add detect-latest-release command

.appveyor.yml

@@ -13,6 +13,7 @@ build: off
 test_script:
     - go build ./selfupdate
     - go build ./cmd/selfupdate-example
+    - go build ./cmd/detect-latest-release
     - go test -v -race -coverprofile=coverage.txt ./selfupdate
 after_test:
     - "SET PATH=C:\\Python34;C:\\Python34\\Scripts;%PATH%"

.gitignore

@@ -1,3 +1,4 @@
 /selfupdate-example
 /release
 /env.sh
+/detect-latest-release

.travis.yml

@@ -9,6 +9,7 @@ install:
 script:
   - go build ./selfupdate/
   - go build ./cmd/selfupdate-example/
+  - go build ./cmd/detect-latest-release/
   - go test -v -race -coverprofile=coverage.txt ./selfupdate
 after_success:
   - bash <(curl -s https://codecov.io/bash)

README.md

@@ -27,6 +27,10 @@ If newer version than itself is detected, it downloads released binary from GitH
 - Tested on Linux, macOS and Windows (using Travis CI and AppVeyor)
 - Many archive and compression formats are supported (zip, gzip, tar)
 
+And small wrapper CLI is provided:
+
+- [detect-latest-release](./cmd/detect-latest-release): Detect the latest release of given GitHub repository from command line
+
 [go-github-selfupdate]: https://github.com/rhysd/go-github-selfupdate
 [GitHub Releases API]: https://developer.github.com/v3/repos/releases/
 

cmd/detect-latest-release/README.md

@@ -0,0 +1,14 @@
+This command line tool is a small wrapper of [`selfupdate.DetectLatest()`](https://godoc.org/github.com/rhysd/go-github-selfupdate/selfupdate#DetectLatest).
+
+Please install using `go get`.
+
+```
+$ go get -u github.com/rhysd/go-github-selfupdate/cmd/detect-latest-release
+```
+
+To know the usage, please try the command without any argument.
+
+```
+$ detect-latest-release
+```
+

cmd/detect-latest-release/main.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"github.com/rhysd/go-github-selfupdate/selfupdate"
+	"os"
+	"regexp"
+	"strings"
+)
+
+func usage() {
+	fmt.Fprintln(os.Stderr, "Usage: detect-latest-release [flags] {repo}\n\n  {repo} must be URL to GitHub repository or in 'owner/name' format.\n\nFlags:\n")
+	flag.PrintDefaults()
+}
+
+func main() {
+	asset := flag.Bool("asset", false, "Output URL to asset")
+	notes := flag.Bool("release-notes", false, "Output release notes additionally")
+	url := flag.Bool("url", false, "Output URL for release page")
+
+	flag.Usage = usage
+	flag.Parse()
+
+	if flag.NArg() != 1 {
+		usage()
+		os.Exit(1)
+	}
+
+	repo := flag.Arg(0)
+	if strings.HasPrefix(repo, "https://") {
+		repo = repo[len("https://"):]
+	}
+	if strings.HasPrefix(repo, "github.com/") {
+		repo = repo[len("github.com/"):]
+	}
+
+	matched, err := regexp.MatchString("[^/]+/[^/]+", repo)
+	if err != nil {
+		panic(err)
+	}
+	if !matched {
+		usage()
+		os.Exit(1)
+	}
+
+	latest, found, err := selfupdate.DetectLatest(repo)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	if !found {
+		fmt.Println("No release was found")
+	} else {
+		if *asset {
+			fmt.Println(latest.AssetURL)
+		} else if *url {
+			fmt.Println(latest.URL)
+		} else {
+			fmt.Println(latest.Version)
+			if *notes {
+				fmt.Printf("\nRelease Notes:\n%s\n", latest.ReleaseNotes)
+			}
+		}
+	}
+}

selfupdate/doc.go

@@ -30,5 +30,8 @@ Naming Rules of Git Tags:
 
 This package is hosted on GitHub:
   https://github.com/rhysd/go-github-selfupdate
+
+Small CLI tool as wrapper of this library is available also:
+  https://github.com/rhysd/go-github-selfupdate/cmd/detect-latest-release
 */
 package selfupdate