'use client';

import { useEffect, useState } from 'react';
import Link from 'next/link';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
import { StatusDot } from '@/components/status-badge';
import { ProgressRing } from '@/components/progress-ring';
import { useUser } from '@/components/user-context';
import { calculateProgress, getDaysRemaining, formatDateRange, isKRActive, getTodayInTokyo } from '@/lib/kr-utils';
import { PERIOD_TYPES, REASON_CODES } from '@/lib/constants';
import type { KR, User } from '@/types/database';
import { Target, Clock, AlertTriangle, CheckCircle, History } from 'lucide-react';
import { fetchApi } from '@/lib/api-client';

interface KRWithRelations extends KR {
  owner: User | null;
  project: { id: string; name: string; status: string } | null;
}

export default function MyKRsPage() {
  const { currentUser, users } = useUser();
  const [krs, setKRs] = useState<KRWithRelations[]>([]);
  const [isLoading, setIsLoading] = useState(true);

  // Group KRs by owner for owner view
  const krsByOwner = users.map(user => ({
    user,
    krs: krs.filter(kr => kr.owner_user_id === user.id && isKRActive(kr))
  })).filter(group => group.krs.length > 0 || group.user.role !== 'owner') // Filter out users with no active KRs unless it's a member/pm we want to track
  .sort((a, b) => {
    // Sort by KR count descending (users with KRs first)
    if (a.krs.length > 0 && b.krs.length === 0) return -1;
    if (a.krs.length === 0 && b.krs.length > 0) return 1;
    return 0;
  });

  useEffect(() => {
    async function fetchKRs() {
      try {
        const res = await fetchApi('/api/krs');
        if (res.ok) {
          const data = await res.json();
          setKRs(data);
        }
      } catch (error) {
        console.error('Failed to fetch KRs:', error);
      } finally {
        setIsLoading(false);
      }
    }

    fetchKRs();
  }, []);

  const myKRs = krs.filter(kr => kr.owner_user_id === currentUser?.id);
  const activeKRs = myKRs.filter(isKRActive);
  const completedKRs = activeKRs.filter(kr => calculateProgress(kr) >= 1);
  const pastKRs = myKRs.filter(kr => !isKRActive(kr));

  const isOwner = currentUser?.role === 'owner';

  if (isLoading) {
    return (
      <div className="max-w-5xl mx-auto px-4 py-8">
        <div className="animate-pulse space-y-6">
          <div className="h-8 bg-slate-200 rounded w-32" />
          <div className="space-y-4">
            {[1, 2, 3].map(i => (
              <div key={i} className="h-24 bg-slate-200 rounded-lg" />
            ))}
          </div>
        </div>
      </div>
    );
  }

  return (
    <div className="max-w-5xl mx-auto px-4 py-8">
      <div className="mb-8">
        <h1 className="text-2xl font-bold text-slate-800">
            {isOwner ? '全员 KR 概览' : '我的 KR'}
        </h1>
        <p className="text-muted-foreground mt-1">
          {isOwner 
            ? '查看所有成员的当前周期目标执行情况' 
            : `${currentUser?.name} 负责的执行目标`
          }
        </p>
      </div>

      {isOwner ? (
        <div className="space-y-8">
          {krsByOwner.map(({ user, krs }) => (
            <div key={user.id} className="space-y-4">
              <div className="flex items-center gap-3 border-b pb-2">
                <div className="h-8 w-8 rounded-full bg-slate-200 flex items-center justify-center text-sm font-medium text-slate-600">
                    {user.name[0]}
                </div>
                <div>
                    <h2 className="text-lg font-semibold text-slate-800">{user.name}</h2>
                    <p className="text-xs text-muted-foreground">
                        {krs.length} 个进行中的 KR
                    </p>
                </div>
              </div>
              
              {krs.length === 0 ? (
                <div className="p-8 text-center bg-slate-50 rounded-lg border border-dashed">
                    <p className="text-muted-foreground text-sm">暂无进行中的 KR</p>
                </div>
              ) : (
                <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                    {krs.map(kr => <KRCard key={kr.id} kr={kr} />)}
                </div>
              )}
            </div>
          ))}
          
          {krsByOwner.length === 0 && (
              <div className="text-center py-12">
                  <p className="text-muted-foreground">没有任何成员有正在进行的 KR</p>
              </div>
          )}
        </div>
      ) : (
        <>
        <div className="grid grid-cols-3 gap-4 mb-8">
        <Card>
          <CardContent className="pt-6 text-center">
            <Target className="h-8 w-8 text-slate-300 mx-auto mb-2" />
            <p className="text-3xl font-bold text-slate-800">{activeKRs.length}</p>
            <p className="text-sm text-muted-foreground">进行中</p>
          </CardContent>
        </Card>
        <Card>
          <CardContent className="pt-6 text-center">
            <CheckCircle className="h-8 w-8 text-emerald-300 mx-auto mb-2" />
            <p className="text-3xl font-bold text-emerald-600">{completedKRs.length}</p>
            <p className="text-sm text-muted-foreground">已达标</p>
          </CardContent>
        </Card>
        <Card>
          <CardContent className="pt-6 text-center">
            <AlertTriangle className="h-8 w-8 text-rose-300 mx-auto mb-2" />
            <p className="text-3xl font-bold text-rose-600">
              {activeKRs.filter(kr => kr.status === 'red').length}
            </p>
            <p className="text-sm text-muted-foreground">需关注</p>
          </CardContent>
        </Card>
      </div>

      <Tabs defaultValue="active" className="space-y-6">
        <TabsList>
          <TabsTrigger value="active">进行中 ({activeKRs.length})</TabsTrigger>
          <TabsTrigger value="past">已结束 ({pastKRs.length})</TabsTrigger>
          <TabsTrigger value="all">全部 ({myKRs.length})</TabsTrigger>
        </TabsList>

        <TabsContent value="active" className="space-y-4">
          {activeKRs.length === 0 ? (
            <Card>
              <CardContent className="py-12 text-center">
                <Target className="h-12 w-12 text-slate-300 mx-auto mb-4" />
                <p className="text-muted-foreground">暂无进行中的 KR</p>
              </CardContent>
            </Card>
          ) : (
            activeKRs.map(kr => <KRCard key={kr.id} kr={kr} />)
          )}
        </TabsContent>

        <TabsContent value="past" className="space-y-4">
          {pastKRs.length === 0 ? (
            <Card>
              <CardContent className="py-12 text-center">
                <History className="h-12 w-12 text-slate-300 mx-auto mb-4" />
                <p className="text-muted-foreground">暂无已结束的 KR</p>
              </CardContent>
            </Card>
          ) : (
            pastKRs.map(kr => <KRCard key={kr.id} kr={kr} showEnded />)
          )}
        </TabsContent>

        <TabsContent value="all" className="space-y-4">
          {myKRs.length === 0 ? (
            <Card>
              <CardContent className="py-12 text-center">
                <Target className="h-12 w-12 text-slate-300 mx-auto mb-4" />
                <p className="text-muted-foreground">暂无 KR</p>
              </CardContent>
            </Card>
          ) : (
            myKRs.map(kr => <KRCard key={kr.id} kr={kr} showEnded={!isKRActive(kr)} />)
          )}
        </TabsContent>
      </Tabs>
      </>
      )}
    </div>
  );
}

function KRCard({ kr, showEnded }: { kr: KRWithRelations; showEnded?: boolean }) {
  const progress = calculateProgress(kr);
  const daysLeft = getDaysRemaining(kr.period_end);
  const isActive = isKRActive(kr);

  return (
    <Link href={`/krs/${kr.id}`}>
      <Card className={`hover:shadow-md transition-shadow ${!isActive ? 'opacity-70' : ''}`}>
        <CardContent className="py-4">
          <div className="flex items-center gap-4">
            <ProgressRing progress={progress} status={kr.status} size={64} />
            <div className="flex-1 min-w-0">
              <div className="flex items-center gap-2 mb-1">
                <h3 className="font-medium text-slate-800 truncate">{kr.title}</h3>
                {showEnded && (
                  <span className="text-xs bg-slate-200 text-slate-600 px-2 py-0.5 rounded">已结束</span>
                )}
              </div>
              <div className="flex items-center gap-3 text-sm text-muted-foreground mb-2">
                <span>{kr.project?.name}</span>
                <span className="text-xs bg-slate-100 px-2 py-0.5 rounded">
                  {PERIOD_TYPES[kr.period_type]}
                </span>
                <span>{formatDateRange(kr.period_start, kr.period_end)}</span>
              </div>
              {kr.reason_code && kr.status !== 'green' && (
                <div className="flex items-center gap-1 text-xs text-amber-600">
                  <AlertTriangle className="h-3 w-3" />
                  {REASON_CODES[kr.reason_code]}
                  {kr.note && ` - ${kr.note}`}
                </div>
              )}
            </div>
            <div className="text-right">
              <p className="text-lg font-semibold">
                {kr.current_value}/{kr.target_value}
              </p>
              <p className="text-sm text-muted-foreground">{kr.unit}</p>
              {isActive && (
                <p className={`text-xs mt-1 ${daysLeft <= 3 ? 'text-amber-600 font-medium' : 'text-muted-foreground'}`}>
                  <Clock className="h-3 w-3 inline mr-1" />
                  剩余 {daysLeft} 天
                </p>
              )}
            </div>
            <Button variant="outline" size="sm">
              打卡
            </Button>
          </div>
        </CardContent>
      </Card>
    </Link>
  );
}