/*
SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)

SPDX-License-Identifier: AGPL-3.0-only
*/

import { Editor, EditorChange, EditorConfiguration, ScrollInfo } from 'codemirror'
import 'codemirror/addon/comment/comment'
import 'codemirror/addon/dialog/dialog'
import 'codemirror/addon/display/autorefresh'
import 'codemirror/addon/display/fullscreen'
import 'codemirror/addon/display/placeholder'
import 'codemirror/addon/edit/closebrackets'
import 'codemirror/addon/edit/closetag'
import 'codemirror/addon/edit/continuelist'
import 'codemirror/addon/edit/matchbrackets'
import 'codemirror/addon/edit/matchtags'
import 'codemirror/addon/fold/foldcode'
import 'codemirror/addon/fold/foldgutter'
import 'codemirror/addon/fold/markdown-fold'
import 'codemirror/addon/hint/show-hint'
import 'codemirror/addon/search/jump-to-line'
import 'codemirror/addon/search/match-highlighter'
import 'codemirror/addon/search/search'
import 'codemirror/addon/selection/active-line'
import 'codemirror/keymap/emacs'
import 'codemirror/keymap/sublime'
import 'codemirror/keymap/vim'
import 'codemirror/mode/gfm/gfm'
import equal from 'fast-deep-equal'
import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react'
import { Controlled as ControlledCodeMirror } from 'react-codemirror2'
import { useTranslation } from 'react-i18next'
import { useSelector } from 'react-redux'
import { ApplicationState } from '../../../redux'
import { MaxLengthWarningModal } from '../editor-modals/max-length-warning-modal'
import { ScrollProps, ScrollState } from '../scroll/scroll-props'
import { allHinters, findWordAtCursor } from './autocompletion'
import './editor-pane.scss'
import { defaultKeyMap } from './key-map'
import { createStatusInfo, defaultState, StatusBar, StatusBarInfo } from './status-bar/status-bar'
import { ToolBar } from './tool-bar/tool-bar'
import { handleUpload } from './upload-handler'

export interface EditorPaneProps {
  onContentChange: (content: string) => void
  content: string
}

const onChange = (editor: Editor) => {
  for (const hinter of allHinters) {
    const searchTerm = findWordAtCursor(editor)
    if (hinter.wordRegExp.test(searchTerm.text)) {
      editor.showHint({
        hint: hinter.hint,
        completeSingle: false,
        completeOnSingleClick: false,
        alignWithWord: true
      })
      return
    }
  }
}

interface PasteEvent {
  clipboardData: {
    files: FileList
  },
  preventDefault: () => void
}

const onPaste = (pasteEditor: Editor, event: PasteEvent) => {
  if (event && event.clipboardData && event.clipboardData.files && event.clipboardData.files.length > 0) {
    event.preventDefault()
    const files: FileList = event.clipboardData.files
    if (files && files.length >= 1) {
      handleUpload(files[0], pasteEditor)
    }
  }
}

interface DropEvent {
  pageX: number,
  pageY: number,
  dataTransfer: {
    files: FileList
    effectAllowed: string
  } | null
  preventDefault: () => void
}

export const EditorPane: React.FC<EditorPaneProps & ScrollProps> = ({ onContentChange, content, scrollState, onScroll, onMakeScrollSource }) => {
  const { t } = useTranslation()
  const maxLength = useSelector((state: ApplicationState) => state.config.maxDocumentLength)
  const [showMaxLengthWarning, setShowMaxLengthWarning] = useState(false)
  const maxLengthWarningAlreadyShown = useRef(false)
  const [editor, setEditor] = useState<Editor>()
  const [statusBarInfo, setStatusBarInfo] = useState<StatusBarInfo>(defaultState)
  const editorPreferences = useSelector((state: ApplicationState) => state.editorConfig.preferences, equal)
  const ligaturesEnabled = useSelector((state: ApplicationState) => state.editorConfig.ligatures, equal)

  const lastScrollPosition = useRef<number>()
  const [editorScroll, setEditorScroll] = useState<ScrollInfo>()
  const onEditorScroll = useCallback((editor: Editor, data: ScrollInfo) => setEditorScroll(data), [])

  useEffect(() => {
    if (!editor || !onScroll || !editorScroll) {
      return
    }
    const scrollEventValue = editorScroll.top as number
    const line = editor.lineAtHeight(scrollEventValue, 'local')
    const startYOfLine = editor.heightAtLine(line, 'local')
    const lineInfo = editor.lineInfo(line)
    if (lineInfo === null) {
      return
    }
    const heightOfLine = (lineInfo.handle as { height: number }).height
    const percentageRaw = (Math.max(scrollEventValue - startYOfLine, 0)) / heightOfLine
    const percentage = Math.floor(percentageRaw * 100)

    const newScrollState: ScrollState = { firstLineInView: line + 1, scrolledPercentage: percentage }
    onScroll(newScrollState)
  }, [editor, editorScroll, onScroll])

  useEffect(() => {
    if (!editor || !scrollState) {
      return
    }
    const startYOfLine = editor.heightAtLine(scrollState.firstLineInView - 1, 'local')
    const heightOfLine = (editor.lineInfo(scrollState.firstLineInView - 1).handle as { height: number }).height
    const newPositionRaw = startYOfLine + (heightOfLine * scrollState.scrolledPercentage / 100)
    const newPosition = Math.floor(newPositionRaw)
    if (newPosition !== lastScrollPosition.current) {
      lastScrollPosition.current = newPosition
      editor.scrollTo(0, newPosition)
    }
  }, [editor, scrollState])

  const onBeforeChange = useCallback((editor: Editor, data: EditorChange, value: string) => {
    if (value.length > maxLength && !maxLengthWarningAlreadyShown.current) {
      setShowMaxLengthWarning(true)
      maxLengthWarningAlreadyShown.current = true
    }
    if (value.length <= maxLength) {
      maxLengthWarningAlreadyShown.current = false
    }
    onContentChange(value)
  }, [onContentChange, maxLength, maxLengthWarningAlreadyShown])
  const onEditorDidMount = useCallback(mountedEditor => {
    setStatusBarInfo(createStatusInfo(mountedEditor, maxLength))
    setEditor(mountedEditor)
  }, [maxLength])

  const onCursorActivity = useCallback((editorWithActivity) => {
    setStatusBarInfo(createStatusInfo(editorWithActivity, maxLength))
  }, [maxLength])

  const onDrop = useCallback((dropEditor: Editor, event: DropEvent) => {
    if (event && dropEditor && event.pageX && event.pageY && event.dataTransfer &&
      event.dataTransfer.files && event.dataTransfer.files.length >= 1) {
      event.preventDefault()
      const top: number = event.pageY
      const left: number = event.pageX
      const newCursor = dropEditor.coordsChar({ top, left }, 'page')
      dropEditor.setCursor(newCursor)
      const files: FileList = event.dataTransfer.files
      handleUpload(files[0], dropEditor)
    }
  }, [])

  const onMaxLengthHide = useCallback(() => setShowMaxLengthWarning(false), [])

  const codeMirrorOptions: EditorConfiguration = useMemo<EditorConfiguration>(() => ({
    ...editorPreferences,
    mode: 'gfm',
    viewportMargin: 20,
    styleActiveLine: true,
    lineNumbers: true,
    lineWrapping: true,
    showCursorWhenSelecting: true,
    highlightSelectionMatches: true,
    inputStyle: 'textarea',
    matchBrackets: true,
    autoCloseBrackets: true,
    matchTags: {
      bothTags: true
    },
    autoCloseTags: true,
    foldGutter: true,
    gutters: [
      'CodeMirror-linenumbers',
      'authorship-gutters',
      'CodeMirror-foldgutter'
    ],
    extraKeys: defaultKeyMap,
    flattenSpans: true,
    addModeClass: true,
    autoRefresh: true,
    // otherCursors: true,
    placeholder: t('editor.placeholder')
  }), [t, editorPreferences])

  return (
    <div className={'d-flex flex-column h-100 position-relative'} onMouseEnter={onMakeScrollSource}>
      <MaxLengthWarningModal show={showMaxLengthWarning} onHide={onMaxLengthHide} maxLength={maxLength}/>
      <ToolBar
        editor={editor}
      />
      <ControlledCodeMirror
        className={`overflow-hidden w-100 flex-fill ${ligaturesEnabled ? '' : 'no-ligatures'}`}
        value={content}
        options={codeMirrorOptions}
        onChange={onChange}
        onPaste={onPaste}
        onDrop={onDrop}
        onCursorActivity={onCursorActivity}
        editorDidMount={onEditorDidMount}
        onBeforeChange={onBeforeChange}
        onScroll={onEditorScroll}
      />
      <StatusBar {...statusBarInfo} />
    </div>
  )
}