"use client";

import React, { useEffect, useState, useCallback } from "react";
import { getCustomers, CustomerStats } from "@/services/customerService";
import { formatCurrency } from "@/utils/format";
import { useRouter } from "next/navigation";
import { toast } from "sonner";
import Layout from "@/components/layout/layout";
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "@/components/ui/table";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogDescription,
  DialogFooter,
} from "@/components/ui/dialog";
import { Button } from "@/components/ui/button";
import { 
  ChevronLeft, 
  ChevronRight, 
  Loader2, 
  Users, 
  ArrowUpDown,
  MessageCircle,
  UserPlus,
  MoreHorizontal,
  Search,
  X
} from "lucide-react";
import { Badge } from "@/components/ui/badge";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import {
  DropdownMenu,
  DropdownMenuTrigger,
  DropdownMenuContent,
  DropdownMenuItem,
} from "@/components/ui/dropdown-menu";

export default function CustomerManagementPage() {
  const router = useRouter();
  const [customers, setCustomers] = useState<CustomerStats[]>([]);
  const [filteredCustomers, setFilteredCustomers] = useState<CustomerStats[]>([]);
  const [searchQuery, setSearchQuery] = useState("");
  const [loading, setLoading] = useState(true);
  const [page, setPage] = useState(1);
  const [totalPages, setTotalPages] = useState(1);
  const [itemsPerPage, setItemsPerPage] = useState(25);
  const [selectedCustomer, setSelectedCustomer] = useState<CustomerStats | null>(null);
  const [sortConfig, setSortConfig] = useState<{
    column: "totalOrders" | "totalSpent" | "lastOrderDate";
    direction: "asc" | "desc";
  }>({ column: "totalSpent", direction: "desc" });

  const fetchCustomers = useCallback(async () => {
    try {
      setLoading(true);
      const response = await getCustomers(page, itemsPerPage);
      
      // Sort customers based on current sort config
      let sortedCustomers = [...response.customers];
      sortedCustomers.sort((a, b) => {
        if (sortConfig.column === "totalOrders") {
          return sortConfig.direction === "asc" 
            ? a.totalOrders - b.totalOrders 
            : b.totalOrders - a.totalOrders;
        } else if (sortConfig.column === "totalSpent") {
          return sortConfig.direction === "asc" 
            ? a.totalSpent - b.totalSpent 
            : b.totalSpent - a.totalSpent;
        } else if (sortConfig.column === "lastOrderDate") {
          // Handle null lastOrderDate values
          if (!a.lastOrderDate && !b.lastOrderDate) return 0;
          if (!a.lastOrderDate) return sortConfig.direction === "asc" ? -1 : 1;
          if (!b.lastOrderDate) return sortConfig.direction === "asc" ? 1 : -1;
          
          // Both have valid dates
          return sortConfig.direction === "asc" 
            ? new Date(a.lastOrderDate).getTime() - new Date(b.lastOrderDate).getTime() 
            : new Date(b.lastOrderDate).getTime() - new Date(a.lastOrderDate).getTime();
        }
        return 0;
      });
      
      setCustomers(sortedCustomers);
      setFilteredCustomers(sortedCustomers);
      setTotalPages(Math.ceil(response.total / itemsPerPage));
    } catch (err) {
      toast.error("Failed to fetch customers");
      console.error(err);
    } finally {
      setLoading(false);
    }
  }, [page, itemsPerPage, sortConfig]);

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

  useEffect(() => {
    const authToken = document.cookie
      .split("; ")
      .find((row) => row.startsWith("Authorization="))
      ?.split("=")[1];

    if (!authToken) {
      router.push("/login");
    }
  }, [router]);

  // Add filter function to filter customers when search query changes
  useEffect(() => {
    if (!searchQuery.trim()) {
      setFilteredCustomers(customers);
    } else {
      const query = searchQuery.toLowerCase().trim();
      const filtered = customers.filter(customer => {
        const usernameMatch = customer.telegramUsername?.toLowerCase().includes(query);
        const userIdMatch = customer.telegramUserId.toString().includes(query);
        return usernameMatch || userIdMatch;
      });
      setFilteredCustomers(filtered);
    }
  }, [searchQuery, customers]);

  const handlePageChange = (newPage: number) => {
    setPage(newPage);
  };

  const handleItemsPerPageChange = (value: string) => {
    setItemsPerPage(parseInt(value, 10));
    setPage(1); // Reset to first page when changing items per page
  };

  const handleSort = (column: "totalOrders" | "totalSpent" | "lastOrderDate") => {
    setSortConfig(prev => ({
      column,
      direction: prev.column === column && prev.direction === "asc" ? "desc" : "asc"
    }));
  };

  const clearSearch = () => {
    setSearchQuery("");
  };

  // Format date with time
  const formatDate = (dateString: string | null | undefined) => {
    if (!dateString) return "N/A";
    try {
      const date = new Date(dateString);
      return new Intl.DateTimeFormat('en-GB', {
        day: '2-digit',
        month: 'short',
        year: 'numeric',
        hour: '2-digit',
        minute: '2-digit'
      }).format(date);
    } catch (error) {
      return "N/A";
    }
  };

  return (
    <Layout>
      <div className="space-y-6">
        <div className="flex items-center justify-between">
          <h1 className="text-2xl font-semibold text-white flex items-center">
            <Users className="mr-2 h-6 w-6" />
            Customer Management
          </h1>
        </div>

        <div className="bg-black/40 border border-zinc-800 rounded-md overflow-hidden">
          <div className="p-4 border-b border-zinc-800 bg-black/60 flex flex-col md:flex-row md:justify-between md:items-center gap-4">
            <div className="flex items-center gap-4">
              <div className="flex items-center gap-2">
                <div className="text-sm font-medium text-gray-400">Show:</div>
                <Select value={itemsPerPage.toString()} onValueChange={handleItemsPerPageChange}>
                  <SelectTrigger className="w-[70px]">
                    <SelectValue placeholder="25" />
                  </SelectTrigger>
                  <SelectContent>
                    {[5, 10, 25, 50, 100].map(size => (
                      <SelectItem key={size} value={size.toString()}>{size}</SelectItem>
                    ))}
                  </SelectContent>
                </Select>
              </div>
            </div>

            <div className="relative flex-1 max-w-md">
              <div className="absolute inset-y-0 left-0 flex items-center pl-3 pointer-events-none">
                <Search className="h-4 w-4 text-gray-400" />
              </div>
              <Input
                type="text"
                placeholder="Search by username or Telegram ID..."
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                className="pl-10 pr-10 py-2 w-full bg-black/40 border-zinc-700 text-white"
              />
              {searchQuery && (
                <button
                  className="absolute inset-y-0 right-0 flex items-center pr-3"
                  onClick={clearSearch}
                >
                  <X className="h-4 w-4 text-gray-400 hover:text-gray-200" />
                </button>
              )}
            </div>

            <div className="text-sm text-gray-400 whitespace-nowrap">
              {loading 
                ? "Loading..." 
                : searchQuery 
                  ? `Found ${filteredCustomers.length} matching customers` 
                  : `Showing ${filteredCustomers.length} of ${totalPages * itemsPerPage} customers`}
            </div>
          </div>

          {loading ? (
            <div className="p-8 flex justify-center bg-black/60">
              <Loader2 className="h-8 w-8 animate-spin text-primary" />
            </div>
          ) : filteredCustomers.length === 0 ? (
            <div className="p-8 text-center bg-black/60">
              <Users className="h-12 w-12 mx-auto text-gray-500 mb-4" />
              <h3 className="text-lg font-medium mb-2 text-white">
                {searchQuery ? "No customers matching your search" : "No customers found"}
              </h3>
              <p className="text-gray-500">
                {searchQuery 
                  ? "Try a different search term or clear the search" 
                  : "Once you have customers placing orders, they will appear here."}
              </p>
              {searchQuery && (
                <Button variant="outline" size="sm" onClick={clearSearch} className="mt-4">
                  Clear search
                </Button>
              )}
            </div>
          ) : (
            <div className="overflow-x-auto">
              <Table className="[&_tr]:border-b [&_tr]:border-zinc-800 [&_tr:last-child]:border-b-0 [&_td]:border-r [&_td]:border-zinc-800 [&_td:last-child]:border-r-0 [&_th]:border-r [&_th]:border-zinc-800 [&_th:last-child]:border-r-0 [&_tr:hover]:bg-zinc-900/70">
                <TableHeader className="bg-black/60 sticky top-0 z-10">
                  <TableRow>
                    <TableHead className="w-[250px] text-gray-300">Customer</TableHead>
                    <TableHead 
                      className="cursor-pointer w-[100px] text-gray-300"
                      onClick={() => handleSort("totalOrders")}
                    >
                      <div className="flex items-center">
                        Orders
                        <ArrowUpDown className="ml-2 h-4 w-4" />
                      </div>
                    </TableHead>
                    <TableHead 
                      className="cursor-pointer w-[150px] text-gray-300"
                      onClick={() => handleSort("totalSpent")}
                    >
                      <div className="flex items-center">
                        Total Spent
                        <ArrowUpDown className="ml-2 h-4 w-4" />
                      </div>
                    </TableHead>
                    <TableHead 
                      className="cursor-pointer w-[180px] text-gray-300"
                      onClick={() => handleSort("lastOrderDate")}
                    >
                      <div className="flex items-center">
                        Last Order
                        <ArrowUpDown className="ml-2 h-4 w-4" />
                      </div>
                    </TableHead>
                    <TableHead className="w-[250px] text-gray-300">Status</TableHead>
                  </TableRow>
                </TableHeader>
                <TableBody>
                  {filteredCustomers.map((customer) => (
                    <TableRow 
                      key={customer.userId}
                      className={`cursor-pointer ${!customer.hasOrders ? "bg-black/30" : ""}`}
                      onClick={() => setSelectedCustomer(customer)}
                    >
                      <TableCell>
                        <div className="font-medium text-gray-100">
                          @{customer.telegramUsername || "Unknown"}
                          {!customer.hasOrders && (
                            <Badge variant="outline" className="ml-2 bg-purple-900/30 text-purple-300 border-purple-700">
                              <UserPlus className="h-3 w-3 mr-1" />
                              New
                            </Badge>
                          )}
                        </div>
                        <div className="text-sm text-gray-400">ID: {customer.telegramUserId}</div>
                      </TableCell>
                      <TableCell>
                        <Badge className="bg-gray-700 text-white hover:bg-gray-600">{customer.totalOrders}</Badge>
                      </TableCell>
                      <TableCell className="font-medium text-gray-100">
                        {formatCurrency(customer.totalSpent)}
                      </TableCell>
                      <TableCell className="text-sm text-gray-100">
                        {customer.lastOrderDate ? formatDate(customer.lastOrderDate) : "N/A"}
                      </TableCell>
                      <TableCell>
                        {customer.hasOrders ? (
                          <div className="flex space-x-1">
                            <Badge className="bg-blue-500 text-white hover:bg-blue-600">
                              {customer.ordersByStatus.paid} Paid
                            </Badge>
                            <Badge className="bg-green-500 text-white hover:bg-green-600">
                              {customer.ordersByStatus.completed} Completed
                            </Badge>
                            <Badge className="bg-amber-500 text-white hover:bg-amber-600">
                              {customer.ordersByStatus.shipped} Shipped
                            </Badge>
                          </div>
                        ) : (
                          <Badge variant="outline" className="bg-gray-800 text-gray-300 border-gray-700">
                            No orders yet
                          </Badge>
                        )}
                      </TableCell>
                    </TableRow>
                  ))}
                </TableBody>
              </Table>
            </div>
          )}

          <div className="p-4 border-t border-zinc-800 bg-black/40 flex justify-between items-center">
            <div className="text-sm text-gray-400">
              Page {page} of {totalPages}
            </div>
            <div className="flex gap-2">
              <Button
                variant="outline"
                size="sm"
                onClick={() => handlePageChange(Math.max(1, page - 1))}
                disabled={page === 1 || loading}
              >
                <ChevronLeft className="h-4 w-4 mr-1" />
                Previous
              </Button>
              
              {totalPages > 2 && (
                <DropdownMenu>
                  <DropdownMenuTrigger asChild>
                    <Button variant="outline" size="sm">
                      <span className="sr-only">Go to page</span>
                      <MoreHorizontal className="h-4 w-4" />
                    </Button>
                  </DropdownMenuTrigger>
                  <DropdownMenuContent align="center" className="bg-black/90 border-zinc-800 max-h-60 overflow-y-auto">
                    {Array.from({ length: totalPages }, (_, i) => i + 1).map((pageNum) => (
                      <DropdownMenuItem
                        key={pageNum}
                        onClick={() => handlePageChange(pageNum)}
                        className={`cursor-pointer ${pageNum === page ? 'bg-zinc-800 text-white' : 'text-gray-300'}`}
                      >
                        Page {pageNum}
                      </DropdownMenuItem>
                    ))}
                  </DropdownMenuContent>
                </DropdownMenu>
              )}
              
              <Button
                variant="outline"
                size="sm"
                onClick={() => handlePageChange(Math.min(totalPages, page + 1))}
                disabled={page === totalPages || loading}
              >
                Next
                <ChevronRight className="h-4 w-4 ml-1" />
              </Button>
            </div>
          </div>
        </div>

        {/* Customer Details Dialog */}
        {selectedCustomer && (
          <Dialog open={!!selectedCustomer} onOpenChange={(open) => !open && setSelectedCustomer(null)}>
            <DialogContent className="max-w-[95vw] sm:max-w-2xl w-full overflow-y-auto max-h-[90vh] z-[80]">
              <DialogHeader>
                <DialogTitle className="text-base">
                  Customer Details
                </DialogTitle>
              </DialogHeader>
              
              <div className="grid grid-cols-1 md:grid-cols-2 gap-8 py-4">
                {/* Customer Information */}
                <div>
                  <div className="mb-4">
                    <h3 className="text-sm font-medium mb-2">Customer Information</h3>
                    <div className="space-y-3">
                      <div className="flex justify-between items-center text-sm">
                        <div className="text-muted-foreground">Username:</div>
                        <div className="font-medium">@{selectedCustomer.telegramUsername || "Unknown"}</div>
                      </div>
                      <div className="flex justify-between items-center text-sm">
                        <div className="text-muted-foreground">Telegram ID:</div>
                        <div className="font-medium">{selectedCustomer.telegramUserId}</div>
                      </div>
                      <div className="flex justify-between items-center text-sm">
                        <div className="text-muted-foreground">Chat ID:</div>
                        <div className="font-medium">{selectedCustomer.chatId}</div>
                      </div>
                    </div>
                  </div>
                  
                  <Button 
                    variant="outline" 
                    size="sm" 
                    className="w-full"
                    onClick={() => {
                      window.open(`https://t.me/${selectedCustomer.telegramUsername || selectedCustomer.telegramUserId}`, '_blank');
                    }}
                  >
                    <MessageCircle className="h-4 w-4 mr-2" />
                    Open Telegram Chat
                  </Button>
                </div>

                {/* Order Statistics */}
                <div>
                  <h3 className="text-sm font-medium mb-2">Order Statistics</h3>
                  <div className="bg-background rounded-lg border border-border p-4 space-y-3">
                    <div className="flex justify-between items-center text-sm">
                      <div className="text-muted-foreground">Total Orders:</div>
                      <div className="font-medium">{selectedCustomer.totalOrders}</div>
                    </div>
                    <div className="flex justify-between items-center text-sm">
                      <div className="text-muted-foreground">Total Spent:</div>
                      <div className="font-medium">{formatCurrency(selectedCustomer.totalSpent)}</div>
                    </div>
                    <div className="flex justify-between items-center text-sm">
                      <div className="text-muted-foreground">First Order:</div>
                      <div className="font-medium">
                        {formatDate(selectedCustomer.firstOrderDate)}
                      </div>
                    </div>
                    <div className="flex justify-between items-center text-sm">
                      <div className="text-muted-foreground">Last Order:</div>
                      <div className="font-medium">
                        {formatDate(selectedCustomer.lastOrderDate)}
                      </div>
                    </div>
                  </div>
                </div>
              </div>

              {/* Order Status Breakdown */}
              <div className="mb-4">
                <h3 className="text-sm font-medium mb-2">Order Status Breakdown</h3>
                <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
                  <div className="bg-blue-500/10 rounded-lg border border-blue-500/20 p-3">
                    <p className="text-sm text-muted-foreground">Paid</p>
                    <p className="text-xl font-semibold">{selectedCustomer.ordersByStatus.paid}</p>
                  </div>
                  <div className="bg-purple-500/10 rounded-lg border border-purple-500/20 p-3">
                    <p className="text-sm text-muted-foreground">Acknowledged</p>
                    <p className="text-xl font-semibold">{selectedCustomer.ordersByStatus.acknowledged}</p>
                  </div>
                  <div className="bg-amber-500/10 rounded-lg border border-amber-500/20 p-3">
                    <p className="text-sm text-muted-foreground">Shipped</p>
                    <p className="text-xl font-semibold">{selectedCustomer.ordersByStatus.shipped}</p>
                  </div>
                  <div className="bg-green-500/10 rounded-lg border border-green-500/20 p-3">
                    <p className="text-sm text-muted-foreground">Completed</p>
                    <p className="text-xl font-semibold">{selectedCustomer.ordersByStatus.completed}</p>
                  </div>
                </div>
              </div>

              <DialogFooter>
                <Button 
                  variant="outline" 
                  onClick={() => setSelectedCustomer(null)}
                >
                  Close
                </Button>
                <Button 
                  onClick={() => router.push(`/dashboard/storefront/chat/new?userId=${selectedCustomer.telegramUserId}`)}
                >
                  <MessageCircle className="h-4 w-4 mr-2" />
                  Start Chat
                </Button>
              </DialogFooter>
            </DialogContent>
          </Dialog>
        )}
      </div>
    </Layout>
  );
}