"""
PDF Generation Module

This module handles saving research papers to PDF format with enhanced error handling.
"""

import os
import re
from typing import Optional, Tuple

from reportlab.lib import colors
from reportlab.lib.pagesizes import A4, letter
from reportlab.lib.styles import ParagraphStyle, getSampleStyleSheet
from reportlab.lib.units import inch
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.platypus import PageBreak, Paragraph, SimpleDocTemplate, Spacer


def create_custom_styles() -> Tuple[ParagraphStyle, ParagraphStyle, ParagraphStyle]:
    """
    Create custom paragraph styles for the PDF
    
    Returns:
        Tuple of (title_style, heading_style, body_style)
    """
    styles = getSampleStyleSheet()
    
    # Title style
    title_style = ParagraphStyle(
        'CustomTitle',
        parent=styles['Title'],
        fontSize=18,
        spaceAfter=30,
        alignment=1,  # Center alignment
        textColor=colors.darkblue
    )
    
    # Heading style
    heading_style = ParagraphStyle(
        'CustomHeading',
        parent=styles['Heading1'],
        fontSize=14,
        spaceAfter=12,
        spaceBefore=20,
        textColor=colors.darkblue
    )
    
    # Body style
    body_style = ParagraphStyle(
        'CustomBody',
        parent=styles['Normal'],
        fontSize=11,
        spaceAfter=6,
        leading=14
    )
    
    return title_style, heading_style, body_style



def save_draft_to_pdf(topic: str, draft_text: str, bibliography: str, filename: str) -> None:
    """
    Save research paper draft and bibliography to PDF
    
    Args:
        topic: The research topic
        draft_text: The draft text content
        bibliography: The bibliography content
        filename: Output PDF filename
    """

    
    try:
        # Setup fonts
        font_dir = "font"
        if os.path.exists(font_dir):
            dejavu_bold = os.path.join(font_dir, "dejavu-sans.bold.ttf")
            dejavu_regular = os.path.join(font_dir, "DejaVuSans.ttf")
            
            if os.path.exists(dejavu_bold):
                pdfmetrics.registerFont(TTFont('DejaVu-Bold', dejavu_bold))
            
            if os.path.exists(dejavu_regular):
                pdfmetrics.registerFont(TTFont('DejaVu-Regular', dejavu_regular))
        
        # Create PDF document
        doc = SimpleDocTemplate(filename, pagesize=A4)
        story = []
        
        # Get custom styles
        title_style, heading_style, body_style = create_custom_styles()
        
        # Add title
        title = Paragraph(topic, title_style)
        story.append(title)
        story.append(Spacer(1, 20))
        
        # Process draft text
        if draft_text and draft_text.strip():
            # Split draft into paragraphs
            paragraphs = draft_text.split('\n\n')
            
            for paragraph in paragraphs:
                paragraph = paragraph.strip()
                if paragraph:
                    # Check if it's a heading (starts with # or numbers)
                    if paragraph.startswith('#') or re.match(r'^\d+\.', paragraph):
                        # It's a heading
                        heading_text = re.sub(r'^#+\s*', '', paragraph)  # Remove # marks
                        heading_text = re.sub(r'^\d+\.\s*', '', heading_text)  # Remove numbers
                        heading = Paragraph(heading_text, heading_style)
                        story.append(heading)
                    else:
                        # It's a body paragraph
                        body = Paragraph(paragraph, body_style)
                        story.append(body)
                    
                    story.append(Spacer(1, 6))
        
        # Add bibliography section
        if bibliography and bibliography.strip():
            story.append(PageBreak())
            story.append(Paragraph("Bibliography", heading_style))
            story.append(Spacer(1, 12))
            
            # Process bibliography
            bib_paragraphs = bibliography.split('\n')
            for bib_para in bib_paragraphs:
                bib_para = bib_para.strip()
                if bib_para:
                    bib_body = Paragraph(bib_para, body_style)
                    story.append(bib_body)
                    story.append(Spacer(1, 6))
        
        # Build PDF
        doc.build(story)
        
        print("✅ PDF saved successfully!")
        
    except Exception as e:
        print(f"❌ Error saving PDF: {e}")
        raise