import io
import os
import subprocess
import tempfile
import zipfile
from flask import Flask, render_template, request, send_file, jsonify

app = Flask(__name__)

# Max upload size: 100 MB
app.config['MAX_CONTENT_LENGTH'] = 100 * 1024 * 1024

ALLOWED_EXTENSIONS = {'.doc', '.docx', '.ppt', '.pptx', '.xls', '.xlsx'}

def is_allowed_file(filename):
    _, ext = os.path.splitext(filename.lower())
    return ext in ALLOWED_EXTENSIONS

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/convert', methods=['POST'])
def convert():
    if 'files' not in request.files:
        return jsonify({'error': 'No files found in the request.'}), 400

    files = request.files.getlist('files')
    if not files or all(file.filename == '' for file in files):
        return jsonify({'error': 'No files selected for upload.'}), 400

    # Build the ZIP archive in memory
    zip_buffer = io.BytesIO()
    converted_files_count = 0
    failed_conversions = []

    # Use TemporaryDirectory context manager to ensure automatic clean-up of files
    with tempfile.TemporaryDirectory() as temp_dir:
        for file in files:
            if not file.filename:
                continue

            _, ext = os.path.splitext(file.filename.lower())
            if ext not in ALLOWED_EXTENSIONS:
                failed_conversions.append((file.filename, f"Unsupported extension '{ext}'"))
                continue

            # Save the uploaded file in the temporary directory
            input_path = os.path.join(temp_dir, file.filename)
            try:
                file.save(input_path)
            except Exception as e:
                failed_conversions.append((file.filename, f"Failed to save file: {e}"))
                continue

            # Build the LibreOffice execution command
            cmd = [
                "soffice",
                "--headless",
                "--convert-to",
                "pdf",
                "--outdir",
                temp_dir,
                input_path
            ]

            print(f"Web conversion: executing {' '.join(cmd)}")

            try:
                # Convert the file safely using subprocess list invocation with a 180s timeout per file
                result = subprocess.run(
                    cmd,
                    stdout=subprocess.PIPE,
                    stderr=subprocess.PIPE,
                    text=True,
                    timeout=180
                )
                if result.returncode != 0:
                    failed_conversions.append((file.filename, f"LibreOffice failed (code {result.returncode})"))
                    continue
            except subprocess.TimeoutExpired:
                failed_conversions.append((file.filename, "Conversion timed out (180s)"))
                continue
            except Exception as e:
                failed_conversions.append((file.filename, f"Conversion error: {e}"))
                continue

            # Verify that the PDF was successfully created
            base_name, _ = os.path.splitext(file.filename)
            pdf_filename = f"{base_name}.pdf"
            pdf_path = os.path.join(temp_dir, pdf_filename)

            if os.path.exists(pdf_path):
                converted_files_count += 1
            else:
                failed_conversions.append((file.filename, "Expected PDF output was not created"))

        # If zero files were successfully converted, return a detailed error response
        if converted_files_count == 0:
            error_details = ", ".join([f"'{name}': {reason}" for name, reason in failed_conversions])
            return jsonify({'error': f'Failed to convert any files. Details: {error_details}'}), 400

        # If only a single file was successfully converted, return the PDF directly
        if converted_files_count == 1:
            pdf_filename = None
            pdf_path = None
            for file in files:
                base_name, _ = os.path.splitext(file.filename)
                pdf_filename = f"{base_name}.pdf"
                pdf_path = os.path.join(temp_dir, pdf_filename)
                if os.path.exists(pdf_path):
                    break
            
            if pdf_path and pdf_filename:
                # Read PDF file into memory buffer so we can safely delete temporary directory
                pdf_buffer = io.BytesIO()
                with open(pdf_path, 'rb') as f:
                    pdf_buffer.write(f.read())
                pdf_buffer.seek(0)
                
                return send_file(
                    pdf_buffer,
                    mimetype='application/pdf',
                    as_attachment=True,
                    download_name=pdf_filename
                )

        # Create the ZIP archive containing all successfully converted PDFs (for 2 or more files)
        with zipfile.ZipFile(zip_buffer, 'w', zipfile.ZIP_DEFLATED) as zip_file:
            for file in files:
                base_name, _ = os.path.splitext(file.filename)
                pdf_filename = f"{base_name}.pdf"
                pdf_path = os.path.join(temp_dir, pdf_filename)
                if os.path.exists(pdf_path):
                    # Write to the zip archive with only the filename (avoiding temp directory paths)
                    zip_file.write(pdf_path, pdf_filename)

            # Append a conversion log if any files failed
            if failed_conversions:
                log_lines = ["Conversion Report (Some files failed to convert):\n", "="*50, "\n"]
                for name, reason in failed_conversions:
                    log_lines.append(f"FAILED: {name} | Reason: {reason}\n")
                zip_file.writestr("conversion_errors.log", "".join(log_lines))

    # Move pointer to the beginning of the memory buffer
    zip_buffer.seek(0)

    # Return the zip file for download
    return send_file(
        zip_buffer,
        mimetype='application/zip',
        as_attachment=True,
        download_name='converted_pdfs.zip'
    )


if __name__ == '__main__':
    # Get port from environment (Hugging Face defaults to 7860) or default to 7860
    port = int(os.environ.get('PORT', 7860))
    app.run(host='0.0.0.0', port=port)