avoid !important;
            break-inside: avoid !important;
        }}
        
        h1, h2, h3, h4, h5, h6 {{
            page-break-after: avoid !important;
            break-after: avoid !important;
            page-break-inside: avoid !important;
            break-inside: avoid !important;
        }}
        
        img, figure, table, pre, blockquote {{
            page-break-inside: avoid !important;
            break-inside: avoid !important;
        }}
        
        * {{
            -webkit-print-color-adjust: exact !important;
            print-color-adjust: exact !important;
            color-adjust: exact !important;
        }}
    </style>
    """
    
    if '</head>' in html_content:
        html_content = html_content.replace('</head>', page_css + '</head>')
    elif '<body' in html_content:
        html_content = html_content.replace('<body', page_css + '<body', 1)
    else:
        html_content = page_css + html_content
    
    return html_content

def convert_html_to_pdf(html_content, aspect_ratio, temp_dir, image_files=None):
    """Convert HTML content to PDF using Puppeteer"""
    try:
        # Normalize image paths in HTML
        html_content, path_replacements = normalize_image_paths(html_content)
        
        # Inject page breaks
        html_content = inject_page_breaks(html_content, aspect_ratio)
        
        # Save HTML file
        html_file = os.path.join(temp_dir, "input.html")
        with open(html_file, 'w', encoding='utf-8') as f:
            f.write(html_content)
        
        # Save image files to the same directory
        if image_files:
            print(f"Saving {len(image_files)} image(s) to {temp_dir}")
            for filename, img_bytes in image_files.items():
                img_path = os.path.join(temp_dir, filename)
                with open(img_path, 'wb') as f:
                    f.write(img_bytes)
                print(f"  Saved: {filename} ({len(img_bytes)} bytes)")
        
        # Debug: Log what's in the temp directory
        dir_contents = os.listdir(temp_dir)
        print(f"Temp directory contents: {dir_contents}")
        
        # Find puppeteer script
        possible_paths = [
            'puppeteer_pdf.js',
            '/app/puppeteer_pdf.js',
            os.path.join(os.path.dirname(__file__), 'puppeteer_pdf.js'),
        ]
        
        puppeteer_script = None
        for path in possible_paths:
            if os.path.exists(path):
                puppeteer_script = path
                break
        
        if not puppeteer_script:
            raise Exception("puppeteer_pdf.js not found")
        
        # Run Puppeteer
        result = subprocess.run(
            ['node', puppeteer_script, html_file, aspect_ratio],
            capture_output=True,
            text=True,
            timeout=60,
            cwd=os.path.dirname(os.path.abspath(puppeteer_script))
        )
        
        if result.returncode != 0:
            raise Exception(f"PDF conversion failed: {result.stderr}")
        
        pdf_file = html_file.replace('.html', '.pdf')
        if not os.path.exists(pdf_file):
            raise Exception("PDF file was not generated")
        
        with open(pdf_file, 'rb') as f:
            pdf_bytes = f.read()
        
        return pdf_bytes, path_replacements
        
    except subprocess.TimeoutExpired:
        raise Exception("PDF conversion timed out (60 seconds)")
    except Exception as e:
        raise Exception(f"Error: {str(e)}")

@app.get("/")
async def root():
    """API root endpoint"""
    return {
        "message": "HTML to PDF Converter API",
        "version": "1.0.0",
        "endpoints": {
            "POST /convert": "Convert HTML to PDF",
            "GET /health": "Health check",
            "GET /docs": "API documentation"
        }
    }

@app.get("/health")
async def health():
    """Health check endpoint"""
    return {"status": "healthy"}

@app.post("/convert")
async def convert_to_pdf(
    html_file: UploadFile = File(..., description="HTML file to convert"),
    aspect_ratio: Optional[str] = Form(None, description="Aspect ratio: 16:9, 1:1, or 9:16"),
    auto_detect: bool = Form(True, description="Auto-detect aspect ratio from HTML"),
    images: Optional[List[UploadFile]] = File(None, description="Images referenced in HTML")
):
    """
    Convert HTML to PDF with image files in same directory
    
    - **html_file**: HTML file to convert (required)
    - **aspect_ratio**: Page aspect ratio (optional if auto_detect=true)
    - **auto_detect**: Auto-detect aspect ratio from HTML content
    - **images**: Image files referenced in HTML (saved to temp directory)
    """
    temp_dir = None
    try:
        # Read HTML content
        html_content = await html_file.read()
        try:
            html_content = html_content.decode('utf-8')
        except UnicodeDecodeError:
            html_content = html_content.decode('latin-1')
        
        # Detect or use provided aspect ratio
        if auto_detect:
            detected_ratio = detect_aspect_ratio(html_content)
            aspect_ratio = detected_ratio
        elif not aspect_ratio:
            aspect_ratio = "9:16"
        
        # Validate aspect ratio
        if aspect_ratio not in ["16:9", "1:1", "9:16"]:
            raise HTTPException(status_code=400, detail="Invalid aspect ratio. Must be 16:9, 1:1, or 9:16")
        
        # Create temp directory
        temp_dir = tempfile.mkdtemp()
        
        # Read images into dictionary - extract just the filename without path
        image_files = {}
        if images:
            for img in images:
                img_bytes = await img.read()
                # Extract just the filename from path (e.g., "images/photo.png" -> "photo.png")
                clean_filename = os.path.basename(img.filename)
                image_files[clean_filename] = img_bytes
        
        # Convert to PDF
        pdf_bytes, path_replacements = convert_html_to_pdf(
            html_content, 
            aspect_ratio, 
            temp_dir, 
            image_files
        )
        
        # Return PDF
        return Response(
            content=pdf_bytes,
            media_type="application/pdf",
            headers={
                "Content-Disposition": f"attachment; filename=converted.pdf",
                "X-Aspect-Ratio": aspect_ratio,
                "X-Path-Replacements": str(len(path_replacements)),
                "X-PDF-Size": str(len(pdf_bytes))
            }
        )
        
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))
    finally:
        if temp_dir and os.path.exists(temp_dir):
            shutil.rmtree(temp_dir, ignore_errors=True)

@app.post("/convert-string")
async def convert_string_to_pdf(
    html_content: str = Form(..., description="HTML content as string"),
    aspect_ratio: Optional[str] = Form(None, description="Aspect ratio: 16:9, 1:1, or 9:16"),
    auto_detect: bool = Form(True, description="Auto-detect aspect ratio from HTML")
):
    """
    Convert HTML string to PDF (for HTML without external images)
    
    - **html_content**: HTML content as string (required)
    - **aspect_ratio**: Page aspect ratio (optional if auto_detect=true)
    - **auto_detect**: Auto-detect aspect ratio from HTML content
    """
    temp_dir = None
    try:
        # Detect or use provided aspect ratio
        if auto_detect:
            detected_ratio = detect_aspect_ratio(html_content)
            aspect_ratio = detected_ratio
        elif not aspect_ratio:
            aspect_ratio = "9:16"
        
        # Validate aspect ratio
        if aspect_ratio not in ["16:9", "1:1", "9:16"]:
            raise HTTPException(status_code=400, detail="Invalid aspect ratio. Must be 16:9, 1:1, or 9:16")
        
        # Create temp directory and convert
        temp_dir = tempfile.mkdtemp()
        pdf_bytes, path_replacements = convert_html_to_pdf(html_content, aspect_ratio, temp_dir, None)
        
        return Response(
            content=pdf_bytes,
            media_type="application/pdf",
            headers={
                "Content-Disposition": f"attachment; filename=converted.pdf",
                "X-Aspect-Ratio": aspect_ratio,
                "X-Path-Replacements": str(len(path_replacements)),
                "X-PDF-Size": str(len(pdf_bytes))
            }
        )
        
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))
    finally:
        if temp_dir and os.path.exists(temp_dir):
            shutil.rmtree(temp_dir, ignore_errors=True)

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)