package store

import (
	"context"
	"sync"
	"testing"
)

func TestMemoryConcurrentLastAdminDemotion(t *testing.T) {
	m := NewMemory()
	ctx := context.Background()
	a := &User{Username: "admin_a", PasswordHash: "x", Role: RoleUser}
	b := &User{Username: "admin_b", PasswordHash: "x", Role: RoleUser}
	if err := m.CreateUser(ctx, a); err != nil {
		t.Fatal(err)
	}
	if err := m.CreateUser(ctx, b); err != nil {
		t.Fatal(err)
	}
	if err := m.SetUserRole(ctx, a.ID, RoleAdmin); err != nil {
		t.Fatal(err)
	}
	if err := m.SetUserRole(ctx, b.ID, RoleAdmin); err != nil {
		t.Fatal(err)
	}

	var wg sync.WaitGroup
	errs := make(chan error, 2)
	wg.Add(2)
	go func() {
		defer wg.Done()
		errs <- m.SetUserRole(ctx, a.ID, RoleUser)
	}()
	go func() {
		defer wg.Done()
		errs <- m.SetUserRole(ctx, b.ID, RoleUser)
	}()
	wg.Wait()
	close(errs)

	var ok, lastAdmin int
	for err := range errs {
		switch err {
		case nil:
			ok++
		case ErrLastAdmin:
			lastAdmin++
		default:
			t.Fatalf("unexpected error: %v", err)
		}
	}
	if ok != 1 || lastAdmin != 1 {
		t.Fatalf("want 1 success and 1 ErrLastAdmin, got ok=%d lastAdmin=%d", ok, lastAdmin)
	}
	n, err := m.CountAdmins(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Fatalf("admins remaining = %d, want 1", n)
	}
}

func TestMemoryConcurrentBootstrapAdmin(t *testing.T) {
	m := NewMemory()
	ctx := context.Background()
	a := &User{Username: "boot_a", PasswordHash: "x", Role: RoleAdmin}
	b := &User{Username: "boot_b", PasswordHash: "x", Role: RoleAdmin}

	var wg sync.WaitGroup
	errs := make(chan error, 2)
	wg.Add(2)
	go func() {
		defer wg.Done()
		errs <- m.CreateUser(ctx, a)
	}()
	go func() {
		defer wg.Done()
		errs <- m.CreateUser(ctx, b)
	}()
	wg.Wait()
	close(errs)
	for err := range errs {
		if err != nil {
			t.Fatal(err)
		}
	}
	n, err := m.CountAdmins(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Fatalf("bootstrap race left %d admins, want 1", n)
	}
	if a.Role == RoleAdmin && b.Role == RoleAdmin {
		t.Fatal("both users kept RoleAdmin")
	}
	if a.Role != RoleAdmin && b.Role != RoleAdmin {
		t.Fatal("neither user is admin")
	}
}