package gitutil

import (
	"context"
	"os"
	"os/exec"
	"path/filepath"
	"testing"
)

func TestPackObjectsIsIncremental(t *testing.T) {
	dir := initTestRepository(t)
	git := Git{Dir: dir}
	ctx := context.Background()
	first := commitFile(t, dir, "example.txt", "first\n", "first")
	firstPack, err := git.PackObjects(ctx, []string{first}, nil)
	if err != nil {
		t.Fatal(err)
	}
	defer firstPack.Close()
	if firstPack.Objects != 3 {
		t.Fatalf("first pack has %d objects, want 3", firstPack.Objects)
	}
	if _, err := os.Stat(firstPack.IndexPath); err != nil {
		t.Fatalf("pack index was not created: %v", err)
	}

	second := commitFile(t, dir, "example.txt", "second\n", "second")
	secondPack, err := git.PackObjects(ctx, []string{second}, []string{first})
	if err != nil {
		t.Fatal(err)
	}
	defer secondPack.Close()
	if secondPack.Objects != 3 {
		t.Fatalf("incremental pack has %d objects, want 3", secondPack.Objects)
	}
	loose, ok, err := git.SmallLooseObjects(ctx, secondPack, 64, 8<<20)
	if err != nil {
		t.Fatal(err)
	}
	if !ok || len(loose) != int(secondPack.Objects) {
		t.Fatalf("SmallLooseObjects() returned %d objects, ok=%v; want %d", len(loose), ok, secondPack.Objects)
	}
	for _, object := range loose {
		if _, err := os.Stat(object.Path); err != nil {
			t.Fatalf("loose object %s is unavailable: %v", object.OID, err)
		}
	}
}

func initTestRepository(t *testing.T) string {
	t.Helper()
	dir := t.TempDir()
	runTestGit(t, dir, "init", "-b", "main")
	runTestGit(t, dir, "config", "user.name", "Dumbforge Test")
	runTestGit(t, dir, "config", "user.email", "test@dumbforge.invalid")
	return dir
}

func commitFile(t *testing.T, dir, name, contents, message string) string {
	t.Helper()
	filename := filepath.Join(dir, name)
	if err := os.MkdirAll(filepath.Dir(filename), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filename, []byte(contents), 0o644); err != nil {
		t.Fatal(err)
	}
	runTestGit(t, dir, "add", name)
	runTestGit(t, dir, "commit", "-m", message)
	cmd := exec.Command("git", "-C", dir, "rev-parse", "HEAD")
	out, err := cmd.Output()
	if err != nil {
		t.Fatal(err)
	}
	return string(out[:len(out)-1])
}

func runTestGit(t *testing.T, dir string, args ...string) {
	t.Helper()
	args = append([]string{"-C", dir}, args...)
	cmd := exec.Command("git", args...)
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("git %v: %v\n%s", args, err, out)
	}
}