package greeter_test

import (
	"strings"
	"testing"

	"gitea.djmil.dev/djmil/go-template/internal/greeter"
	"gitea.djmil.dev/djmil/go-template/internal/logger"
)

// ── Service (unit tests) ──────────────────────────────────────────────────────

func TestGreet(t *testing.T) {
	svc := greeter.New(logger.NewNop())

	t.Run("returns personalized greeting", func(t *testing.T) {
		msg, err := svc.Greet("World")
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if msg != "Hello, World!" {
			t.Errorf("got %q, want %q", msg, "Hello, World!")
		}
	})

	t.Run("rejects empty name", func(t *testing.T) {
		_, err := svc.Greet("")
		if err == nil {
			t.Fatal("expected error, got nil")
		}
		if !strings.Contains(err.Error(), "name must not be empty") {
			t.Errorf("error %q does not contain %q", err.Error(), "name must not be empty")
		}
	})
}

// ── Manual fake example ───────────────────────────────────────────────────────
// For consumers that depend on the Greeter interface, write a manual fake.
// No code generation required — just implement the interface directly.

type fakeGreeter struct {
	greetFn func(name string) (string, error)
}

func (f *fakeGreeter) Greet(name string) (string, error) {
	return f.greetFn(name)
}

func TestFakeUsageExample(t *testing.T) {
	fake := &fakeGreeter{
		greetFn: func(name string) (string, error) {
			return "Hello, " + name + "!", nil
		},
	}

	msg, err := fake.Greet("Alice")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if msg != "Hello, Alice!" {
		t.Errorf("got %q, want %q", msg, "Hello, Alice!")
	}
}