// tslint:disable:no-conditional-assignment

import {
  DocumentHighlightProvider, TextDocument, Position, CancellationToken, Range, DocumentHighlight
} from 'vscode'

import { Config } from './lib/config'

const TagRegexp = /<([\w:-]+)|<\/([\w:-]+)>/g

export default class WxmlDocumentHighlight implements DocumentHighlightProvider {
  constructor(public config: Config) {}

  provideDocumentHighlights(doc: TextDocument, pos: Position, token: CancellationToken) {
    let range = doc.getWordRangeAtPosition(pos, /[\w:-]+/)
    if (!range) return []

    let content = doc.getText()
    let name = doc.getText(range)
    let res: Range[] = [range]

    if (prev(doc, range.start) === '<') { // start tag
      let nextStartIndex = doc.offsetAt(range.end)
      let nextText = this.normalize(content.slice(nextStartIndex))

      if (!(/^[^<>]*\/>/.test(nextText))) { // not self close tag
        let nextEndIndex = this.findMatchedEndTag(name, nextText)
        if (typeof nextEndIndex === 'number') {
          res.push(new Range(
            doc.positionAt(nextStartIndex + nextEndIndex + 2),
            doc.positionAt(nextStartIndex + nextEndIndex + 2 + name.length)
          ))
        }
      }
    } else if (prev(doc, range.start, 2) === '</' && next(doc, range.end, 1) === '>') { // end tag
      let prevEndIndex = doc.offsetAt(range.start) - 2
      let prevText = this.normalize(content.slice(0, prevEndIndex))
      let prevStartIndex = this.findMatchedStartTag(name, prevText)
      if (typeof prevStartIndex === 'number') {
        res.push(new Range(
          doc.positionAt(prevStartIndex + 1),
          doc.positionAt(prevStartIndex + 1 + name.length)
        ))
      }
    }

    return res.map(r => new DocumentHighlight(r))
  }

  /**
   * 因为只需要 tag，所以这里把所有的注释属性替换成特殊字符
   */
  private normalize(content: string) {
    let replacer = (raw: string) => new Array(raw.length).fill(' ').join('')

    return content
      .replace(/<!--.*?-->/g, replacer)         // 去除注释
      .replace(/("[^"]*"|'[^']*')/g, replacer)  // 去除属性
      // .replace(/>[\s\S]*?</g, (raw) => '>' + replacer(raw.substr(2)) + '<') // 去除标签内容
      .replace(/<[\w:-]+\s+[^<>]*\/>/g, replacer)          // 去除自闭合的标签
  }

  private findMatchedEndTag(name: string, nextContent: string) {
    TagRegexp.lastIndex = 0
    let mat: RegExpExecArray | null
    let stack: string[] = []
    while (mat = TagRegexp.exec(nextContent)) {
      let [, startName, endName] = mat
      if (startName) {
        stack.push(startName)
      } else if (endName) {
        let last = stack.pop()
        if (!last) { // 最后一个了
          if (endName === name) {
            return mat.index
          }
        } else if (last !== endName) { // wxml 解析错误
          break
        }
      }
    }
    return
  }
  private findMatchedStartTag(name: string, prevContent: string) {
    TagRegexp.lastIndex = 0
    let mat: RegExpExecArray | null
    let stack: Array<[string, number]> = []
    while (mat = TagRegexp.exec(prevContent)) {
      let [, startName, endName] = mat
      if (startName) {
        stack.push([startName, mat.index])
      } else if (endName) {
        let last = stack.pop()
        if (!last) {
          break
        } else if (last[0] !== endName) { // wxml 解析错误
          break
        }
      }
    }
    let l = stack[stack.length - 1]
    return l ? l[1] : undefined
  }
}

function next(doc: TextDocument, pos: Position, length: number = 1) {
  let start = new Position(pos.line, pos.character)
  let end = new Position(pos.line, pos.character + length)
  return doc.getText(new Range(start, end))
}
function prev(doc: TextDocument, pos: Position, length: number = 1) {
  let start = new Position(pos.line, pos.character - length)
  let end = new Position(pos.line, pos.character)
  return doc.getText(new Range(start, end))
}