"use client";

// ============================================================================
// Dashboard Overview (Главная)
// ============================================================================

import { useEffect, useMemo, useState } from "react";
import { format, subDays, startOfDay, endOfDay } from "date-fns";
import { ru } from "date-fns/locale";
import {
  ArrowDown,
  ArrowUp,
  Calendar as CalendarIcon,
  BarChart3,
  BarChartHorizontal,
  Gauge,
  Loader2,
  Sparkles,
  TrendingUp,
  Users,
} from "lucide-react";
import {
  Bar,
  BarChart,
  CartesianGrid,
  Cell,
  ReferenceLine,
  XAxis,
  YAxis,
} from "recharts";
import { DateRange } from "react-day-picker";
import { DashboardHeader } from "@/components/layout/dashboard-header";
import { useWorkspace } from "@/components/providers/workspace-provider";
import { demoAwareAnalyticsApi } from "@/lib/demo";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { ChartContainer, ChartTooltip, ChartTooltipContent } from "@/components/ui/chart";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { Button } from "@/components/ui/button";
import { Popover, PopoverContent, PopoverTrigger } from "@/components/ui/popover";
import { Calendar } from "@/components/ui/calendar";
import { cn } from "@/lib/utils";
import type { OverviewAnalytics } from "@/lib/types/api";

// ============================================================================
// Helpers
// ============================================================================

const formatNumber = (value: number | null | undefined, showSign = false): string => {
  if (value === null || value === undefined) return "—";
  const formatted = new Intl.NumberFormat("ru-RU").format(value);
  if (showSign && value > 0) return `+${formatted}`;
  return formatted;
};

const formatCurrency = (
  value: number | null | undefined,
  digits = 0
): string => {
  if (value === null || value === undefined) return "—";
  return new Intl.NumberFormat("ru-RU", {
    style: "currency",
    currency: "RUB",
    minimumFractionDigits: digits,
    maximumFractionDigits: digits,
  }).format(value);
};

const formatDateShort = (value: string): string => {
  const [year, month, day] = value.split("-");
  if (!year || !month || !day) return value;
  return `${day}.${month}`;
};

const DeltaPill: React.FC<{ delta?: number }> = ({ delta }) => {
  if (delta === undefined || delta === null) return null;
  const isPositive = delta > 0;
  const isZero = delta === 0;
  const color = isZero
    ? "bg-muted text-muted-foreground"
    : isPositive
      ? "bg-emerald-100 text-emerald-700 dark:bg-emerald-900/40 dark:text-emerald-200"
      : "bg-rose-100 text-rose-700 dark:bg-rose-900/40 dark:text-rose-200";
  const Icon = isZero ? Sparkles : isPositive ? ArrowUp : ArrowDown;
  const sign = delta > 0 ? "+" : "";
  return (
    <span className={`inline-flex items-center gap-1 rounded-full px-2 py-0.5 text-xs font-medium ${color}`}>
      <Icon className="h-3 w-3" />
      {sign}
      {delta.toFixed(1)}%
    </span>
  );
};

// ============================================================================
// Component
// ============================================================================

export default function DashboardPage() {
  const {
    currentWorkspace,
    isLoading: workspaceLoading,
    selectedProjects,
    projects,
    getProjectFilterId,
  } = useWorkspace();

  const [overview, setOverview] = useState<OverviewAnalytics | null>(null);
  const [loading, setLoading] = useState(true);
  const [cpfMode, setCpfMode] = useState<"top" | "worst">("top");
  const [projectPage, setProjectPage] = useState(1);
  const pageSize = 5;
  const [dateRange, setDateRange] = useState<DateRange | undefined>(() => ({
    from: subDays(new Date(), 29),
    to: new Date(),
  }));

  const dateFromIso = useMemo(() => {
    return dateRange?.from
      ? startOfDay(dateRange.from).toISOString()
      : undefined;
  }, [dateRange?.from]);

  const dateToIso = useMemo(() => {
    return dateRange?.to ? endOfDay(dateRange.to).toISOString() : undefined;
  }, [dateRange?.to]);

  const dateRangeLabel = useMemo(() => {
    if (dateRange?.from && dateRange?.to) {
      const sameYear =
        dateRange.from.getFullYear() === dateRange.to.getFullYear();
      const sameMonth =
        sameYear && dateRange.from.getMonth() === dateRange.to.getMonth();
      const fromFormat = sameMonth ? "d MMM" : "d MMM yyyy";
      return `${format(dateRange.from, fromFormat, { locale: ru })} — ${format(dateRange.to, "d MMM yyyy", { locale: ru })}`;
    }
    if (dateRange?.from) {
      return format(dateRange.from, "d MMM yyyy", { locale: ru });
    }
    return "За всё время";
  }, [dateRange]);

  const projectFilterId = getProjectFilterId();

  useEffect(() => {
    if (!currentWorkspace) {
      setLoading(false);
      return;
    }

    const loadData = async () => {
      try {
        setLoading(true);
        const data = await demoAwareAnalyticsApi.overview(currentWorkspace.id, {
          project_id: projectFilterId,
          date_from: dateFromIso,
          date_to: dateToIso,
        });
        setOverview(data);
        setProjectPage(1);
      } catch (err) {
        console.error("Failed to load overview:", err);
      } finally {
        setLoading(false);
      }
    };

    loadData();
  }, [currentWorkspace?.id, projectFilterId, dateFromIso, dateToIso]);

  const stats = useMemo(
    () => [
      {
        title: "Сумма закупов",
        value: overview?.total_cost.value,
        delta: overview?.total_cost.delta_percent,
        format: (v: number | null | undefined) => formatCurrency(v, 0),
        icon: BarChartHorizontal,
      },
      {
        title: "Общий охват",
        value: overview?.total_reach.value,
        delta: overview?.total_reach.delta_percent,
        format: (v: number | null | undefined) => formatNumber(v),
        icon: Users,
      },
      {
        title: "Всего размещений",
        value: overview?.placements_count.value,
        delta: overview?.placements_count.delta_percent,
        format: (v: number | null | undefined) => formatNumber(v),
        icon: Gauge,
      },
      {
        title: "Кол-во подписок",
        value: overview?.subscriptions_count.value,
        delta: overview?.subscriptions_count.delta_percent,
        format: (v: number | null | undefined) => formatNumber(v),
        icon: TrendingUp,
      },
      {
        title: "Средний CPM",
        value: overview?.avg_cpm.value,
        delta: overview?.avg_cpm.delta_percent,
        format: (v: number | null | undefined) => formatCurrency(v, 2),
        icon: BarChart3,
      },
      {
        title: "Средний CPF",
        value: overview?.avg_cpf.value,
        delta: overview?.avg_cpf.delta_percent,
        format: (v: number | null | undefined) => formatCurrency(v, 2),
        icon: Sparkles,
      },
    ],
    [overview]
  );

  const dailyStats = overview?.daily_stats ?? [];

  const subscriptionsChartData = useMemo(
    () =>
      dailyStats.map((item) => ({
        date: item.date,
        dateLabel: formatDateShort(item.date),
        value: item.subscriptions_delta,
      })),
    [dailyStats]
  );

  const costChartData = useMemo(
    () =>
      dailyStats.map((item) => ({
        date: item.date,
        dateLabel: formatDateShort(item.date),
        value: item.cost,
      })),
    [dailyStats]
  );

  const cpfChartData = useMemo(
    () =>
      dailyStats.map((item) => ({
        date: item.date,
        dateLabel: formatDateShort(item.date),
        value: item.cpf,
      })),
    [dailyStats]
  );

  const projectSpending = overview?.project_spending ?? [];
  const totalProjectPages = Math.max(1, Math.ceil(projectSpending.length / pageSize));
  const paginatedProjects = projectSpending.slice(
    (projectPage - 1) * pageSize,
    projectPage * pageSize
  );

  if (workspaceLoading) {
    return (
      <>
        <DashboardHeader breadcrumbs={[{ label: "Главная" }]} />
        <div className="flex flex-1 items-center justify-center">
          <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
        </div>
      </>
    );
  }

  if (!currentWorkspace) {
    return (
      <>
        <DashboardHeader breadcrumbs={[{ label: "Главная" }]} />
        <div className="flex flex-1 items-center justify-center">
          <div className="text-center">
            <h2 className="text-2xl font-semibold mb-2">Нет доступных воркспейсов</h2>
            <p className="text-muted-foreground">
              Создайте новый воркспейс для начала работы
            </p>
          </div>
        </div>
      </>
    );
  }

  return (
    <>
      <DashboardHeader breadcrumbs={[{ label: "Главная" }]} />

      <div className="flex flex-1 flex-col gap-4 p-4 pt-0 mt-4">
        <div className="flex flex-wrap items-center justify-between gap-3 rounded-lg border border-border/70 bg-card/40 p-3">
          <div>
            <p className="text-sm text-muted-foreground">Статистика за период</p>
            <p className="text-base font-semibold">{dateRangeLabel}</p>
          </div>
          <Popover>
            <PopoverTrigger asChild>
              <Button
                variant="outline"
                className={cn(
                  "min-w-[260px] justify-start text-left font-normal",
                  !dateRange?.from && "text-muted-foreground"
                )}
              >
                <CalendarIcon className="mr-2 h-4 w-4" />
                {dateRange?.from ? (
                  dateRange.to ? (
                    <>
                      {format(dateRange.from, "d MMM yyyy", { locale: ru })} —{" "}
                      {format(dateRange.to, "d MMM yyyy", { locale: ru })}
                    </>
                  ) : (
                    format(dateRange.from, "d MMM yyyy", { locale: ru })
                  )
                ) : (
                  <span>Выберите период</span>
                )}
              </Button>
            </PopoverTrigger>
            <PopoverContent className="w-auto p-0" align="end">
              <Calendar
                initialFocus
                mode="range"
                numberOfMonths={2}
                locale={ru}
                defaultMonth={dateRange?.from}
                selected={dateRange}
                onSelect={(range) => setDateRange(range)}
              />
            </PopoverContent>
          </Popover>
        </div>

        {/* Строка 1 — компактные показатели */}
        <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-3">
          {stats.map((item) => (
            <Card key={item.title} className="border-border/70">
              <CardHeader className="flex flex-row items-start justify-between space-y-0 pb-2">
                <div className="space-y-1">
                  <CardTitle className="text-sm font-medium text-muted-foreground">
                    {item.title}
                  </CardTitle>
                  <DeltaPill delta={item.delta} />
                </div>
                <item.icon className="h-4 w-4 text-muted-foreground" />
              </CardHeader>
              <CardContent>
                {loading ? (
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                ) : (
                  <div className="text-2xl font-bold">{item.format(item.value)}</div>
                )}
              </CardContent>
            </Card>
          ))}
        </div>

        {/* Строка 2 — три диаграммы */}
        <div className="grid gap-4 lg:grid-cols-3">
          <Card className="border-border/70">
            <CardHeader className="flex items-start justify-between space-y-0 pb-2">
              <CardTitle className="text-base font-semibold">Динамика подписчиков по дням</CardTitle>
              <DeltaPill delta={overview?.subscriptions_count.delta_percent} />
            </CardHeader>
            <CardContent>
              {loading ? (
                <div className="flex h-[240px] items-center justify-center">
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                </div>
              ) : (
                <ChartContainer
                  config={{
                    subscriptions_delta: {
                      label: "Δ подписок",
                      color: "hsl(var(--chart-1))",
                    },
                  }}
                  className="aspect-auto h-[260px] w-full"
                >
                  <BarChart data={subscriptionsChartData} margin={{ left: 8, right: 8, top: 8 }}>
                    <CartesianGrid strokeDasharray="3 3" vertical={false} />
                    <XAxis dataKey="dateLabel" tickLine={false} axisLine={false} tickMargin={8} />
                    <YAxis tickLine={false} axisLine={false} tickMargin={8} />
                    <ReferenceLine y={0} stroke="#cbd5e1" />
                    <Bar
                      dataKey="value"
                      radius={[4, 4, 0, 0]}
                      label={false}
                    >
                      {subscriptionsChartData.map((entry) => (
                        <Cell
                          key={`cell-${entry.date}`}
                          fill={entry.value >= 0 ? "#22c55e" : "#ef4444"}
                        />
                      ))}
                    </Bar>
                    <ChartTooltip
                      content={
                        <ChartTooltipContent
                          labelFormatter={(_, payload) => payload?.[0]?.payload?.date || ""}
                          formatter={(value: number) => [formatNumber(value, true), "Δ подписок"]}
                        />
                      }
                    />
                  </BarChart>
                </ChartContainer>
              )}
            </CardContent>
          </Card>

          <Card className="border-border/70">
            <CardHeader className="flex items-start justify-between space-y-0 pb-2">
              <CardTitle className="text-base font-semibold">Траты по дням</CardTitle>
              <DeltaPill delta={overview?.total_cost.delta_percent} />
            </CardHeader>
            <CardContent>
              {loading ? (
                <div className="flex h-[240px] items-center justify-center">
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                </div>
              ) : (
                <ChartContainer
                  config={{
                    cost: {
                      label: "Затраты",
                      color: "hsl(var(--chart-2))",
                    },
                  }}
                  className="aspect-auto h-[260px] w-full"
                >
                  <BarChart data={costChartData} margin={{ left: 8, right: 8, top: 8 }}>
                    <CartesianGrid strokeDasharray="3 3" vertical={false} />
                    <XAxis dataKey="dateLabel" tickLine={false} axisLine={false} tickMargin={8} />
                    <YAxis
                      tickLine={false}
                      axisLine={false}
                      tickMargin={8}
                      tickFormatter={(value: number) => formatCurrency(value, 0)}
                    />
                    <Bar dataKey="value" fill="var(--color-cost)" radius={[4, 4, 0, 0]} />
                    <ChartTooltip
                      content={
                        <ChartTooltipContent
                          labelFormatter={(_, payload) => payload?.[0]?.payload?.date || ""}
                          formatter={(value: number) => [formatCurrency(value, 0), "Затраты"]}
                        />
                      }
                    />
                  </BarChart>
                </ChartContainer>
              )}
            </CardContent>
          </Card>

          <Card className="border-border/70">
            <CardHeader className="flex items-start justify-between space-y-0 pb-2">
              <CardTitle className="text-base font-semibold">Стоимость подписчика (CPF)</CardTitle>
              <DeltaPill delta={overview?.avg_cpf.delta_percent} />
            </CardHeader>
            <CardContent>
              {loading ? (
                <div className="flex h-[240px] items-center justify-center">
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                </div>
              ) : (
                <ChartContainer
                  config={{
                    cpf: {
                      label: "CPF",
                      color: "hsl(var(--chart-3))",
                    },
                  }}
                  className="aspect-auto h-[260px] w-full"
                >
                  <BarChart data={cpfChartData} margin={{ left: 8, right: 8, top: 8 }}>
                    <CartesianGrid strokeDasharray="3 3" vertical={false} />
                    <XAxis dataKey="dateLabel" tickLine={false} axisLine={false} tickMargin={8} />
                    <YAxis
                      tickLine={false}
                      axisLine={false}
                      tickMargin={8}
                      tickFormatter={(value: number) => formatCurrency(value, 0)}
                    />
                    <Bar dataKey="value" fill="var(--color-cpf)" radius={[4, 4, 0, 0]} />
                    <ChartTooltip
                      content={
                        <ChartTooltipContent
                          labelFormatter={(_, payload) => payload?.[0]?.payload?.date || ""}
                          formatter={(value: number) => [formatCurrency(value, 2), "CPF"]}
                        />
                      }
                    />
                  </BarChart>
                </ChartContainer>
              )}
            </CardContent>
          </Card>
        </div>

        {/* Строка 3 — таблицы */}
        <div className="grid gap-4 lg:grid-cols-2">
          <Card className="border-border/70">
            <Tabs value={cpfMode} onValueChange={(value) => setCpfMode(value as "top" | "worst")}>
              <CardHeader className="flex flex-col gap-2 pb-3">
                <div className="flex items-center justify-between">
                  <CardTitle className="text-base font-semibold">Топ / Антитоп по CPF</CardTitle>
                  <TabsList className="h-8">
                    <TabsTrigger value="top" className="h-8 px-3 text-sm">
                      Топ 5
                    </TabsTrigger>
                    <TabsTrigger value="worst" className="h-8 px-3 text-sm">
                      Антитоп 5
                    </TabsTrigger>
                  </TabsList>
                </div>
              </CardHeader>
              <CardContent>
                {loading ? (
                  <div className="flex h-[200px] items-center justify-center">
                    <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                  </div>
                ) : (
                  <>
                    <TabsContent value="top" className="mt-0">
                      {overview?.top_channels_by_cpf?.length ? (
                        <Table>
                          <TableHeader>
                            <TableRow>
                              <TableHead className="w-2/3">Канал</TableHead>
                              <TableHead className="text-right">CPF</TableHead>
                            </TableRow>
                          </TableHeader>
                          <TableBody>
                            {overview.top_channels_by_cpf.slice(0, 5).map((row) => (
                              <TableRow key={row.channel_id}>
                                <TableCell className="space-y-0.5">
                                  <div className="font-medium">{row.title}</div>
                                  {row.username && (
                                    <a
                                      href={`https://t.me/${row.username}`}
                                      className="text-xs text-primary hover:underline"
                                      target="_blank"
                                      rel="noreferrer"
                                    >
                                      @{row.username}
                                    </a>
                                  )}
                                </TableCell>
                                <TableCell className="text-right font-mono font-semibold">
                                  {formatCurrency(row.cpf, 2)}
                                </TableCell>
                              </TableRow>
                            ))}
                          </TableBody>
                        </Table>
                      ) : (
                        <p className="text-sm text-muted-foreground">Нет данных</p>
                      )}
                    </TabsContent>
                    <TabsContent value="worst" className="mt-0">
                      {overview?.worst_channels_by_cpf?.length ? (
                        <Table>
                          <TableHeader>
                            <TableRow>
                              <TableHead className="w-2/3">Канал</TableHead>
                              <TableHead className="text-right">CPF</TableHead>
                            </TableRow>
                          </TableHeader>
                          <TableBody>
                            {overview.worst_channels_by_cpf.slice(0, 5).map((row) => (
                              <TableRow key={row.channel_id}>
                                <TableCell className="space-y-0.5">
                                  <div className="font-medium">{row.title}</div>
                                  {row.username && (
                                    <a
                                      href={`https://t.me/${row.username}`}
                                      className="text-xs text-primary hover:underline"
                                      target="_blank"
                                      rel="noreferrer"
                                    >
                                      @{row.username}
                                    </a>
                                  )}
                                </TableCell>
                                <TableCell className="text-right font-mono font-semibold">
                                  {formatCurrency(row.cpf, 2)}
                                </TableCell>
                              </TableRow>
                            ))}
                          </TableBody>
                        </Table>
                      ) : (
                        <p className="text-sm text-muted-foreground">Нет данных</p>
                      )}
                    </TabsContent>
                  </>
                )}
              </CardContent>
            </Tabs>
          </Card>

          <Card className="border-border/70">
            <CardHeader className="flex items-center justify-between pb-3">
              <CardTitle className="text-base font-semibold">Сумма закупов по проектам</CardTitle>
              <div className="flex items-center gap-2">
                <Button
                  size="sm"
                  variant="outline"
                  onClick={() => setProjectPage((p) => Math.max(1, p - 1))}
                  disabled={projectPage === 1}
                >
                  Назад
                </Button>
                <span className="text-sm text-muted-foreground">
                  {projectPage}/{totalProjectPages}
                </span>
                <Button
                  size="sm"
                  variant="outline"
                  onClick={() => setProjectPage((p) => Math.min(totalProjectPages, p + 1))}
                  disabled={projectPage === totalProjectPages}
                >
                  Вперед
                </Button>
              </div>
            </CardHeader>
            <CardContent>
              {loading ? (
                <div className="flex h-[200px] items-center justify-center">
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                </div>
              ) : paginatedProjects.length === 0 ? (
                <p className="text-sm text-muted-foreground">Нет данных</p>
              ) : (
                <Table>
                  <TableHeader>
                    <TableRow>
                      <TableHead className="w-2/3">Проект</TableHead>
                      <TableHead className="text-right">Сумма</TableHead>
                    </TableRow>
                  </TableHeader>
                  <TableBody>
                    {paginatedProjects.map((row) => (
                      <TableRow key={row.project_id}>
                        <TableCell className="space-y-0.5">
                          <div className="font-medium">{row.project_title}</div>
                          {row.project_username && (
                            <span className="text-xs text-muted-foreground">@{row.project_username}</span>
                          )}
                        </TableCell>
                        <TableCell className="text-right font-mono font-semibold">
                          {formatCurrency(row.total_cost, 0)}
                        </TableCell>
                      </TableRow>
                    ))}
                  </TableBody>
                </Table>
              )}
            </CardContent>
          </Card>
        </div>
      </div>
    </>
  );
}