From 1fc68a692b4a494e7acd24ddf33e130eee45779d Mon Sep 17 00:00:00 2001
From: Drew DeVault <sir@cmpwn.com>
Date: Mon, 13 Apr 2020 13:41:24 -0400
Subject: [PATCH] api: implement query { user }

---
 api/go.sum                    |  1 +
 api/graph/schema.resolvers.go |  2 +-
 api/loaders/middleware.go     | 44 +++++++++++++++++++++++++++++++++--
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/api/go.sum b/api/go.sum
index 047b528..fca2176 100644
--- a/api/go.sum
+++ b/api/go.sum
@@ -1,4 +1,5 @@
 git.sr.ht/~sircmpwn/git.sr.ht v0.0.0-20200405134845-b8fbf5bf484f h1:SW8+xV65kcga0rHmQbnZkLG36yp286BcbVOdQTVo1m8=
+git.sr.ht/~sircmpwn/git.sr.ht v0.0.0-20200413150414-046cd382d7b7 h1:PYRTIcsHR5W+aPn98OCC73ly528uw5o/4Z3b5Rvc7vA=
 git.sr.ht/~sircmpwn/gqlgen v0.0.0-20200412134447-57d7234737d4 h1:J/Sb88htNHzZaN6ZEF8BnRWj3LzYoTrOL4WRhZEEiQE=
 git.sr.ht/~sircmpwn/gqlgen v0.0.0-20200412134447-57d7234737d4/go.mod h1:W1cijL2EqAyL1eo1WAJ3ijNVkZM2okpYyCF5TRu1VfI=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
diff --git a/api/graph/schema.resolvers.go b/api/graph/schema.resolvers.go
index a187a4a..87f4f2e 100644
--- a/api/graph/schema.resolvers.go
+++ b/api/graph/schema.resolvers.go
@@ -69,7 +69,7 @@ func (r *queryResolver) Me(ctx context.Context) (*model.User, error) {
 }
 
 func (r *queryResolver) User(ctx context.Context, username string) (*model.User, error) {
-	panic(fmt.Errorf("not implemented"))
+	return loaders.ForContext(ctx).UsersByName.Load(username)
 }
 
 func (r *queryResolver) Repositories(ctx context.Context, next *int, filter *model.FilterBy) ([]*model.Repository, error) {
diff --git a/api/loaders/middleware.go b/api/loaders/middleware.go
index 57c9858..75aa823 100644
--- a/api/loaders/middleware.go
+++ b/api/loaders/middleware.go
@@ -24,12 +24,12 @@ type contextKey struct {
 
 type Loaders struct {
 	UsersByID        UsersByIDLoader
+	UsersByName      UsersByNameLoader
 	RepositoriesByID RepositoriesByIDLoader
 }
 
 func fetchUsersByID(ctx context.Context,
 	db *sql.DB) func (ids []int) ([]*model.User, []error) {
-
 	return func (ids []int) ([]*model.User, []error) {
 		var (
 			err  error
@@ -64,9 +64,44 @@ func fetchUsersByID(ctx context.Context,
 	}
 }
 
+func fetchUsersByName(ctx context.Context,
+	db *sql.DB) func (names []string) ([]*model.User, []error) {
+	return func (names []string) ([]*model.User, []error) {
+		var (
+			err  error
+			rows *sql.Rows
+		)
+		if rows, err = db.QueryContext(ctx,`
+			SELECT `+(&model.User{}).Columns(ctx, "u")+`
+			FROM "user" u
+			WHERE u.username = ANY($1)`, pq.Array(names)); err != nil {
+			panic(err)
+		}
+		defer rows.Close()
+
+		usersByName := map[string]*model.User{}
+		for rows.Next() {
+			user := model.User{}
+			if err := rows.Scan(user.Fields(ctx)...); err != nil {
+				panic(err)
+			}
+			usersByName[user.Username] = &user
+		}
+		if err = rows.Err(); err != nil {
+			panic(err)
+		}
+
+		users := make([]*model.User, len(names))
+		for i, name := range names {
+			users[i] = usersByName[name]
+		}
+
+		return users, nil
+	}
+}
+
 func fetchRepositoriesByID(ctx context.Context,
 	db *sql.DB) func (ids []int) ([]*model.Repository, []error) {
-
 	return func (ids []int) ([]*model.Repository, []error) {
 		var (
 			err  error
@@ -117,6 +152,11 @@ func Middleware(db *sql.DB) func(http.Handler) http.Handler {
 					wait: 1 * time.Millisecond,
 					fetch: fetchUsersByID(r.Context(), db),
 				},
+				UsersByName: UsersByNameLoader{
+					maxBatch: 100,
+					wait: 1 * time.Millisecond,
+					fetch: fetchUsersByName(r.Context(), db),
+				},
 				RepositoriesByID: RepositoriesByIDLoader{
 					maxBatch: 100,
 					wait: 1 * time.Millisecond,
-- 
2.38.4