import os
from reportlab.lib.pagesizes import A4
from reportlab.pdfgen import canvas
from reportlab.lib.units import inch
from reportlab.lib import colors
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, Image
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
import markdown2
from datetime import datetime

class PDFReportGenerator:
    def __init__(self, output_dir="data/reports"):
        self.output_dir = output_dir
        os.makedirs(output_dir, exist_ok=True)
        self.styles = getSampleStyleSheet()
        self._setup_custom_styles()

    def _setup_custom_styles(self):
        self.styles.add(ParagraphStyle(
            name='LegalHeading',
            parent=self.styles['Heading1'],
            fontSize=16,
            textColor=colors.darkblue,
            spaceAfter=12
        ))
        self.styles.add(ParagraphStyle(
            name='LegalBody',
            parent=self.styles['BodyText'],
            fontSize=11,
            leading=14,
            spaceAfter=8
        ))

    def _draw_watermark(self, canvas, doc):
        """Draws a diagonal watermark on every page."""
        canvas.saveState()
        canvas.setFont("Helvetica-Bold", 60)
        canvas.setFillColor(colors.lightgrey, alpha=0.2)
        canvas.translate(A4[0]/2, A4[1]/2)
        canvas.rotate(45)
        canvas.drawCentredString(0, 0, "CONFIDENTIAL - AI ADVISORY")
        canvas.restoreState()
        
        # Add Footer
        canvas.saveState()
        canvas.setFont("Helvetica", 9)
        canvas.setFillColor(colors.grey)
        canvas.drawString(inch, 0.75 * inch, f"Generated by LETA AI - {datetime.now().strftime('%Y-%m-%d %H:%M')}")
        canvas.drawRightString(A4[0] - inch, 0.75 * inch, f"Page {doc.page}")
        canvas.restoreState()

    def generate_report(self, markdown_content: str, filename: str = "advisory.pdf") -> str:
        """
        Converts Markdown to a professional PDF with watermark.
        """
        filepath = os.path.join(self.output_dir, filename)
        doc = SimpleDocTemplate(filepath, pagesize=A4)
        
        # Convert Markdown to HTML (ReportLab handles basic HTML-like tags)
        # We use a simple parser or just treat paragraphs. 
        # For robustness, we will split by newlines and style accordingly.
        
        story = []
        
        # Logo (if exists)
        # logo_path = "assets/logo.png"
        # if os.path.exists(logo_path):
        #    story.append(Image(logo_path, width=2*inch, height=1*inch))
        
        # Title
        story.append(Paragraph("LEGAL ADVISORY OPINION", self.styles['Title']))
        story.append(Spacer(1, 24))
        
        # Process Content
        # Cleaning markdown for ReportLab Paragraphs (basic bold/italic support)
        lines = markdown_content.split('\n')
        for line in lines:
            line = line.strip()
            if not line:
                story.append(Spacer(1, 6))
                continue
                
            if line.startswith('# '):
                story.append(Paragraph(line[2:], self.styles['LegalHeading']))
            elif line.startswith('### ') or line.startswith('**'):
                # Subheading or bold line
                clean_line = line.replace('### ', '').replace('**', '')
                story.append(Paragraph(f"<b>{clean_line}</b>", self.styles['Heading3']))
            elif line.startswith('* ') or line.startswith('- '):
                # Bullet
                story.append(Paragraph(f"• {line[2:]}", self.styles['LegalBody']))
            else:
                story.append(Paragraph(line, self.styles['LegalBody']))

        # Build PDF with Watermark
        doc.build(story, onFirstPage=self._draw_watermark, onLaterPages=self._draw_watermark)
        
        return filepath