const path = require('path')
const shellQuote = require('shell-quote')
const childProcess = require('child_process')

// Map from full process name to binary that starts the process
// We can't just re-use full process name, because it will spawn a new instance
// of the app every time
const COMMON_EDITORS_OSX = require('./editor-info/osx')
const COMMON_EDITORS_LINUX = require('./editor-info/linux')
const COMMON_EDITORS_WIN = require('./editor-info/windows')

module.exports = function guessEditor (specifiedEditor) {
  if (specifiedEditor) {
    return shellQuote.parse(specifiedEditor)
  }

  if (process.env.LAUNCH_EDITOR) {
    return [process.env.LAUNCH_EDITOR]
  }

  if (process.versions.webcontainer) {
    return [process.env.EDITOR || 'code']
  }

  // We can find out which editor is currently running by:
  // `ps x` on macOS and Linux
  // `Get-Process` on Windows
  try {
    if (process.platform === 'darwin') {
      const output = childProcess
        .execSync('ps x -o comm=', {
          stdio: ['pipe', 'pipe', 'ignore']
        })
        .toString()
      const processNames = Object.keys(COMMON_EDITORS_OSX)
      const processList = output.split('\n')
      for (let i = 0; i < processNames.length; i++) {
        const processName = processNames[i]
        // Find editor by exact match.
        if (output.indexOf(processName) !== -1) {
          return [COMMON_EDITORS_OSX[processName]]
        }
        const processNameWithoutApplications = processName.replace('/Applications', '')
        // Find editor installation not in /Applications.
        if (output.indexOf(processNameWithoutApplications) !== -1) {
          // Use the CLI command if one is specified
          if (processName !== COMMON_EDITORS_OSX[processName]) {
            return [COMMON_EDITORS_OSX[processName]]
          }
          // Use a partial match to find the running process path.  If one is found, use the
          // existing path since it can be running from anywhere.
          const runningProcess = processList.find((procName) => procName.endsWith(processNameWithoutApplications))
          if (runningProcess !== undefined) {
            return [runningProcess]
          }
        }
      }
    } else if (process.platform === 'win32') {
      const output = childProcess
        .execSync(
          'powershell -NoProfile -Command "Get-CimInstance -Query \\"select executablepath from win32_process where executablepath is not null\\" | % { $_.ExecutablePath }"',
          {
            stdio: ['pipe', 'pipe', 'ignore']
          }
        )
        .toString()
      const runningProcesses = output.split('\r\n')
      for (let i = 0; i < runningProcesses.length; i++) {
        const fullProcessPath = runningProcesses[i].trim()
        const shortProcessName = path.basename(fullProcessPath)

        if (COMMON_EDITORS_WIN.indexOf(shortProcessName) !== -1) {
          return [fullProcessPath]
        }
      }
    } else if (process.platform === 'linux') {
      // --no-heading No header line
      // x List all processes owned by you
      // -o comm Need only names column
      const output = childProcess
        .execSync('ps x --no-heading -o comm --sort=comm', {
          stdio: ['pipe', 'pipe', 'ignore']
        })
        .toString()
      const processNames = Object.keys(COMMON_EDITORS_LINUX)
      for (let i = 0; i < processNames.length; i++) {
        const processName = processNames[i]
        if (output.indexOf(processName) !== -1) {
          return [COMMON_EDITORS_LINUX[processName]]
        }
      }
    }
  } catch (error) {
    // Ignore...
  }

  // Last resort, use old skool env vars
  if (process.env.VISUAL) {
    return [process.env.VISUAL]
  } else if (process.env.EDITOR) {
    return [process.env.EDITOR]
  }

  return [null]
}