add support for generating github resource links

scm/client.go

@@ -88,6 +88,7 @@ type (
 
 		// Services used for communicating with the API.
 		Driver        Driver
+		Linker        Linker
 		Contents      ContentService
 		Git           GitService
 		Organizations OrganizationService

scm/driver/github/github.go

@@ -25,10 +25,15 @@ func New(uri string) (*scm.Client, error) {
 	if !strings.HasSuffix(base.Path, "/") {
 		base.Path = base.Path + "/"
 	}
+	home := base.String()
+	if home == "https://api.github.com/" {
+		home = "https://github.com/"
+	}
 	client := &wrapper{new(scm.Client)}
 	client.BaseURL = base
 	// initialize services
 	client.Driver = scm.DriverGithub
+	client.Linker = &linker{home}
 	client.Contents = &contentService{client}
 	client.Git = &gitService{client}
 	client.Issues = &issueService{client}

scm/driver/github/linker.go

@@ -0,0 +1,49 @@
+// Copyright 2017 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package github
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/drone/go-scm/scm"
+)
+
+type linker struct {
+	base string
+}
+
+// Resource returns a link to the resource.
+func (l *linker) Resource(ctx context.Context, repo string, ref scm.Reference) (string, error) {
+	switch {
+	case scm.IsTag(ref.Path):
+		t := scm.TrimRef(ref.Path)
+		return fmt.Sprintf("%s%s/tree/%s", l.base, repo, t), nil
+	case scm.IsPullRequest(ref.Path):
+		d := scm.ExtractPullRequest(ref.Path)
+		return fmt.Sprintf("%s%s/pull/%d", l.base, repo, d), nil
+	default:
+		return fmt.Sprintf("%s%s/commit/%s", l.base, repo, ref.Sha), nil
+	}
+}
+
+// Diff returns a link to the diff.
+func (l *linker) Diff(ctx context.Context, repo string, source, target scm.Reference) (string, error) {
+	if scm.IsPullRequest(target.Path) {
+		d := scm.ExtractPullRequest(target.Path)
+		return fmt.Sprintf("%s%s/pull/%d/files", l.base, repo, d), nil
+	}
+
+	s := source.Sha
+	t := target.Sha
+	if s == "" {
+		s = scm.TrimRef(source.Path)
+	}
+	if t == "" {
+		t = scm.TrimRef(target.Path)
+	}
+
+	return fmt.Sprintf("%s%s/compare/%s...%s", l.base, repo, s, t), nil
+}

scm/driver/github/linker_test.go

@@ -0,0 +1,110 @@
+// Copyright 2017 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package github
+
+import (
+	"context"
+	"testing"
+
+	"github.com/drone/go-scm/scm"
+)
+
+func TestLink(t *testing.T) {
+	tests := []struct {
+		path string
+		sha  string
+		want string
+	}{
+		{
+			path: "refs/heads/master",
+			sha:  "a7389057b0eb027e73b32a81e3c5923a71d01dde",
+			want: "https://github.com/octocat/hello-world/commit/a7389057b0eb027e73b32a81e3c5923a71d01dde",
+		},
+		{
+			path: "refs/pull/42/head",
+			sha:  "a7389057b0eb027e73b32a81e3c5923a71d01dde",
+			want: "https://github.com/octocat/hello-world/pull/42",
+		},
+		{
+			path: "refs/tags/v1.0.0",
+			want: "https://github.com/octocat/hello-world/tree/v1.0.0",
+		},
+	}
+
+	for _, test := range tests {
+		client := NewDefault()
+		ref := scm.Reference{
+			Path: test.path,
+			Sha:  test.sha,
+		}
+		got, err := client.Linker.Resource(context.Background(), "octocat/hello-world", ref)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		want := test.want
+		if got != want {
+			t.Errorf("Want link %q, got %q", want, got)
+		}
+	}
+}
+
+func TestDiff(t *testing.T) {
+	tests := []struct {
+		source scm.Reference
+		target scm.Reference
+		want   string
+	}{
+		{
+			source: scm.Reference{Sha: "a7389057b0eb027e73b32a81e3c5923a71d01dde"},
+			target: scm.Reference{Sha: "49bbaf4a113bbebfa21cf604cad9aa1503c3f04d"},
+			want:   "https://github.com/octocat/hello-world/compare/a7389057b0eb027e73b32a81e3c5923a71d01dde...49bbaf4a113bbebfa21cf604cad9aa1503c3f04d",
+		},
+		{
+			source: scm.Reference{Path: "refs/heads/master"},
+			target: scm.Reference{Sha: "49bbaf4a113bbebfa21cf604cad9aa1503c3f04d"},
+			want:   "https://github.com/octocat/hello-world/compare/master...49bbaf4a113bbebfa21cf604cad9aa1503c3f04d",
+		},
+		{
+			source: scm.Reference{Sha: "a7389057b0eb027e73b32a81e3c5923a71d01dde"},
+			target: scm.Reference{Path: "refs/heads/master"},
+			want:   "https://github.com/octocat/hello-world/compare/a7389057b0eb027e73b32a81e3c5923a71d01dde...master",
+		},
+		{
+			target: scm.Reference{Path: "refs/pull/12/head"},
+			want:   "https://github.com/octocat/hello-world/pull/12/files",
+		},
+	}
+
+	for _, test := range tests {
+		client := NewDefault()
+		got, err := client.Linker.Diff(context.Background(), "octocat/hello-world", test.source, test.target)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		want := test.want
+		if got != want {
+			t.Errorf("Want link %q, got %q", want, got)
+		}
+	}
+}
+
+func TestLink_GitHub_Enterprise(t *testing.T) {
+	client, _ := New("https://github.acme.com")
+	ref := scm.Reference{
+		Path: "refs/heads/master",
+		Sha:  "a7389057b0eb027e73b32a81e3c5923a71d01dde",
+	}
+	got, err := client.Linker.Resource(context.Background(), "octocat/hello-world", ref)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	want := "https://github.acme.com/octocat/hello-world/commit/a7389057b0eb027e73b32a81e3c5923a71d01dde"
+	if got != want {
+		t.Errorf("Want link %q, got %q", want, got)
+	}
+}

scm/linker.go

@@ -0,0 +1,16 @@
+// Copyright 2017 Drone.IO Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package scm
+
+import "context"
+
+// Linker provides deep links to resources.
+type Linker interface {
+	// Resource returns a link to the resource.
+	Resource(ctx context.Context, repo string, ref Reference) (string, error)
+
+	// Diff returns a link to the diff.
+	Diff(ctx context.Context, repo string, source, target Reference) (string, error)
+}

scm/util.go

@@ -4,7 +4,15 @@
 
 package scm
 
-import "strings"
+import (
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// regular expression to extract the pull request number
+// from the git ref (e.g. refs/pulls/{d}/head)
+var re = regexp.MustCompile("\\d+")
 
 // Split splits the full repository name into segments.
 func Split(s string) (owner, name string) {
@@ -42,8 +50,24 @@ func ExpandRef(name, prefix string) string {
 	return prefix + "/" + name
 }
 
+// ExtractPullRequest returns name extraced pull request
+// number from the reference path.
+func ExtractPullRequest(ref string) int {
+	s := re.FindString(ref)
+	d, _ := strconv.Atoi(s)
+	return d
+}
+
 // IsTag returns true if the reference path points to
 // a tag object.
 func IsTag(ref string) bool {
 	return strings.HasPrefix(ref, "refs/tags/")
 }
+
+// IsPullRequest returns true if the reference path points
+// to a pull request object.
+func IsPullRequest(ref string) bool {
+	return strings.HasPrefix(ref, "refs/pull/") ||
+		strings.HasPrefix(ref, "refs/pull-request/") ||
+		strings.HasPrefix(ref, "refs/merge-requests/")
+}

scm/util_test.go

@@ -101,7 +101,7 @@ func TestExpandRef(t *testing.T) {
 	}
 }
 
-func TestIsRef(t *testing.T) {
+func TestIsTag(t *testing.T) {
 	tests := []struct {
 		name string
 		tag  bool
@@ -122,3 +122,74 @@ func TestIsRef(t *testing.T) {
 		}
 	}
 }
+
+func TestIsPullRequest(t *testing.T) {
+	tests := []struct {
+		name string
+		tag  bool
+	}{
+		{
+			name: "refs/pull/12/head",
+			tag:  true,
+		},
+		{
+			name: "refs/pull/12/merge",
+			tag:  true,
+		},
+		{
+			name: "refs/pull-request/12/head",
+			tag:  true,
+		},
+		{
+			name: "refs/merge-requests/12/head",
+			tag:  true,
+		},
+		// not pull requests
+		{
+			name: "refs/tags/v1.0.0",
+			tag:  false,
+		},
+		{
+			name: "refs/heads/master",
+			tag:  false,
+		},
+	}
+	for _, test := range tests {
+		if got, want := IsPullRequest(test.name), test.tag; got != want {
+			t.Errorf("Got IsPullRequest %v, want %v", got, want)
+		}
+	}
+}
+
+func TestExtractPullRequest(t *testing.T) {
+	tests := []struct {
+		name   string
+		number int
+	}{
+		{
+			name:   "refs/pull/12/head",
+			number: 12,
+		},
+		{
+			name:   "refs/pull/12/merge",
+			number: 12,
+		},
+		{
+			name:   "refs/pull-request/12/head",
+			number: 12,
+		},
+		{
+			name:   "refs/merge-requests/12/head",
+			number: 12,
+		},
+		{
+			name:   "refs/heads/master",
+			number: 0,
+		},
+	}
+	for _, test := range tests {
+		if got, want := ExtractPullRequest(test.name), test.number; got != want {
+			t.Errorf("Got pull request number %v, want %v", got, want)
+		}
+	}
+}