package main

import (

"bufio"

"os"

"regexp"

)

func openFile(filePath string, errorCode int, optional bool) *os.File {

file, err := os.Open(filePath)

if err != nil {

if optional && os.IsNotExist(err) {

return nil

}

Error(errorCode, filePath, err)

}

return file

}

func createFile(filePath string, errorCode int) *os.File {

file, err := os.Create(filePath)

if err != nil {

Error(errorCode, filePath, err)

}

return file

}

// OpenTaskfile opens a taskfile for reading and handles errors.

func OpenTaskfile(filePath string, optional bool) (taskfile *os.File) {

return openFile(filePath, ErrTaskfileOpen, optional)

}

// CreateTaskfile opens a taskfile for writing and handles errors.

func CreateTaskfile(filePath string) (taskfile *os.File) {

return createFile(filePath, ErrTaskfileOpen)

}

// OpenSyncfile opens a syncfile for reading and handles errors.

func OpenSyncfile(optional bool) (syncfile *os.File) {

return openFile(SyncfilePath, ErrSyncfileOpen, optional)

}

// CreateSyncfile opens a syncfile for writing and handles errors.

func CreateSyncfile() (syncfile *os.File) {

return createFile(SyncfilePath, ErrSyncfileOpen)

}

// ReplaceOrAppendSyncfileLine essentialy makes sure that an "entry" appears in a

// syncfile exactly once.

func ReplaceOrAppendSyncfileLine(pattern *regexp.Regexp, repl string) {

// Read Syncfile contents into an array, skipping lines that match the

// pattern.

syncfile, err := os.OpenFile(SyncfilePath, os.O_CREATE|os.O_RDWR, 0644)

if err != nil {

Error(ErrSyncfileOpen, SyncfilePath, err)

}

defer syncfile.Close()

var contents []byte

scanner := bufio.NewScanner(syncfile)

for scanner.Scan() {

line := scanner.Text()

if !pattern.MatchString(line) {

contents = append(contents, line+"\n"...)

}

}

if err := scanner.Err(); err != nil {

Error(ErrSyncfileRead, SyncfilePath, err)

}

// Add the replacement to the end of the list and write the array back into

// the file.

contents = append(contents, repl...)

err = syncfile.Truncate(0)

if err != nil {

Error(ErrSyncfileWrite, SyncfilePath, err)

}

syncfile.Seek(0, 0)

_, err = syncfile.Write(contents)

if err != nil {

Error(ErrSyncfileWrite, SyncfilePath, err)

}

}