path: root/frontend/src/app/(main)/loans/page.tsx

'use client';

import { useState } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Table, TableHeader, TableRow, TableHead, TableBody, TableCell } from '@/components/ui/table';
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogTrigger } from '@/components/ui/dialog';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { loanApi, Loan, LoanInput } from '@/lib/api';

export default function LoansPage() {
  const queryClient = useQueryClient();
  const [isAddDialogOpen, setIsAddDialogOpen] = useState(false);
  const [isDeleteDialogOpen, setIsDeleteDialogOpen] = useState(false);
  const [loanToDelete, setLoanToDelete] = useState<number | null>(null);
  const [selectedLoan, setSelectedLoan] = useState<Loan | null>(null);

  // Form state
  const [loanName, setLoanName] = useState('');
  const [originalAmount, setOriginalAmount] = useState('');
  const [currentBalance, setCurrentBalance] = useState('');
  const [interestRate, setInterestRate] = useState('');
  const [startDate, setStartDate] = useState('');
  const [endDate, setEndDate] = useState('');
  const [formError, setFormError] = useState('');

  // Query loans
  const { data, isLoading, error } = useQuery({
    queryKey: ['loans'],
    queryFn: async () => {
      const response = await loanApi.getLoans();
      console.log('API Response:', response); // Debug the response structure
      
      // The response might be the array directly rather than nested under a 'loans' property
      if (Array.isArray(response)) {
        return response as Loan[];
      }
      
      // Or it might be nested under a 'loans' or 'data' property
      return (response.loans || response.data || []) as Loan[];
    }
  });

  // Create loan mutation
  const createLoanMutation = useMutation({
    mutationFn: (loanData: LoanInput) => loanApi.createLoan(loanData),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['loans'] });
      resetForm();
      setIsAddDialogOpen(false);
    },
    onError: (error: Error) => {
      setFormError(error.message);
    }
  });

  // Delete loan mutation
  const deleteLoanMutation = useMutation({
    mutationFn: (id: number) => loanApi.deleteLoan(id),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['loans'] });
      setIsDeleteDialogOpen(false);
      setLoanToDelete(null);
    }
  });

  const resetForm = () => {
    setLoanName('');
    setOriginalAmount('');
    setCurrentBalance('');
    setInterestRate('');
    setStartDate('');
    setEndDate('');
    setFormError('');
    setSelectedLoan(null);
  };

  const handleCreateLoan = (e: React.FormEvent) => {
    e.preventDefault();
    setFormError('');

    try {
      // Validate inputs
      if (!loanName || !originalAmount || !currentBalance || !startDate || !endDate) {
        setFormError('Please fill in all required fields');
        return;
      }

      const loanData: LoanInput = {
        name: loanName,
        originalAmount: Number(originalAmount) * 100, // Convert to cents
        currentBalance: Number(currentBalance) * 100, // Convert to cents
        interestRate: Number(interestRate) || 0,
        startDate,
        endDate,
      };

      createLoanMutation.mutate(loanData);
    } catch (err: any) {
      setFormError(err.message || 'Error creating loan');
    }
  };

  const handleDeleteLoan = (id: number) => {
    setLoanToDelete(id);
    setIsDeleteDialogOpen(true);
  };

  const confirmDeleteLoan = () => {
    if (loanToDelete !== null) {
      deleteLoanMutation.mutate(loanToDelete);
    }
  };

  // Format currency (convert cents to dollars)
  const formatCurrency = (amount: number) => {
    return new Intl.NumberFormat('en-US', {
      style: 'currency',
      currency: 'USD',
    }).format(amount / 100);
  };

  // Format date
  const formatDate = (dateString: string) => {
    return new Date(dateString).toLocaleDateString();
  };

  if (isLoading) {
    return <div>Loading loans...</div>;
  }

  if (error) {
    return <div>Error loading loans: {error.toString()}</div>;
  }

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between">
        <h1 className="text-3xl font-bold">Loans</h1>
        <Dialog open={isAddDialogOpen} onOpenChange={setIsAddDialogOpen}>
          <DialogTrigger asChild>
            <Button onClick={resetForm}>Add New Loan</Button>
          </DialogTrigger>
          <DialogContent>
            <DialogHeader>
              <DialogTitle>Add New Loan</DialogTitle>
            </DialogHeader>
            <form onSubmit={handleCreateLoan} className="space-y-4">
              <div className="space-y-2">
                <Label htmlFor="name">Loan Name</Label>
                <Input
                  id="name"
                  placeholder="e.g., Car Loan"
                  value={loanName}
                  onChange={(e) => setLoanName(e.target.value)}
                  required
                />
              </div>
              
              <div className="space-y-2">
                <Label htmlFor="originalAmount">Original Amount ($)</Label>
                <Input
                  id="originalAmount"
                  type="number"
                  step="0.01"
                  placeholder="10000.00"
                  value={originalAmount}
                  onChange={(e) => setOriginalAmount(e.target.value)}
                  required
                />
              </div>
              
              <div className="space-y-2">
                <Label htmlFor="currentBalance">Current Balance ($)</Label>
                <Input
                  id="currentBalance"
                  type="number"
                  step="0.01"
                  placeholder="9500.00"
                  value={currentBalance}
                  onChange={(e) => setCurrentBalance(e.target.value)}
                  required
                />
              </div>
              
              <div className="space-y-2">
                <Label htmlFor="interestRate">Interest Rate (%)</Label>
                <Input
                  id="interestRate"
                  type="number"
                  step="0.01"
                  placeholder="5.25"
                  value={interestRate}
                  onChange={(e) => setInterestRate(e.target.value)}
                />
              </div>
              
              <div className="space-y-2">
                <Label htmlFor="startDate">Start Date</Label>
                <Input
                  id="startDate"
                  type="date"
                  value={startDate}
                  onChange={(e) => setStartDate(e.target.value)}
                  required
                />
              </div>
              
              <div className="space-y-2">
                <Label htmlFor="endDate">End Date</Label>
                <Input
                  id="endDate"
                  type="date"
                  value={endDate}
                  onChange={(e) => setEndDate(e.target.value)}
                  required
                />
              </div>
              
              {formError && (
                <div className="text-sm text-red-500">
                  {formError}
                </div>
              )}
              
              <div className="flex justify-end space-x-2">
                <Button type="button" variant="outline" onClick={() => setIsAddDialogOpen(false)}>
                  Cancel
                </Button>
                <Button type="submit" disabled={createLoanMutation.isPending}>
                  {createLoanMutation.isPending ? 'Saving...' : 'Save Loan'}
                </Button>
              </div>
            </form>
          </DialogContent>
        </Dialog>
      </div>

      {/* Delete Confirmation Dialog */}
      <Dialog open={isDeleteDialogOpen} onOpenChange={setIsDeleteDialogOpen}>
        <DialogContent className="sm:max-w-md">
          <DialogHeader>
            <DialogTitle>Confirm Deletion</DialogTitle>
          </DialogHeader>
          <div className="space-y-4 py-4">
            <p>Are you sure you want to delete this loan? This action cannot be undone.</p>
          </div>
          <div className="flex justify-end space-x-2">
            <Button variant="outline" onClick={() => setIsDeleteDialogOpen(false)}>
              Cancel
            </Button>
            <Button 
              variant="destructive" 
              onClick={confirmDeleteLoan}
              disabled={deleteLoanMutation.isPending}
            >
              {deleteLoanMutation.isPending ? 'Deleting...' : 'Delete Loan'}
            </Button>
          </div>
        </DialogContent>
      </Dialog>

      {data && data.length > 0 ? (
        <Card>
          <CardHeader>
            <CardTitle>Your Loans</CardTitle>
          </CardHeader>
          <CardContent>
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead>Name</TableHead>
                  <TableHead>Original Amount</TableHead>
                  <TableHead>Current Balance</TableHead>
                  <TableHead>Interest Rate</TableHead>
                  <TableHead>Start Date</TableHead>
                  <TableHead>End Date</TableHead>
                  <TableHead>Actions</TableHead>
                </TableRow>
              </TableHeader>
              <TableBody>
                {data.map((loan) => (
                  <TableRow key={loan.ID}>
                    <TableCell className="font-medium">{loan.Name}</TableCell>
                    <TableCell>{formatCurrency(loan.OriginalAmount)}</TableCell>
                    <TableCell>{formatCurrency(loan.CurrentBalance)}</TableCell>
                    <TableCell>{loan.InterestRate}%</TableCell>
                    <TableCell>{formatDate(loan.StartDate)}</TableCell>
                    <TableCell>{formatDate(loan.EndDate)}</TableCell>
                    <TableCell>
                      <div className="flex items-center space-x-2">
                        <Button
                          variant="destructive"
                          size="sm"
                          onClick={() => handleDeleteLoan(loan.ID)}
                          disabled={deleteLoanMutation.isPending}
                        >
                          Delete
                        </Button>
                      </div>
                    </TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          </CardContent>
        </Card>
      ) : (
        <Card>
          <CardContent className="flex flex-col items-center justify-center p-10">
            <p className="text-muted-foreground mb-4">You don&apos;t have any loans yet.</p>
            <Button onClick={() => setIsAddDialogOpen(true)}>Add Your First Loan</Button>
          </CardContent>
        </Card>
      )}
    </div>
  );
}