"use client";

import { useState, useEffect } from "react";
import { aiAssistantApi } from "@/lib/api/aiAssistant";
import type { UsageSummary } from "@/lib/api/aiAssistant";
import { BarChart3, Calendar, Loader2, TrendingUp, Zap, DollarSign } from "lucide-react";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Progress } from "@/components/ui/progress";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import { toast } from "sonner";

interface DailyUsageItem {
  date?: string;
  totalTokens?: number;
  requestCount?: number;
}

export default function AiAssistantUsagePage() {
  const [loading, setLoading] = useState(true);
  const [usage, setUsage] = useState<UsageSummary | null>(null);
  const [dailyUsage, setDailyUsage] = useState<DailyUsageItem[]>([]);
  const [period, setPeriod] = useState("7");

  useEffect(() => {
    loadUsage();
  }, [period]);

  const loadUsage = async () => {
    setLoading(true);
    try {
      const [usageRes, dailyRes] = await Promise.all([
        aiAssistantApi.get("/usage"),
        aiAssistantApi.get(`/usage/daily?days=${period}`),
      ]);
      setUsage(usageRes.data?.data ?? null);
      setDailyUsage((dailyRes.data?.data as { usage?: DailyUsageItem[] })?.usage ?? []);
    } catch {
      toast.error("사용량 데이터를 불러오는데 실패했습니다.");
    } finally {
      setLoading(false);
    }
  };

  if (loading) {
    return (
      <div className="flex h-64 items-center justify-center">
        <Loader2 className="text-primary h-8 w-8 animate-spin" />
      </div>
    );
  }

  const todayTokens = usage?.usage?.today?.tokens ?? 0;
  const todayRequests = usage?.usage?.today?.requests ?? 0;
  const monthlyTokens = usage?.usage?.monthly?.totalTokens ?? 0;
  const monthlyCost = usage?.usage?.monthly?.totalCost ?? 0;
  const monthlyLimit = usage?.limit?.monthly ?? 0;
  const usagePercent = monthlyLimit > 0 ? Math.round((monthlyTokens / monthlyLimit) * 100) : 0;
  const maxTokens = Math.max(...dailyUsage.map((d) => d.totalTokens ?? 0), 1);

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-3xl font-bold tracking-tight">사용량</h1>
        <p className="text-muted-foreground mt-1">API 사용량 및 비용을 확인합니다.</p>
      </div>

      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">오늘 토큰</CardTitle>
            <Zap className="text-muted-foreground h-4 w-4" />
          </CardHeader>
          <CardContent>
            <div className="text-2xl font-bold">{todayTokens.toLocaleString()}</div>
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">오늘 요청</CardTitle>
            <TrendingUp className="text-muted-foreground h-4 w-4" />
          </CardHeader>
          <CardContent>
            <div className="text-2xl font-bold">{todayRequests.toLocaleString()}</div>
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">이번 달 토큰</CardTitle>
            <BarChart3 className="text-muted-foreground h-4 w-4" />
          </CardHeader>
          <CardContent>
            <div className="text-2xl font-bold">{monthlyTokens.toLocaleString()}</div>
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">이번 달 비용</CardTitle>
            <DollarSign className="text-muted-foreground h-4 w-4" />
          </CardHeader>
          <CardContent>
            <div className="text-2xl font-bold">${monthlyCost.toFixed(4)}</div>
          </CardContent>
        </Card>
      </div>

      <Card>
        <CardHeader className="flex flex-row items-center justify-between">
          <div>
            <CardTitle>일별 사용량</CardTitle>
            <CardDescription>기간별 토큰 사용량 추이</CardDescription>
          </div>
          <Select value={period} onValueChange={setPeriod}>
            <SelectTrigger className="w-[140px]">
              <Calendar className="mr-2 h-4 w-4" />
              <SelectValue />
            </SelectTrigger>
            <SelectContent>
              <SelectItem value="7">최근 7일</SelectItem>
              <SelectItem value="14">최근 14일</SelectItem>
              <SelectItem value="30">최근 30일</SelectItem>
            </SelectContent>
          </Select>
        </CardHeader>
        <CardContent>
          {dailyUsage.length === 0 ? (
            <div className="flex flex-col items-center justify-center py-12 text-center">
              <BarChart3 className="text-muted-foreground mb-4 h-12 w-12" />
              <p className="text-muted-foreground">사용 기록이 없습니다.</p>
            </div>
          ) : (
            <div className="space-y-3">
              {dailyUsage.map((day, idx) => (
                <div key={day.date ?? idx} className="flex items-center gap-4">
                  <div className="text-muted-foreground w-20 text-sm">
                    {day.date
                      ? new Date(day.date).toLocaleDateString("ko-KR", {
                          month: "short",
                          day: "numeric",
                        })
                      : "-"}
                  </div>
                  <div className="flex-1">
                    <div className="bg-muted h-8 overflow-hidden rounded-lg">
                      <div
                        className="bg-primary h-full rounded-lg transition-all duration-500"
                        style={{
                          width: `${((day.totalTokens ?? 0) / maxTokens) * 100}%`,
                        }}
                      />
                    </div>
                  </div>
                  <div className="w-28 text-right">
                    <span className="text-sm font-medium">
                      {(day.totalTokens ?? 0).toLocaleString()}
                    </span>
                    <span className="text-muted-foreground ml-1 text-xs">토큰</span>
                  </div>
                  <div className="text-muted-foreground w-16 text-right text-sm">
                    {day.requestCount ?? 0}회
                  </div>
                </div>
              ))}
            </div>
          )}
        </CardContent>
      </Card>

      <Card className="bg-gradient-to-r from-primary to-primary/80 text-primary-foreground">
        <CardContent className="pt-6">
          <div className="mb-4 flex items-center justify-between">
            <div>
              <h3 className="text-lg font-semibold">
                현재 플랜: {(usage?.plan ?? "FREE").toUpperCase()}
              </h3>
              <p className="text-primary-foreground/70">
                월간 한도: {monthlyLimit > 0 ? monthlyLimit.toLocaleString() : "무제한"} 토큰
              </p>
            </div>
            <div className="text-right">
              <p className="text-3xl font-bold">{usagePercent}%</p>
              <p className="text-primary-foreground/70 text-sm">사용률</p>
            </div>
          </div>
          <Progress value={usagePercent} className="bg-primary-foreground/20 h-3" />
        </CardContent>
      </Card>
    </div>
  );
}