"use client";

import React, { useState, useEffect } from "react";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
import { Search, Ban, UserCheck, Package, DollarSign, Loader2, Repeat } from "lucide-react";
import { fetchClient } from "@/lib/api-client";
import { useToast } from "@/hooks/use-toast";

interface TelegramUser {
  telegramUserId: string;
  telegramUsername: string;
  totalOrders: number;
  totalSpent: number;
  paidOrders: number;
  completedOrders: number;
  firstOrderDate: string | null;
  lastOrderDate: string | null;
  isBlocked: boolean;
  blockedReason: string | null;
  createdAt?: string;
}

interface PaginationResponse {
  success: boolean;
  users: TelegramUser[];
  pagination: {
    page: number;
    limit: number;
    total: number;
    totalPages: number;
    hasNextPage: boolean;
    hasPrevPage: boolean;
  };
}

function formatCurrency(amount: number): string {
  return new Intl.NumberFormat('en-GB', {
    style: 'currency',
    currency: 'GBP',
  }).format(amount);
}

export default function AdminUsersPage() {
  const { toast } = useToast();
  const [loading, setLoading] = useState(true);
  const [users, setUsers] = useState<TelegramUser[]>([]);
  const [searchQuery, setSearchQuery] = useState("");
  const [page, setPage] = useState(1);
  const [pagination, setPagination] = useState<PaginationResponse['pagination'] | null>(null);

  useEffect(() => {
    fetchUsers();
  }, [page, searchQuery]);

  const fetchUsers = async () => {
    try {
      setLoading(true);
      const params = new URLSearchParams({
        page: page.toString(),
        limit: '25'
      });
      if (searchQuery.trim()) {
        params.append('search', searchQuery.trim());
      }
      const data = await fetchClient<PaginationResponse>(`/admin/users?${params.toString()}`);
      setUsers(data.users);
      setPagination(data.pagination);
    } catch (error: any) {
      console.error("Failed to fetch users:", error);
      toast({
        title: "Error",
        description: error.message || "Failed to load users",
        variant: "destructive",
      });
    } finally {
      setLoading(false);
    }
  };

  const usersWithOrders = users.filter(u => u.totalOrders > 0);
  const returningCustomers = users.filter(u => u.totalOrders > 1);
  const blockedUsers = users.filter(u => u.isBlocked);
  const totalSpent = users.reduce((sum, u) => sum + u.totalSpent, 0);
  const totalOrders = users.reduce((sum, u) => sum + u.totalOrders, 0);

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-semibold tracking-tight">Telegram Users</h1>
        <p className="text-sm text-muted-foreground mt-1">Manage Telegram user accounts and view statistics</p>
      </div>

      {/* Stats Cards */}
      <div className="grid gap-4 md:grid-cols-5">
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">Total Users</CardTitle>
          </CardHeader>
          <CardContent>
            {loading ? (
              <div className="flex items-center justify-center py-4">
                <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
              </div>
            ) : (
              <>
                <div className="text-2xl font-bold">{users.length}</div>
                <p className="text-xs text-muted-foreground">Registered users</p>
              </>
            )}
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">Users with Orders</CardTitle>
          </CardHeader>
          <CardContent>
            {loading ? (
              <div className="flex items-center justify-center py-4">
                <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
              </div>
            ) : (
              <>
                <div className="text-2xl font-bold">{usersWithOrders.length}</div>
                <p className="text-xs text-muted-foreground">
                  {users.length > 0 ? Math.round((usersWithOrders.length / users.length) * 100) : 0}% conversion rate
                </p>
              </>
            )}
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">Total Revenue</CardTitle>
          </CardHeader>
          <CardContent>
            {loading ? (
              <div className="flex items-center justify-center py-4">
                <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
              </div>
            ) : (
              <>
                <div className="text-2xl font-bold">{formatCurrency(totalSpent)}</div>
                <p className="text-xs text-muted-foreground">{totalOrders} total orders</p>
              </>
            )}
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">Returning Customers</CardTitle>
            <Repeat className="h-4 w-4 text-muted-foreground" />
          </CardHeader>
          <CardContent>
            {loading ? (
              <div className="flex items-center justify-center py-4">
                <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
              </div>
            ) : (
              <>
                <div className="text-2xl font-bold">{returningCustomers.length}</div>
                <p className="text-xs text-muted-foreground">
                  {usersWithOrders.length > 0 ? Math.round((returningCustomers.length / usersWithOrders.length) * 100) : 0}% of customers
                </p>
              </>
            )}
          </CardContent>
        </Card>
        <Card>
          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
            <CardTitle className="text-sm font-medium">Blocked Users</CardTitle>
          </CardHeader>
          <CardContent>
            {loading ? (
              <div className="flex items-center justify-center py-4">
                <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
              </div>
            ) : (
              <>
                <div className="text-2xl font-bold">{blockedUsers.length}</div>
                <p className="text-xs text-muted-foreground">
                  {users.length > 0 ? Math.round((blockedUsers.length / users.length) * 100) : 0}% blocked rate
                </p>
              </>
            )}
          </CardContent>
        </Card>
      </div>

      {/* Search and Filters */}
      <Card>
        <CardHeader>
          <div className="flex items-center justify-between">
            <div>
              <CardTitle>User Management</CardTitle>
              <CardDescription>View and manage all Telegram user accounts</CardDescription>
            </div>
            <div className="flex items-center space-x-2">
              <div className="relative">
                <Search className="absolute left-2 top-2.5 h-4 w-4 text-muted-foreground" />
                <Input 
                  placeholder="Search users..." 
                  className="pl-8 w-64" 
                  value={searchQuery}
                  onChange={(e) => {
                    setSearchQuery(e.target.value);
                    setPage(1);
                  }}
                />
              </div>
            </div>
          </div>
        </CardHeader>
        <CardContent>
          {loading ? (
            <div className="flex items-center justify-center py-12">
              <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
            </div>
          ) : users.length === 0 ? (
            <div className="text-center py-8 text-muted-foreground">
              {searchQuery ? "No users found matching your search" : "No users found"}
            </div>
          ) : (
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead>User ID</TableHead>
                  <TableHead>Username</TableHead>
                  <TableHead>Orders</TableHead>
                  <TableHead>Total Spent</TableHead>
                  <TableHead>Status</TableHead>
                  <TableHead>First Order</TableHead>
                  <TableHead>Last Order</TableHead>
                  <TableHead className="text-right">Actions</TableHead>
                </TableRow>
              </TableHeader>
              <TableBody>
                {users.map((user) => (
                  <TableRow key={user.telegramUserId}>
                    <TableCell>
                      <div className="font-mono text-sm">{user.telegramUserId}</div>
                    </TableCell>
                    <TableCell>
                      <div className="font-medium">
                        {user.telegramUsername !== "Unknown" ? `@${user.telegramUsername}` : "Unknown"}
                      </div>
                    </TableCell>
                    <TableCell>
                      <div className="flex items-center space-x-2">
                        <Package className="h-4 w-4 text-muted-foreground" />
                        <span>{user.totalOrders}</span>
                        {user.completedOrders > 0 && (
                          <Badge variant="secondary" className="text-xs">
                            {user.completedOrders} completed
                          </Badge>
                        )}
                      </div>
                    </TableCell>
                    <TableCell>
                      <div className="flex items-center space-x-1">
                        <DollarSign className="h-4 w-4 text-muted-foreground" />
                        <span className="font-medium">{formatCurrency(user.totalSpent)}</span>
                      </div>
                    </TableCell>
                    <TableCell>
                      {user.isBlocked ? (
                        <TooltipProvider>
                          <Tooltip>
                            <TooltipTrigger asChild>
                              <Badge variant="destructive">
                                <Ban className="h-3 w-3 mr-1" />
                                Blocked
                              </Badge>
                            </TooltipTrigger>
                            {user.blockedReason && (
                              <TooltipContent>
                                <p className="max-w-xs">{user.blockedReason}</p>
                              </TooltipContent>
                            )}
                          </Tooltip>
                        </TooltipProvider>
                      ) : user.totalOrders > 0 ? (
                        <Badge variant="default">Active</Badge>
                      ) : (
                        <Badge variant="secondary">No Orders</Badge>
                      )}
                    </TableCell>
                    <TableCell>
                      {user.firstOrderDate 
                        ? new Date(user.firstOrderDate).toLocaleDateString() 
                        : 'N/A'}
                    </TableCell>
                    <TableCell>
                      {user.lastOrderDate 
                        ? new Date(user.lastOrderDate).toLocaleDateString() 
                        : 'N/A'}
                    </TableCell>
                    <TableCell className="text-right">
                      <div className="flex items-center justify-end space-x-2">
                        {!user.isBlocked ? (
                          <Button variant="outline" size="sm">
                            <Ban className="h-4 w-4" />
                          </Button>
                        ) : (
                          <Button variant="outline" size="sm">
                            <UserCheck className="h-4 w-4" />
                          </Button>
                        )}
                      </div>
                    </TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          )}
          {pagination && pagination.totalPages > 1 && (
            <div className="mt-4 flex items-center justify-between">
              <div className="text-sm text-muted-foreground">
                Showing page {pagination.page} of {pagination.totalPages} ({pagination.total} total users)
              </div>
              <div className="flex gap-2">
                <Button
                  variant="outline"
                  size="sm"
                  onClick={() => setPage(p => Math.max(1, p - 1))}
                  disabled={!pagination.hasPrevPage}
                >
                  Previous
                </Button>
                <Button
                  variant="outline"
                  size="sm"
                  onClick={() => setPage(p => p + 1)}
                  disabled={!pagination.hasNextPage}
                >
                  Next
                </Button>
              </div>
            </div>
          )}
        </CardContent>
      </Card>
    </div>
  );
}