Show diffs before merging

This is what 5775e3..43d2a6 has been leading up to. Git fetch will be
called on all pkgbuilds, then the user is offered a chance to view the
diffs. If they choose to continue, merging happens. This allows users to
abort the install after viewing diffs and still be able to see thoes
diffs again if they try to install later on.

This also makes the git stuff a little more modular which should help in
organzing diff showing + pkgbuild editing.

download.go

@@ -44,13 +44,22 @@ func downloadFile(path string, url string) (err error) {
 	return err
 }
 
-func gitGetHash(path string, name string) (string, error) {
+func gitHasDiff(path string, name string) (bool, error) {
 	stdout, stderr, err := passToGitCapture(filepath.Join(path, name), "rev-parse", "HEAD")
 	if err != nil {
-		return "", fmt.Errorf("%s%s", stderr, err)
+		return false, fmt.Errorf("%s%s", stderr, err)
 	}
 
-	return strings.TrimSpace(stdout), nil
+	head := strings.TrimSpace(stdout)
+
+	stdout, stderr, err = passToGitCapture(filepath.Join(path, name), "rev-parse", "HEAD@{upstream}")
+	if err != nil {
+		return false, fmt.Errorf("%s%s", stderr, err)
+	}
+
+	upstream := strings.TrimSpace(stdout)
+
+	return head != upstream, nil
 }
 
 func gitDownload(url string, path string, name string) error {

install.go

@@ -155,27 +155,17 @@ func install(parser *arguments) error {
 
 		cleanBuilds(toClean)
 
-		oldHashes, err := getHashes(do.Aur)
-		if err != nil {
-			return err
-		}
-		
 		toSkip := pkgBuildsToSkip(do.Aur, targets)
 		err = downloadPkgBuilds(do.Aur, do.Bases, toSkip)
 		if err != nil {
 			return err
 		}
-
-		err = mergePkgBuilds(do.Aur)
-		if err != nil {
-			return err
-		}
-
+	
 		if len(toEdit) > 0 {
 			if config.ShowDiffs {
-				err = showPkgBuildDiffs(toEdit, do.Bases, oldHashes)
+				err = showPkgBuildDiffs(toEdit, do.Bases)
 			} else {
-				err = editPkgBuilds(toEdit, do.Bases, oldHashes)
+				err = editPkgBuilds(toEdit, do.Bases)
 			}
 			if err != nil {
 				return err
@@ -189,6 +179,12 @@ func install(parser *arguments) error {
 			config.NoConfirm = oldValue
 		}
 
+		err = mergePkgBuilds(do.Aur)
+		if err != nil {
+			return err
+		}
+
+
 		//initial srcinfo parse before pkgver() bump
 		err = parseSRCINFOFiles(do.Aur, srcinfosStale, do.Bases)
 		if err != nil {
@@ -504,26 +500,21 @@ func cleanBuilds(pkgs []*rpc.Pkg) {
 	}
 }
 
-func showPkgBuildDiffs(pkgs []*rpc.Pkg, bases map[string][]*rpc.Pkg, hashes map[string]string) error {
+func showPkgBuildDiffs(pkgs []*rpc.Pkg, bases map[string][]*rpc.Pkg) error {
 	for _, pkg := range pkgs {
 		dir := filepath.Join(config.BuildDir, pkg.PackageBase)
 		if shouldUseGit(dir) {
-			hash, _ := hashes[pkg.PackageBase]
-			if hash == "" {
-				hash = gitEmptyTree
-			}
-
-			head, err := gitGetHash(config.BuildDir, pkg.PackageBase)
+			hasDiff, err := gitHasDiff(config.BuildDir, pkg.PackageBase)
 			if err != nil {
 				return err
 			}
 
-			if head == hash {
+			if !hasDiff {
 				fmt.Printf("%s %s: %s\n", bold(yellow(arrow)), cyan(formatPkgbase(pkg, bases)), bold("No changes -- skipping"))
 				continue
 			}
 
-			args := []string{"diff", hash + "..HEAD", "--src-prefix", dir + "/", "--dst-prefix", dir + "/"}
+			args := []string{"diff", "HEAD..HEAD@{upstream}", "--src-prefix", dir + "/", "--dst-prefix", dir + "/"}
 			if useColor {
 				args = append(args, "--color=always")
 			} else {
@@ -548,7 +539,7 @@ func showPkgBuildDiffs(pkgs []*rpc.Pkg, bases map[string][]*rpc.Pkg, hashes map[
 	return nil
 }
 
-func editPkgBuilds(pkgs []*rpc.Pkg, bases map[string][]*rpc.Pkg, hashes map[string]string) error {
+func editPkgBuilds(pkgs []*rpc.Pkg, bases map[string][]*rpc.Pkg) error {
 	pkgbuilds := make([]string, 0, len(pkgs))
 	for _, pkg := range pkgs {
 		dir := filepath.Join(config.BuildDir, pkg.PackageBase)
@@ -627,23 +618,6 @@ func pkgBuildsToSkip(pkgs []*rpc.Pkg, targets stringSet) stringSet {
 	return toSkip
 }
 
-func getHashes(pkgs []*rpc.Pkg) (map[string]string, error) {
-	hashes := make(map[string]string)
-
-	for _, pkg := range pkgs {
-		if shouldUseGit(filepath.Join(config.BuildDir, pkg.PackageBase)) {
-			hash, err := gitGetHash(config.BuildDir, pkg.PackageBase)
-			if err != nil {
-				return hashes, err
-			}
-
-			hashes[pkg.PackageBase] = hash
-		}
-	}
-	
-	return hashes, nil
-}
-
 func mergePkgBuilds(pkgs []*rpc.Pkg) error {
 	for _, pkg := range pkgs {
 		if shouldUseGit(filepath.Join(config.BuildDir, pkg.PackageBase)) {