import React, {
  createContext,
  useCallback,
  useReducer,
  useContext,
  useEffect,
} from 'react'
import PropTypes from 'prop-types'

import {
  renameInTree,
  deleteInTree,
  moveInTree,
  createEntityInTree,
} from '../util/mutate-in-tree'

const FileTreeMutableContext = createContext()

const ACTION_TYPES = {
  RENAME: 'RENAME',
  RESET: 'RESET',
  DELETE: 'DELETE',
  MOVE: 'MOVE',
  CREATE_ENTITY: 'CREATE_ENTITY',
}

function fileTreeMutableReducer({ fileTreeData }, action) {
  switch (action.type) {
    case ACTION_TYPES.RESET: {
      const newFileTreeData = action.fileTreeData

      return {
        fileTreeData: newFileTreeData,
        fileCount: countFiles(newFileTreeData),
      }
    }

    case ACTION_TYPES.RENAME: {
      const newFileTreeData = renameInTree(fileTreeData, action.id, {
        newName: action.newName,
      })

      return {
        fileTreeData: newFileTreeData,
        fileCount: countFiles(newFileTreeData),
      }
    }

    case ACTION_TYPES.DELETE: {
      const newFileTreeData = deleteInTree(fileTreeData, action.id)

      return {
        fileTreeData: newFileTreeData,
        fileCount: countFiles(newFileTreeData),
      }
    }

    case ACTION_TYPES.MOVE: {
      const newFileTreeData = moveInTree(
        fileTreeData,
        action.entityId,
        action.toFolderId
      )

      return {
        fileTreeData: newFileTreeData,
        fileCount: countFiles(newFileTreeData),
      }
    }

    case ACTION_TYPES.CREATE_ENTITY: {
      const newFileTreeData = createEntityInTree(
        fileTreeData,
        action.parentFolderId,
        action.entity
      )

      return {
        fileTreeData: newFileTreeData,
        fileCount: countFiles(newFileTreeData),
      }
    }

    default: {
      throw new Error(`Unknown mutable file tree action type: ${action.type}`)
    }
  }
}

const initialState = rootFolder => ({
  fileTreeData: rootFolder[0],
  fileCount: countFiles(rootFolder[0]),
})

export const FileTreeMutableProvider = function ({ rootFolder, children }) {
  const [{ fileTreeData, fileCount }, dispatch] = useReducer(
    fileTreeMutableReducer,
    rootFolder,
    initialState
  )

  useEffect(() => {
    dispatch({
      type: ACTION_TYPES.RESET,
      fileTreeData: rootFolder[0],
    })
  }, [rootFolder])

  const dispatchCreateFolder = useCallback((parentFolderId, entity) => {
    entity.type = 'folder'
    dispatch({
      type: ACTION_TYPES.CREATE_ENTITY,
      parentFolderId,
      entity,
    })
  }, [])

  const dispatchCreateDoc = useCallback((parentFolderId, entity) => {
    entity.type = 'doc'
    dispatch({
      type: ACTION_TYPES.CREATE_ENTITY,
      parentFolderId,
      entity,
    })
  }, [])

  const dispatchCreateFile = useCallback((parentFolderId, entity) => {
    entity.type = 'fileRef'
    dispatch({
      type: ACTION_TYPES.CREATE_ENTITY,
      parentFolderId,
      entity,
    })
  }, [])

  const dispatchRename = useCallback((id, newName) => {
    dispatch({
      type: ACTION_TYPES.RENAME,
      newName,
      id,
    })
  }, [])

  const dispatchDelete = useCallback(id => {
    dispatch({ type: ACTION_TYPES.DELETE, id })
  }, [])

  const dispatchMove = useCallback((entityId, toFolderId) => {
    dispatch({ type: ACTION_TYPES.MOVE, entityId, toFolderId })
  }, [])

  const value = {
    dispatchCreateDoc,
    dispatchCreateFile,
    dispatchCreateFolder,
    dispatchDelete,
    dispatchMove,
    dispatchRename,
    fileCount,
    fileTreeData,
  }

  return (
    <FileTreeMutableContext.Provider value={value}>
      {children}
    </FileTreeMutableContext.Provider>
  )
}

FileTreeMutableProvider.propTypes = {
  rootFolder: PropTypes.array.isRequired,
  children: PropTypes.oneOfType([
    PropTypes.arrayOf(PropTypes.node),
    PropTypes.node,
  ]).isRequired,
}

export function useFileTreeMutable() {
  const context = useContext(FileTreeMutableContext)

  if (!context) {
    throw new Error(
      'useFileTreeMutable is only available in FileTreeMutableProvider'
    )
  }

  return context
}

function filesInFolder({ docs, folders, fileRefs }) {
  const files = [...docs, ...fileRefs]

  for (const folder of folders) {
    files.push(...filesInFolder(folder))
  }

  return files
}

function countFiles(fileTreeData) {
  const files = filesInFolder(fileTreeData)

  // count all the non-deleted entities
  const value = files.filter(item => !item.deleted).length

  const limit = window.ExposedSettings.maxEntitiesPerProject
  const status = fileCountStatus(value, limit, Math.ceil(limit / 20))

  return { value, status, limit }
}

function fileCountStatus(value, limit, range) {
  if (value >= limit) {
    return 'error'
  }

  if (value >= limit - range) {
    return 'warning'
  }

  return 'success'
}