Add some options to the branch page

Add handling for some query parameters to the branch page. This takes
advantage of the improvements for building forms and query parameter
validation.

guix-data-service/model/git-branch.scm

@@ -1,8 +1,9 @@
 (define-module (guix-data-service model git-branch)
   #:use-module (squee)
+  #:use-module (srfi srfi-19)
   #:export (insert-git-branch-entry
             git-branches-for-commit
-            most-recent-100-commits-for-branch
+            most-recent-commits-for-branch
             all-branches-with-most-recent-commit))
 
 (define (insert-git-branch-entry conn
@@ -27,14 +28,30 @@ ORDER BY datetime DESC")
 
   (exec-query conn query (list commit)))
 
-(define (most-recent-100-commits-for-branch conn branch-name)
+(define* (most-recent-commits-for-branch conn branch-name
+                                         #:key
+                                         (limit 100)
+                                         after-date
+                                         before-date)
   (define query
     (string-append
      "SELECT git_branches.commit, datetime, "
      "(guix_revisions.id IS NOT NULL) as guix_revision_exists "
      "FROM git_branches "
      "LEFT OUTER JOIN guix_revisions ON git_branches.commit = guix_revisions.commit "
-     "WHERE name = $1 ORDER BY datetime DESC LIMIT 100;"))
+     "WHERE name = $1 "
+     (if after-date
+         (simple-format #f " AND datetime > '~A'"
+                        (date->string after-date "~1 ~3"))
+         "")
+     (if before-date
+         (simple-format #f " AND datetime < '~A'"
+                        (date->string before-date "~1 ~3"))
+         "")
+     "ORDER BY datetime DESC"
+     (if limit
+         (simple-format #f " LIMIT ~A;" limit)
+         "")))
 
   (exec-query
    conn