test-results: Add revisions handler

go/src/infra/appengine/test-results/frontend/revision.go

Index: go/src/infra/appengine/test-results/frontend/revision.go
diff --git a/go/src/infra/appengine/test-results/frontend/revision.go b/go/src/infra/appengine/test-results/frontend/revision.go
new file mode 100644
index 0000000000000000000000000000000000000000..1c3fe9ba1942535ef8c36870b894c8471b06714d
--- /dev/null
+++ b/go/src/infra/appengine/test-results/frontend/revision.go
@@ -0,0 +1,84 @@
+package frontend
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync"
+
+	"github.com/luci/gae/service/urlfetch"
+	"github.com/luci/luci-go/server/router"
+)
+
+// TODO(estaab): Comment copied from python implementation:
+//   Get rid of this one crrev.com supports this directly.
+//   See http://crbug.com/407198.
+
+// crRevURL is the base URL of the Chromium Revision's API.
+const crRevURL = "https://cr-rev.appspot.com/_ah/api/crrev/v1/redirect"
+
+type crRevClient struct {
+	HTTPClient *http.Client
+	BaseURL    string
+}
+
+// commitHash returns the commit hash for the supplied commit
+// position.
+func (c *crRevClient) commitHash(pos string) (string, error) {
+	resp, err := c.HTTPClient.Get(c.BaseURL + "/" + pos)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("HTTP status code %d from %s", resp.StatusCode, resp.Request.URL)
+	}
+
+	hash := struct {
+		Hash string `json:"git_sha"`
+	}{}
+	if err := json.NewDecoder(resp.Body).Decode(&hash); err != nil {
+		return "", err
+	}
+	return hash.Hash, nil
+}
+
+func revisionHandler(c *router.Context) {
+	client := crRevClient{
+		HTTPClient: &http.Client{Transport: urlfetch.Get(c.Context)},
+		BaseURL:    crRevURL,
+	}
+	type result struct {
+		hash string
+		err  error
+	}
+	results := make([]result, 2)
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	go func() {
+		defer wg.Done()
+		hash, err := client.commitHash(c.Request.FormValue("start"))
+		results[0] = result{hash, err}
+	}()
+	go func() {
+		defer wg.Done()
+		hash, err := client.commitHash(c.Request.FormValue("end"))
+		results[1] = result{hash, err}
+	}()
+
+	wg.Wait()
+	for _, r := range results {
+		if r.err != nil {
+			http.Error(c.Writer, r.err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+
+	http.Redirect(c.Writer, c.Request, fmt.Sprintf(
+		"https://chromium.googlesource.com/chromium/src/+log/%s^..%s?pretty=fuller",
+		results[0].hash,
+		results[1].hash,
+	), http.StatusMovedPermanently)
+}