internal/app: unexport outcome, remove app struct

The App struct no longer does anything, and the outcome struct is entirely opaque.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/app.go

@@ -3,83 +3,28 @@ package app
 
 import (
 	"context"
-	"fmt"
 	"log"
-	"sync"
+	"os"
 
 	"hakurei.app/hst"
 	"hakurei.app/internal/app/state"
 	"hakurei.app/internal/sys"
 )
 
-// New returns the address of a newly initialised [App] struct.
-func New(ctx context.Context, os sys.State) (*App, error) {
-	a := new(App)
-	a.sys = os
-	a.ctx = ctx
-
-	id := new(state.ID)
-	err := state.NewAppID(id)
-	a.id = newID(id)
-
-	return a, err
-}
-
-// MustNew calls [New] and panics if an error is returned.
-func MustNew(ctx context.Context, os sys.State) *App {
-	a, err := New(ctx, os)
-	if err != nil {
-		log.Fatalf("cannot create app: %v", err)
-	}
-	return a
-}
-
-// An App keeps track of the hakurei container lifecycle.
-type App struct {
-	outcome *Outcome
-
-	id  *stringPair[state.ID]
-	sys sys.State
-	ctx context.Context
-	mu  sync.RWMutex
-}
-
-// 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 {
-	if a == nil {
-		return "<nil>"
+// Main runs an app according to [hst.Config] and terminates. Main does not return.
+func Main(ctx context.Context, k sys.State, config *hst.Config) {
+	var id state.ID
+	if err := state.NewAppID(&id); err != nil {
+		log.Fatal(err)
 	}
 
-	a.mu.RLock()
-	defer a.mu.RUnlock()
-
-	if a.outcome != nil {
-		if a.outcome.user.uid == nil {
-			return "<invalid>"
-		}
-		return fmt.Sprintf("sealed app %s as uid %s", a.id, a.outcome.user.uid)
+	var seal outcome
+	seal.id = &stringPair[state.ID]{id, id.String()}
+	if err := seal.finalise(ctx, k, config); err != nil {
+		printMessageError("cannot seal app:", err)
+		os.Exit(1)
 	}
 
-	return fmt.Sprintf("unsealed app %s", a.id)
-}
-
-// Seal determines the [Outcome] of [hst.Config].
-// 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) (*Outcome, error) {
-	a.mu.Lock()
-	defer a.mu.Unlock()
-
-	if a.outcome != nil {
-		panic("attempting to seal app twice")
-	}
-
-	seal := new(Outcome)
-	seal.id = a.id
-	err := seal.finalise(a.ctx, a.sys, config)
-	if err == nil {
-		a.outcome = seal
-	}
-	return seal, err
+	seal.main()
+	panic("unreachable")
 }