import PropTypes from 'prop-types'
import {
  createContext,
  useCallback,
  useContext,
  useLayoutEffect,
  useRef,
  useState
} from 'react'
import { HolderOutlined } from '@ant-design/icons'
import classNames from 'classnames'

const SegmentedNavReorderContext = createContext(null)

const getEnabledOptions = (options, disabled) =>
  options.filter((option) => !disabled && !option.disabled)

const getItemMetrics = (element) => {
  if (!element) {
    return null
  }

  return {
    left: element.offsetLeft,
    top: element.offsetTop,
    width: element.offsetWidth,
    height: element.offsetHeight
  }
}

export const SegmentedNavDragHandle = ({ value }) => {
  const reorder = useContext(SegmentedNavReorderContext)
  const dragProps = reorder?.getDragHandleProps?.(value)

  if (!dragProps) {
    return null
  }

  return (
    <span
      className='segmented-nav-drag-handle overview-drag-handle'
      draggable
      onClick={(event) => event.stopPropagation()}
      onMouseDown={(event) => event.stopPropagation()}
      onDragStart={(event) => dragProps.onDragStart(event)}
      onDragEnd={dragProps.onDragEnd}
    >
      <HolderOutlined />
    </span>
  )
}

SegmentedNavDragHandle.propTypes = {
  value: PropTypes.oneOfType([PropTypes.string, PropTypes.number]).isRequired
}

const SegmentedNav = ({
  value,
  options = [],
  onChange,
  onReorder,
  className,
  disabled = false
}) => {
  const groupRef = useRef(null)
  const thumbRef = useRef(null)
  const itemRefs = useRef(new Map())
  const prevValueRef = useRef(value)
  const transitionGenRef = useRef(0)
  const finishGenRef = useRef(0)
  const [isAnimating, setIsAnimating] = useState(false)
  const [thumbRect, setThumbRect] = useState(null)
  const [draggedValue, setDraggedValue] = useState(null)
  const [dropTarget, setDropTarget] = useState(null)

  const enabledOptions = getEnabledOptions(options, disabled)
  const isReordering = Boolean(onReorder && draggedValue != null)

  const setItemRef = useCallback((optionValue, element) => {
    if (element) {
      itemRefs.current.set(optionValue, element)
    } else {
      itemRefs.current.delete(optionValue)
    }
  }, [])

  useLayoutEffect(() => {
    if (prevValueRef.current === value) {
      return undefined
    }

    const fromMetrics = getItemMetrics(
      itemRefs.current.get(prevValueRef.current)
    )
    const toMetrics = getItemMetrics(itemRefs.current.get(value))
    prevValueRef.current = value

    if (!fromMetrics || !toMetrics) {
      return undefined
    }

    const transitionGen = transitionGenRef.current + 1
    transitionGenRef.current = transitionGen

    setIsAnimating(true)
    setThumbRect(fromMetrics)

    let endFrame = 0
    const startFrame = requestAnimationFrame(() => {
      endFrame = requestAnimationFrame(() => {
        if (transitionGenRef.current === transitionGen) {
          finishGenRef.current = transitionGen
          setThumbRect(toMetrics)
        }
      })
    })

    return () => {
      cancelAnimationFrame(startFrame)
      cancelAnimationFrame(endFrame)
    }
  }, [value])

  const finishAnimation = useCallback(() => {
    setIsAnimating(false)
    setThumbRect(null)
  }, [])

  const handleThumbTransitionEnd = useCallback(
    (event) => {
      if (event.target !== thumbRef.current) {
        return
      }

      if (
        (event.propertyName === 'transform' ||
          event.propertyName === 'width') &&
        finishGenRef.current === transitionGenRef.current
      ) {
        finishAnimation()
      }
    },
    [finishAnimation]
  )

  const clearDragState = useCallback(() => {
    setDraggedValue(null)
    setDropTarget(null)
  }, [])

  const handleDragStart = useCallback(
    (event, optionValue) => {
      if (!onReorder) return

      event.stopPropagation()
      const item = event.currentTarget.closest('.segmented-nav-item')
      if (item) {
        const rect = item.getBoundingClientRect()
        event.dataTransfer.setDragImage(
          item,
          event.clientX - rect.left,
          event.clientY - rect.top
        )
      }

      setDraggedValue(optionValue)
      event.dataTransfer.effectAllowed = 'move'
      event.dataTransfer.setData('text/plain', String(optionValue))
    },
    [onReorder]
  )

  const handleDragEnd = useCallback(() => {
    clearDragState()
  }, [clearDragState])

  const handleItemDragOver = useCallback(
    (event, option) => {
      if (!onReorder || draggedValue == null || !option.reorderable) {
        return
      }
      if (String(option.value) === String(draggedValue)) {
        return
      }

      event.preventDefault()
      event.stopPropagation()
      event.dataTransfer.dropEffect = 'move'

      const rect = event.currentTarget.getBoundingClientRect()
      setDropTarget({
        value: option.value,
        insertBefore: event.clientX < rect.left + rect.width / 2
      })
    },
    [draggedValue, onReorder]
  )

  const handleItemDrop = useCallback(
    (event, option) => {
      if (!onReorder || draggedValue == null || !option.reorderable) {
        return
      }

      event.preventDefault()
      event.stopPropagation()

      const target = dropTarget || {
        value: option.value,
        insertBefore: true
      }

      if (String(draggedValue) !== String(target.value)) {
        onReorder(draggedValue, target.value, target.insertBefore)
      }

      clearDragState()
    },
    [clearDragState, draggedValue, dropTarget, onReorder]
  )

  const handleGroupDragOver = useCallback(
    (event) => {
      if (!onReorder || draggedValue == null) {
        return
      }

      const reorderableOptions = options.filter((option) => option.reorderable)
      if (reorderableOptions.length === 0) {
        return
      }

      if (
        event.target instanceof Element &&
        event.target.closest('.segmented-nav-item')
      ) {
        return
      }

      event.preventDefault()
      event.dataTransfer.dropEffect = 'move'

      const lastOption = reorderableOptions[reorderableOptions.length - 1]
      setDropTarget({
        value: lastOption.value,
        insertBefore: false
      })
    },
    [draggedValue, onReorder, options]
  )

  const handleGroupDrop = useCallback(
    (event) => {
      if (!onReorder || draggedValue == null) {
        return
      }

      if (
        event.target instanceof Element &&
        event.target.closest('.segmented-nav-item')
      ) {
        return
      }

      event.preventDefault()
      event.stopPropagation()

      const reorderableOptions = options.filter((option) => option.reorderable)
      const lastOption = reorderableOptions[reorderableOptions.length - 1]
      if (lastOption && String(draggedValue) !== String(lastOption.value)) {
        onReorder(draggedValue, lastOption.value, false)
      }

      clearDragState()
    },
    [clearDragState, draggedValue, onReorder, options]
  )

  const getDragHandleProps = useCallback(
    (optionValue) => {
      const option = options.find(
        (item) => String(item.value) === String(optionValue)
      )
      if (!onReorder || !option?.reorderable) {
        return null
      }

      return {
        onDragStart: (event) => handleDragStart(event, optionValue),
        onDragEnd: handleDragEnd
      }
    },
    [handleDragEnd, handleDragStart, onReorder, options]
  )

  const handleKeyDown = (event, optionIndex) => {
    if (event.key !== 'ArrowRight' && event.key !== 'ArrowLeft') {
      return
    }

    event.preventDefault()

    const direction = event.key === 'ArrowRight' ? 1 : -1
    const currentEnabledIndex = enabledOptions.findIndex(
      (option) => option.value === value
    )
    const startIndex =
      currentEnabledIndex === -1 ? optionIndex : currentEnabledIndex
    const nextIndex =
      (startIndex + direction + enabledOptions.length) % enabledOptions.length

    onChange?.(enabledOptions[nextIndex].value)
  }

  const reorderContextValue = onReorder ? { getDragHandleProps } : null

  return (
    <SegmentedNavReorderContext.Provider value={reorderContextValue}>
      <div
        className={classNames('segmented-nav', className, {
          'segmented-nav-disabled': disabled,
          'segmented-nav-reordering': isReordering
        })}
        role='radiogroup'
      >
        <div
          className={classNames('segmented-nav-group', {
            'segmented-nav-animating': isAnimating
          })}
          ref={groupRef}
          onDragOver={handleGroupDragOver}
          onDrop={handleGroupDrop}
        >
          {isAnimating && thumbRect && (
            <div
              ref={thumbRef}
              className='segmented-nav-thumb'
              style={{
                width: thumbRect.width,
                height: thumbRect.height,
                transform: `translate3d(${thumbRect.left}px, ${thumbRect.top}px, 0)`
              }}
              onTransitionEnd={handleThumbTransitionEnd}
              aria-hidden='true'
            />
          )}
          {options.map((option, index) => {
            const isSelected = value === option.value
            const isDisabled = disabled || option.disabled
            const isDragging =
              draggedValue != null &&
              String(draggedValue) === String(option.value)
            const isDropTarget =
              dropTarget != null &&
              String(dropTarget.value) === String(option.value) &&
              String(draggedValue) !== String(option.value)

            return (
              <button
                key={option.value}
                ref={(element) => setItemRef(option.value, element)}
                type='button'
                role='radio'
                aria-checked={isSelected}
                disabled={isDisabled}
                tabIndex={isSelected ? 0 : -1}
                className={classNames('segmented-nav-item', option.className, {
                  'segmented-nav-item-selected': isSelected,
                  'segmented-nav-item-disabled': isDisabled,
                  'segmented-nav-item-dragging': isDragging,
                  'segmented-nav-item-drop-before':
                    isDropTarget && dropTarget.insertBefore,
                  'segmented-nav-item-drop-after':
                    isDropTarget && !dropTarget.insertBefore,
                  'segmented-nav-item-icon': option.icon
                })}
                onClick={() => {
                  if (!isDisabled) {
                    onChange?.(option.value)
                  }
                }}
                onKeyDown={(event) => handleKeyDown(event, index)}
                onDragOver={
                  option.reorderable
                    ? (event) => handleItemDragOver(event, option)
                    : undefined
                }
                onDrop={
                  option.reorderable
                    ? (event) => handleItemDrop(event, option)
                    : undefined
                }
              >
                {option.icon && (
                  <span className='segmented-nav-item-icon-contents'>
                    {option.icon}
                  </span>
                )}
                {option.label && (
                  <span className='segmented-nav-item-label'>
                    {option.label}
                  </span>
                )}
              </button>
            )
          })}
        </div>
      </div>
    </SegmentedNavReorderContext.Provider>
  )
}

SegmentedNav.propTypes = {
  value: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
  options: PropTypes.arrayOf(
    PropTypes.shape({
      value: PropTypes.oneOfType([PropTypes.string, PropTypes.number])
        .isRequired,
      label: PropTypes.node,
      disabled: PropTypes.bool,
      reorderable: PropTypes.bool,
      className: PropTypes.string
    })
  ),
  onChange: PropTypes.func,
  onReorder: PropTypes.func,
  className: PropTypes.string,
  disabled: PropTypes.bool
}

export default SegmentedNav