import * as React from 'react';

import {
  ChevronDownIcon,
  ChevronLeftIcon,
  ChevronRightIcon,
} from 'lucide-react';
import {
  type DayButton,
  DayPicker,
  getDefaultClassNames,
} from 'react-day-picker';

import {
  Button,
  buttonVariants,
} from '@/components/ui/button';
import {
  TimePicker,
  TimePickerContent,
  TimePickerHour,
  TimePickerInput,
  TimePickerInputGroup,
  TimePickerMinute,
  TimePickerPeriod,
  TimePickerSeparator,
  TimePickerTrigger,
} from '@/components/ui/time-picker';
import { Lang } from '@/lang/Lang';
import { cn } from '@/lib/utils';

function formatHoursMinutes(date: Date): string {
  return `${date.getHours().toString().padStart(2, '0')}:${date.getMinutes().toString().padStart(2, '0')}`
}

function parseDraftTime(timeStr: string): { hour: number; minute: number } {
  const parts = timeStr.split(':')
  const hour = Number.parseInt(parts[0] ?? '', 10)
  const minute = Number.parseInt(parts[1] ?? '', 10)
  return {
    hour: Number.isNaN(hour) ? 0 : hour,
    minute: Number.isNaN(minute) ? 0 : minute,
  }
}

function Calendar({
  className,
  classNames,
  showOutsideDays = true,
  captionLayout = "label",
  buttonVariant = "ghost",
  formatters,
  components,
  value,
  onChange,
  withTime = false,
  ...props
}: React.ComponentProps<typeof DayPicker> & {
  buttonVariant?: React.ComponentProps<typeof Button>["variant"]
  value?: number | null // unix timestamp in seconds
  onChange?: (unixTimestamp: number | null) => void
  withTime?: boolean
}) {
  const defaultClassNames = getDefaultClassNames()
  const propsAny = props as any
  const selected = propsAny.selected
  const onSelect = propsAny.onSelect

  // Exclude selected and onSelect from props to avoid conflicts
  const { selected: _, onSelect: __, ...restProps } = propsAny

  // Convert unix timestamp to Date for DayPicker
  const selectedDate = React.useMemo(() => {
    if (value !== undefined && value !== null) {
      return new Date(value * 1000)
    }
    return selected as Date | undefined
  }, [value, selected])

  const [draftDate, setDraftDate] = React.useState<Date | undefined>(selectedDate)
  const [draftTime, setDraftTime] = React.useState(() =>
    selectedDate ? formatHoursMinutes(selectedDate) : ''
  )

  React.useEffect(() => {
    if (!withTime) return
    setDraftDate(selectedDate)
    setDraftTime(selectedDate ? formatHoursMinutes(selectedDate) : '')
  }, [withTime, selectedDate])

  // Handle date selection and convert to unix timestamp
  const handleSelect = React.useCallback((date: Date | undefined) => {
    if (onChange) {
      onChange(date ? Math.floor(date.getTime() / 1000) : null)
    }
    // Call original onSelect if provided (for backward compatibility)
    if (onSelect && typeof onSelect === 'function') {
      (onSelect as any)(date)
    }
  }, [onChange, onSelect])

  const handleDraftSelect = React.useCallback((date: Date | undefined) => {
    setDraftDate(date)
  }, [])

  const handleSave = React.useCallback(() => {
    if (!draftDate) {
      if (onChange) onChange(null)
      if (onSelect && typeof onSelect === 'function') {
        (onSelect as any)(undefined)
      }
      return
    }

    const { hour, minute } = parseDraftTime(draftTime)
    const result = new Date(draftDate)
    result.setHours(hour, minute, 0, 0)

    if (onChange) {
      onChange(Math.floor(result.getTime() / 1000))
    }
    if (onSelect && typeof onSelect === 'function') {
      (onSelect as any)(result)
    }
  }, [draftDate, draftTime, onChange, onSelect])

  // Определяем первый день недели: понедельник для ru, воскресенье для остальных
  // Вычисляем при каждом рендере, чтобы учитывать изменения языка
  const weekStartsOn = Lang.getCurrentLang() === 'ru' ? 1 : 0;

  // Маппинг дня недели к ключу локализации
  const getWeekdayKey = React.useCallback((date: Date): string => {
    const dayOfWeek = date.getDay(); // 0 = воскресенье, 1 = понедельник, ..., 6 = суббота
    const keys: Record<number, string> = {
      0: 'calendar_su_sort', // воскресенье
      1: 'calendar_mo_sort', // понедельник
      2: 'calendar_tu_sort', // вторник
      3: 'calendar_we_sort', // среда
      4: 'calendar_th_sort', // четверг
      5: 'calendar_fr_sort', // пятница
      6: 'calendar_sa_sort', // суббота
    };
    return keys[dayOfWeek] || 'calendar_mo_sort';
  }, []);

  const dayPicker = (
    <DayPicker
      showOutsideDays={showOutsideDays}
      weekStartsOn={weekStartsOn}
      className={cn(
        "bg-background group/calendar p-3 [--cell-size:--spacing(8)] [[data-slot=card-content]_&]:bg-transparent [[data-slot=popover-content]_&]:bg-transparent",
        String.raw`rtl:**:[.rdp-button\_next>svg]:rotate-180`,
        String.raw`rtl:**:[.rdp-button\_previous>svg]:rotate-180`,
        withTime && "pb-0",
        className
      )}
      captionLayout={captionLayout}
      formatters={{
        formatMonthDropdown: (date) =>
          date.toLocaleString("default", { month: "short" }),
        formatWeekdayName: (date) => {
          const key = getWeekdayKey(date);
          return Lang.key(key);
        },
        ...formatters,
      }}
      classNames={{
        root: cn("w-fit", defaultClassNames.root),
        months: cn(
          "flex gap-4 flex-col md:flex-row relative",
          defaultClassNames.months
        ),
        month: cn("flex flex-col w-full gap-4", defaultClassNames.month),
        nav: cn(
          "flex items-center gap-1 w-full absolute top-0 inset-x-0 justify-between",
          defaultClassNames.nav
        ),
        button_previous: cn(
          buttonVariants({ variant: buttonVariant }),
          "size-(--cell-size) aria-disabled:opacity-50 p-0 select-none",
          defaultClassNames.button_previous
        ),
        button_next: cn(
          buttonVariants({ variant: buttonVariant }),
          "size-(--cell-size) aria-disabled:opacity-50 p-0 select-none",
          defaultClassNames.button_next
        ),
        month_caption: cn(
          "flex items-center justify-center h-(--cell-size) w-full px-(--cell-size)",
          defaultClassNames.month_caption
        ),
        dropdowns: cn(
          "w-full flex items-center text-sm font-medium justify-center h-(--cell-size) gap-1.5",
          defaultClassNames.dropdowns
        ),
        dropdown_root: cn(
          "relative has-focus:border-ring border border-input shadow-xs has-focus:ring-ring/50 has-focus:ring-[3px] rounded-md",
          defaultClassNames.dropdown_root
        ),
        dropdown: cn(
          "absolute bg-popover inset-0 opacity-0",
          defaultClassNames.dropdown
        ),
        caption_label: cn(
          "select-none font-medium",
          captionLayout === "label"
            ? "text-sm"
            : "rounded-md pl-2 pr-1 flex items-center gap-1 text-sm h-8 [&>svg]:text-muted-foreground [&>svg]:size-3.5",
          defaultClassNames.caption_label
        ),
        table: "w-full border-collapse",
        weekdays: cn("flex", defaultClassNames.weekdays),
        weekday: cn(
          "text-muted-foreground rounded-md flex-1 font-normal text-[0.8rem] select-none",
          defaultClassNames.weekday
        ),
        week: cn("flex w-full mt-2", defaultClassNames.week),
        week_number_header: cn(
          "select-none w-(--cell-size)",
          defaultClassNames.week_number_header
        ),
        week_number: cn(
          "text-[0.8rem] select-none text-muted-foreground",
          defaultClassNames.week_number
        ),
        day: cn(
          "relative w-full h-full p-0 text-center [&:last-child[data-selected=true]_button]:rounded-r-md group/day aspect-square select-none",
          props.showWeekNumber
            ? "[&:nth-child(2)[data-selected=true]_button]:rounded-l-md"
            : "[&:first-child[data-selected=true]_button]:rounded-l-md",
          defaultClassNames.day
        ),
        range_start: cn(
          "rounded-l-md bg-accent",
          defaultClassNames.range_start
        ),
        range_middle: cn("rounded-none", defaultClassNames.range_middle),
        range_end: cn("rounded-r-md bg-accent", defaultClassNames.range_end),
        today: cn(
          "bg-accent text-accent-foreground rounded-md data-[selected=true]:rounded-none",
          defaultClassNames.today
        ),
        outside: cn(
          "text-muted-foreground aria-selected:text-muted-foreground",
          defaultClassNames.outside
        ),
        disabled: cn(
          "text-muted-foreground opacity-50",
          defaultClassNames.disabled
        ),
        hidden: cn("invisible", defaultClassNames.hidden),
        ...classNames,
      }}
      components={{
        Root: ({ className, rootRef, ...props }) => {
          return (
            <div
              data-slot="calendar"
              ref={rootRef}
              className={cn(className)}
              {...props}
            />
          )
        },
        Chevron: ({ className, orientation, ...props }) => {
          if (orientation === "left") {
            return (
              <ChevronLeftIcon className={cn("size-4", className)} {...props} />
            )
          }

          if (orientation === "right") {
            return (
              <ChevronRightIcon
                className={cn("size-4", className)}
                {...props}
              />
            )
          }

          return (
            <ChevronDownIcon className={cn("size-4", className)} {...props} />
          )
        },
        DayButton: CalendarDayButton,
        WeekNumber: ({ children, ...props }) => {
          return (
            <td {...props}>
              <div className="flex size-(--cell-size) items-center justify-center text-center">
                {children}
              </div>
            </td>
          )
        },
        ...components,
      }}
      selected={withTime ? draftDate : selectedDate}
      onSelect={(withTime ? handleDraftSelect : handleSelect) as any}
      {...restProps}
    />
  )

  if (!withTime) {
    return dayPicker
  }

  return (
    <div className="flex flex-col" data-slot="calendar-with-time">
      {dayPicker}
      <div className="border-t px-3 pt-2 pb-1">
        <TimePicker openOnFocus value={draftTime} onValueChange={setDraftTime}>
          <TimePickerInputGroup className="h-8">
            <TimePickerInput segment="hour" placeholder="00" />
            <TimePickerSeparator />
            <TimePickerInput segment="minute" placeholder="00" />
            <TimePickerTrigger />
          </TimePickerInputGroup>
          <TimePickerContent>
            <TimePickerHour />
            <TimePickerMinute />
            <TimePickerPeriod />
          </TimePickerContent>
        </TimePicker>
      </div>
      <div className="px-3 pb-3 pt-1">
        <Button className="w-full" disabled={!draftDate} onClick={handleSave}>
          {Lang.key('save')}
        </Button>
      </div>
    </div>
  )
}

function CalendarDayButton({
  className,
  day,
  modifiers,
  ...props
}: React.ComponentProps<typeof DayButton>) {
  const defaultClassNames = getDefaultClassNames()

  const ref = React.useRef<HTMLButtonElement>(null)
  React.useEffect(() => {
    if (modifiers.focused) ref.current?.focus()
  }, [modifiers.focused])

  return (
    <Button
      ref={ref}
      variant="ghost"
      size="icon"
      data-day={day.date.toLocaleDateString()}
      data-selected-single={
        modifiers.selected &&
        !modifiers.range_start &&
        !modifiers.range_end &&
        !modifiers.range_middle
      }
      data-range-start={modifiers.range_start}
      data-range-end={modifiers.range_end}
      data-range-middle={modifiers.range_middle}
      className={cn(
        "data-[selected-single=true]:bg-primary data-[selected-single=true]:text-primary-foreground data-[range-middle=true]:bg-accent data-[range-middle=true]:text-accent-foreground data-[range-start=true]:bg-primary data-[range-start=true]:text-primary-foreground data-[range-end=true]:bg-primary data-[range-end=true]:text-primary-foreground group-data-[focused=true]/day:border-ring group-data-[focused=true]/day:ring-ring/50 dark:hover:text-accent-foreground flex aspect-square size-auto w-full min-w-(--cell-size) flex-col gap-1 leading-none font-normal group-data-[focused=true]/day:relative group-data-[focused=true]/day:z-10 group-data-[focused=true]/day:ring-[3px] data-[range-end=true]:rounded-md data-[range-end=true]:rounded-r-md data-[range-middle=true]:rounded-none data-[range-start=true]:rounded-md data-[range-start=true]:rounded-l-md [&>span]:text-xs [&>span]:opacity-70",
        defaultClassNames.day,
        className
      )}
      {...props}
    />
  )
}

export { Calendar, CalendarDayButton };
