'use client'

import type { ReactNode } from 'react'
import type { UserProfile } from '@/app/components/workflow/comment/types'
import { Avatar } from '@langgenius/dify-ui/avatar'
import { Button } from '@langgenius/dify-ui/button'
import { cn } from '@langgenius/dify-ui/cn'
import { RiArrowUpLine, RiAtLine, RiLoader2Line } from '@remixicon/react'
import {
  forwardRef,
  memo,
  useCallback,
  useEffect,
  useImperativeHandle,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from 'react'
import { createPortal } from 'react-dom'
import { useTranslation } from 'react-i18next'
import Textarea from 'react-textarea-autosize'
import EnterKey from '@/app/components/base/icons/src/public/common/EnterKey'
import { useParams } from '@/next/navigation'
import { consoleClient } from '@/service/client'
import { useStore, useWorkflowStore } from '../store'

type MentionInputProps = {
  value: string
  onChange: (value: string) => void
  onSubmit: (content: string, mentionedUserIds: string[]) => void
  onCancel?: () => void
  placeholder?: string
  disabled?: boolean
  loading?: boolean
  className?: string
  isEditing?: boolean
  autoFocus?: boolean
}

const EMPTY_USERS: UserProfile[] = []

const MentionInputInner = forwardRef<HTMLTextAreaElement, MentionInputProps>(
  (
    {
      value,
      onChange,
      onSubmit,
      onCancel,
      placeholder,
      disabled = false,
      loading = false,
      className,
      isEditing = false,
      autoFocus = false,
    },
    forwardedRef,
  ) => {
    const params = useParams()
    const { t } = useTranslation()
    const appId = params.appId as string
    const textareaRef = useRef<HTMLTextAreaElement>(null)
    const highlightContentRef = useRef<HTMLDivElement>(null)
    const actionContainerRef = useRef<HTMLDivElement | null>(null)
    const actionRightRef = useRef<HTMLDivElement | null>(null)
    const baseTextareaHeightRef = useRef<number | null>(null)

    // Expose textarea ref to parent component
    useImperativeHandle(forwardedRef, () => textareaRef.current!, [])

    const workflowStore = useWorkflowStore()
    const mentionUsersFromStore = useStore((state) =>
      appId ? state.mentionableUsersCache[appId] : undefined,
    )
    const mentionUsers = useMemo(
      () => mentionUsersFromStore ?? EMPTY_USERS,
      [mentionUsersFromStore],
    )

    const [showMentionDropdown, setShowMentionDropdown] = useState(false)
    const [mentionQuery, setMentionQuery] = useState('')
    const [mentionPosition, setMentionPosition] = useState(0)
    const [selectedMentionIndex, setSelectedMentionIndex] = useState(0)
    const [mentionedUserIds, setMentionedUserIds] = useState<string[]>([])
    const resolvedPlaceholder =
      placeholder ?? t(($) => $['comments.placeholder.add'], { ns: 'workflow' })
    const BASE_PADDING = 4
    const [shouldReserveButtonGap, setShouldReserveButtonGap] = useState(isEditing)
    const [shouldReserveHorizontalSpace, setShouldReserveHorizontalSpace] = useState(
      () => !isEditing,
    )
    const [paddingRight, setPaddingRight] = useState(() => BASE_PADDING + (isEditing ? 0 : 48))
    const [paddingBottom, setPaddingBottom] = useState(() => BASE_PADDING + (isEditing ? 32 : 0))

    const mentionNameList = useMemo(() => {
      const names = mentionUsers
        .map((user) => user.name?.trim())
        .filter((name): name is string => Boolean(name))

      const uniqueNames = Array.from(new Set(names))
      uniqueNames.sort((a, b) => b.length - a.length)
      return uniqueNames
    }, [mentionUsers])

    const highlightedValue = useMemo<ReactNode>(() => {
      if (!value) return ''

      if (mentionNameList.length === 0) return value

      const segments: ReactNode[] = []
      let cursor = 0
      let hasMention = false

      while (cursor < value.length) {
        let nextMatchStart = -1
        let matchedName = ''

        for (const name of mentionNameList) {
          const searchStart = value.indexOf(`@${name}`, cursor)
          if (searchStart === -1) continue

          const previousChar = searchStart > 0 ? value[searchStart - 1] : ''
          if (searchStart > 0 && !/\s/.test(previousChar!)) continue

          if (
            nextMatchStart === -1 ||
            searchStart < nextMatchStart ||
            (searchStart === nextMatchStart && name.length > matchedName.length)
          ) {
            nextMatchStart = searchStart
            matchedName = name
          }
        }

        if (nextMatchStart === -1) break

        if (nextMatchStart > cursor)
          segments.push(<span key={`text-${cursor}`}>{value.slice(cursor, nextMatchStart)}</span>)

        const mentionEnd = nextMatchStart + matchedName.length + 1
        segments.push(
          <span key={`mention-${nextMatchStart}`} className="text-primary-600">
            {value.slice(nextMatchStart, mentionEnd)}
          </span>,
        )

        hasMention = true
        cursor = mentionEnd
      }

      if (!hasMention) return value

      if (cursor < value.length)
        segments.push(<span key={`text-${cursor}`}>{value.slice(cursor)}</span>)

      return segments
    }, [value, mentionNameList])

    const loadMentionableUsers = useCallback(async () => {
      if (!appId) return

      const state = workflowStore.getState()
      if (state.mentionableUsersCache[appId] !== undefined) return

      if (state.mentionableUsersLoading[appId]) return

      state.setMentionableUsersLoading(appId, true)
      try {
        const response = await consoleClient.apps.byAppId.workflow.comments.mentionUsers.get({
          params: { app_id: appId },
        })
        workflowStore.getState().setMentionableUsersCache(appId, response.users)
      } catch (error) {
        console.error('Failed to load mentionable users:', error)
      } finally {
        workflowStore.getState().setMentionableUsersLoading(appId, false)
      }
    }, [appId, workflowStore])

    useEffect(() => {
      loadMentionableUsers()
    }, [loadMentionableUsers])
    const syncHighlightScroll = useCallback(() => {
      const textarea = textareaRef.current
      const highlightContent = highlightContentRef.current
      if (!textarea || !highlightContent) return

      const { scrollTop, scrollLeft } = textarea
      highlightContent.style.transform = `translate(${-scrollLeft}px, ${-scrollTop}px)`
    }, [])

    const evaluateContentLayout = useCallback(() => {
      const textarea = textareaRef.current
      if (!textarea) return

      const extraBottom = Math.max(0, paddingBottom - BASE_PADDING)
      const effectiveClientHeight = textarea.clientHeight - extraBottom

      if (baseTextareaHeightRef.current === null)
        baseTextareaHeightRef.current = effectiveClientHeight

      const baseHeight = baseTextareaHeightRef.current ?? effectiveClientHeight
      const hasMultiline = effectiveClientHeight > baseHeight + 1
      const shouldReserveVertical = isEditing ? true : hasMultiline

      setShouldReserveButtonGap(shouldReserveVertical)
      setShouldReserveHorizontalSpace(!hasMultiline)
    }, [isEditing, paddingBottom])

    const updateLayoutPadding = useCallback(() => {
      const actionEl = actionContainerRef.current
      const rect = actionEl?.getBoundingClientRect()
      const rightRect = actionRightRef.current?.getBoundingClientRect()
      let actionWidth = 0
      if (rightRect) actionWidth = Math.ceil(rightRect.width)
      else if (rect) actionWidth = Math.ceil(rect.width)

      const actionHeight = rect ? Math.ceil(rect.height) : 0
      const fallbackWidth = Math.max(0, paddingRight - BASE_PADDING)
      const fallbackHeight = Math.max(0, paddingBottom - BASE_PADDING)
      const effectiveWidth = actionWidth > 0 ? actionWidth : fallbackWidth
      const effectiveHeight = actionHeight > 0 ? actionHeight : fallbackHeight

      const nextRight = BASE_PADDING + (shouldReserveHorizontalSpace ? effectiveWidth : 0)
      const nextBottom = BASE_PADDING + (shouldReserveButtonGap ? effectiveHeight : 0)

      setPaddingRight((prev) => (prev === nextRight ? prev : nextRight))
      setPaddingBottom((prev) => (prev === nextBottom ? prev : nextBottom))
    }, [shouldReserveButtonGap, shouldReserveHorizontalSpace, paddingRight, paddingBottom])

    const setActionContainerRef = useCallback(
      (node: HTMLDivElement | null) => {
        actionContainerRef.current = node

        if (!isEditing) actionRightRef.current = node
        else if (!node) actionRightRef.current = null

        if (node && typeof window !== 'undefined')
          window.requestAnimationFrame(() => updateLayoutPadding())
      },
      [isEditing, updateLayoutPadding],
    )

    const setActionRightRef = useCallback(
      (node: HTMLDivElement | null) => {
        actionRightRef.current = node

        if (node && typeof window !== 'undefined')
          window.requestAnimationFrame(() => updateLayoutPadding())
      },
      [updateLayoutPadding],
    )

    useLayoutEffect(() => {
      syncHighlightScroll()
    }, [value, syncHighlightScroll])

    useLayoutEffect(() => {
      Promise.resolve().then(() => {
        evaluateContentLayout()
      })
    }, [value, evaluateContentLayout])

    useLayoutEffect(() => {
      Promise.resolve().then(() => {
        updateLayoutPadding()
      })
    }, [updateLayoutPadding, isEditing, shouldReserveButtonGap])

    useEffect(() => {
      const handleResize = () => {
        evaluateContentLayout()
        updateLayoutPadding()
      }

      window.addEventListener('resize', handleResize)
      return () => window.removeEventListener('resize', handleResize)
    }, [evaluateContentLayout, updateLayoutPadding])

    useEffect(() => {
      Promise.resolve().then(() => {
        baseTextareaHeightRef.current = null
        evaluateContentLayout()
        setShouldReserveHorizontalSpace(!isEditing)
      })
    }, [isEditing, evaluateContentLayout])

    const filteredMentionUsers = useMemo(() => {
      if (!mentionQuery) return mentionUsers
      return mentionUsers.filter(
        (user) =>
          user.name.toLowerCase().includes(mentionQuery.toLowerCase()) ||
          user.email.toLowerCase().includes(mentionQuery.toLowerCase()),
      )
    }, [mentionUsers, mentionQuery])

    const shouldDisableMentionButton = useMemo(() => {
      if (showMentionDropdown) return true

      const textarea = textareaRef.current
      if (!textarea) return false

      const cursorPosition = textarea.selectionStart || 0
      const textBeforeCursor = value.slice(0, cursorPosition)
      return /@\w*$/.test(textBeforeCursor)
    }, [showMentionDropdown, value])

    const dropdownPosition = useMemo(() => {
      if (!showMentionDropdown || !textareaRef.current)
        return { x: 0, y: 0, placement: 'bottom' as const }

      const textareaRect = textareaRef.current.getBoundingClientRect()
      const dropdownHeight = 160 // max-h-40 = 10rem = 160px
      const viewportHeight = window.innerHeight
      const spaceBelow = viewportHeight - textareaRect.bottom
      const spaceAbove = textareaRect.top

      const shouldPlaceAbove = spaceBelow < dropdownHeight && spaceAbove > spaceBelow

      return {
        x: textareaRect.left,
        y: shouldPlaceAbove ? textareaRect.top - 4 : textareaRect.bottom + 4,
        placement: shouldPlaceAbove ? ('top' as const) : ('bottom' as const),
      }
    }, [showMentionDropdown])

    const handleContentChange = useCallback(
      (newValue: string) => {
        onChange(newValue)

        setTimeout(() => {
          const cursorPosition = textareaRef.current?.selectionStart || 0
          const textBeforeCursor = newValue.slice(0, cursorPosition)
          const mentionMatch = textBeforeCursor.match(/@(\w*)$/)

          if (mentionMatch) {
            setMentionQuery(mentionMatch[1]!)
            setMentionPosition(cursorPosition - mentionMatch[0].length)
            setShowMentionDropdown(true)
            setSelectedMentionIndex(0)
          } else {
            setShowMentionDropdown(false)
          }

          if (typeof window !== 'undefined') {
            window.requestAnimationFrame(() => {
              evaluateContentLayout()
              syncHighlightScroll()
            })
          }
        }, 0)
      },
      [onChange, evaluateContentLayout, syncHighlightScroll],
    )

    const handleMentionButtonClick = useCallback(
      (e: React.MouseEvent) => {
        e.preventDefault()
        e.stopPropagation()

        const textarea = textareaRef.current
        if (!textarea) return

        const cursorPosition = textarea.selectionStart || 0
        const textBeforeCursor = value.slice(0, cursorPosition)

        if (showMentionDropdown) return

        if (/@\w*$/.test(textBeforeCursor)) return

        const newContent = `${value.slice(0, cursorPosition)}@${value.slice(cursorPosition)}`

        onChange(newContent)

        setTimeout(() => {
          const newCursorPos = cursorPosition + 1
          textarea.setSelectionRange(newCursorPos, newCursorPos)
          textarea.focus()

          setMentionQuery('')
          setMentionPosition(cursorPosition)
          setShowMentionDropdown(true)
          setSelectedMentionIndex(0)

          if (typeof window !== 'undefined') {
            window.requestAnimationFrame(() => {
              evaluateContentLayout()
              syncHighlightScroll()
            })
          }
        }, 0)
      },
      [value, onChange, evaluateContentLayout, syncHighlightScroll, showMentionDropdown],
    )

    const insertMention = useCallback(
      (user: UserProfile) => {
        const textarea = textareaRef.current
        if (!textarea) return

        const beforeMention = value.slice(0, mentionPosition)
        const afterMention = value.slice(textarea.selectionStart || 0)

        const needsSpaceBefore = mentionPosition > 0 && !/\s/.test(value[mentionPosition - 1]!)
        const prefix = needsSpaceBefore ? ' ' : ''
        const newContent = `${beforeMention}${prefix}@${user.name} ${afterMention}`

        onChange(newContent)
        setShowMentionDropdown(false)

        const newMentionedUserIds = [...mentionedUserIds, user.id]
        setMentionedUserIds(newMentionedUserIds)

        setTimeout(() => {
          const extraSpace = needsSpaceBefore ? 1 : 0
          const newCursorPos = mentionPosition + extraSpace + user.name.length + 2 // (space) + @ + name + space
          textarea.setSelectionRange(newCursorPos, newCursorPos)
          textarea.focus()
          if (typeof window !== 'undefined') {
            window.requestAnimationFrame(() => {
              evaluateContentLayout()
              syncHighlightScroll()
            })
          }
        }, 0)
      },
      [
        value,
        mentionPosition,
        onChange,
        mentionedUserIds,
        evaluateContentLayout,
        syncHighlightScroll,
      ],
    )

    const handleSubmit = useCallback(
      async (e?: React.MouseEvent) => {
        if (e) {
          e.preventDefault()
          e.stopPropagation()
        }

        if (value.trim()) {
          try {
            await onSubmit(value.trim(), mentionedUserIds)
            setMentionedUserIds([])
            setShowMentionDropdown(false)
          } catch (error) {
            console.error('Failed to submit', error)
          }
        }
      },
      [value, mentionedUserIds, onSubmit],
    )

    const handleKeyDown = useCallback(
      (e: React.KeyboardEvent) => {
        // Ignore key events during IME composition (e.g., Chinese, Japanese input)
        if (e.nativeEvent.isComposing) return

        if (showMentionDropdown) {
          if (e.key === 'ArrowDown') {
            e.preventDefault()
            setSelectedMentionIndex((prev) =>
              prev < filteredMentionUsers.length - 1 ? prev + 1 : 0,
            )
          } else if (e.key === 'ArrowUp') {
            e.preventDefault()
            setSelectedMentionIndex((prev) =>
              prev > 0 ? prev - 1 : filteredMentionUsers.length - 1,
            )
          } else if (e.key === 'Enter') {
            e.preventDefault()
            if (filteredMentionUsers[selectedMentionIndex])
              insertMention(filteredMentionUsers[selectedMentionIndex])

            return
          } else if (e.key === 'Escape') {
            e.preventDefault()
            setShowMentionDropdown(false)
            return
          }
        }

        if (e.key === 'Enter' && !e.shiftKey && !showMentionDropdown) {
          e.preventDefault()
          handleSubmit()
        }
      },
      [
        showMentionDropdown,
        filteredMentionUsers,
        selectedMentionIndex,
        insertMention,
        handleSubmit,
      ],
    )

    const resetMentionState = useCallback(() => {
      setMentionedUserIds([])
      setShowMentionDropdown(false)
      setMentionQuery('')
      setMentionPosition(0)
      setSelectedMentionIndex(0)
    }, [])

    useEffect(() => {
      if (!value) {
        Promise.resolve().then(() => {
          resetMentionState()
        })
      }
    }, [value, resetMentionState])

    useEffect(() => {
      if (!autoFocus || !textareaRef.current) return

      const textarea = textareaRef.current
      const timeout = window.setTimeout(() => {
        textarea.focus()
        const length = textarea.value.length
        textarea.setSelectionRange(length, length)
      }, 0)

      return () => window.clearTimeout(timeout)
    }, [autoFocus])

    return (
      <>
        <div className={cn('relative flex items-center', className)}>
          <div
            aria-hidden
            className={cn(
              'pointer-events-none absolute inset-0 z-0 overflow-hidden p-1 leading-6 wrap-break-word whitespace-pre-wrap',
              'body-lg-regular text-text-primary',
            )}
            style={{ paddingRight, paddingBottom }}
          >
            <div
              ref={highlightContentRef}
              className="min-h-full"
              style={{ willChange: 'transform' }}
            >
              {highlightedValue}
            </div>
          </div>
          <Textarea
            ref={textareaRef}
            className={cn(
              'relative z-10 w-full resize-none bg-transparent p-1 body-lg-regular leading-6 text-transparent caret-primary-500 outline-hidden',
              'placeholder:text-text-tertiary',
            )}
            style={{ paddingRight, paddingBottom }}
            placeholder={resolvedPlaceholder}
            autoFocus={autoFocus}
            minRows={isEditing ? 4 : 1}
            maxRows={4}
            value={value}
            disabled={disabled || loading}
            onChange={(e) => handleContentChange(e.target.value)}
            onKeyDown={handleKeyDown}
            onScroll={syncHighlightScroll}
          />

          {!isEditing && (
            <div
              ref={setActionContainerRef}
              className="absolute right-1 bottom-0 z-20 flex items-end gap-1"
            >
              <div
                className={cn(
                  'z-20 flex size-8 items-center justify-center rounded-lg transition-opacity',
                  shouldDisableMentionButton
                    ? 'cursor-not-allowed opacity-40'
                    : 'cursor-pointer hover:bg-state-base-hover',
                )}
                onClick={shouldDisableMentionButton ? undefined : handleMentionButtonClick}
              >
                <RiAtLine className="size-4 text-text-tertiary" />
              </div>
              <Button
                className="z-20 ml-2 w-8 px-0"
                variant="primary"
                disabled={!value.trim() || disabled || loading}
                onClick={handleSubmit}
              >
                {loading ? (
                  <RiLoader2Line className="size-4 animate-spin text-components-button-primary-text" />
                ) : (
                  <RiArrowUpLine className="size-4 text-components-button-primary-text" />
                )}
              </Button>
            </div>
          )}

          {isEditing && (
            <div
              ref={setActionContainerRef}
              className="absolute inset-x-1 bottom-0 z-20 flex items-end justify-between"
            >
              <div
                className={cn(
                  'z-20 flex size-8 items-center justify-center rounded-lg transition-opacity',
                  shouldDisableMentionButton
                    ? 'cursor-not-allowed opacity-40'
                    : 'cursor-pointer hover:bg-state-base-hover',
                )}
                onClick={shouldDisableMentionButton ? undefined : handleMentionButtonClick}
              >
                <RiAtLine className="size-4 text-text-tertiary" />
              </div>
              <div ref={setActionRightRef} className="flex items-center gap-2">
                <Button variant="secondary" size="small" onClick={onCancel} disabled={loading}>
                  {t(($) => $['operation.cancel'], { ns: 'common' })}
                </Button>
                <Button
                  variant="primary"
                  size="small"
                  disabled={loading || !value.trim()}
                  onClick={() => handleSubmit()}
                  className="gap-1"
                >
                  {loading && <RiLoader2Line className="mr-1 size-3.5 animate-spin" />}
                  <span>{t(($) => $['operation.save'], { ns: 'common' })}</span>
                  {!loading && <EnterKey className="size-4" />}
                </Button>
              </div>
            </div>
          )}
        </div>

        {showMentionDropdown &&
          filteredMentionUsers.length > 0 &&
          typeof document !== 'undefined' &&
          createPortal(
            <div
              className="fixed z-50 max-h-62 w-70 overflow-y-auto rounded-xl border-[0.5px] border-components-panel-border bg-components-panel-bg/95 shadow-lg backdrop-blur-[10px]"
              style={{
                left: dropdownPosition.x,
                [dropdownPosition.placement === 'top' ? 'bottom' : 'top']:
                  dropdownPosition.placement === 'top'
                    ? window.innerHeight - dropdownPosition.y
                    : dropdownPosition.y,
              }}
              data-mention-dropdown
            >
              {filteredMentionUsers.map((user, index) => (
                <div
                  key={user.id}
                  className={cn(
                    'flex cursor-pointer items-center gap-2 rounded-md py-1 pr-3 pl-2 hover:bg-state-base-hover',
                    index === selectedMentionIndex && 'bg-state-base-hover',
                  )}
                  onClick={() => insertMention(user)}
                >
                  <Avatar
                    avatar={user.avatar_url || null}
                    name={user.name}
                    size="sm"
                    className="shrink-0"
                  />
                  <div className="min-w-0 flex-1">
                    <div className="truncate text-sm font-medium text-text-primary">
                      {user.name}
                    </div>
                    <div className="truncate text-xs text-text-tertiary">{user.email}</div>
                  </div>
                </div>
              ))}
            </div>,
            document.body,
          )}
      </>
    )
  },
)

MentionInputInner.displayName = 'MentionInputInner'

export const MentionInput = memo(MentionInputInner)
