"use client";

import { useState, useEffect, useCallback } from "react";
import { useRouter } from "next/navigation";
import { useForm } from "react-hook-form";
import { zodResolver } from "@hookform/resolvers/zod";
import * as z from "zod";
import { CalendarIcon } from "lucide-react";
import { format } from "date-fns";

import { Button } from "@/components/ui/button";
import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form";
import { Input } from "@/components/ui/input";
import { Card, CardContent } from "@/components/ui/card";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import {
  Popover,
  PopoverContent,
  PopoverTrigger,
} from "@/components/ui/popover";
import { Calendar } from "@/components/ui/calendar";
import { useToast } from "@/components/ui/use-toast";
import { api } from "@/lib/api";

// Validation schema
const formSchema = z.object({
  name: z
    .string()
    .min(3, { message: "Name must be at least 3 characters" })
    .max(100, { message: "Name must be less than 100 characters" }),
  targetAmount: z
    .number()
    .min(1, { message: "Target amount must be greater than 0" }),
  currentAmount: z
    .number()
    .min(0, { message: "Current amount cannot be negative" })
    .optional(),
  targetDate: z.date().optional(),
  status: z.enum(["Active", "Paused", "Achieved", "Cancelled"]),
});

type FormValues = z.infer<typeof formSchema>;

interface GoalFormProps {
  goalId?: number;
  isEditing?: boolean;
  onSuccess?: () => void;
}

export function GoalForm({ 
  goalId, 
  isEditing = false,
  onSuccess
}: GoalFormProps) {
  const [loading, setLoading] = useState(false);
  const [initialLoading, setInitialLoading] = useState(false);
  const router = useRouter();
  const { toast } = useToast();

  // Set up form with validation
  const form = useForm<FormValues>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      name: "",
      targetAmount: 0,
      currentAmount: 0,
      status: "Active",
    },
  });

  const fetchGoalData = useCallback(async () => {
    setInitialLoading(true);
    try {
      const response = await api.get(`/goals/${goalId}`);
      const goalData = response.data;
      
      // Set form values
      form.reset({
        name: goalData.name,
        targetAmount: goalData.targetAmount,
        currentAmount: goalData.currentAmount,
        status: goalData.status as "Active" | "Paused" | "Achieved" | "Cancelled",
        ...(goalData.targetDate && { targetDate: new Date(goalData.targetDate) }),
      });
    } catch (error) {
      toast({
        title: "Error",
        description: "Failed to fetch goal data. Please try again.",
        variant: "destructive",
      });
      console.error("Error fetching goal:", error);
      router.push("/goals");
    } finally {
      setInitialLoading(false);
    }
  }, [goalId, form, toast, router]);

  // Fetch goal data if editing
  useEffect(() => {
    if (isEditing && goalId) {
      fetchGoalData();
    }
  }, [isEditing, goalId, fetchGoalData]);

  const onSubmit = async (values: FormValues) => {
    try {
      setLoading(true);
      
      // Format data for API
      const formattedData = {
        ...values,
        targetDate: values.targetDate ? format(values.targetDate, "yyyy-MM-dd") : undefined,
      };
      
      console.log("Submitting goal:", formattedData);
      
      if (isEditing) {
        // Update existing goal
        await api.put(`/goals/${goalId}`, formattedData);
        toast({
          title: "Goal updated",
          description: "Your goal has been updated successfully.",
        });
      } else {
        // Create new goal
        const response = await api.post("/goals", formattedData);
        console.log("Goal created response:", response.data);
        toast({
          title: "Goal created",
          description: "Your new goal has been created successfully.",
        });
      }
      
      // Call onSuccess callback if provided
      if (onSuccess) {
        onSuccess();
      } else {
        // Force a full page reload directly to the goals page
        window.location.href = "/goals";
      }
      
    } catch (error) {
      toast({
        title: "Error",
        description: `Failed to ${isEditing ? "update" : "create"} goal. Please try again.`,
        variant: "destructive",
      });
      console.error(`Error ${isEditing ? "updating" : "creating"} goal:`, error);
    } finally {
      setLoading(false);
    }
  };

  if (initialLoading) {
    return <div className="text-center py-8">Loading goal data...</div>;
  }

  return (
    <Card>
      <CardContent className="pt-6">
        <Form {...form}>
          <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-6">
            <FormField
              control={form.control}
              name="name"
              render={({ field }) => (
                <FormItem>
                  <FormLabel>Goal Name</FormLabel>
                  <FormControl>
                    <Input placeholder="e.g., Down Payment for House" {...field} />
                  </FormControl>
                  <FormDescription>
                    A descriptive name for your financial goal
                  </FormDescription>
                  <FormMessage />
                </FormItem>
              )}
            />

            <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
              <FormField
                control={form.control}
                name="targetAmount"
                render={({ field }) => (
                  <FormItem>
                    <FormLabel>Target Amount</FormLabel>
                    <FormControl>
                      <Input
                        type="number"
                        placeholder="10000"
                        {...field}
                        onChange={(e) => field.onChange(Number(e.target.value))}
                      />
                    </FormControl>
                    <FormDescription>
                      The total amount you want to save
                    </FormDescription>
                    <FormMessage />
                  </FormItem>
                )}
              />

              <FormField
                control={form.control}
                name="currentAmount"
                render={({ field }) => (
                  <FormItem>
                    <FormLabel>Current Amount</FormLabel>
                    <FormControl>
                      <Input
                        type="number"
                        placeholder="0"
                        {...field}
                        value={field.value || ""}
                        onChange={(e) => field.onChange(Number(e.target.value) || 0)}
                      />
                    </FormControl>
                    <FormDescription>
                      How much you&apos;ve already saved towards this goal
                    </FormDescription>
                    <FormMessage />
                  </FormItem>
                )}
              />
            </div>

            <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
              <FormField
                control={form.control}
                name="targetDate"
                render={({ field }) => (
                  <FormItem className="flex flex-col">
                    <FormLabel>Target Date (Optional)</FormLabel>
                    <Popover>
                      <PopoverTrigger asChild>
                        <FormControl>
                          <Button
                            variant={"outline"}
                            className={`w-full pl-3 text-left font-normal ${
                              !field.value ? "text-muted-foreground" : ""
                            }`}
                          >
                            {field.value ? (
                              format(field.value, "PPP")
                            ) : (
                              <span>Pick a date</span>
                            )}
                            <CalendarIcon className="ml-auto h-4 w-4 opacity-50" />
                          </Button>
                        </FormControl>
                      </PopoverTrigger>
                      <PopoverContent className="w-auto p-0" align="start">
                        <Calendar
                          mode="single"
                          selected={field.value || undefined}
                          onSelect={field.onChange}
                          disabled={(date) => date < new Date()}
                          initialFocus
                        />
                      </PopoverContent>
                    </Popover>
                    <FormDescription>
                      When you aim to achieve this goal
                    </FormDescription>
                    <FormMessage />
                  </FormItem>
                )}
              />

              <FormField
                control={form.control}
                name="status"
                render={({ field }) => (
                  <FormItem>
                    <FormLabel>Status</FormLabel>
                    <Select
                      onValueChange={field.onChange}
                      defaultValue={field.value}
                      value={field.value}
                    >
                      <FormControl>
                        <SelectTrigger>
                          <SelectValue placeholder="Select a status" />
                        </SelectTrigger>
                      </FormControl>
                      <SelectContent>
                        <SelectItem value="Active">Active</SelectItem>
                        <SelectItem value="Paused">Paused</SelectItem>
                        <SelectItem value="Achieved">Achieved</SelectItem>
                        <SelectItem value="Cancelled">Cancelled</SelectItem>
                      </SelectContent>
                    </Select>
                    <FormDescription>
                      The current status of your goal
                    </FormDescription>
                    <FormMessage />
                  </FormItem>
                )}
              />
            </div>

            <div className="mb-6">
              <h3 className="text-sm font-medium text-muted-foreground mb-2">
                Don&apos;t see the amount you need?
              </h3>
              <p className="text-sm">
                Use the calculator to determine your target amount.
              </p>
            </div>

            <div className="flex justify-end space-x-4">
              <Button
                type="button"
                variant="outline"
                onClick={() => router.push("/goals")}
                disabled={loading}
              >
                Cancel
              </Button>
              <Button type="submit" disabled={loading}>
                {loading
                  ? isEditing
                    ? "Updating..."
                    : "Creating..."
                  : isEditing
                  ? "Update Goal"
                  : "Create Goal"}
              </Button>
            </div>
          </form>
        </Form>
      </CardContent>
    </Card>
  );
}