import { useState } from "react";
import { zodResolver } from "@hookform/resolvers/zod";
import { useForm } from "react-hook-form";
import * as z from "zod";
import { format } from "date-fns";
import { CalendarIcon, Check, ChevronDown } from "lucide-react";

import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import {
  Form,
  FormControl,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form";
import { Popover, PopoverContent, PopoverTrigger } from "@/components/ui/popover";
import { Calendar } from "@/components/ui/calendar";
import { cn } from "@/lib/utils";
import { AppraisalCycle, AppraisalCycleCreateRequest, AppraisalCycleUpdateRequest } from "@/types";
import CustomDialog from "@/components/CustomDialog";

// Custom date dropdown component
interface CustomDateDropdownProps {
  value?: Date;
  onChange: (date: Date) => void;
  placeholder: string;
  label: string;
  disabled?: boolean;
  minDate?: Date;
  error?: string;
}

function CustomDateDropdown({ 
  value, 
  onChange, 
  placeholder, 
  label, 
  disabled = false,
  minDate,
  error
}: CustomDateDropdownProps) {
  const [open, setOpen] = useState(false);
  
  const handleButtonClick = (e: React.MouseEvent) => {
    if (disabled) return;
    setOpen(!open);
  };
  
  const handleDateSelect = (date: Date | undefined) => {
    if (date) {
      onChange(date);
      setOpen(false);
    }
  };
  
  return (
    <div className="w-full space-y-2">
      <div className="font-medium text-sm">{label}</div>
      <div className="relative w-full">
        <div
          className={cn(
            "flex h-10 w-full items-center justify-between rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background cursor-pointer",
            open && "ring-2 ring-ring ring-offset-2",
            disabled && "opacity-50 cursor-not-allowed"
          )}
          onClick={handleButtonClick}
        >
          <span className={!value ? "text-muted-foreground" : ""}>
            {value ? format(value, "PPP") : placeholder}
          </span>
          <CalendarIcon className="h-4 w-4 opacity-50" />
        </div>
        
        {open && (
          <div className="absolute z-50 mt-1 w-full rounded-md border bg-popover p-1 text-popover-foreground shadow-md">
            <Calendar
              mode="single"
              selected={value}
              onSelect={handleDateSelect}
              disabled={(date) => minDate ? date < minDate : false}
              initialFocus
            />
          </div>
        )}
      </div>
      {error && <p className="text-sm font-medium text-destructive">{error}</p>}
    </div>
  );
}

// Define form schema
const formSchema = z.object({
  name: z.string().min(2, { message: "Name must be at least 2 characters." }),
  startDate: z.date({ required_error: "Start date is required." }),
  endDate: z.date({ required_error: "End date is required." }),
}).refine(data => data.endDate > data.startDate, {
  message: "End date must be after start date.",
  path: ["endDate"],
});

interface AppraisalCycleDialogProps {
  open: boolean;
  onOpenChange: (open: boolean) => void;
  onSubmit: (data: AppraisalCycleCreateRequest | AppraisalCycleUpdateRequest) => void;
  cycleToEdit?: AppraisalCycle;
  isLoading?: boolean;
}

export function AppraisalCycleDialog({
  open,
  onOpenChange,
  onSubmit,
  cycleToEdit,
  isLoading = false,
}: AppraisalCycleDialogProps) {
  const [error, setError] = useState<string | null>(null);

  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      name: cycleToEdit?.name || "",
      startDate: cycleToEdit?.startDate ? new Date(cycleToEdit.startDate) : undefined,
      endDate: cycleToEdit?.endDate ? new Date(cycleToEdit.endDate) : undefined,
    },
  });

  function handleSubmit(values: z.infer<typeof formSchema>) {
    setError(null);
    const formattedData = {
      name: values.name,
      startDate: format(values.startDate, "yyyy-MM-dd"),
      endDate: format(values.endDate, "yyyy-MM-dd"),
    };

    if (cycleToEdit) {
      onSubmit({
        ...formattedData,
        cycleId: cycleToEdit.cycleId,
      } as AppraisalCycleUpdateRequest);
    } else {
      onSubmit(formattedData as AppraisalCycleCreateRequest);
    }
  }

  // Handle dialog closing
  const handleClose = () => {
    onOpenChange(false);
  };

  return (
    <CustomDialog
      isOpen={open}
      onClose={handleClose}
      title={cycleToEdit ? "Edit Appraisal Cycle" : "Create Appraisal Cycle"}
      description={cycleToEdit ? "Edit the details of this appraisal cycle." : "Add a new appraisal cycle to the system."}
      allowClose={!isLoading}
      isPending={isLoading}
    >
      <Form {...form}>
        <form onSubmit={form.handleSubmit(handleSubmit)} className="space-y-6">
          <FormField
            control={form.control}
            name="name"
            render={({ field }) => (
              <FormItem>
                <FormLabel>Name</FormLabel>
                <FormControl>
                  <Input placeholder="Annual Appraisal 2023" {...field} />
                </FormControl>
                <FormMessage />
              </FormItem>
            )}
          />
          
          <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
            <FormField
              control={form.control}
              name="startDate"
              render={({ field, fieldState }) => (
                <CustomDateDropdown
                  label="Start Date"
                  placeholder="Select start date"
                  value={field.value}
                  onChange={field.onChange}
                  disabled={isLoading}
                  error={fieldState.error?.message}
                />
              )}
            />
            
            <FormField
              control={form.control}
              name="endDate"
              render={({ field, fieldState }) => (
                <CustomDateDropdown
                  label="End Date"
                  placeholder="Select end date"
                  value={field.value}
                  onChange={field.onChange}
                  disabled={isLoading}
                  minDate={form.watch("startDate")}
                  error={fieldState.error?.message}
                />
              )}
            />
          </div>
          
          {error && <p className="text-sm font-medium text-destructive">{error}</p>}
          
          <div className="flex justify-end space-x-2 pt-4">
            <Button 
              type="button" 
              variant="outline" 
              onClick={handleClose}
              disabled={isLoading}
            >
              Cancel
            </Button>
            <Button type="submit" disabled={isLoading}>
              {isLoading ? "Saving..." : cycleToEdit ? "Update" : "Create"}
            </Button>
          </div>
        </form>
      </Form>
    </CustomDialog>
  );
}