From 16413d769e9967517bc2477494eb74d1049308fb Mon Sep 17 00:00:00 2001
From: Googol Lee <i@googol.im>
Date: Wed, 27 Sep 2023 10:19:19 +0200
Subject: [PATCH] Add module.Build

---
 module/build.go         | 66 +++++++++++++++++++++++++++++++++++++++++
 module/build_context.go | 28 -----------------
 module/module_test.go   | 56 ++++++++++++++++++++++++++++++++--
 module/type.go          | 16 ++++------
 4 files changed, 125 insertions(+), 41 deletions(-)
 create mode 100644 module/build.go
 delete mode 100644 module/build_context.go

diff --git a/module/build.go b/module/build.go
new file mode 100644
index 0000000..5a39934
--- /dev/null
+++ b/module/build.go
@@ -0,0 +1,66 @@
+package module
+
+import (
+	"context"
+
+	"github.com/googollee/go-espresso"
+)
+
+func Build(ctx context.Context, server *espresso.Server, modules []Module) ([]ModuleImplementer, error) {
+	bctx := newBuildContext(ctx, server)
+
+	for _, m := range modules {
+		if err := m.build(bctx); err != nil {
+			return nil, err
+		}
+	}
+
+	return bctx.Modules(), nil
+}
+
+type buildContext struct {
+	context.Context
+	server    *espresso.Server
+	deps      map[moduleName]struct{}
+	instances map[moduleName]ModuleImplementer
+	err       error
+}
+
+func newBuildContext(ctx context.Context, server *espresso.Server) *buildContext {
+	return &buildContext{
+		Context:   ctx,
+		server:    server,
+		deps:      make(map[moduleName]struct{}),
+		instances: make(map[moduleName]ModuleImplementer),
+	}
+}
+
+func (c *buildContext) Child() *buildContext {
+	return &buildContext{
+		Context:   c.Context,
+		server:    c.server,
+		deps:      make(map[moduleName]struct{}),
+		instances: c.instances,
+	}
+}
+
+func (c *buildContext) Value(key any) any {
+	name, ok := key.(moduleName)
+	if !ok {
+		return c.Context.Value(key)
+	}
+
+	return c.Module(name)
+}
+
+func (c *buildContext) Module(name moduleName) ModuleImplementer {
+	return c.instances[name]
+}
+
+func (c *buildContext) Modules() []ModuleImplementer {
+	ret := make([]ModuleImplementer, 0, len(c.instances))
+	for _, i := range c.instances {
+		ret = append(ret, i)
+	}
+	return ret
+}
diff --git a/module/build_context.go b/module/build_context.go
deleted file mode 100644
index 00d8c98..0000000
--- a/module/build_context.go
+++ /dev/null
@@ -1,28 +0,0 @@
-package module
-
-import (
-	"context"
-
-	"github.com/googollee/go-espresso"
-)
-
-type buildContext struct {
-	context.Context
-	server  *espresso.Server
-	deps    map[moduleName]struct{}
-	modules map[moduleName]ModuleImplementer
-	err     error
-}
-
-func (c *buildContext) Value(key any) any {
-	name, ok := key.(moduleName)
-	if !ok {
-		return c.Context.Value(key)
-	}
-
-	return c.modules[name]
-}
-
-func (c *buildContext) module(name moduleName) ModuleImplementer {
-	return c.modules[name]
-}
diff --git a/module/module_test.go b/module/module_test.go
index f4725be..1551443 100644
--- a/module/module_test.go
+++ b/module/module_test.go
@@ -1,9 +1,61 @@
 package module
 
-import "context"
+import (
+	"context"
+	"testing"
+
+	"github.com/googollee/go-espresso"
+)
+
+// - Module1
+//   - Module2
+//   - Module3
+//     - Module5
+// - Module2
+// - Module4
+//   - Module5
 
 type fakeModule struct{}
 
 func (fakeModule) CheckHealthy(context.Context) error { return nil }
 
-var _ Module = &ModuleType[fakeModule]{}
+func buildFake[T ModuleImplementer](context.Context, *espresso.Server) (*T, error) {
+	var t T
+	return &t, nil
+}
+
+type Module1 struct{ fakeModule }
+type Module2 struct{ fakeModule }
+type Module3 struct{ fakeModule }
+type Module4 struct{ fakeModule }
+type Module5 struct{ fakeModule }
+
+var (
+	build1 = buildFake[Module1]
+	build2 = buildFake[Module2]
+	build3 = buildFake[Module3]
+	build4 = buildFake[Module4]
+	build5 = buildFake[Module5]
+)
+
+var (
+	module1 = NewModule(build1)
+	module2 = NewModule(build2)
+	module3 = NewModule(build3)
+	module4 = NewModule(build4)
+	module5 = NewModule(build5)
+)
+
+func TestModule(t *testing.T) {
+	ctx := context.Background()
+	server := &espresso.Server{}
+
+	modules, err := Build(ctx, server, []Module{module1, module2, module5})
+	if err != nil {
+		t.Fatalf("Build(ctx, server, {module1, module2, module5}) returns error: %v", err)
+	}
+
+	if got, want := len(modules), 5; got != want {
+		t.Fatalf("len(modules) = %v, want: %v", got, want)
+	}
+}
diff --git a/module/type.go b/module/type.go
index a9530a5..74e3fe7 100644
--- a/module/type.go
+++ b/module/type.go
@@ -73,7 +73,7 @@ func (m *ModuleType[T]) CheckHealthy(ctx context.Context) (err error) {
 
 func (m *ModuleType[T]) valueWithBuilder(ctx *buildContext) T {
 	ctx.deps[m.Name()] = struct{}{}
-	if ret, ok := ctx.modules[m.Name()]; ok {
+	if ret, ok := ctx.instances[m.Name()]; ok {
 		return ret.(T)
 	}
 
@@ -82,19 +82,13 @@ func (m *ModuleType[T]) valueWithBuilder(ctx *buildContext) T {
 		panic(errBuildError)
 	}
 
-	return ctx.modules[m.Name()].(T)
+	return ctx.instances[m.Name()].(T)
 }
 
 func (m *ModuleType[T]) build(ctx *buildContext) error {
-	bctx := buildContext{
-		Context: ctx.Context,
-		server:  ctx.server,
-		deps:    make(map[moduleName]struct{}),
-		modules: ctx.modules,
-		err:     nil,
-	}
+	bctx := ctx.Child()
 
-	ret, err := m.builder(&bctx, bctx.server)
+	ret, err := m.builder(bctx, bctx.server)
 	if err != nil {
 		return err
 	}
@@ -104,7 +98,7 @@ func (m *ModuleType[T]) build(ctx *buildContext) error {
 		m.depends = append(m.depends, name)
 	}
 
-	ctx.modules[m.Name()] = ret
+	ctx.instances[m.Name()] = ret
 
 	return nil
 }