Add history function for the past page view.

cache/cache.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"archive/zip"
+	"bufio"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -12,13 +13,15 @@ import (
 	"os/user"
 	"path"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 )
 
 const (
 	indexJSON      = "index.json"
 	pagesDirectory = "pages"
+	historyPath    = "/history"
 	pageSuffix     = ".md"
 	zipPath        = "/tldr.zip"
 )
@@ -32,6 +35,16 @@ type Repository struct {
 	ttl       time.Duration
 }
 
+// HistoryRecord represent the search history of certain page
+type HistoryRecord struct {
+	page  string
+	count int
+}
+
+func (h HistoryRecord) String() string {
+	return fmt.Sprintf("%s %d", h.page, h.count)
+}
+
 // NewRepository returns a new cache repository. The data is loaded from the
 // remote if missing or stale.
 func NewRepository(remote string, ttl time.Duration) (*Repository, error) {
@@ -204,7 +217,21 @@ func (r *Repository) loadFromRemote() error {
 }
 
 func (r *Repository) makeCacheDir() error {
-	return os.MkdirAll(r.directory, 0755)
+	if err := os.MkdirAll(r.directory, 0755); err != nil {
+		return fmt.Errorf("ERROR: creating directory %s: %s", r.directory, err)
+	}
+	// touching the history file.
+	historyFile := path.Join(r.directory, historyPath)
+	return touchFile(historyFile)
+}
+
+func touchFile(fileName string) error {
+	file, err := os.Create(fileName)
+	if err != nil {
+		return fmt.Errorf("ERROR: creating file %s: %s", fileName, err)
+	}
+	defer file.Close()
+	return nil
 }
 
 func (r *Repository) unzip() error {
@@ -259,3 +286,87 @@ func (r Repository) isReachable() bool {
 	_, err = net.DialTimeout("tcp", u.Hostname()+":"+u.Port(), timeout)
 	return err == nil
 }
+
+func (r Repository) RecordHistory(page string) error {
+	records, err := r.LoadHistory()
+	if err != nil {
+		return fmt.Errorf("ERROR: loading history failed %s", err)
+	}
+
+	newRecord := HistoryRecord{
+		page:  page,
+		count: 1,
+	}
+
+	foundIdx := -1
+	for idx, r := range *records {
+		if r.page == page {
+			newRecord.count = r.count + 1
+			foundIdx = idx
+			break
+		}
+	}
+
+	if foundIdx != -1 { //found in history, we want to put the last search at the end of the history.
+		newRecords := append((*records)[:foundIdx], (*records)[foundIdx+1:]...)
+		records = &newRecords
+	}
+
+	newRecords := append(*records, newRecord)
+	return r.saveHistory(&newRecords)
+}
+
+func (r Repository) saveHistory(history *[]HistoryRecord) error {
+	hisFile := path.Join(r.directory, historyPath)
+	inFile, err := os.Create(hisFile)
+	if err != nil {
+		return fmt.Errorf("ERROR: opening history file %s", hisFile)
+	}
+	defer inFile.Close()
+
+	for _, his := range *history {
+		fmt.Fprintln(inFile, fmt.Sprintf("%s,%d", his.page, his.count))
+	}
+	return nil
+}
+
+func (r Repository) LoadHistory() (*[]HistoryRecord, error) {
+	// read the history file line by line, into a map.
+	history := path.Join(r.directory, historyPath)
+	//if it is not exist, touch it.
+	_, err := os.Stat(history)
+
+	if os.IsNotExist(err) {
+		if err := touchFile(history); err != nil {
+			return nil, fmt.Errorf("ERROR: cannot create the history file %s, %s", history, err)
+		}
+	}
+
+	inFile, err := os.Open(history)
+	if err != nil {
+		return nil, fmt.Errorf("ERROR: opening history file %s", history)
+
+	}
+
+	defer inFile.Close()
+
+	scanner := bufio.NewScanner(inFile)
+	historyRecords := make([]HistoryRecord, 0, 10)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		lineParts := strings.Split(line, ",")
+		count, err := strconv.Atoi(lineParts[1])
+
+		if err != nil {
+			return nil, err
+		}
+
+		historyRecords = append(historyRecords, HistoryRecord{
+			page:  lineParts[0],
+			count: count,
+		})
+	}
+
+	return &historyRecords, nil
+}

cache/cache_test.go

@@ -109,13 +109,13 @@ func TestMarkdown(t *testing.T) {
 	_, err := r.Markdown("linux", "hostname")
 
 	if err != nil {
-		t.Error("Exptected to successfully pull a page from the cache")
+		t.Error("Expected to successfully pull a page from the cache")
 	}
 
 	_, err = r.Markdown("linux", "hostnamee")
 
 	if err == nil {
-		t.Error("Exptected to return an error for non existing pages")
+		t.Error("Expected to return an error for non existing pages")
 	}
 }
 
@@ -127,10 +127,70 @@ func TestPages(t *testing.T) {
 	pages, err := r.Pages()
 
 	if err != nil {
-		t.Error("Exptected to successfully retrieve all pages.")
+		t.Error("Expected to successfully retrieve all pages.")
 	}
 
 	if len(pages) == 0 {
-		t.Error("Exptected to find some pages")
+		t.Error("Expected to find some pages")
 	}
 }
+
+func TestHistory(t *testing.T) {
+
+	repo := Repository{
+		directory: "/tmp/.cache/tldr",
+		remote:    "https://tldr.sh/assets/tldr.zip",
+		ttl:       time.Hour * 24 * 7,
+	}
+
+	repo.makeCacheDir()
+
+	if err2 := repo.RecordHistory("git-pull"); err2 != nil {
+		t.Error("Expected to record history successful.")
+	}
+
+	repo.RecordHistory("git-pull")
+	repo.RecordHistory("git-pull")
+	repo.RecordHistory("git-push")
+	repo.RecordHistory("git-push")
+	repo.RecordHistory("git-fetch")
+	repo.RecordHistory("git-pull")
+
+	history, err := repo.LoadHistory()
+	if err != nil {
+		t.Error("Expected to load history successful.")
+	}
+
+	length := len(*history)
+	if length != 3 {
+		t.Error("Expected to have 3 history records.")
+	}
+
+	rec1 := HistoryRecord{
+		page:  "git-push",
+		count: 2,
+	}
+
+	if (*history)[0] != rec1 {
+		t.Errorf("Expected first record to be %+v", rec1)
+	}
+
+	rec2 := HistoryRecord{
+		page:  "git-fetch",
+		count: 1,
+	}
+
+	if (*history)[1] != rec2 {
+		t.Errorf("Expected second record to be %+v", rec2)
+	}
+
+	rec3 := HistoryRecord{
+		page:  "git-pull",
+		count: 4,
+	}
+
+	if (*history)[2] != rec3 {
+		t.Errorf("Expected third record to be %+v", rec3)
+	}
+
+}

cmd/tldr/main.go

@@ -5,6 +5,7 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"math"
 	"math/rand"
 	"os"
 	"runtime"
@@ -22,6 +23,7 @@ const (
 	updateUsage   = "update local database"
 	versionUsage  = "print version and exit"
 	randomUsage   = "prints a random page"
+	historyUsage  = "show the latest search history"
 )
 
 const (
@@ -106,6 +108,11 @@ func printPage(page string) {
 	if err != nil {
 		log.Fatalf("ERROR: writing markdown: %s", err)
 	}
+
+	err2 := repository.RecordHistory(page)
+	if err2 != nil {
+		log.Fatalf("ERROR: saving history: %s", err2)
+	}
 }
 
 func printPageForPlatform(page string, platform string) {
@@ -156,6 +163,29 @@ func updatePages() {
 	}
 }
 
+func printHistory() {
+	repository, err := cache.NewRepository(remoteURL, ttl)
+	if err != nil {
+		log.Fatalf("ERROR: creating cache repository: %s", err)
+	}
+
+	history, err := repository.LoadHistory()
+	if err != nil {
+		log.Fatalf("ERROR: error loading history: %s", err)
+	}
+
+	hisLen := len(*history)
+	if hisLen == 0 {
+		fmt.Println("No history is available yet")
+	} else { //default print last 10.
+		size := int(math.Min(10, float64(hisLen)))
+		for i := 1; i <= size; i++ {
+			record := (*history)[hisLen-i]
+			fmt.Printf("%s\n", record)
+		}
+	}
+}
+
 func main() {
 	version := flag.Bool("version", false, versionUsage)
 	flag.BoolVar(version, "v", false, versionUsage)
@@ -176,6 +206,9 @@ func main() {
 	random := flag.Bool("random", false, randomUsage)
 	flag.BoolVar(random, "r", false, randomUsage)
 
+	history := flag.Bool("history", false, historyUsage)
+	flag.BoolVar(history, "t", false, historyUsage)
+
 	flag.Parse()
 
 	if *version {
@@ -191,6 +224,8 @@ func main() {
 		printPageForPlatform(page, *platform)
 	} else if *random {
 		printRandomPage()
+	} else if *history {
+		printHistory()
 	} else {
 		page := flag.Arg(0)
 		printPage(page)