import childProcess from 'child_process'
import escape from 'escape-html'
import * as Diff from 'diff'
import {type Repository, ParsedDiff} from './dataTypes.ts'
import { type ReposConfigurationWithDefaultsApplied } from './configTypes.ts'

const getGitDiffsFromPatchText = (lines: string[]): Array<ParsedDiff> => {
  const hunks: Array<ParsedDiff> = []
  let previousHunk = -1
  const filenameRegex = RegExp(/diff --git a\/(.*?) b\/(.*?)/)
  const lineNumberRegex = RegExp(/@@ -(.*?)[,| ].*/)
  let previousFilename = ''
  let currentFilename = ''
  let skipFourStartingAt = -1
  let index = -1

  // lines is an array of each line that would be in `git show` output
  for (const line of lines) {
    index = index + 1

    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
        continue
      }

      let hunkEndIndex = index + 1
      if (skipFourStartingAt !== -1 && skipFourStartingAt < hunkEndIndex) {
        hunkEndIndex = skipFourStartingAt
        skipFourStartingAt = -1
      }
      const lastHunk = lines.slice(previousHunk, hunkEndIndex)

      let lastHunkBeforeLength = lastHunk.filter((line) => {
        return line.startsWith("-")
      }).length

      let lastHunkAfterLength = lastHunk.filter((line) => {
        return line.startsWith("+")
      }).length

      hunks.push({
        fileName: previousFilename !== '' ? previousFilename : currentFilename,
        lineNumber: parseInt(lines[previousHunk].match(lineNumberRegex)[1]),
        unifiedDiff: lastHunk,
        added: lastHunkAfterLength,
        removed: lastHunkBeforeLength,
      })
      previousFilename = ''
      previousHunk = index
    }
  }

  return hunks
}

const getDiffHtmlMarkup = (unifiedDiff: string[]): { beforeText: string, afterText: string } => {
  let lastHunkBefore = unifiedDiff.filter((line) => {
    return line.startsWith("-") || line.startsWith(" ")
  }).map((str) => {
    if (str.startsWith('-')) { return str.replace("-", "") }
    if (str.startsWith(' ')) { return str.replace(" ", "") }
  }).join("\n")

  let lastHunkAfter = unifiedDiff.filter((line) => {
    return line.startsWith("+") || line.startsWith(" ")
  }).map((str) => {
    if (str.startsWith('+')) { return str.replace("+", "") }
    if (str.startsWith(' ')) { return str.replace(" ", "") }
  }).join("\n")

  const changeObject = (lastHunkBefore.length > 50000 || lastHunkAfter.length > 50000)
    ? []
    : Diff.diffWordsWithSpace(lastHunkBefore, lastHunkAfter)
  let beforeText = ""
  let afterText = ""

  for (const obj of changeObject) {
    const numNewLines = obj.value.split('').filter(char => char === '\n').length

    if (!obj.added && !obj.removed) {
      beforeText = beforeText + escape(obj.value)
      afterText = afterText + escape(obj.value)
    }
    if (obj.added) {
      afterText = afterText + "<mark>" + escape(obj.value) + "</mark>"
      if (numNewLines > 0) {
        let insertAt = beforeText.lastIndexOf("\n")
        insertAt = insertAt === -1 ? 0 : insertAt

        beforeText = beforeText.slice(0, insertAt + 1) + (new Array(numNewLines).fill('\u{2063}\n', 0).join('')) + beforeText.slice(insertAt + 1)
      }
    }
    if (obj.removed) {
      beforeText = beforeText + "<mark>" + escape(obj.value) + "</mark>"
      if (numNewLines > 0) {
        let insertAt = afterText.lastIndexOf("\n")
        insertAt = insertAt === -1 ? 0 : insertAt

        afterText = afterText.slice(0, insertAt + 1) + (new Array(numNewLines).fill('\u{2063}\n', 0).join('')) + afterText.slice(insertAt + 1)
      }
    }
  }

  return {
    beforeText,
    afterText
  }
}

const getLocation = (reposConfig: ReposConfigurationWithDefaultsApplied, outputDir: string, repoName: string, slugify: Function): string => {
  return outputDir + (reposConfig.path) + "/" + slugify(repoName) + ".git"
}

const readChunkedCommandOutput = async (executable, args): Promise<string> => {
  return new Promise((resolve) => {
    const cmd = childProcess.spawn(executable, args, {
      stdio: [0, "pipe", "inherit"],
    })
    let output = ""

    cmd.stdout.on('data', (data) => {
      output = output + data
    })

    cmd.on('close', () => {
      resolve(output)
    })
  })
}

export {
  getGitDiffsFromPatchText,
  getDiffHtmlMarkup,
  getLocation,
  readChunkedCommandOutput,
}