'use client';

import { useState, useEffect, useCallback } from 'react';

import Box from '@mui/material/Box';
import Card from '@mui/material/Card';
import Stack from '@mui/material/Stack';
import Divider from '@mui/material/Divider';
import Avatar from '@mui/material/Avatar';
import Typography from '@mui/material/Typography';
import CircularProgress from '@mui/material/CircularProgress';
import LinearProgress from '@mui/material/LinearProgress';
import { useTheme } from '@mui/material/styles';

import { fDateTime } from 'src/utils/format-time';
import { getClientDashboard, getChildDashboard } from 'src/utils/dashboard-api';
import { DashboardContent } from 'src/layouts/dashboard';
import { useAuthContext } from 'src/auth/hooks';
import { CONFIG } from 'src/config-global';
import { varAlpha } from 'src/theme/styles';
import { Iconify } from 'src/components/iconify';

import { CourseWidgetSummary } from '../../course/course-widget-summary';
import { CourseProgress } from '../../course/course-progress';
import { CourseMyAccount } from '../../course/course-my-account';

// ----------------------------------------------------------------------

const formatDateTime = (str) => {
  if (!str) return '—';
  try {
    const date = new Date(str);
    if (isNaN(date.getTime())) return '—';
    const today = new Date();
    const tomorrow = new Date(today);
    tomorrow.setDate(today.getDate() + 1);
    const time = date.toLocaleTimeString('ru-RU', { hour: '2-digit', minute: '2-digit' });
    if (date.toDateString() === today.toDateString()) return `Сегодня, ${time}`;
    if (date.toDateString() === tomorrow.toDateString()) return `Завтра, ${time}`;
    return date.toLocaleDateString('ru-RU', { day: 'numeric', month: 'short', hour: '2-digit', minute: '2-digit' });
  } catch {
    return '—';
  }
};

// ----------------------------------------------------------------------

function LessonItem({ lesson }) {
  const mentorName = lesson.mentor
    ? `${lesson.mentor.first_name || ''} ${lesson.mentor.last_name || ''}`.trim() || 'Ментор'
    : 'Ментор';

  return (
    <Stack
      direction="row"
      spacing={2}
      alignItems="center"
      sx={{
        py: 1.5,
        px: 2,
        borderRadius: 1.5,
        '&:hover': { bgcolor: 'action.hover' },
      }}
    >
      <Avatar sx={{ width: 40, height: 40, bgcolor: 'primary.main', fontSize: 14 }}>
        {mentorName[0]?.toUpperCase()}
      </Avatar>
      <Box sx={{ flex: 1, minWidth: 0 }}>
        <Typography variant="subtitle2" noWrap>
          {lesson.title || lesson.subject || 'Занятие'}
        </Typography>
        <Typography variant="caption" sx={{ color: 'text.secondary' }}>
          {mentorName}
        </Typography>
      </Box>
      <Typography variant="caption" sx={{ color: 'text.secondary', flexShrink: 0 }}>
        {formatDateTime(lesson.start_time)}
      </Typography>
    </Stack>
  );
}

// ----------------------------------------------------------------------

function HomeworkItem({ homework }) {
  const statusColor = {
    pending: 'warning',
    submitted: 'info',
    reviewed: 'success',
    completed: 'success',
  }[homework.status] || 'default';

  return (
    <Stack
      direction="row"
      spacing={2}
      alignItems="center"
      sx={{
        py: 1.5,
        px: 2,
        borderRadius: 1.5,
        '&:hover': { bgcolor: 'action.hover' },
      }}
    >
      <Box
        sx={{
          width: 40,
          height: 40,
          borderRadius: 1,
          bgcolor: `${statusColor}.main`,
          display: 'flex',
          alignItems: 'center',
          justifyContent: 'center',
          flexShrink: 0,
          opacity: 0.8,
        }}
      >
        <Iconify icon="solar:document-bold" width={20} sx={{ color: 'white' }} />
      </Box>
      <Box sx={{ flex: 1, minWidth: 0 }}>
        <Typography variant="subtitle2" noWrap>
          {homework.title}
        </Typography>
        <Typography variant="caption" sx={{ color: 'text.secondary' }}>
          {homework.subject || 'Предмет не указан'}
        </Typography>
      </Box>
      {homework.grade != null && (
        <Typography variant="caption" sx={{ color: `${statusColor}.main`, fontWeight: 600, flexShrink: 0 }}>
          {homework.grade}/5
        </Typography>
      )}
    </Stack>
  );
}

// ----------------------------------------------------------------------

export function OverviewClientView({ childId, childName }) {
  const theme = useTheme();
  const { user } = useAuthContext();
  const [stats, setStats] = useState(null);
  const [loading, setLoading] = useState(true);

  const fetchData = useCallback(
    async (signal) => {
      try {
        setLoading(true);
        const data = childId
          ? await getChildDashboard(childId, { signal })
          : await getClientDashboard({ signal });
        if (!signal?.aborted) setStats(data);
      } catch (err) {
        if (err?.name === 'AbortError' || err?.name === 'CanceledError') return;
        console.error('Client dashboard error:', err);
      } finally {
        if (!signal?.aborted) setLoading(false);
      }
    },
    [childId]
  );

  useEffect(() => {
    const controller = new AbortController();
    fetchData(controller.signal);
    return () => controller.abort();
  }, [fetchData]);

  const displayName = childName || user?.first_name || 'Студент';

  const completionPct =
    stats?.total_lessons > 0
      ? Math.round((stats.completed_lessons / stats.total_lessons) * 100)
      : 0;

  if (loading && !stats) {
    return (
      <Box sx={{ display: 'flex', height: '80vh', alignItems: 'center', justifyContent: 'center' }}>
        <CircularProgress />
      </Box>
    );
  }

  return (
    <DashboardContent
      maxWidth={false}
      disablePadding
      sx={{ borderTop: { lg: `solid 1px ${varAlpha(theme.vars.palette.grey['500Channel'], 0.12)}` } }}
    >
      <Box sx={{ display: 'flex', flex: '1 1 auto', flexDirection: { xs: 'column', lg: 'row' } }}>
        {/* LEFT */}
        <Box
          sx={{
            gap: 3,
            display: 'flex',
            flex: '1 1 auto',
            flexDirection: 'column',
            px: { xs: 2, sm: 3, xl: 5 },
            py: 3,
            borderRight: { lg: `solid 1px ${varAlpha(theme.vars.palette.grey['500Channel'], 0.12)}` },
          }}
        >
          {/* Greeting */}
          <Box>
            <Typography variant="h4" sx={{ mb: 0.5 }}>
              Привет, {displayName}! 👋
            </Typography>
            <Typography sx={{ color: 'text.secondary' }}>
              Твой прогресс и ближайшие занятия.
            </Typography>
          </Box>

          {/* Stat widgets */}
          <Box
            sx={{
              gap: 3,
              display: 'grid',
              gridTemplateColumns: { xs: 'repeat(2, 1fr)', md: 'repeat(4, 1fr)' },
            }}
          >
            <CourseWidgetSummary
              title="Занятий всего"
              total={Number(stats?.total_lessons || 0)}
              icon={`${CONFIG.site.basePath}/assets/icons/courses/ic-courses-progress.svg`}
              color="primary"
            />
            <CourseWidgetSummary
              title="Пройдено"
              total={Number(stats?.completed_lessons || 0)}
              icon={`${CONFIG.site.basePath}/assets/icons/courses/ic-courses-certificates.svg`}
              color="success"
            />
            <CourseWidgetSummary
              title="ДЗ к выполнению"
              total={Number(stats?.homework_pending || 0)}
              icon={`${CONFIG.site.basePath}/assets/icons/courses/ic-courses-completed.svg`}
              color="warning"
            />
            <CourseWidgetSummary
              title="Средняя оценка"
              total={
                stats?.average_grade
                  ? `${parseFloat(Number(stats.average_grade).toFixed(1))}/5`
                  : '—'
              }
              icon={`${CONFIG.site.basePath}/assets/icons/glass/ic-glass-bag.svg`}
              color="info"
            />
          </Box>

          {/* Progress bar */}
          <Card sx={{ p: 3 }}>
            <Stack direction="row" alignItems="center" justifyContent="space-between" sx={{ mb: 2 }}>
              <Typography variant="h6">Прогресс занятий</Typography>
              <Typography variant="h6" sx={{ color: 'primary.main' }}>
                {completionPct}%
              </Typography>
            </Stack>
            <LinearProgress
              variant="determinate"
              value={completionPct}
              sx={{ height: 8, borderRadius: 1, bgcolor: 'background.neutral' }}
            />
            <Stack direction="row" justifyContent="space-between" sx={{ mt: 1 }}>
              <Typography variant="caption" sx={{ color: 'text.secondary' }}>
                Пройдено: {stats?.completed_lessons || 0}
              </Typography>
              <Typography variant="caption" sx={{ color: 'text.secondary' }}>
                Всего: {stats?.total_lessons || 0}
              </Typography>
            </Stack>
          </Card>

          {/* Upcoming lessons + homework */}
          <Box
            sx={{
              gap: 3,
              display: 'grid',
              gridTemplateColumns: { xs: '1fr', md: 'repeat(2, 1fr)' },
            }}
          >
            {/* Upcoming lessons */}
            <Card>
              <Stack
                direction="row"
                alignItems="center"
                justifyContent="space-between"
                sx={{ px: 3, py: 2 }}
              >
                <Typography variant="h6">Ближайшие занятия</Typography>
                <Iconify icon="solar:calendar-bold" width={20} sx={{ color: 'primary.main' }} />
              </Stack>
              <Divider />
              {loading ? (
                <Box sx={{ p: 3, textAlign: 'center' }}>
                  <CircularProgress size={24} />
                </Box>
              ) : stats?.upcoming_lessons?.length > 0 ? (
                <Box sx={{ py: 1 }}>
                  {stats.upcoming_lessons.slice(0, 4).map((lesson) => (
                    <LessonItem key={lesson.id} lesson={lesson} />
                  ))}
                </Box>
              ) : (
                <Box sx={{ p: 3, textAlign: 'center', color: 'text.secondary' }}>
                  <Iconify icon="solar:calendar-bold" width={40} sx={{ mb: 1, opacity: 0.3 }} />
                  <Typography variant="body2">Нет запланированных занятий</Typography>
                </Box>
              )}
            </Card>

            {/* Homework */}
            <Card>
              <Stack
                direction="row"
                alignItems="center"
                justifyContent="space-between"
                sx={{ px: 3, py: 2 }}
              >
                <Typography variant="h6">Домашние задания</Typography>
                <Iconify icon="solar:document-bold" width={20} sx={{ color: 'warning.main' }} />
              </Stack>
              <Divider />
              {loading ? (
                <Box sx={{ p: 3, textAlign: 'center' }}>
                  <CircularProgress size={24} />
                </Box>
              ) : stats?.recent_homework?.length > 0 ? (
                <Box sx={{ py: 1 }}>
                  {stats.recent_homework.slice(0, 4).map((hw) => (
                    <HomeworkItem key={hw.id} homework={hw} />
                  ))}
                </Box>
              ) : (
                <Box sx={{ p: 3, textAlign: 'center', color: 'text.secondary' }}>
                  <Iconify icon="solar:document-bold" width={40} sx={{ mb: 1, opacity: 0.3 }} />
                  <Typography variant="body2">Нет домашних заданий</Typography>
                </Box>
              )}
            </Card>
          </Box>
        </Box>

        {/* RIGHT sidebar */}
        <Box
          sx={{
            width: 1,
            display: 'flex',
            flexDirection: 'column',
            px: { xs: 2, sm: 3, xl: 5 },
            pt: { lg: 8 },
            pb: { xs: 8, xl: 10 },
            flexShrink: 0,
            gap: 3,
            maxWidth: { lg: 300, xl: 340 },
            bgcolor: { lg: 'background.neutral' },
          }}
        >
          <CourseMyAccount user={childId ? { first_name: childName } : user} />

          {/* Next lesson highlight */}
          {stats?.next_lesson && (
            <Card sx={{ p: 2.5, bgcolor: 'primary.lighter' }}>
              <Typography variant="subtitle2" sx={{ mb: 1, color: 'primary.dark' }}>
                Следующее занятие
              </Typography>
              <Typography variant="body2" sx={{ fontWeight: 600, mb: 0.5 }}>
                {stats.next_lesson.title || 'Занятие'}
              </Typography>
              <Typography variant="caption" sx={{ color: 'text.secondary' }}>
                {formatDateTime(stats.next_lesson.start_time)}
              </Typography>
              {stats.next_lesson.mentor && (
                <Stack direction="row" alignItems="center" spacing={1} sx={{ mt: 1.5 }}>
                  <Avatar sx={{ width: 24, height: 24, fontSize: 10, bgcolor: 'primary.main' }}>
                    {(stats.next_lesson.mentor.first_name || 'М')[0]}
                  </Avatar>
                  <Typography variant="caption">
                    {`${stats.next_lesson.mentor.first_name || ''} ${stats.next_lesson.mentor.last_name || ''}`.trim()}
                  </Typography>
                </Stack>
              )}
            </Card>
          )}
        </Box>
      </Box>
    </DashboardContent>
  );
}
