import _ from 'lodash'
import * as Diff from 'diff'

type NavValues = {
  repoName: string | ((data: any) => string),
  branchName: string | ((data: any) => string),
  path: string | ((data: any) => string),
  title: string | ((data: any) => string),
}
type Hunk = {
  file: string,
  lineNumber: number,
  previousText: string,
  afterText: string,
}

type DiffInfo = {
  file: string,
  lineNumber: number,
  previousText: string,
  afterText: string,
}

const getGitDiffsFromPatchText = (patchText: string): Array<DiffInfo> => {
  const lines = patchText.split("\n")
  const hunks: Array<Hunk> = []
  let previousHunk = -1
  const filenameRegex = RegExp(/diff --git a\/(.*?) b\/(.*?)/)
  const lineNumberRegex = RegExp(/@@ -(.*?)[,| ].*/)
  let previousFilename = ''
  let currentFilename = ''
  let skipFourStartingAt = -1
  lines.forEach((line, index) => {
    if (line.startsWith("diff")) {
      previousFilename = currentFilename
      currentFilename = line.match(filenameRegex)[1]
      if (previousHunk !== -1) {
        skipFourStartingAt = index
      }
    }
    if (line.startsWith("@@") || index == lines.length - 1) {
      if (previousHunk === -1) {
        previousHunk = index
        return
      }

      let hunkEndIndex = index + 1
      if (skipFourStartingAt !== -1 && skipFourStartingAt < hunkEndIndex) {
        hunkEndIndex = skipFourStartingAt
        skipFourStartingAt = -1
      }
      const lastHunk = lines.slice(previousHunk, hunkEndIndex)
      let lastHunkBefore = lastHunk.filter(line => line.startsWith("-")).map(str => str.replace("-", "")).join("\n")
      let lastHunkAfter = lastHunk.filter(line => line.startsWith("+")).map(str => str.replace("+", "")).join("\n")
      lastHunkBefore = _.escape(lastHunkBefore)
      lastHunkAfter = _.escape(lastHunkAfter)
      const changeObject = Diff.diffWordsWithSpace(lastHunkBefore, lastHunkAfter)
      let previousText = ""
      let afterText = ""

      changeObject.forEach((obj) => {
        if (!obj.added && !obj.removed) {
          previousText = previousText + obj.value
          afterText = afterText + obj.value
        }
        if (obj.added) {
          afterText = afterText + "<mark>" + obj.value + "</mark>"
        }
        if (obj.removed) {
          previousText = previousText + "<mark>" + obj.value + "</mark>"
        }
      })

      hunks.push({
        file: previousFilename !== '' ? previousFilename : currentFilename,
        lineNumber: parseInt(lines[previousHunk].match(lineNumberRegex)[1]),
        previousText,
        afterText,
      })
      previousFilename = ''
      previousHunk = index
    }
  })

  return hunks
}

/** @hidden */
const getDarcsDiffsFromPatchText = (patchText: string): Array<DiffInfo> => {
  const lines = patchText.split("\n")
  const hunks: Array<Hunk> = []
  let previousHunk = -1
  lines.forEach((line, index) => {
    if (line.startsWith("hunk") || index === lines.length - 1) {
      if (previousHunk === -1) {
        previousHunk = index
        return
      }
      // get diff from previous hunk to this next one
      const lastHunk = lines.slice(previousHunk, index + 1) // slice is non-inclusive for the end argument
      let lastHunkBefore = lastHunk.filter(line => line.startsWith("-")).map(str => str.replace("-", "")).join("\n")
      let lastHunkAfter = lastHunk.filter(line => line.startsWith("+")).map(str => str.replace("+", "")).join("\n")
      lastHunkBefore = _.escape(lastHunkBefore)
      lastHunkAfter = _.escape(lastHunkAfter)
      let filename = lines[previousHunk].replace("hunk ./", "")
      const changeObject = Diff.diffWords(lastHunkBefore, lastHunkAfter)
      let previousText = ""
      let afterText = ""

      changeObject.forEach((obj) => {
        if (!obj.added && !obj.removed) {
          previousText = previousText + obj.value
          afterText = afterText + obj.value
        }
        if (obj.added) {
          afterText = afterText + "<mark>" + obj.value + "</mark>"
        }
        if (obj.removed) {
          previousText = previousText + "<mark>" + obj.value + "</mark>"
        }
      })
      const regex = RegExp(/(.*) ([0-9]+)$/)
      const matches = filename.match(regex)
      const file = matches[1]
      const lineNumber: number = parseInt(matches[2])

      hunks.push({
        file,
        lineNumber,
        previousText,
        afterText,
      })
      previousHunk = index
    }
  })
  return hunks
}

const getLocation = (reposConfig: any, branchName: string, repoName: string): string => {
  const config = reposConfig.repos[repoName]
  if (config._type === "darcs") {
    return config.branches[branchName].location
  }
  else if (config._type === "git") {
    return config.location
  }
}

export {
  NavValues,
  getDarcsDiffsFromPatchText,
  getGitDiffsFromPatchText,
  getLocation,
}