package main

import (
	"bufio"
	"io"
	"io/ioutil"
	"log"
	"os"
	"os/user"
	"path"
	"strings"
)

type HistoryFile struct {
	Dir        string
	History    *BashHistory
	FileHandle *os.File
}

type Tmpfile struct {
	Dir        string
	FileHandle *os.File
}

type BashHistory struct {
	Old map[string]int
	Tmp []string
}

func (tempfile *Tmpfile) WriteFresh(historyfile *HistoryFile, makebackup bool) {

	defer os.RemoveAll(tempfile.Dir)
	defer tempfile.FileHandle.Close()

	if makebackup {
		historyfile.Makebackup()
	}

	if err := historyfile.FileHandle.Truncate(0); err != nil {
		log.Fatalf("h.trunc: %s\n", err)
	}

	if _, err := historyfile.FileHandle.Seek(0, 0); err != nil {
		log.Fatalf("writefresh h.Seek(): %s\n", err)
	}

	if _, err := tempfile.FileHandle.Seek(0, 0); err != nil {
		log.Fatalf("t.Seek(): %s\n", err)
	}

	if _, err := io.Copy(historyfile.FileHandle, tempfile.FileHandle); err != nil {
		log.Fatalf("tmp io.copy: %s\n", err)
	}
}

func (tempfile *Tmpfile) SaveTmp(h *BashHistory) (wrote int) {
	for key, val := range h.Old {
		h.Tmp[val] = key
	}
	wrote = 0
	for _, key := range h.Tmp {
		if len(key) > 0 {
			if _, err := tempfile.FileHandle.WriteString(key + "\n"); err != nil {
				log.Fatalf("Error writing line %d value %s : %s \n", wrote, key, err)
			}
			wrote++
		}
	}
	return wrote
}

func (historyfile *HistoryFile) Makebackup() {
	if _, err := historyfile.FileHandle.Seek(0, 0); err != nil {
		log.Fatalf("makebackup Seek(): %s\n", err)
	}
	backup, err := os.Create(historyfile.FileHandle.Name() + ".old")
	if err != nil {
		log.Fatalf("makebackup os.Create() .old: %s\n", err)
	}
	if _, err := io.Copy(backup, historyfile.FileHandle); err != nil {
		log.Fatalf("makebackup io.Copy(): %s\n", err)
	}
	backup.Close()
}

func (historyfile *HistoryFile) ReadHistory() {
	if historyfile.FileHandle == nil {
		historyfile.Open()
	}
	historyfile.History = new(BashHistory)
	historyfile.History.Old = make(map[string]int)

	scanner := bufio.NewScanner(historyfile.FileHandle)
	var nr = 0
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		historyfile.History.Old[line] = nr
		nr++
	}
	historyfile.History.Tmp = make([]string, nr)
	delete(historyfile.History.Old, "")
}

func (historyfile *HistoryFile) Open() {
	h, err := os.OpenFile(path.Join(historyfile.Dir, ".bash_history"), os.O_RDWR, 0600)
	if err != nil {
		log.Fatalf("historyfile Open(): %s\n", err)
	}
	historyfile.FileHandle = h

}
func NewBashHistoryFile() *HistoryFile {
	u, err := user.Current()
	if err != nil {
		log.Fatalf("NewBashHistoryFile() user.Current():  %s\n ", err)
	}
	historyfile := new(HistoryFile)
	historyfile.Dir = u.HomeDir
	return historyfile
}

func NewBashHistoryTmpFile() *Tmpfile {
	tmpdir, err := ioutil.TempDir(os.TempDir(), "hipa")
	if err != nil {
		log.Fatalf("NewBashHistoryTmpFile() TempDir():  %s\n ", err)
	}
	tmpfile, err := ioutil.TempFile(tmpdir, "hipa")
	if err != nil {
		log.Fatalf("NewBashHistoryTmpFile() TempDir():  %s\n ", err)
	}

	tempfile := new(Tmpfile)
	tempfile.Dir = tmpdir
	tempfile.FileHandle = tmpfile
	return tempfile
}