package buildstep

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"os"
	"path/filepath"
	"testing"
	"time"
)

// fixture writes three files in two directories (modes 0644 and 0755).
func fixture(t *testing.T) string {
	t.Helper()
	root := t.TempDir()
	for _, f := range []struct {
		p    string
		mode os.FileMode
		body string
	}{{"a/x.txt", 0o644, "x\n"}, {"a/run.sh", 0o755, "#!/bin/sh\necho hi\n"}, {"b/c/y.txt", 0o644, "why\n"}} {
		path := filepath.Join(root, f.p)
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(path, []byte(f.body), f.mode); err != nil {
			t.Fatal(err)
		}
		if err := os.Chmod(path, f.mode); err != nil {
			t.Fatal(err)
		}
	}
	return root
}

// 1479/AC1: the archive equals the bytes mesh-controller's pack makes for this tree. testdata/pack-golden.tar.gz
// was made once by running mesh-controller internal/builder/builder.go pack (origin/main 073ccc29, :1351-1425)
// on this fixture (fixture above, modes set by chmod).
func TestPackEqualsTheBuildAgentsArchive(t *testing.T) {
	golden, err := os.ReadFile("testdata/pack-golden.tar.gz")
	if err != nil {
		t.Fatal(err)
	}
	archive, digest, err := Pack(fixture(t))
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(archive, golden) {
		t.Errorf("the archive is %d bytes, the build agent's %d, and they differ", len(archive), len(golden))
	}
	sum := sha256.Sum256(golden)
	if digest != "sha256:"+hex.EncodeToString(sum[:]) {
		t.Errorf("digest = %s", digest)
	}
}

// 1479/AC2: touching every file's time changes nothing.
func TestPackDigestIgnoresFileTimes(t *testing.T) {
	root := fixture(t)
	_, first, err := Pack(root)
	if err != nil {
		t.Fatal(err)
	}
	later := time.Now().Add(48 * time.Hour)
	filepath.Walk(root, func(p string, _ os.FileInfo, _ error) error { return os.Chtimes(p, later, later) })
	if _, second, err := Pack(root); err != nil || second != first {
		t.Errorf("digests %s and %s (%v)", first, second, err)
	}
}