From d0b6852cd7db2bb1214c3267719d3ac108c0a53e Mon Sep 17 00:00:00 2001
From: Ophestra <cat@gensokyo.uk>
Date: Thu, 28 Aug 2025 00:54:44 +0900
Subject: [PATCH] internal/app: remove app interface

It is very clear at this point that there will not be multiple implementations of App, and the internal/app package will never move out of internal due to hsu.

Signed-off-by: Ophestra <cat@gensokyo.uk>
---
 internal/app/app.go               | 14 --------------
 internal/app/app_linux.go         | 17 ++++++++++-------
 internal/app/export_linux_test.go |  9 ++++-----
 3 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/internal/app/app.go b/internal/app/app.go
index 506703c..d59b145 100644
--- a/internal/app/app.go
+++ b/internal/app/app.go
@@ -4,22 +4,8 @@ package app
 import (
 	"syscall"
 	"time"
-
-	"hakurei.app/hst"
-	"hakurei.app/internal/app/state"
 )
 
-type App interface {
-	// ID returns a copy of [state.ID] held by App.
-	ID() state.ID
-
-	// Seal determines the outcome of config as a [SealedApp].
-	// The value of config might be overwritten and must not be used again.
-	Seal(config *hst.Config) (SealedApp, error)
-
-	String() string
-}
-
 type SealedApp interface {
 	// Run commits sealed system setup and starts the app process.
 	Run(rs *RunState) error
diff --git a/internal/app/app_linux.go b/internal/app/app_linux.go
index bdfc9ea..eebfacd 100644
--- a/internal/app/app_linux.go
+++ b/internal/app/app_linux.go
@@ -11,8 +11,8 @@ import (
 	"hakurei.app/internal/sys"
 )
 
-func New(ctx context.Context, os sys.State) (App, error) {
-	a := new(app)
+func New(ctx context.Context, os sys.State) (*App, error) {
+	a := new(App)
 	a.sys = os
 	a.ctx = ctx
 
@@ -23,7 +23,7 @@ func New(ctx context.Context, os sys.State) (App, error) {
 	return a, err
 }
 
-func MustNew(ctx context.Context, os sys.State) App {
+func MustNew(ctx context.Context, os sys.State) *App {
 	a, err := New(ctx, os)
 	if err != nil {
 		log.Fatalf("cannot create app: %v", err)
@@ -31,7 +31,7 @@ func MustNew(ctx context.Context, os sys.State) App {
 	return a
 }
 
-type app struct {
+type App struct {
 	id  *stringPair[state.ID]
 	sys sys.State
 	ctx context.Context
@@ -40,9 +40,10 @@ type app struct {
 	mu sync.RWMutex
 }
 
-func (a *app) ID() state.ID { a.mu.RLock(); defer a.mu.RUnlock(); return a.id.unwrap() }
+// ID returns a copy of [state.ID] held by App.
+func (a *App) ID() state.ID { a.mu.RLock(); defer a.mu.RUnlock(); return a.id.unwrap() }
 
-func (a *app) String() string {
+func (a *App) String() string {
 	if a == nil {
 		return "(invalid app)"
 	}
@@ -60,7 +61,9 @@ func (a *app) String() string {
 	return fmt.Sprintf("(unsealed app %s)", a.id)
 }
 
-func (a *app) Seal(config *hst.Config) (SealedApp, error) {
+// Seal determines the outcome of [hst.Config] as a [SealedApp].
+// Values stored in and referred to by [hst.Config] might be overwritten and must not be used again.
+func (a *App) Seal(config *hst.Config) (SealedApp, error) {
 	a.mu.Lock()
 	defer a.mu.Unlock()
 
diff --git a/internal/app/export_linux_test.go b/internal/app/export_linux_test.go
index 73c9df9..f7af527 100644
--- a/internal/app/export_linux_test.go
+++ b/internal/app/export_linux_test.go
@@ -7,17 +7,16 @@ import (
 	"hakurei.app/system"
 )
 
-func NewWithID(id state.ID, os sys.State) App {
-	a := new(app)
+func NewWithID(id state.ID, os sys.State) *App {
+	a := new(App)
 	a.id = newID(&id)
 	a.sys = os
 	return a
 }
 
-func AppIParams(a App, sa SealedApp) (*system.I, *container.Params) {
-	v := a.(*app)
+func AppIParams(a *App, sa SealedApp) (*system.I, *container.Params) {
 	seal := sa.(*outcome)
-	if v.outcome != seal || v.id != seal.id {
+	if a.outcome != seal || a.id != seal.id {
 		panic("broken app/outcome link")
 	}
 	return seal.sys, seal.container