Added Caching Module

The Caching Module Caches the images that have been extracted and for
persistence writes the images to a cache file.

In the cache file the data is stored by tab separated values

        `%s\t%s\t%s`

the cache is first loaded in the memory ( CACHE_LIST ) during the start of application
and then extracted images are added to the map CACHE_LIST which is
writtern to the cache file before exiting the program.

cache/cache.go

@@ -0,0 +1,41 @@
+package cache
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+var (
+	CACHE_LIST map[[2]string]string = make(map[[2]string]string)
+)
+
+func loadCache(path string) {
+	cacheFileContent, err := ioutil.ReadFile(path)
+	if err != nil {
+		fmt.Println("Could Not Read From Cache File")
+	}
+	lineSlice := strings.Split(string(cacheFileContent), "\n")
+	for _, line := range lineSlice {
+		if len(line) != 0 {
+			param := strings.Split(line, "\t")
+			if len(param) == 3 {
+				CACHE_LIST[[2]string{param[0], param[1]}] = param[2]
+			}
+		}
+	}
+}
+
+func writeToCache(path string) {
+	b, err := os.Create(path)
+	if err == nil {
+		for k, v := range CACHE_LIST {
+			b.Write([]byte(fmt.Sprintf("%s\t%s\t%s\n", k[0], k[1], v)))
+		}
+	}
+}
+
+func generateName(artist, album string) string {
+	return fmt.Sprintf("%s-%s.jpg", artist, album)
+}

cache/cache_test.go

@@ -0,0 +1,16 @@
+package cache
+
+import "testing"
+
+func TestLoadCache(t *testing.T) {
+	expectedResult := [2]string{"hello/wer.jpg", "hello/iwer.jpg"}
+	loadCache("./testdata/cache.txt")
+	var i int = 0
+	for _, v := range CACHE_LIST {
+		if v != expectedResult[i] {
+			if v != expectedResult[i+1] {
+				t.Errorf("Didn't Get The Expected Value receieved %s", v)
+			}
+		}
+	}
+}

cache/testdata/cache.txt

@@ -0,0 +1,2 @@
+Kanye West	Life Of Pablo	hello/wer.jpg
+Niravana	Heart Shaped Box	hello/iwer.jpg