"use client";

import { useState, useEffect, useCallback } from "react";
import { motion } from "motion/react";
import { 
  FileText, 
  Filter,
  ArrowRight,
  Loader2,
  ChevronLeft,
  ChevronRight
} from "lucide-react";
import { Card, CardContent } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { useRouter } from "next/navigation";
import { api } from "@/lib/api/client";
import ENDPOINTS from "@/lib/api/endpoints";

interface Task {
  id: number;
  period: string;
  status: string;
  total_employees: number;
  matched_count: number;
  exception_count: number;
  created_at: string;
  completed_at: string | null;
}

const statusLabels: Record<string, { label: string; color: string; bgColor: string }> = {
  PENDING: { label: "待处理", color: "text-gray-700 dark:text-gray-300", bgColor: "bg-gray-100 dark:bg-gray-800" },
  PROCESSING: { label: "处理中", color: "text-blue-700 dark:text-blue-300", bgColor: "bg-blue-100 dark:bg-blue-900/50" },
  MAPPING_COMPLETED: { label: "映射完成", color: "text-amber-700 dark:text-amber-300", bgColor: "bg-amber-100 dark:bg-amber-900/50" },
  COMPLETED: { label: "已完成", color: "text-emerald-700 dark:text-emerald-300", bgColor: "bg-emerald-100 dark:bg-emerald-900/50" },
  FAILED: { label: "失败", color: "text-red-700 dark:text-red-300", bgColor: "bg-red-100 dark:bg-red-900/50" },
};

// 生成可选月份列表（近12个月）
const getAvailablePeriods = () => {
  const periods = [];
  const now = new Date();
  for (let i = 0; i < 12; i++) {
    const date = new Date(now.getFullYear(), now.getMonth() - i, 1);
    const year = date.getFullYear();
    const month = String(date.getMonth() + 1).padStart(2, "0");
    periods.push(`${year}-${month}`);
  }
  return periods;
};

const formatPeriod = (period: string) => {
  const [year, month] = period.split("-");
  return `${year}年${parseInt(month)}月`;
};

export default function TasksPage() {
  const router = useRouter();
  const [tasks, setTasks] = useState<Task[]>([]);
  const [loading, setLoading] = useState(true);
  const [selectedPeriod, setSelectedPeriod] = useState<string>("");
  const [availablePeriods] = useState(getAvailablePeriods);

  const loadTasks = useCallback(async () => {
    try {
      setLoading(true);
      const params = selectedPeriod ? { period: selectedPeriod } : {};
      const res = await api.get<Task[]>(ENDPOINTS.TASK.LIST, { params });
      setTasks(res.data);
    } catch (error) {
      console.error("加载任务列表失败:", error);
    } finally {
      setLoading(false);
    }
  }, [selectedPeriod]);

  useEffect(() => {
    loadTasks();
  }, [loadTasks]);

  const getMatchRate = (task: Task) => {
    if (task.total_employees === 0) return "0%";
    const rate = Math.round((task.matched_count / task.total_employees) * 100);
    return `${rate}%`;
  };

  return (
    <div className="min-h-full p-6 lg:p-8 max-w-6xl mx-auto">
      {/* Header */}
      <motion.div 
        initial={{ opacity: 0, y: -8 }}
        animate={{ opacity: 1, y: 0 }}
        transition={{ duration: 0.4, ease: [0.16, 1, 0.3, 1] as const }}
        className="mb-8"
      >
        <h1 className="text-heading-1 text-foreground mb-2">对账任务</h1>
        <p className="text-muted-foreground text-body">
          管理所有对账任务，查看对账结果
        </p>
      </motion.div>

      {/* Filter Bar */}
      <motion.div
        initial={{ opacity: 0, y: 8 }}
        animate={{ opacity: 1, y: 0 }}
        transition={{ duration: 0.4, delay: 0.1 }}
        className="mb-6 flex items-center gap-4 flex-wrap"
      >
        <div className="flex items-center gap-2">
          <Filter className="w-4 h-4 text-muted-foreground" />
          <span className="text-body-small text-muted-foreground">筛选月份：</span>
        </div>
        
        <div className="flex items-center gap-2 flex-wrap">
          <Button
            variant={selectedPeriod === "" ? "default" : "outline"}
            size="sm"
            onClick={() => setSelectedPeriod("")}
            className="text-body-small"
          >
            全部
          </Button>
          
          {availablePeriods.slice(0, 6).map((period) => (
            <Button
              key={period}
              variant={selectedPeriod === period ? "default" : "outline"}
              size="sm"
              onClick={() => setSelectedPeriod(period)}
              className="text-body-small"
            >
              {formatPeriod(period)}
            </Button>
          ))}
        </div>

        {selectedPeriod && (
          <Button
            variant="ghost"
            size="sm"
            onClick={() => setSelectedPeriod("")}
            className="text-caption"
          >
            清除筛选
          </Button>
        )}
      </motion.div>

      {/* Tasks List */}
      {loading ? (
        <div className="flex items-center justify-center py-20">
          <Loader2 className="w-8 h-8 animate-spin text-primary" />
        </div>
      ) : tasks.length === 0 ? (
        <motion.div
          initial={{ opacity: 0 }}
          animate={{ opacity: 1 }}
          transition={{ duration: 0.3 }}
        >
          <Card>
            <CardContent className="p-12 text-center">
              <div className="w-16 h-16 rounded-full bg-muted mx-auto mb-4 flex items-center justify-center">
                <FileText className="w-8 h-8 text-muted-foreground" />
              </div>
              <h3 className="text-heading-3 text-foreground mb-2">暂无任务</h3>
              <p className="text-body text-muted-foreground mb-6">
                {selectedPeriod 
                  ? `没有 ${formatPeriod(selectedPeriod)} 的对账任务`
                  : "当前没有任何对账任务"
                }
              </p>
              <Button onClick={() => router.push("/tasks/new")}>
                新建对账任务
                <ArrowRight className="w-4 h-4 ml-2" />
              </Button>
            </CardContent>
          </Card>
        </motion.div>
      ) : (
        <div className="space-y-4">
          {tasks.map((task, index) => (
            <motion.div
              key={task.id}
              initial={{ opacity: 0, y: 8 }}
              animate={{ opacity: 1, y: 0 }}
              transition={{ 
                duration: 0.3, 
                delay: index * 0.05,
              }}
            >
              <Card 
                className="cursor-pointer hover-lift transition-all group"
                onClick={() => router.push(`/tasks/${task.id}/result`)}
              >
                <CardContent className="p-5">
                  <div className="flex items-start justify-between">
                    <div className="flex items-start gap-4">
                      <div className="p-3 rounded-lg bg-primary/10 group-hover:bg-primary/20 transition-colors">
                        <FileText className="w-6 h-6 text-primary" />
                      </div>
                      
                      <div>
                        <div className="flex items-center gap-3 mb-2">
                          <h3 className="text-heading-3 text-foreground">
                            {formatPeriod(task.period)} 对账任务
                          </h3>
                          <span className={`px-2.5 py-1 rounded-full text-xs font-medium ${statusLabels[task.status]?.bgColor} ${statusLabels[task.status]?.color}`}>
                            {statusLabels[task.status]?.label || task.status}
                          </span>
                        </div>
                        
                        <div className="flex items-center gap-6 text-body-small text-muted-foreground">
                          <span className="flex items-center gap-1.5">
                            <span className="font-medium text-foreground">{task.total_employees}</span> 名员工
                          </span>
                          <span className="flex items-center gap-1.5">
                            <span className="font-medium text-emerald-600">{task.matched_count}</span> 已匹配
                          </span>
                          <span className="flex items-center gap-1.5">
                            <span className={`font-medium ${task.exception_count > 0 ? "text-amber-600" : "text-muted-foreground"}`}>
                              {task.exception_count}
                            </span> 异常
                          </span>
                          <span className="flex items-center gap-1.5">
                            匹配率: <span className="font-medium text-foreground">{getMatchRate(task)}</span>
                          </span>
                        </div>
                      </div>
                    </div>
                    
                    <div className="flex items-center gap-4">
                      <span className="text-caption text-muted-foreground">
                        {task.completed_at 
                          ? new Date(task.completed_at).toLocaleDateString("zh-CN")
                          : new Date(task.created_at).toLocaleDateString("zh-CN")
                        }
                      </span>
                      <ArrowRight className="w-5 h-5 text-muted-foreground group-hover:text-primary group-hover:translate-x-1 transition-all" />
                    </div>
                  </div>
                </CardContent>
              </Card>
            </motion.div>
          ))}
        </div>
      )}

      {/* Pagination hint */}
      {tasks.length > 0 && (
        <div className="mt-6 flex items-center justify-center gap-2 text-caption text-muted-foreground">
          <ChevronLeft className="w-4 h-4" />
          <span>显示最近 50 条记录</span>
          <ChevronRight className="w-4 h-4" />
        </div>
      )}
    </div>
  );
}