#!/usr/bin/env python3
"""
Enhanced DOCX to PDF Converter
Professional FastAPI Backend with Docker Support
"""

import os
import tempfile
import shutil
import subprocess
import logging
import uuid
from pathlib import Path
from typing import Optional, List
import base64
import json

from fastapi import FastAPI, File, UploadFile, Form, HTTPException, BackgroundTasks
from fastapi.responses import FileResponse, JSONResponse
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

app = FastAPI(
    title="Enhanced DOCX to PDF Converter",
    description="Professional API for converting DOCX files to PDF with perfect formatting preservation",
    version="2.0.0"
)

# Add CORS middleware for browser integration
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # In production, specify exact origins
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Configuration
MAX_FILE_SIZE = 50 * 1024 * 1024  # 50MB
SUPPORTED_MIME_TYPES = ["application/vnd.openxmlformats-officedocument.wordprocessingml.document"]

class ConversionRequest(BaseModel):
    """Request model for base64 conversion"""
    file_content: str  # base64 encoded file
    filename: str

class BatchConversionRequest(BaseModel):
    """Request model for batch conversion"""
    files: List[ConversionRequest]

class ConversionResponse(BaseModel):
    """Response model for conversion results"""
    success: bool
    pdf_url: Optional[str] = None
    message: Optional[str] = None
    error: Optional[str] = None

def setup_libreoffice():
    """Ensure LibreOffice is properly configured"""
    try:
        result = subprocess.run(
            ["libreoffice", "--version"],
            capture_output=True,
            text=True,
            timeout=10
        )
        if result.returncode != 0:
            raise Exception("LibreOffice not found or not working")
        
        logger.info(f"LibreOffice version: {result.stdout.strip()}")
        return True
    except Exception as e:
        logger.error(f"LibreOffice setup error: {e}")
        return False

def convert_docx_to_pdf(input_path: str, output_path: str) -> bool:
    """Convert DOCX to PDF using LibreOffice"""
    try:
        # Use LibreOffice headless mode for conversion
        cmd = [
            "libreoffice",
            "--headless",
            "--convert-to", "pdf",
            "--outdir", os.path.dirname(output_path),
            input_path
        ]
        
        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            timeout=120  # 2 minutes timeout
        )
        
        if result.returncode != 0:
            logger.error(f"Conversion failed: {result.stderr}")
            return False
            
        # Check if PDF was created
        if not os.path.exists(output_path):
            logger.error("PDF file was not created")
            return False
            
        logger.info(f"Successfully converted {input_path} to {output_path}")
        return True
        
    except subprocess.TimeoutExpired:
        logger.error("Conversion timed out")
        return False
    except Exception as e:
        logger.error(f"Conversion error: {e}")
        return False

def validate_file(file_path: str, mime_type: str) -> bool:
    """Validate uploaded file"""
    # Check file size
    if os.path.getsize(file_path) > MAX_FILE_SIZE:
        return False
    
    # Check MIME type
    if mime_type not in SUPPORTED_MIME_TYPES:
        return False
        
    # Check file extension
    if not file_path.lower().endswith('.docx'):
        return False
        
    return True

@app.on_event("startup")
async def startup_event():
    """Initialize application on startup"""
    logger.info("Starting Enhanced DOCX to PDF Converter...")
    
    # Setup LibreOffice
    if not setup_libreoffice():
        logger.warning("LibreOffice setup failed - conversions may not work")
    
    # Create temp directory if it doesn't exist
    os.makedirs("/tmp/conversions", exist_ok=True)
    
    logger.info("Application started successfully")

@app.get("/health")
async def health_check():
    """Health check endpoint"""
    return {"status": "healthy", "version": "2.0.0"}

@app.post("/convert", response_model=ConversionResponse)
async def convert_docx(
    background_tasks: BackgroundTasks,
    file: Optional[UploadFile] = File(None),
    file_content: Optional[str] = Form(None),
    filename: Optional[str] = Form(None)
):
    """
    Convert DOCX to PDF
    
    Supports two input methods:
    1. Multipart file upload (file parameter)
    2. Base64 encoded content (file_content and filename parameters)
    """
    temp_dir = None
    input_path = None
    output_path = None
    
    try:
        # Create temporary directory for this conversion
        temp_dir = tempfile.mkdtemp(dir="/tmp/conversions")
        
        # Handle file upload
        if file and file.filename:
            # Validate file
            if not validate_file(file.filename, file.content_type or ""):
                raise HTTPException(status_code=400, detail="Invalid file type or size")
            
            # Save uploaded file
            input_path = os.path.join(temp_dir, file.filename)
            with open(input_path, "wb") as buffer:
                content = await file.read()
                buffer.write(content)
                
        # Handle base64 content
        elif file_content and filename:
            # Validate filename
            if not filename.lower().endswith('.docx'):
                raise HTTPException(status_code=400, detail="Filename must have .docx extension")
            
            # Decode base64 content
            try:
                file_data = base64.b64decode(file_content)
            except Exception:
                raise HTTPException(status_code=400, detail="Invalid base64 content")
            
            # Save decoded file
            input_path = os.path.join(temp_dir, filename)
            with open(input_path, "wb") as buffer:
                buffer.write(file_data)
                
            # Validate saved file
            if not validate_file(input_path, "application/vnd.openxmlformats-officedocument.wordprocessingml.document"):
                raise HTTPException(status_code=400, detail="Invalid file content")
                
        else:
            raise HTTPException(status_code=400, detail="Either file or file_content+filename must be provided")
        
        # Generate output path
        output_filename = os.path.splitext(os.path.basename(input_path))[0] + ".pdf"
        output_path = os.path.join(temp_dir, output_filename)
        
        # Perform conversion
        if not convert_docx_to_pdf(input_path, output_path):
            raise HTTPException(status_code=500, detail="Conversion failed")
        
        # Return success response
        pdf_url = f"/download/{os.path.basename(temp_dir)}/{output_filename}"
        return ConversionResponse(
            success=True,
            pdf_url=pdf_url,
            message="Conversion successful"
        )
        
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Conversion error: {e}")
        raise HTTPException(status_code=500, detail=f"Conversion failed: {str(e)}")
    finally:
        # Cleanup will be handled by download endpoint or background task
        pass

@app.get("/download/{temp_id}/{filename}")
async def download_pdf(temp_id: str, filename: str):
    """Download converted PDF file"""
    try:
        file_path = f"/tmp/conversions/{temp_id}/{filename}"
        
        if not os.path.exists(file_path):
            raise HTTPException(status_code=404, detail="File not found")
            
        return FileResponse(
            path=file_path,
            filename=filename,
            media_type='application/pdf'
        )
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Download error: {e}")
        raise HTTPException(status_code=500, detail="Download failed")

@app.post("/convert/batch", response_model=List[ConversionResponse])
async def batch_convert(request: BatchConversionRequest):
    """
    Batch convert multiple DOCX files to PDF
    """
    results = []
    
    for file_req in request.files:
        try:
            # Create temporary directory for this conversion
            temp_dir = tempfile.mkdtemp(dir="/tmp/conversions")
            
            # Decode base64 content
            try:
                file_data = base64.b64decode(file_req.file_content)
            except Exception:
                results.append(ConversionResponse(
                    success=False,
                    error="Invalid base64 content"
                ))
                continue
            
            # Save decoded file
            input_path = os.path.join(temp_dir, file_req.filename)
            with open(input_path, "wb") as buffer:
                buffer.write(file_data)
                
            # Validate saved file
            if not validate_file(input_path, "application/vnd.openxmlformats-officedocument.wordprocessingml.document"):
                results.append(ConversionResponse(
                    success=False,
                    error="Invalid file content"
                ))
                continue
            
            # Generate output path
            output_filename = os.path.splitext(os.path.basename(input_path))[0] + ".pdf"
            output_path = os.path.join(temp_dir, output_filename)
            
            # Perform conversion
            if convert_docx_to_pdf(input_path, output_path):
                pdf_url = f"/download/{os.path.basename(temp_dir)}/{output_filename}"
                results.append(ConversionResponse(
                    success=True,
                    pdf_url=pdf_url,
                    message="Conversion successful"
                ))
            else:
                results.append(ConversionResponse(
                    success=False,
                    error="Conversion failed"
                ))
                
        except Exception as e:
            logger.error(f"Batch conversion error: {e}")
            results.append(ConversionResponse(
                success=False,
                error=str(e)
            ))
    
    return results

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)