'use client';

import { useState, useEffect, useRef } from 'react';
import { createPortal } from 'react-dom';
import { DayPicker } from 'react-day-picker';
import { ChevronLeft, ChevronRight, Calendar, X } from 'lucide-react';
import { format, parse, isValid } from 'date-fns';
import { cn } from '@/lib/utils';

interface DatePickerProps {
  value: string; // YYYY-MM-DD
  onChange: (value: string) => void;
  placeholder?: string;
  disabled?: boolean;
  minDate?: Date;
  className?: string;
}

export default function DatePicker({
  value,
  onChange,
  placeholder = 'Pick a date',
  disabled = false,
  minDate,
  className,
}: DatePickerProps) {
  const [open, setOpen] = useState(false);
  const [mounted, setMounted] = useState(false);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const [popoverPos, setPopoverPos] = useState({ top: 0, left: 0 });

  useEffect(() => { setMounted(true); }, []);

  useEffect(() => {
    if (!open) return;
    const handler = (e: KeyboardEvent) => { if (e.key === 'Escape') setOpen(false); };
    document.addEventListener('keydown', handler);
    return () => document.removeEventListener('keydown', handler);
  }, [open]);

  const selected = value
    ? parse(value, 'yyyy-MM-dd', new Date())
    : undefined;
  const validSelected = selected && isValid(selected) ? selected : undefined;

  // Clear the value if it's now before the minDate
  useEffect(() => {
    if (minDate && validSelected && validSelected < minDate) {
      onChange('');
    }
  }, [minDate, validSelected, onChange]);

  function handleOpen() {
    if (disabled) return;
    if (triggerRef.current) {
      const rect = triggerRef.current.getBoundingClientRect();
      setPopoverPos({
        top: rect.bottom + window.scrollY + 6,
        left: rect.left + window.scrollX,
      });
    }
    setOpen(true);
  }

  function handleSelect(date: Date | undefined) {
    if (date && isValid(date)) {
      onChange(format(date, 'yyyy-MM-dd'));
    }
    setOpen(false);
  }

  function handleClear(e: React.MouseEvent) {
    e.stopPropagation();
    onChange('');
  }

  const displayText = validSelected
    ? format(validSelected, 'MMM d, yyyy')
    : null;

  const popover = open && mounted ? createPortal(
    <>
      <div
        className="fixed inset-0"
        style={{ zIndex: 9999 }}
        onClick={() => setOpen(false)}
      />
      <div
        className="absolute bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-xl shadow-xl p-3"
        style={{ zIndex: 10000, top: popoverPos.top, left: popoverPos.left }}
        onClick={e => e.stopPropagation()}
      >
        <DayPicker
          mode="single"
          selected={validSelected}
          onSelect={handleSelect}
          disabled={minDate ? { before: minDate } : undefined}
          showOutsideDays
          classNames={{
            root: 'w-full',
            months: 'w-full',
            month: 'w-full',
            month_caption: 'flex items-center justify-between mb-3',
            caption_label: 'text-sm font-semibold text-gray-900 dark:text-white',
            nav: 'flex items-center gap-1',
            button_previous: 'h-7 w-7 rounded-lg flex items-center justify-center text-gray-500 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors',
            button_next: 'h-7 w-7 rounded-lg flex items-center justify-center text-gray-500 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors',
            month_grid: 'w-full border-collapse',
            weekdays: 'flex w-full mb-1',
            weekday: 'flex-1 text-center text-xs font-medium text-gray-400 dark:text-gray-500 py-1',
            weeks: '',
            week: 'flex w-full mt-0.5',
            day: 'flex-1 flex items-center justify-center p-0',
            day_button: 'h-8 w-8 text-xs rounded-lg flex items-center justify-center transition-colors hover:bg-gray-100 dark:hover:bg-gray-800 cursor-pointer text-gray-700 dark:text-gray-300',
            selected: '',
            today: '',
            outside: 'opacity-30',
            disabled: 'opacity-20 cursor-not-allowed',
            hidden: 'invisible',
            range_start: '',
            range_end: '',
            range_middle: '',
            focused: 'ring-1 ring-blue-500/50',
            chevron: '',
            dropdowns: '',
            dropdown: '',
            dropdown_root: '',
            footer: '',
            months_dropdown: '',
            week_number: '',
            week_number_header: '',
            years_dropdown: '',
            weeks_after_enter: '',
            weeks_after_exit: '',
            weeks_before_enter: '',
            weeks_before_exit: '',
          }}
          components={{
            Chevron: ({ orientation }) =>
              orientation === 'left'
                ? <ChevronLeft className="h-4 w-4" />
                : <ChevronRight className="h-4 w-4" />,
            DayButton: ({ day, modifiers, className: cls, ...props }) => (
              <button
                {...props}
                className={cn(
                  cls,
                  modifiers.selected && 'bg-blue-600 text-white font-semibold hover:bg-blue-700',
                  modifiers.today && !modifiers.selected && 'text-blue-600 dark:text-blue-400 font-bold',
                )}
              />
            ),
          }}
        />
      </div>
    </>,
    document.body,
  ) : null;

  return (
    <div className={cn('relative', className)}>
      <button
        ref={triggerRef}
        type="button"
        onClick={handleOpen}
        disabled={disabled}
        className={cn(
          'flex items-center gap-2 px-3 py-2 rounded-lg border text-sm transition-colors',
          'border-gray-300 dark:border-gray-600 bg-white dark:bg-gray-800',
          'text-gray-900 dark:text-white',
          'focus:outline-none focus:ring-2 focus:ring-blue-500',
          'disabled:opacity-40 disabled:cursor-not-allowed',
          !displayText && 'text-gray-400 dark:text-gray-500',
        )}
      >
        <Calendar className="w-4 h-4 shrink-0 text-gray-400 dark:text-gray-500" />
        <span className="min-w-[90px] text-left">{displayText ?? placeholder}</span>
        {displayText && !disabled && (
          <X
            className="w-3.5 h-3.5 shrink-0 text-gray-400 hover:text-gray-600 dark:hover:text-gray-200 ml-1"
            onClick={handleClear}
          />
        )}
      </button>
      {popover}
    </div>
  );
}