import { NextRequest, NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth';
import { prisma } from '@/lib/prisma';
import { AttendanceStatus } from '@prisma/client';

export async function GET(request: NextRequest) {
  try {
    // Verificar sesión
    const session = await getServerSession(authOptions);
    if (!session?.user?.id) {
      return NextResponse.json(
        { error: 'No autorizado' },
        { status: 401 }
      );
    }

    // Verificar que el usuario sea estudiante
    const user = await prisma.user.findUnique({
      where: { id: session.user.id },
      include: { student: true }
    });

    if (!user || user.role !== 'STUDENT' || !user.student) {
      return NextResponse.json(
        { error: 'Acceso denegado. Solo estudiantes pueden acceder.' },
        { status: 403 }
      );
    }

    // Obtener parámetros de consulta
    const { searchParams } = new URL(request.url);
    const sectionId = searchParams.get('sectionId');
    const status = searchParams.get('status') as AttendanceStatus | 'all' | null;
    const startDate = searchParams.get('startDate');
    const endDate = searchParams.get('endDate');
    const periodId = searchParams.get('periodId');

    // Construir filtros
    const whereClause: any = {
      studentId: user.student.id,
    };

    if (sectionId && sectionId !== 'all') {
      whereClause.sectionId = sectionId;
    }

    if (status && status !== 'all') {
      whereClause.status = status;
    }

    if (startDate) {
      whereClause.date = {
        ...whereClause.date,
        gte: new Date(startDate)
      };
    }

    if (endDate) {
      whereClause.date = {
        ...whereClause.date,
        lte: new Date(endDate)
      };
    }

    // Si se especifica un período, filtrar por secciones de ese período
    if (periodId && periodId !== 'all') {
      whereClause.section = {
        class: {
          periodId: periodId
        }
      };
    }

    // Obtener registros de asistencia
    const attendanceRecords = await prisma.attendance.findMany({
      where: whereClause,
      include: {
        section: {
          include: {
            class: {
              include: {
                period: true
              }
            },
            teacherAssignments: {
              where: { isActive: true },
              include: {
                teacher: true
              }
            }
          }
        }
      },
      orderBy: {
        date: 'desc'
      }
    });

    // Obtener estadísticas generales
    const totalRecords = attendanceRecords.length;
    const presentCount = attendanceRecords.filter(r => r.status === 'PRESENT').length;
    const absentCount = attendanceRecords.filter(r => r.status === 'ABSENT').length;
    const justifiedCount = attendanceRecords.filter(r => r.status === 'JUSTIFIED').length;
    const attendanceRate = totalRecords > 0 ? Math.round((presentCount / totalRecords) * 100) : 0;

    // Estadísticas por sección
    const sectionStats = attendanceRecords.reduce((acc, record) => {
      const sectionId = record.sectionId;
      if (!acc[sectionId]) {
        acc[sectionId] = {
          sectionId,
          sectionName: record.section.name,
          className: record.section.class.name,
          classCode: record.section.class.code,
          periodName: record.section.class.period.name,
          total: 0,
          present: 0,
          absent: 0,
          justified: 0,
          attendanceRate: 0
        };
      }
      
      acc[sectionId].total++;
      if (record.status === 'PRESENT') acc[sectionId].present++;
      if (record.status === 'ABSENT') acc[sectionId].absent++;
      if (record.status === 'JUSTIFIED') acc[sectionId].justified++;
      
      acc[sectionId].attendanceRate = Math.round(
        (acc[sectionId].present / acc[sectionId].total) * 100
      );
      
      return acc;
    }, {} as Record<string, any>);

    // Estadísticas por período
    const periodStats = attendanceRecords.reduce((acc, record) => {
      const periodId = record.section.class.period.id;
      if (!acc[periodId]) {
        acc[periodId] = {
          periodId,
          periodName: record.section.class.period.name,
          isActive: record.section.class.period.isActive,
          total: 0,
          present: 0,
          absent: 0,
          justified: 0,
          attendanceRate: 0
        };
      }
      
      acc[periodId].total++;
      if (record.status === 'PRESENT') acc[periodId].present++;
      if (record.status === 'ABSENT') acc[periodId].absent++;
      if (record.status === 'JUSTIFIED') acc[periodId].justified++;
      
      acc[periodId].attendanceRate = Math.round(
        (acc[periodId].present / acc[periodId].total) * 100
      );
      
      return acc;
    }, {} as Record<string, any>);

    // Obtener todas las secciones matriculadas para filtros
    const enrolledSections = await prisma.studentEnrollment.findMany({
      where: {
        studentId: user.student.id,
        isActive: true
      },
      include: {
        section: {
          include: {
            class: {
              include: {
                period: true
              }
            }
          }
        }
      }
    });

    // Obtener períodos únicos
    const periods = Array.from(
      new Set(
        enrolledSections.map(e => e.section.class.period)
      )
    ).filter((period, index, self) => 
      self.findIndex(p => p.id === period.id) === index
    );

    return NextResponse.json({
      student: {
        id: user.student.id,
        firstName: user.student.firstName,
        lastName: user.student.lastName,
        admissionNumber: user.student.admissionNumber
      },
      attendanceRecords: attendanceRecords.map(record => ({
        id: record.id,
        date: record.date,
        status: record.status,
        reason: record.reason,
        section: {
          id: record.section.id,
          name: record.section.name,
          class: {
            id: record.section.class.id,
            name: record.section.class.name,
            code: record.section.class.code,
            period: {
              id: record.section.class.period.id,
              name: record.section.class.period.name,
              isActive: record.section.class.period.isActive
            }
          },
          teachers: record.section.teacherAssignments.map(ta => ({
            id: ta.teacher.id,
            firstName: ta.teacher.firstName,
            lastName: ta.teacher.lastName,
            email: ta.teacher.email
          }))
        }
      })),
      statistics: {
        overall: {
          totalRecords,
          present: presentCount,
          absent: absentCount,
          justified: justifiedCount,
          attendanceRate
        },
        bySections: Object.values(sectionStats),
        byPeriods: Object.values(periodStats)
      },
      filters: {
        sections: enrolledSections.map(e => ({
          id: e.section.id,
          name: e.section.name,
          className: e.section.class.name,
          classCode: e.section.class.code,
          periodName: e.section.class.period.name
        })),
        periods: periods.map(p => ({
          id: p.id,
          name: p.name,
          isActive: p.isActive
        }))
      }
    });

  } catch (error) {
    console.error('Error al obtener historial de asistencia:', error);
    return NextResponse.json(
      { error: 'Error interno del servidor' },
      { status: 500 }
    );
  }
}