extract lib, parallel download-decode step

avg/difference.go

@@ -0,0 +1,32 @@
+package avg
+
+import (
+	"github.com/Nr90/imgsim"
+	"image"
+)
+
+func Difference(img1, img2 image.Image) int {
+	// Hashing
+	ahash1 := imgsim.AverageHash(img1)
+	ahash2 := imgsim.AverageHash(img2)
+
+	// distance
+	avgDistance := imgsim.Distance(ahash1, ahash2)
+
+	return avgDistance % 64 // because 64 bit hash
+}
+
+//func Difference(img1, img2 image.Image) int {
+//	// Hashing
+//	ahash1 := imgsim.AverageHash(img1)
+//	ahash2 := imgsim.AverageHash(img2)
+//
+//	dhash1 := imgsim.DifferenceHash(img1)
+//	dhash2 := imgsim.DifferenceHash(img2)
+//
+//	// distance
+//	avgDistance := imgsim.Distance(ahash1, ahash2)
+//	diffDistance := imgsim.Distance(dhash1, dhash2)
+//
+//	return (avgDistance + diffDistance) % 128
+//}

go.mod

@@ -2,5 +2,6 @@ module github.com/AskAlexSharov/imgdiff
 
 require (
 	github.com/Nr90/imgsim v0.0.0-20180202144352-5caa057144b0
+	github.com/aws/aws-lambda-go v1.8.1
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 // indirect
 )

go.sum

@@ -1,4 +1,6 @@
 github.com/Nr90/imgsim v0.0.0-20180202144352-5caa057144b0 h1:8cjsGKoi/1QBb0V2ps3iBra9c4o+qY/NaJ15NsdjmQ4=
 github.com/Nr90/imgsim v0.0.0-20180202144352-5caa057144b0/go.mod h1:PSWPVD+KeWK3XVt0i/AahAMRw38OZ1k1vJpJLuvIY1w=
+github.com/aws/aws-lambda-go v1.8.1 h1:nHBpP6XC30bwF6qWKrw/BrK2A8i4GKmSZzajTBIJS4A=
+github.com/aws/aws-lambda-go v1.8.1/go.mod h1:zUsUQhAUjYzR8AuduJPCfhBuKWUaDbQiPOG+ouzmE1A=
 github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 h1:zYyBkD/k9seD2A7fsi6Oo2LfFZAehjjQMERAvZLEDnQ=
 github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646/go.mod h1:jpp1/29i3P1S/RLdc7JQKbRpFeM1dOBd8T9ki5s+AY8=

loader/loader.go

@@ -0,0 +1,106 @@
+package loader
+
+import (
+	"context"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+)
+
+type Result struct {
+	Img image.Image
+	Err error
+}
+
+func ImageAsync(ctx context.Context, filePathOrUrl string) chan Result {
+	res := make(chan Result)
+	go func() {
+		defer close(res)
+
+		select {
+		case res <- img(ctx, filePathOrUrl):
+			return
+		case <-ctx.Done():
+			res <- Result{Err: ctx.Err()}
+			return
+		}
+	}()
+
+	return res
+}
+
+func img(ctx context.Context, filePathOrUrl string) Result {
+	// Read
+	var imgReader io.Reader
+	var fileName string
+
+	parsedUrl, isUrl := parseUrl(filePathOrUrl)
+	if isUrl {
+		resp, err := getByUrl(ctx, filePathOrUrl)
+		if err != nil {
+			return Result{Err: err}
+		}
+		defer resp.Body.Close()
+		imgReader = resp.Body
+		fileName = parsedUrl.Path
+	} else {
+		var err error
+		if imgReader, err = os.Open(filePathOrUrl); err != nil {
+			return Result{Err: err}
+		}
+		fileName = filePathOrUrl
+	}
+
+	return decode(fileName, imgReader)
+}
+
+func parseUrl(rawurl string) (*url.URL, bool) {
+	parsedUrl, err := url.ParseRequestURI(rawurl)
+	if err != nil {
+		return parsedUrl, false
+	}
+	return parsedUrl, true
+}
+
+func decode(fileName string, f io.Reader) Result {
+	ext := filepath.Ext(fileName)
+
+	result := Result{}
+	if ext == ".jpeg" || ext == ".jpg" {
+		result.Img, result.Err = jpeg.Decode(f)
+		return result
+	}
+
+	if ext == ".png" {
+		result.Img, result.Err = png.Decode(f)
+		return result
+	}
+
+	result.Err = fmt.Errorf("not supported file extension: %s", ext)
+	return result
+}
+
+func getByUrl(ctx context.Context, url string) (*http.Response, error) {
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := http.DefaultClient.Do(req.WithContext(ctx))
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+		return nil, err
+	}
+
+	return resp, nil
+}

main.go

@@ -1,18 +1,11 @@
 package main
 
 import (
+	"context"
 	"fmt"
-	"image"
-	"image/jpeg"
-	"image/png"
-	"io"
-	"log"
-	"net/http"
-	"net/url"
+	"github.com/AskAlexSharov/imgdiff/avg"
+	"github.com/AskAlexSharov/imgdiff/loader"
 	"os"
-	"path/filepath"
-
-	"github.com/Nr90/imgsim"
 )
 
 func main() {
@@ -21,95 +14,24 @@ func main() {
 		return
 	}
 
-	fmt.Printf("Diffeernce: %d%%\n", readAndGetDistance(os.Args[1], os.Args[2]))
-}
-
-func readAndGetDistance(fileName1, fileName2 string) int {
-	return distance(<-readAndDecode(fileName1), <-readAndDecode(fileName2))
-}
-
-func parseUrl(rawurl string) (*url.URL, bool) {
-	parsedUrl, err := url.ParseRequestURI(rawurl)
-	if err != nil {
-		return parsedUrl, false
-	}
-	return parsedUrl, true
-}
-
-func mustGet(rawurl string) io.ReadCloser {
-	resp, err := http.Get(rawurl)
+	dist, err := readAndGetDistance(context.Background(), os.Args[1], os.Args[2])
 	if err != nil {
 		panic(err)
 	}
-
-	if resp.StatusCode != http.StatusOK {
-		panic(fmt.Sprintf("Unexpected response from server. Status code: %d", resp.StatusCode))
-	}
-	return resp.Body
-}
-
-func readAndDecode(filePathOrUrl string) chan image.Image {
-	res := make(chan image.Image)
-	go func() {
-		defer close(res)
-
-		// Read
-		parsedUrl, isUrl := parseUrl(filePathOrUrl)
-
-		if isUrl {
-			body := mustGet(filePathOrUrl)
-			defer body.Close()
-			res <- decode(parsedUrl.Path, body)
-			return
-
-		}
-
-		f, err := os.Open(filePathOrUrl)
-		if err != nil {
-			panic(err)
-		}
-		defer f.Close()
-		res <- decode(filePathOrUrl, f)
-		return
-	}()
-
-	return res
+	fmt.Printf("Diffeernce: %d%%\n", dist)
 }
 
-func decode(fileName string, f io.Reader) image.Image {
-	ext := filepath.Ext(fileName)
-
-	if ext == ".jpeg" || ext == ".jpg" {
-		img, err := jpeg.Decode(f)
-		if err != nil {
-			panic(err)
-		}
-		return img
+func readAndGetDistance(ctx context.Context, fileName1, fileName2 string) (int, error) {
+	ch1 := loader.ImageAsync(ctx, fileName1)
+	ch2 := loader.ImageAsync(ctx, fileName2)
+	r1 := <-ch1
+	r2 := <-ch2
+	if r1.Err != nil {
+		return 0, r1.Err
 	}
-
-	if ext == ".png" {
-		img, err := png.Decode(f)
-		if err != nil {
-			panic(err)
-		}
-		return img
+	if r2.Err != nil {
+		return 0, r2.Err
 	}
 
-	log.Fatalf("Not supported file extension: %s", ext)
-	return nil
-}
-
-func distance(img1, img2 image.Image) int {
-	// Hashing
-	ahash1 := imgsim.AverageHash(img1)
-	ahash2 := imgsim.AverageHash(img2)
-
-	dhash1 := imgsim.DifferenceHash(img1)
-	dhash2 := imgsim.DifferenceHash(img2)
-
-	// distance
-	avgDistance := imgsim.Distance(ahash1, ahash2)
-	diffDistance := imgsim.Distance(dhash1, dhash2)
-
-	return (avgDistance + diffDistance) % 128
+	return avg.Difference(r1.Img, r2.Img), nil
 }

main_test.go

@@ -1,6 +1,9 @@
 package main
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 func Test_distance(t *testing.T) {
 	tests := []struct {
@@ -16,21 +19,25 @@ func Test_distance(t *testing.T) {
 			wantDistance: 0,
 		},
 		{
-			name:         "Original vs Damaged - 3%",
+			name:         "Original vs Damaged - 1%",
 			file1:        "./test-png-original.png",
 			file2:        "https://raw.githubusercontent.com/AskAlexSharov/imgdiff/master/test-png-damaged.png",
-			wantDistance: 3,
+			wantDistance: 1,
 		},
 		{
-			name:         "Scaled Down vs Damaged - 3%",
+			name:         "Scaled Down vs Damaged - 1%",
 			file1:        "https://raw.githubusercontent.com/AskAlexSharov/imgdiff/master/test-png-scaled-down.png",
 			file2:        "./test-png-damaged.png",
-			wantDistance: 3,
+			wantDistance: 1,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotDistance := readAndGetDistance(tt.file1, tt.file2)
+			gotDistance, err := readAndGetDistance(context.Background(), tt.file1, tt.file2)
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
 			if gotDistance != tt.wantDistance {
 				t.Errorf("distance() gotDistance = %v, want %v", gotDistance, tt.wantDistance)
 			}