script: Improve changelog layout

Pull issue information from Github to show both the resolved issue
subject and the commit subject. Also show reviewer, when different from
author.

    * #3201: api: /rest/system/browse behaves strangely on Windows

      lib/osutil: Fix globbing at root (by @AudriusButkevicius, reviewed by
      @calmh)

    * #3174: Ignore patterns with non-ASCII characters causes out of memory
      crash

      vendor: Update github.com/gobwas/glob (by @calmh)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3228

build.go

@@ -288,6 +288,7 @@ func setup() {
 	runPrint("go", "get", "-v", "github.com/AlekSi/gocov-xml")
 	runPrint("go", "get", "-v", "bitbucket.org/tebeka/go2xunit")
 	runPrint("go", "get", "-v", "github.com/alecthomas/gometalinter")
+	runPrint("go", "get", "-v", "github.com/mitchellh/go-wordwrap")
 }
 
 func test(pkgs ...string) {

script/changelog.go

@@ -10,11 +10,19 @@ package main
 
 import (
 	"bytes"
+	"encoding/json"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"log"
+	"net/http"
+	"os"
 	"os/exec"
 	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/mitchellh/go-wordwrap"
 )
 
 var (
@@ -25,6 +33,8 @@ var (
 func main() {
 	flag.Parse()
 
+	fmt.Printf("Resolved issues:\n\n")
+
 	// Display changelog since the version given on the command line, or
 	// figure out the last release if there were no arguments.
 	var prevRel string
@@ -39,7 +49,7 @@ func main() {
 	}
 
 	// Get the git log with subject and author nickname
-	bs, err := runError("git", "log", "--reverse", "--pretty=format:%s|%aN", prevRel+"..")
+	bs, err := runError("git", "log", "--reverse", "--pretty=format:%s|%aN|%cN", prevRel+"..")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -50,14 +60,39 @@ func main() {
 		fields := bytes.Split(line, []byte{'|'})
 		subj := fields[0]
 		author := fields[1]
+		committer := fields[2]
 
 		// Check if subject contains a "(fixes ...)" or "(ref ...)""
 		if m := subjectIssues.FindSubmatch(subj); len(m) > 0 {
-			// Find all issue numbers
+			subj := m[1]
 			issues := issueNumbers.FindAll(m[2], -1)
+			for _, issue := range issues {
+				n, err := strconv.Atoi(string(issue[1:]))
+				if err != nil {
+					continue
+				}
+				title, err := githubIssueTitle(n)
+				if err != nil {
+					fmt.Println(err)
+					continue
+				}
+
+				// Format a changelog entry
+				reviewed := ""
+				if !bytes.Equal(committer, author) {
+					reviewed = fmt.Sprintf(", reviewed by @%s", committer)
+				}
 
-			// Format a changelog entry
-			fmt.Printf("* %s (%s, @%s)\n", m[1], bytes.Join(issues, []byte(", ")), author)
+				message := fmt.Sprintf("%s: %s\n\n%s (by @%s%s)\n", issue, title, subj, author, reviewed)
+				para := wordwrap.WrapString(message, 74)
+				for i, line := range strings.Split(para, "\n") {
+					if i == 0 {
+						fmt.Println("*", line)
+					} else {
+						fmt.Println(" ", line)
+					}
+				}
+			}
 		}
 	}
 }
@@ -70,3 +105,33 @@ func runError(cmd string, args ...string) ([]byte, error) {
 	}
 	return bytes.TrimSpace(bs), nil
 }
+
+func githubIssueTitle(n int) (string, error) {
+	req, err := http.NewRequest("GET", fmt.Sprintf("https://api.github.com/repos/syncthing/syncthing/issues/%d", n), nil)
+
+	user, token := os.Getenv("GITHUB_USERNAME"), os.Getenv("GITHUB_TOKEN")
+	if user != "" && token != "" {
+		req.SetBasicAuth(user, token)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	bs, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	var res struct {
+		Title string
+	}
+	err = json.Unmarshal(bs, &res)
+	if err != nil {
+		return "", err
+	}
+
+	return res.Title, nil
+}