import { linter } from '@codemirror/lint' // statically imported by @uiw/codemirror-extensions-basic-setup
import { EditorView } from '@codemirror/view'
import { Extension, keymap } from '@uiw/react-codemirror'
import { useEffect, useMemo, useState } from 'react'

import { getNormalizedExtension } from './utils'

/** 语言对应的 linter 加载器
 * key: 语言文件扩展名（不包含 `.`）
 */
const linterLoaders: Record<string, () => Promise<any>> = {
  json: async () => {
    const jsonParseLinter = await import('@codemirror/lang-json').then((mod) => mod.jsonParseLinter)
    return linter(jsonParseLinter())
  }
}

/**
 * 特殊语言加载器
 * key: 语言文件扩展名（不包含 `.`）
 */
const specialLanguageLoaders: Record<string, () => Promise<Extension>> = {
  dot: async () => {
    const mod = await import('@viz-js/lang-dot')
    return mod.dot()
  },
  // @uiw/codemirror-extensions-langs 4.25.1 移除了 mermaid 支持，这里加回来
  mmd: async () => {
    const mod = await import('codemirror-lang-mermaid')
    return mod.mermaid()
  }
}

/**
 * 加载语言扩展
 */
async function loadLanguageExtension(language: string): Promise<Extension | null> {
  const fileExt = await getNormalizedExtension(language)

  // 尝试加载特殊语言
  const specialLoader = specialLanguageLoaders[fileExt]
  if (specialLoader) {
    try {
      return await specialLoader()
    } catch (error) {
      console.debug(`Failed to load language ${language} (${fileExt})`, error as Error)
      return null
    }
  }

  // 回退到 uiw/codemirror 包含的语言
  try {
    const { loadLanguage } = await import('@uiw/codemirror-extensions-langs')
    const extension = loadLanguage(fileExt as any)
    return extension || null
  } catch (error) {
    console.debug(`Failed to load language ${language} (${fileExt})`, error as Error)
    return null
  }
}

/**
 * 加载 linter 扩展
 */
async function loadLinterExtension(language: string): Promise<Extension | null> {
  const fileExt = await getNormalizedExtension(language)

  const loader = linterLoaders[fileExt]
  if (!loader) return null

  try {
    return await loader()
  } catch (error) {
    console.debug(`Failed to load linter for ${language} (${fileExt})`, error as Error)
    return null
  }
}

/**
 * 加载语言相关扩展
 */
export const useLanguageExtensions = (language: string, lint?: boolean) => {
  const [extensions, setExtensions] = useState<Extension[]>([])

  useEffect(() => {
    let cancelled = false

    const loadAllExtensions = async () => {
      try {
        // 加载所有扩展
        const [languageResult, linterResult] = await Promise.allSettled([
          loadLanguageExtension(language),
          lint ? loadLinterExtension(language) : Promise.resolve(null)
        ])

        if (cancelled) return

        const results: Extension[] = []

        // 语言扩展
        if (languageResult.status === 'fulfilled' && languageResult.value) {
          results.push(languageResult.value)
        }

        // linter 扩展
        if (linterResult.status === 'fulfilled' && linterResult.value) {
          results.push(linterResult.value)
        }

        setExtensions(results)
      } catch (error) {
        if (!cancelled) {
          console.debug('Failed to load language extensions:', error as Error)
          setExtensions([])
        }
      }
    }

    loadAllExtensions()

    return () => {
      cancelled = true
    }
  }, [language, lint])

  return extensions
}

interface UseSaveKeymapProps {
  onSave?: (content: string) => void
  enabled?: boolean
}

/**
 * CodeMirror 扩展，用于处理保存快捷键 (Cmd/Ctrl + S)
 * @param onSave 保存时触发的回调函数
 * @param enabled 是否启用此快捷键
 * @returns 扩展或空数组
 */
export function useSaveKeymap({ onSave, enabled = true }: UseSaveKeymapProps) {
  return useMemo(() => {
    if (!enabled || !onSave) {
      return []
    }

    return keymap.of([
      {
        key: 'Mod-s',
        run: (view: EditorView) => {
          onSave(view.state.doc.toString())
          return true
        },
        preventDefault: true
      }
    ])
  }, [onSave, enabled])
}

interface UseBlurHandlerProps {
  onBlur?: (content: string) => void
}

/**
 * CodeMirror 扩展，用于处理编辑器的 blur 事件
 * @param onBlur blur 事件触发时的回调函数
 * @returns 扩展或空数组
 */
export function useBlurHandler({ onBlur }: UseBlurHandlerProps) {
  return useMemo(() => {
    if (!onBlur) {
      return []
    }
    return EditorView.domEventHandlers({
      blur: (_event, view) => {
        onBlur(view.state.doc.toString())
      }
    })
  }, [onBlur])
}

interface UseHeightListenerProps {
  onHeightChange?: (scrollHeight: number) => void
}

/**
 * CodeMirror 扩展，用于监听编辑器高度变化
 * @param onHeightChange 高度变化时触发的回调函数
 * @returns 扩展或空数组
 */
export function useHeightListener({ onHeightChange }: UseHeightListenerProps) {
  return useMemo(() => {
    if (!onHeightChange) {
      return []
    }

    return EditorView.updateListener.of((update) => {
      if (update.docChanged || update.heightChanged) {
        onHeightChange(update.view.scrollDOM?.scrollHeight ?? 0)
      }
    })
  }, [onHeightChange])
}