"""
Report Service
Generate PDF reports for batch predictions
"""
import io
from typing import List, Dict
from datetime import datetime
from pathlib import Path
from reportlab.lib.pagesizes import letter, A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import inch
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle, 
    PageBreak, Image, Preformatted
)
from reportlab.lib import colors
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
from io import BytesIO
from PIL import Image as PILImage

from app.config import WORDCLOUD_DIR


class ReportService:
    """Service for generating PDF reports"""
    
    def __init__(self):
        self.styles = getSampleStyleSheet()
        self._setup_custom_styles()
        self._setup_fonts()
    
    def _setup_fonts(self):
        """Setup fonts for Vietnamese character support"""
        try:
            # Try to use DejaVu font which supports Vietnamese characters
            pdfmetrics.registerFont(TTFont('DejaVu', '/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf'))
            # Register bold variant
            pdfmetrics.registerFont(TTFont('DejaVuBold', '/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf'))
        except Exception as e:
            # If fonts not found, continue with default fonts
            print(f"Warning: Could not load Vietnamese fonts: {e}")
    
    def _setup_custom_styles(self):
        """Setup custom paragraph styles"""
        # Use DejaVu font for Vietnamese support, fallback to Helvetica
        font_name = 'DejaVu'
        font_name_bold = 'DejaVuBold'
        
        self.styles.add(ParagraphStyle(
            name='CustomTitle',
            parent=self.styles['Heading1'],
            fontSize=24,
            textColor=colors.HexColor('#4F46E5'),
            spaceAfter=30,
            alignment=TA_CENTER,
            fontName=font_name_bold
        ))
        
        self.styles.add(ParagraphStyle(
            name='CustomHeading',
            parent=self.styles['Heading2'],
            fontSize=14,
            textColor=colors.HexColor('#4F46E5'),
            spaceAfter=12,
            fontName=font_name_bold
        ))
        
        self.styles.add(ParagraphStyle(
            name='CustomNormal',
            parent=self.styles['Normal'],
            fontSize=10,
            spaceAfter=6,
            fontName=font_name
        ))
    
    def generate_rating_distribution_chart(self) -> tuple:
        """
        Generate a matplotlib chart for rating distribution
        
        Returns:
            tuple: (buffer, filename)
        """
        pass
    
    def generate_pdf_report(
        self,
        predictions: List[Dict],
        distribution: Dict[int, int],
        wordcloud_path: str,
        username: str,
        filename: str = None
    ) -> bytes:
        """
        Generate comprehensive PDF report for batch predictions
        
        Args:
            predictions: List of prediction results with 'text', 'rating', 'confidence'
            distribution: Rating distribution dict {rating: count}
            wordcloud_path: Path to generated wordcloud image (URL or file path)
            username: Username for the report
            filename: Optional custom filename
            
        Returns:
            bytes: PDF file content
        """
        # Create PDF in memory
        pdf_buffer = io.BytesIO()
        
        # Create document
        doc = SimpleDocTemplate(
            pdf_buffer,
            pagesize=A4,
            rightMargin=0.75*inch,
            leftMargin=0.75*inch,
            topMargin=0.75*inch,
            bottomMargin=0.75*inch
        )
        
        # Build document content
        story = []
        
        # Title
        title = Paragraph(
            "Prediction Report",
            self.styles['CustomTitle']
        )
        story.append(title)
        story.append(Spacer(1, 0.3*inch))
        
        # Report info
        timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        info_text = f"<b>Generated by:</b> {username}<br/><b>Date:</b> {timestamp}"
        story.append(Paragraph(info_text, self.styles['CustomNormal']))
        story.append(Spacer(1, 0.3*inch))
        
        # Summary section
        total_predictions = len(predictions)
        avg_confidence = sum(p.get('confidence', 0) for p in predictions) / total_predictions if predictions else 0
        
        summary_heading = Paragraph("Summary", self.styles['CustomHeading'])
        story.append(summary_heading)
        
        summary_data = [
            ['Metric', 'Value'],
            ['Total Predictions', str(total_predictions)],
            ['Average Confidence', f'{avg_confidence:.2%}'],
        ]
        
        summary_table = Table(summary_data, colWidths=[3*inch, 2*inch])
        summary_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor('#4F46E5')),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.whitesmoke),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'DejaVuBold'),
            ('FONTSIZE', (0, 0), (-1, 0), 12),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
            ('BACKGROUND', (0, 1), (-1, -1), colors.beige),
            ('GRID', (0, 0), (-1, -1), 1, colors.black),
            ('FONTNAME', (0, 1), (-1, -1), 'DejaVu'),
            ('FONTSIZE', (0, 1), (-1, -1), 10)
        ]))
        story.append(summary_table)
        story.append(Spacer(1, 0.3*inch))
        
        # Rating Distribution section
        dist_heading = Paragraph("Rating Distribution", self.styles['CustomHeading'])
        story.append(dist_heading)
        
        dist_data = [['Rating', 'Count', 'Percentage']]
        
        # Normalize distribution keys to integers (they might come as strings from JSON)
        normalized_dist = {}
        for key, value in distribution.items():
            try:
                int_key = int(key)
                normalized_dist[int_key] = int(value)
            except (ValueError, TypeError):
                pass
        
        total = sum(normalized_dist.values())
        
        for rating in range(1, 6):
            count = normalized_dist.get(rating, 0)
            percentage = (count / total * 100) if total > 0 else 0
            # Use star character ★ instead of emoji
            stars = "★" * rating
            dist_data.append([
                f"{stars}",
                str(count),
                f"{percentage:.1f}%"
            ])
        
        dist_table = Table(dist_data, colWidths=[1.5*inch, 1.5*inch, 1.5*inch])
        dist_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor('#4F46E5')),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.whitesmoke),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'DejaVuBold'),
            ('FONTSIZE', (0, 0), (-1, 0), 11),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
            ('BACKGROUND', (0, 1), (-1, -1), colors.lightgrey),
            ('GRID', (0, 0), (-1, -1), 1, colors.black),
            ('FONTNAME', (0, 1), (-1, -1), 'DejaVu'),
            ('FONTSIZE', (0, 1), (-1, -1), 10)
        ]))
        story.append(dist_table)
        story.append(Spacer(1, 0.3*inch))
        
        # Word Cloud section
        if wordcloud_path:
            wc_heading = Paragraph("Word Cloud Analysis", self.styles['CustomHeading'])
            story.append(wc_heading)
            
            try:
                # Convert URL to file path if needed
                file_path = wordcloud_path
                if wordcloud_path.startswith('/'):
                    # It's a URL path, convert to file path
                    file_path = str(WORDCLOUD_DIR / wordcloud_path.split('/')[-1])
                
                if Path(file_path).exists():
                    img = Image(file_path, width=5*inch, height=2.5*inch)
                    story.append(img)
                    story.append(Spacer(1, 0.2*inch))
                    wc_text = Paragraph(
                        "<i>Larger words indicate higher frequency in the comments</i>",
                        self.styles['CustomNormal']
                    )
                    story.append(wc_text)
            except Exception as e:
                print(f"Warning: Could not include word cloud: {e}")
            
            story.append(Spacer(1, 0.3*inch))
        
        # Page break before detailed results
        story.append(PageBreak())
        
        # Detailed Results section
        results_heading = Paragraph("Detailed Results", self.styles['CustomHeading'])
        story.append(results_heading)
        story.append(Spacer(1, 0.2*inch))
        
        # Results table
        results_data = [['Comment', 'Rating', 'Confidence']]
        
        for pred in predictions:
            comment = pred.get('text', '')
            rating = pred.get('rating', 0)
            confidence = pred.get('confidence', 0)
            
            # Create wrapped comment - let ReportLab handle wrapping
            comment_paragraph = Paragraph(comment, self.styles['CustomNormal'])
            
            # Use star character ★ instead of emoji
            stars = "★" * rating
            
            results_data.append([
                comment_paragraph,
                f"{stars}",
                f"{confidence:.2%}"
            ])
        
        # Create table with adjusted column widths - wider comment column for wrapping
        results_table = Table(results_data, colWidths=[3.5*inch, 0.8*inch, 1.2*inch])
        results_table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor('#4F46E5')),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.whitesmoke),
            ('ALIGN', (0, 0), (0, -1), 'LEFT'),
            ('ALIGN', (1, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'DejaVuBold'),
            ('FONTSIZE', (0, 0), (-1, 0), 10),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
            ('BACKGROUND', (0, 1), (-1, -1), colors.lightgrey),
            ('GRID', (0, 0), (-1, -1), 1, colors.grey),
            ('ROWBACKGROUNDS', (0, 1), (-1, -1), [colors.white, colors.lightgrey]),
            ('FONTNAME', (0, 1), (-1, -1), 'DejaVu'),
            ('FONTSIZE', (0, 1), (-1, -1), 9),
            ('VALIGN', (0, 0), (-1, -1), 'TOP'),  # Top alignment for wrapped text
            ('LEFTPADDING', (0, 0), (-1, -1), 8),
            ('RIGHTPADDING', (0, 0), (-1, -1), 8),
            ('TOPPADDING', (0, 0), (-1, -1), 6),
            ('BOTTOMPADDING', (0, 0), (-1, -1), 6),
        ]))
        story.append(results_table)
        
        # Build PDF
        doc.build(story)
        
        # Get PDF bytes
        pdf_buffer.seek(0)
        return pdf_buffer.getvalue()


def get_report_service() -> ReportService:
    """Dependency injection for report service"""
    return ReportService()