"""
PDF Report Generator for Sales Bot
Uses ReportLab for PDF generation and Matplotlib for charts
"""

import io
import os
import logging
from datetime import datetime, timedelta, timezone
from typing import Dict, List, Optional

logger = logging.getLogger(__name__)

# Try to import ReportLab
try:
    from reportlab.lib import colors
    from reportlab.lib.pagesizes import letter, A4
    from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
    from reportlab.lib.units import inch, cm
    from reportlab.platypus import (
        SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
        Image, PageBreak, HRFlowable
    )
    from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT
    REPORTLAB_AVAILABLE = True
except ImportError:
    REPORTLAB_AVAILABLE = False
    logger.warning("ReportLab not available, PDF generation disabled")

# Try to import Matplotlib for charts
try:
    import matplotlib
    matplotlib.use('Agg')  # Use non-interactive backend
    import matplotlib.pyplot as plt
    import matplotlib.dates as mdates
    MATPLOTLIB_AVAILABLE = True
except ImportError:
    MATPLOTLIB_AVAILABLE = False
    logger.warning("Matplotlib not available, charts in PDF disabled")

# Mexico timezone
TZ_MEXICO = timezone(timedelta(hours=-6))


class SalesReportPDF:
    """
    Generates PDF reports for sales data.
    """

    # Color scheme matching the dashboard
    COLORS = {
        'primary': colors.HexColor('#00d4ff'),
        'secondary': colors.HexColor('#00ff88'),
        'warning': colors.HexColor('#ffaa00'),
        'dark': colors.HexColor('#1a1a2e'),
        'text': colors.HexColor('#333333'),
        'muted': colors.HexColor('#666666'),
    }

    def __init__(self, ventas: List[Dict], stats: Dict, vendedor: str = None):
        """
        Initialize the PDF generator.

        Args:
            ventas: List of sales data
            stats: Statistics dictionary
            vendedor: Optional vendor username (None for all)
        """
        if not REPORTLAB_AVAILABLE:
            raise ImportError("ReportLab is required for PDF generation")

        self.ventas = ventas or []
        self.stats = stats or {}
        self.vendedor = vendedor
        self.styles = getSampleStyleSheet()
        self._setup_custom_styles()

    def _setup_custom_styles(self):
        """Setup custom paragraph styles."""
        # Title style
        self.styles.add(ParagraphStyle(
            'CustomTitle',
            parent=self.styles['Heading1'],
            fontSize=24,
            textColor=self.COLORS['dark'],
            spaceAfter=20,
            alignment=TA_CENTER
        ))

        # Subtitle style
        self.styles.add(ParagraphStyle(
            'CustomSubtitle',
            parent=self.styles['Normal'],
            fontSize=12,
            textColor=self.COLORS['muted'],
            spaceAfter=10,
            alignment=TA_CENTER
        ))

        # Section header
        self.styles.add(ParagraphStyle(
            'SectionHeader',
            parent=self.styles['Heading2'],
            fontSize=14,
            textColor=self.COLORS['primary'],
            spaceBefore=15,
            spaceAfter=10
        ))

        # KPI value style
        self.styles.add(ParagraphStyle(
            'KPIValue',
            parent=self.styles['Normal'],
            fontSize=18,
            textColor=self.COLORS['dark'],
            alignment=TA_CENTER
        ))

        # KPI label style
        self.styles.add(ParagraphStyle(
            'KPILabel',
            parent=self.styles['Normal'],
            fontSize=10,
            textColor=self.COLORS['muted'],
            alignment=TA_CENTER
        ))

    def generar_reporte_diario(self) -> bytes:
        """
        Generates a daily sales report.

        Returns:
            PDF content as bytes
        """
        buffer = io.BytesIO()
        doc = SimpleDocTemplate(
            buffer,
            pagesize=letter,
            rightMargin=0.75*inch,
            leftMargin=0.75*inch,
            topMargin=0.75*inch,
            bottomMargin=0.75*inch
        )

        elements = []
        fecha_hoy = datetime.now(TZ_MEXICO).strftime('%d de %B de %Y')

        # Title
        elements.append(Paragraph(
            "Reporte Diario de Ventas",
            self.styles['CustomTitle']
        ))
        elements.append(Paragraph(
            f"{fecha_hoy}",
            self.styles['CustomSubtitle']
        ))
        elements.append(Spacer(1, 20))

        # KPIs Section
        elements.append(self._create_kpi_section())
        elements.append(Spacer(1, 20))

        # Trend Chart (if matplotlib available)
        if MATPLOTLIB_AVAILABLE and self.ventas:
            chart_image = self._create_trend_chart()
            if chart_image:
                elements.append(Paragraph("Tendencia de Ventas (Últimos 7 días)", self.styles['SectionHeader']))
                elements.append(Image(chart_image, width=6*inch, height=3*inch))
                elements.append(Spacer(1, 20))

        # Top Sellers Section
        elements.append(Paragraph("Top Vendedores del Día", self.styles['SectionHeader']))
        elements.append(self._create_top_sellers_table())
        elements.append(Spacer(1, 20))

        # Sales Detail
        if len(self.ventas) <= 20:  # Only include if not too many
            elements.append(Paragraph("Detalle de Ventas", self.styles['SectionHeader']))
            elements.append(self._create_sales_table())

        # Footer
        elements.append(Spacer(1, 30))
        elements.append(HRFlowable(width="100%", thickness=1, color=self.COLORS['muted']))
        elements.append(Spacer(1, 10))
        elements.append(Paragraph(
            f"Generado por Sales Bot - {datetime.now(TZ_MEXICO).strftime('%Y-%m-%d %H:%M')}",
            self.styles['CustomSubtitle']
        ))

        doc.build(elements)
        return buffer.getvalue()

    def generar_reporte_ejecutivo(self) -> bytes:
        """
        Generates an executive summary report.

        Returns:
            PDF content as bytes
        """
        buffer = io.BytesIO()
        doc = SimpleDocTemplate(
            buffer,
            pagesize=letter,
            rightMargin=0.75*inch,
            leftMargin=0.75*inch,
            topMargin=0.75*inch,
            bottomMargin=0.75*inch
        )

        elements = []
        fecha_hoy = datetime.now(TZ_MEXICO).strftime('%d de %B de %Y')
        mes_actual = datetime.now(TZ_MEXICO).strftime('%B %Y')

        # Title
        elements.append(Paragraph(
            "Reporte Ejecutivo",
            self.styles['CustomTitle']
        ))
        elements.append(Paragraph(
            f"{mes_actual}",
            self.styles['CustomSubtitle']
        ))
        elements.append(Spacer(1, 20))

        # Executive KPIs
        elements.append(self._create_executive_kpi_section())
        elements.append(Spacer(1, 20))

        # Monthly Trend Chart
        if MATPLOTLIB_AVAILABLE and self.ventas:
            chart_image = self._create_monthly_chart()
            if chart_image:
                elements.append(Paragraph("Tendencia Mensual", self.styles['SectionHeader']))
                elements.append(Image(chart_image, width=6*inch, height=3*inch))
                elements.append(Spacer(1, 20))

        # Top Performers
        elements.append(Paragraph("Top Performers del Mes", self.styles['SectionHeader']))
        elements.append(self._create_top_performers_table())
        elements.append(Spacer(1, 20))

        # Comparison Section
        elements.append(Paragraph("Comparativa", self.styles['SectionHeader']))
        elements.append(self._create_comparison_section())

        # Footer
        elements.append(Spacer(1, 30))
        elements.append(HRFlowable(width="100%", thickness=1, color=self.COLORS['muted']))
        elements.append(Spacer(1, 10))
        elements.append(Paragraph(
            f"Generado por Sales Bot - {datetime.now(TZ_MEXICO).strftime('%Y-%m-%d %H:%M')}",
            self.styles['CustomSubtitle']
        ))

        doc.build(elements)
        return buffer.getvalue()

    def _create_kpi_section(self) -> Table:
        """Creates KPI cards section."""
        total_ventas = len(self.ventas)
        monto_total = sum(float(v.get('monto', 0) or 0) for v in self.ventas)
        tubos_total = self.stats.get('tubos_totales', 0)
        comision_total = self.stats.get('comision_total', 0)

        data = [
            [
                Paragraph(f"{total_ventas}", self.styles['KPIValue']),
                Paragraph(f"${monto_total:,.2f}", self.styles['KPIValue']),
                Paragraph(f"{tubos_total}", self.styles['KPIValue']),
                Paragraph(f"${comision_total:,.2f}", self.styles['KPIValue']),
            ],
            [
                Paragraph("Ventas", self.styles['KPILabel']),
                Paragraph("Monto Total", self.styles['KPILabel']),
                Paragraph("Tubos", self.styles['KPILabel']),
                Paragraph("Comisiones", self.styles['KPILabel']),
            ]
        ]

        table = Table(data, colWidths=[1.5*inch]*4)
        table.setStyle(TableStyle([
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
            ('BACKGROUND', (0, 0), (-1, -1), colors.HexColor('#f8f9fa')),
            ('BOX', (0, 0), (-1, -1), 1, self.COLORS['primary']),
            ('INNERGRID', (0, 0), (-1, -1), 0.5, colors.HexColor('#e9ecef')),
            ('TOPPADDING', (0, 0), (-1, -1), 12),
            ('BOTTOMPADDING', (0, 0), (-1, -1), 12),
        ]))

        return table

    def _create_executive_kpi_section(self) -> Table:
        """Creates executive KPI section with more metrics."""
        total_ventas = len(self.ventas)
        monto_total = sum(float(v.get('monto', 0) or 0) for v in self.ventas)
        promedio_ticket = monto_total / total_ventas if total_ventas > 0 else 0
        vendedores_activos = len(set(v.get('vendedor_username') for v in self.ventas))

        data = [
            [
                Paragraph(f"${monto_total:,.2f}", self.styles['KPIValue']),
                Paragraph(f"{total_ventas}", self.styles['KPIValue']),
                Paragraph(f"${promedio_ticket:,.2f}", self.styles['KPIValue']),
                Paragraph(f"{vendedores_activos}", self.styles['KPIValue']),
            ],
            [
                Paragraph("Monto Total", self.styles['KPILabel']),
                Paragraph("Total Ventas", self.styles['KPILabel']),
                Paragraph("Ticket Promedio", self.styles['KPILabel']),
                Paragraph("Vendedores", self.styles['KPILabel']),
            ]
        ]

        table = Table(data, colWidths=[1.5*inch]*4)
        table.setStyle(TableStyle([
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
            ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor('#e3f2fd')),
            ('BACKGROUND', (0, 1), (-1, 1), colors.HexColor('#f8f9fa')),
            ('BOX', (0, 0), (-1, -1), 1, self.COLORS['primary']),
            ('TOPPADDING', (0, 0), (-1, -1), 15),
            ('BOTTOMPADDING', (0, 0), (-1, -1), 15),
        ]))

        return table

    def _create_top_sellers_table(self) -> Table:
        """Creates top sellers table."""
        # Group sales by vendor
        vendors = {}
        for venta in self.ventas:
            username = venta.get('vendedor_username', 'Desconocido')
            if username not in vendors:
                vendors[username] = {'ventas': 0, 'monto': 0}
            vendors[username]['ventas'] += 1
            vendors[username]['monto'] += float(venta.get('monto', 0) or 0)

        # Sort by sales count
        sorted_vendors = sorted(vendors.items(), key=lambda x: x[1]['monto'], reverse=True)[:5]

        data = [['#', 'Vendedor', 'Ventas', 'Monto']]
        for i, (username, stats) in enumerate(sorted_vendors, 1):
            medal = ['🥇', '🥈', '🥉', '4.', '5.'][i-1]
            data.append([
                medal,
                username,
                str(stats['ventas']),
                f"${stats['monto']:,.2f}"
            ])

        if len(data) == 1:
            data.append(['', 'Sin datos', '', ''])

        table = Table(data, colWidths=[0.5*inch, 2.5*inch, 1*inch, 1.5*inch])
        table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), self.COLORS['dark']),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.white),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
            ('FONTSIZE', (0, 0), (-1, 0), 10),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 12),
            ('BACKGROUND', (0, 1), (-1, -1), colors.HexColor('#f8f9fa')),
            ('GRID', (0, 0), (-1, -1), 0.5, colors.HexColor('#dee2e6')),
            ('TOPPADDING', (0, 1), (-1, -1), 8),
            ('BOTTOMPADDING', (0, 1), (-1, -1), 8),
        ]))

        return table

    def _create_top_performers_table(self) -> Table:
        """Creates top performers table for executive report."""
        # Similar to top sellers but with more metrics
        return self._create_top_sellers_table()

    def _create_sales_table(self) -> Table:
        """Creates detailed sales table."""
        data = [['ID', 'Fecha', 'Vendedor', 'Cliente', 'Monto']]

        for venta in self.ventas[:15]:  # Limit to 15 rows
            fecha_str = venta.get('fecha_venta', '')
            try:
                fecha = datetime.fromisoformat(fecha_str.replace('Z', '+00:00'))
                fecha_formatted = fecha.strftime('%d/%m %H:%M')
            except:
                fecha_formatted = fecha_str[:16] if fecha_str else ''

            data.append([
                str(venta.get('Id', '')),
                fecha_formatted,
                venta.get('vendedor_username', '')[:15],
                (venta.get('cliente', '') or 'N/A')[:20],
                f"${float(venta.get('monto', 0) or 0):,.2f}"
            ])

        table = Table(data, colWidths=[0.5*inch, 1*inch, 1.5*inch, 1.5*inch, 1*inch])
        table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), self.COLORS['dark']),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.white),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
            ('FONTSIZE', (0, 0), (-1, -1), 9),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 10),
            ('BACKGROUND', (0, 1), (-1, -1), colors.white),
            ('ROWBACKGROUNDS', (0, 1), (-1, -1), [colors.white, colors.HexColor('#f8f9fa')]),
            ('GRID', (0, 0), (-1, -1), 0.5, colors.HexColor('#dee2e6')),
            ('TOPPADDING', (0, 1), (-1, -1), 6),
            ('BOTTOMPADDING', (0, 1), (-1, -1), 6),
        ]))

        return table

    def _create_comparison_section(self) -> Table:
        """Creates comparison section."""
        # Placeholder data - would be filled with real comparison data
        data = [
            ['Métrica', 'Período Actual', 'Período Anterior', 'Cambio'],
            ['Ventas', str(len(self.ventas)), '-', '-'],
            ['Monto', f"${sum(float(v.get('monto', 0) or 0) for v in self.ventas):,.2f}", '-', '-'],
            ['Vendedores', str(len(set(v.get('vendedor_username') for v in self.ventas))), '-', '-'],
        ]

        table = Table(data, colWidths=[1.5*inch, 1.25*inch, 1.25*inch, 1*inch])
        table.setStyle(TableStyle([
            ('BACKGROUND', (0, 0), (-1, 0), self.COLORS['primary']),
            ('TEXTCOLOR', (0, 0), (-1, 0), colors.white),
            ('ALIGN', (0, 0), (-1, -1), 'CENTER'),
            ('FONTNAME', (0, 0), (-1, 0), 'Helvetica-Bold'),
            ('FONTSIZE', (0, 0), (-1, -1), 10),
            ('BOTTOMPADDING', (0, 0), (-1, 0), 10),
            ('BACKGROUND', (0, 1), (-1, -1), colors.white),
            ('GRID', (0, 0), (-1, -1), 0.5, colors.HexColor('#dee2e6')),
            ('TOPPADDING', (0, 1), (-1, -1), 8),
            ('BOTTOMPADDING', (0, 1), (-1, -1), 8),
        ]))

        return table

    def _create_trend_chart(self) -> Optional[io.BytesIO]:
        """Creates a trend chart image."""
        if not MATPLOTLIB_AVAILABLE:
            return None

        try:
            # Group sales by date
            sales_by_date = {}
            for venta in self.ventas:
                fecha_str = venta.get('fecha_venta', '')
                try:
                    fecha = datetime.fromisoformat(fecha_str.replace('Z', '+00:00'))
                    date_key = fecha.strftime('%Y-%m-%d')
                    if date_key not in sales_by_date:
                        sales_by_date[date_key] = 0
                    sales_by_date[date_key] += float(venta.get('monto', 0) or 0)
                except:
                    continue

            if not sales_by_date:
                return None

            # Sort by date
            sorted_dates = sorted(sales_by_date.keys())[-7:]  # Last 7 days
            values = [sales_by_date.get(d, 0) for d in sorted_dates]
            labels = [datetime.strptime(d, '%Y-%m-%d').strftime('%d/%m') for d in sorted_dates]

            # Create chart
            fig, ax = plt.subplots(figsize=(8, 4))
            ax.plot(labels, values, color='#00d4ff', linewidth=2, marker='o')
            ax.fill_between(labels, values, alpha=0.3, color='#00d4ff')
            ax.set_xlabel('Fecha')
            ax.set_ylabel('Monto ($)')
            ax.set_title('Tendencia de Ventas')
            ax.grid(True, alpha=0.3)

            # Format y-axis as currency
            ax.yaxis.set_major_formatter(plt.FuncFormatter(lambda x, p: f'${x:,.0f}'))

            plt.tight_layout()

            # Save to buffer
            buf = io.BytesIO()
            fig.savefig(buf, format='png', dpi=150, bbox_inches='tight')
            buf.seek(0)
            plt.close(fig)

            return buf

        except Exception as e:
            logger.error(f"Error creating trend chart: {str(e)}")
            return None

    def _create_monthly_chart(self) -> Optional[io.BytesIO]:
        """Creates a monthly trend chart."""
        return self._create_trend_chart()  # Use same logic for now


# Convenience functions
def generar_reporte_diario(ventas: List[Dict], stats: Dict, vendedor: str = None) -> bytes:
    """
    Genera un reporte diario en PDF.

    Args:
        ventas: Lista de ventas
        stats: Estadísticas
        vendedor: Username del vendedor (opcional)

    Returns:
        Contenido del PDF en bytes
    """
    if not REPORTLAB_AVAILABLE:
        raise ImportError("ReportLab is required for PDF generation. Install with: pip install reportlab")

    report = SalesReportPDF(ventas, stats, vendedor)
    return report.generar_reporte_diario()


def generar_reporte_ejecutivo(ventas: List[Dict], stats: Dict) -> bytes:
    """
    Genera un reporte ejecutivo en PDF.

    Args:
        ventas: Lista de ventas
        stats: Estadísticas

    Returns:
        Contenido del PDF en bytes
    """
    if not REPORTLAB_AVAILABLE:
        raise ImportError("ReportLab is required for PDF generation. Install with: pip install reportlab")

    report = SalesReportPDF(ventas, stats)
    return report.generar_reporte_ejecutivo()