package main

import (
	"bytes"
	"os"
	"path/filepath"
	"testing"
)

func TestTemplateRenderer(t *testing.T) {
	dir := t.TempDir()

	os.WriteFile(filepath.Join(dir, "test.html"), []byte(`<h1>{{.Title}}</h1>`), 0644)
	os.WriteFile(filepath.Join(dir, "plain.html"), []byte(`<p>Hello</p>`), 0644)

	tr, err := NewTemplateRenderer(dir)
	if err != nil {
		t.Fatalf("NewTemplateRenderer: %v", err)
	}

	t.Run("render with data", func(t *testing.T) {
		var buf bytes.Buffer
		err := tr.Render(&buf, "test.html", map[string]string{"Title": "World"})
		if err != nil {
			t.Fatalf("Render: %v", err)
		}
		if buf.String() != "<h1>World</h1>" {
			t.Errorf("got %q", buf.String())
		}
	})

	t.Run("render plain", func(t *testing.T) {
		var buf bytes.Buffer
		err := tr.Render(&buf, "plain.html", nil)
		if err != nil {
			t.Fatalf("Render: %v", err)
		}
		if buf.String() != "<p>Hello</p>" {
			t.Errorf("got %q", buf.String())
		}
	})

	t.Run("template not found", func(t *testing.T) {
		var buf bytes.Buffer
		err := tr.Render(&buf, "missing.html", nil)
		if err == nil {
			t.Fatal("expected error for missing template")
		}
	})

	t.Run("empty dir", func(t *testing.T) {
		emptyDir := t.TempDir()
		tr2, err := NewTemplateRenderer(emptyDir)
		if err != nil {
			t.Fatalf("NewTemplateRenderer: %v", err)
		}
		var buf bytes.Buffer
		err = tr2.Render(&buf, "anything.html", nil)
		if err == nil {
			t.Fatal("expected error")
		}
	})
}