'use client';

import React, { useEffect, useState } from 'react';
import styled from 'styled-components';
import BarChart from '@/components/admin/BarChart';
import { adminFetch } from '@/lib/adminFetch';

type Period = 'day' | 'week' | 'month';

interface CostData {
  period: string;
  since: string;
  summary: {
    totalTokens: number;
    inputTokens: number;
    outputTokens: number;
    estimatedUsd: number;
    recordCount: number;
  };
  bySister: Array<{ name: string; totalTokens: number; estimatedUsd: number }>;
  byModel: Array<{ model: string; totalTokens: number; estimatedUsd: number; count: number }>;
  timeline: Array<{ date: string; totalTokens: number; estimatedUsd: number }>;
}

const Controls = styled.div`
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
`;

const PeriodBtn = styled.button<{ $active: boolean }>`
  padding: 6px 16px;
  border-radius: 7px;
  font-size: 13px;
  font-weight: ${({ $active }) => $active ? '600' : '400'};
  background: ${({ $active }) => $active ? 'rgba(88,166,255,0.15)' : 'transparent'};
  border: 1px solid ${({ $active }) => $active ? 'rgba(88,166,255,0.4)' : 'var(--border-color)'};
  color: ${({ $active }) => $active ? '#58A6FF' : 'var(--text-secondary)'};
  cursor: pointer;
  transition: all 0.15s;
  &:hover { color: #58A6FF; border-color: rgba(88,166,255,0.3); }
`;

const SummaryGrid = styled.div`
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 14px;
  margin-bottom: 28px;
`;

const SummaryCard = styled.div`
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 16px 18px;
`;

const SummaryLabel = styled.div`
  font-size: 11px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 6px;
`;

const SummaryValue = styled.div`
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
`;

const SummaryUnit = styled.span`
  font-size: 12px;
  color: var(--text-secondary);
  margin-left: 4px;
`;

const ChartsGrid = styled.div`
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 28px;

  @media (max-width: 900px) {
    grid-template-columns: 1fr;
  }
`;

const Card = styled.div`
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 20px 22px;
`;

const RecordBtn = styled.button`
  padding: 8px 16px;
  border-radius: 7px;
  font-size: 12px;
  font-weight: 600;
  background: rgba(88,166,255,0.08);
  border: 1px solid rgba(88,166,255,0.25);
  color: #58A6FF;
  cursor: pointer;
  transition: background 0.15s;
  &:hover { background: rgba(88,166,255,0.18); }
  &:disabled { opacity: 0.5; cursor: not-allowed; }
`;

const EmptyNote = styled.div`
  padding: 32px;
  text-align: center;
  color: var(--text-secondary);
  font-size: 13px;
  line-height: 1.6;
`;

function formatTokens(n: number): string {
  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(1)}M`;
  if (n >= 1_000) return `${(n / 1_000).toFixed(1)}K`;
  return String(n);
}

export default function CostsPage() {
  const [period, setPeriod] = useState<Period>('week');
  const [data, setData] = useState<CostData | null>(null);
  const [loading, setLoading] = useState(true);
  const [recording, setRecording] = useState(false);

  const load = async (p: Period) => {
    setLoading(true);
    try {
      const res = await adminFetch(`/api/admin/costs?period=${p}`);
      if (res.ok) setData(await res.json());
    } catch {
      // silent
    } finally {
      setLoading(false);
    }
  };

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

  const recordAll = async () => {
    setRecording(true);
    try {
      await Promise.all(['harang', 'narang', 'darang', 'erang'].map((name) =>
        adminFetch(`/api/admin/costs/record/${name}`, { method: 'POST' }),
      ));
      await load(period);
    } finally {
      setRecording(false);
    }
  };

  const sisterChartData = data?.bySister.map((s) => ({
    label: { harang: '하랑이', narang: '나랑이', darang: '다랑이', erang: '이랑이' }[s.name] ?? s.name,
    value: s.estimatedUsd,
  })) ?? [];

  const modelChartData = data?.byModel.map((m) => ({
    label: m.model.split('/').pop() ?? m.model,
    value: m.totalTokens,
  })) ?? [];

  const timelineChartData = data?.timeline.map((t) => ({
    label: t.date.slice(5),
    value: t.estimatedUsd,
  })) ?? [];

  return (
    <>
      <Controls>
        {(['day', 'week', 'month'] as Period[]).map((p) => (
          <PeriodBtn key={p} $active={period === p} onClick={() => setPeriod(p)}>
            {p === 'day' ? '오늘' : p === 'week' ? '7일' : '30일'}
          </PeriodBtn>
        ))}
        <RecordBtn onClick={recordAll} disabled={recording} style={{ marginLeft: 'auto' }}>
          {recording ? '수집 중...' : '📊 토큰 수집'}
        </RecordBtn>
      </Controls>

      {loading ? (
        <div style={{ color: 'var(--text-secondary)', fontSize: '14px' }}>로딩 중...</div>
      ) : !data || data.summary.recordCount === 0 ? (
        <EmptyNote>
          아직 비용 데이터가 없어.<br />
          위 "토큰 수집" 버튼으로 자매들의 세션 토큰을 수집해.
        </EmptyNote>
      ) : (
        <>
          <SummaryGrid>
            <SummaryCard>
              <SummaryLabel>총 토큰</SummaryLabel>
              <SummaryValue>{formatTokens(data.summary.totalTokens)}<SummaryUnit>tokens</SummaryUnit></SummaryValue>
            </SummaryCard>
            <SummaryCard>
              <SummaryLabel>예상 비용</SummaryLabel>
              <SummaryValue>${data.summary.estimatedUsd.toFixed(4)}<SummaryUnit>USD</SummaryUnit></SummaryValue>
            </SummaryCard>
            <SummaryCard>
              <SummaryLabel>입력 토큰</SummaryLabel>
              <SummaryValue>{formatTokens(data.summary.inputTokens)}</SummaryValue>
            </SummaryCard>
            <SummaryCard>
              <SummaryLabel>출력 토큰</SummaryLabel>
              <SummaryValue>{formatTokens(data.summary.outputTokens)}</SummaryValue>
            </SummaryCard>
          </SummaryGrid>

          <ChartsGrid>
            <Card>
              <BarChart data={sisterChartData} unit="$" title="자매별 비용 (USD)" />
            </Card>
            <Card>
              <BarChart data={modelChartData} unit=" tok" title="모델별 토큰 사용량" />
            </Card>
          </ChartsGrid>

          {timelineChartData.length > 0 && (
            <Card>
              <BarChart data={timelineChartData} unit="$" title="일별 비용 추이" />
            </Card>
          )}
        </>
      )}
    </>
  );
}