import React from 'react'
import SearchBar from './SearchBar'
import Node from './Node'

import cx from '../utils/cx'
import DOMHelper from '../utils/DOMHelper'
import treeParser from '../utils/treeParser'
import URLHelper from '../utils/URLHelper'
import VisibleNodesGenerator from '../utils/VisibleNodesGenerator'

function getVisibleParentNode(nodes, focusedNode, depths) {
  const focusedNodeIndex = nodes.indexOf(focusedNode)
  const focusedNodeDepth = depths.get(focusedNode)
  let indexOfParentNode = focusedNodeIndex - 1
  while (
    indexOfParentNode !== -1 &&
    depths.get(nodes[indexOfParentNode]) >= focusedNodeDepth
  ) {
    --indexOfParentNode
  }
  const parentNode = nodes[indexOfParentNode]
  return parentNode
}

export default class List extends React.Component {
  static defaultProps = {
    treeData: null,
    metaData: null,
    freeze: false,
  }

  state = {
    // generated by this.visibleNodesGenerator
    visibleNodes: null,
  }  

  tasksAfterRender = []
  visibleNodesGenerator = new VisibleNodesGenerator()

  componentWillMount() {
    const { treeData, metaData } = this.props
    const { root, nodes } = treeParser.parse(treeData, metaData)
    this.visibleNodesGenerator.plantTree(root, nodes)
    const currentPath = URLHelper.getCurrentPath(true)
    this.tasksAfterRender.push(DOMHelper.focusSearchInput)
    if (currentPath.length) {
      const nodeExpandedTo = this.visibleNodesGenerator.expandTo(currentPath)
      if (nodeExpandedTo) {
        this.visibleNodesGenerator.focusNode(nodeExpandedTo)
        const { nodes } = this.visibleNodesGenerator.visibleNodes
        this.tasksAfterRender.push(() => DOMHelper.scrollToNodeElement(nodes.indexOf(nodeExpandedTo)))
      }
    }
    this.updateVisibleNodes()
  }

  componentDidMount() {
    this.execAfterRender()
  }

  componentDidUpdate(prevProps, prevState) {
    this.execAfterRender()
  }

  execAfterRender() {
    for (const task of this.tasksAfterRender) {
      task()
    }
    this.tasksAfterRender.length = 0
  }

  updateVisibleNodes() {
    const { visibleNodes } = this.visibleNodesGenerator
    this.setState({ visibleNodes })
  }

  handleKeyDown = event => {
    const { key } = event
    const { visibleNodes: { nodes, focusedNode, expandedNodes, depths } } = this.state
    let shouldStopPropagation = true // prevent body scrolling
    if (focusedNode) {
      const focusedNodeIndex = nodes.indexOf(focusedNode)
      switch (key) {
        case 'ArrowUp':
          // focus on previous node
          if (focusedNodeIndex === 0) {
            this.focusNode(null)
            this.tasksAfterRender.push(DOMHelper.focusSearchInput)
          } else {
            this.focusNode(nodes[focusedNodeIndex - 1])
          }
          break

        case 'ArrowDown':
          // focus on next node
          if (focusedNodeIndex + 1 < nodes.length) {
            this.focusNode(nodes[focusedNodeIndex + 1])
          } else {
            this.focusNode(null)
            this.tasksAfterRender.push(DOMHelper.focusSearchInput)
          }
          break

        case 'ArrowLeft':
          // collapse node or go to parent node
          if (expandedNodes.has(focusedNode)) {
            this.setExpand(focusedNode, false)
          } else {
            // go forward to the start of the list, find the closest node with lower depth
            const parentNode = getVisibleParentNode(nodes, focusedNode, depths)
            if (parentNode) {
              this.focusNode(parentNode)
            }
          }
          break

        // consider the two keys as 'confirm' key
        case 'ArrowRight':
          // expand node or focus on first content node or redirect to file page
          if (focusedNode.type === 'tree') {
            if (expandedNodes.has(focusedNode)) {
              const nextNode = nodes[focusedNodeIndex + 1]
              if (depths.get(nextNode) > depths.get(focusedNode)) {
                this.focusNode(nextNode)
              }
            } else {
              this.setExpand(focusedNode, true)
            }
          } else if (focusedNode.type === 'blob') {
            DOMHelper.loadWithPJAX(focusedNode.url)
          } else if (focusedNode.type === 'commit') {
            // redirect to its parent folder
            DOMHelper.loadWithPJAX(focusedNode.parent.url)
          }
          break
        case 'Enter':
          // expand node or redirect to file page
          if (focusedNode.type === 'tree') {
            this.setExpand(focusedNode, true)
          } else if (focusedNode.type === 'blob') {
            DOMHelper.loadWithPJAX(focusedNode.url)
          } else if (focusedNode.type === 'commit') {
            // redirect to its parent folder
            DOMHelper.loadWithPJAX(focusedNode.parent.url)
          }
          break

        default:
          shouldStopPropagation = false
      }
    } else {
      // now search input is focused
      if (nodes.length) {
        switch (key) {
          case 'ArrowDown':
            this.focusNode(nodes[0])
            break
          case 'ArrowUp':
            this.focusNode(nodes[nodes.length - 1])
            break
          default:
            shouldStopPropagation = false
        }
      } else {
        shouldStopPropagation = false
      }
    }
    if (shouldStopPropagation) {
      event.stopPropagation()
      event.preventDefault()
    }
  }

  handleSearchKeyChange = async event => {
    const searchKey = event.target.value
    await this.visibleNodesGenerator.search(searchKey)
    this.updateVisibleNodes()
  }

  setExpand = (node, expand) => {
    this.visibleNodesGenerator.setExpand(node, expand)
    this.focusNode(node)
    this.tasksAfterRender.push(DOMHelper.focusSearchInput)
  }

  toggleNodeExpand = (node, skipScrollToNode) => {
    this.visibleNodesGenerator.toggleExpand(node)
    this.focusNode(node, skipScrollToNode)
    this.tasksAfterRender.push(DOMHelper.focusFileExplorer)
  }

  focusNode = (node, skipScroll) => {
    this.visibleNodesGenerator.focusNode(node)
    if (node && !skipScroll) {
      // when focus a node not in viewport(by keyboard), scroll to it
      const { visibleNodes: { nodes } } = this.state
      const indexOfToBeFocusedNode = nodes.indexOf(node)
      this.tasksAfterRender.push(() => DOMHelper.scrollToNodeElement(indexOfToBeFocusedNode))
      this.tasksAfterRender.push(DOMHelper.focusSearchInput)
    }
    this.updateVisibleNodes()
  }

  onNodeClick = (node) => {
    if (node.type === 'tree') {
      this.toggleNodeExpand(node, true)
    } else if (node.type === 'blob') {
      this.focusNode(node, true)
      DOMHelper.loadWithPJAX(node.url)
    } else if (node.type === 'commit') {
      DOMHelper.loadWithPJAX(node.parent.url)
    }
  }

  render() {
    const { visibleNodes: { nodes, depths, focusedNode, expandedNodes } } = this.state
    const { freeze } = this.props
    return (
      <div className={cx(`file-explorer`, { freeze })} tabIndex={-1} onKeyDown={this.handleKeyDown}>
        <SearchBar onSearchKeyChange={this.handleSearchKeyChange} />
        {nodes.length === 0 ? (
          <label className={'no-results'}>No results found.</label>
        ) : (
          <div className={'files'}>
            {nodes.map(node => (
              <Node
                key={node.path}
                node={node}
                depth={depths.get(node)}
                focused={focusedNode === node}
                expanded={expandedNodes.has(node)}
                onClick={this.onNodeClick}
              />
            ))}
          </div>
        )}
      </div>
    )
  }
}