test-results: Add revisions handler

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

+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)
+}