package delivery

import (
	"crypto/sha256"
	"encoding/hex"
	"strings"
	"testing"
)

func sha256Of(s string) string { h := sha256.Sum256([]byte(s)); return hex.EncodeToString(h[:]) }

// A module whose every artifact names its paths takes its tree from its manifest and those paths alone (novox/hq ADR
// 0499 clause 2): a change outside them leaves the value equal, a change to a named path or to the manifest changes it,
// and the order the paths are given in changes nothing.
func TestTheNamedTreeIsOfTheManifestAndTheNamedPathsAlone(t *testing.T) {
	manifest := sha256Of(`{"module":"mesh-sdk"}`)
	paths := map[string]string{"src": strings.Repeat("a", 40), "package.json": strings.Repeat("b", 40)}
	v, err := NamedTree(manifest, paths)
	if err != nil {
		t.Fatal(err)
	}
	if !strings.HasPrefix(v, NamedTreePrefix) || !isHex64(strings.TrimPrefix(v, NamedTreePrefix)) {
		t.Fatalf("the value %q is not %s and 64 hex digits", v, NamedTreePrefix)
	}
	// A change outside the named paths is no input at all: the same inputs give the same value, in any map order.
	again, _ := NamedTree(manifest, map[string]string{"package.json": strings.Repeat("b", 40), "src": strings.Repeat("a", 40)})
	if again != v {
		t.Fatalf("the same inputs gave %q and %q", v, again)
	}
	changed, _ := NamedTree(manifest, map[string]string{"src": strings.Repeat("c", 40), "package.json": strings.Repeat("b", 40)})
	if changed == v {
		t.Fatal("a changed named path left the value equal")
	}
	otherManifest, _ := NamedTree(sha256Of(`{"module":"mesh-sdk","version":"2"}`), paths)
	if otherManifest == v {
		t.Fatal("a changed manifest left the value equal")
	}
	renamed, _ := NamedTree(manifest, map[string]string{"lib": strings.Repeat("a", 40), "package.json": strings.Repeat("b", 40)})
	if renamed == v {
		t.Fatal("a path named differently with the same object left the value equal")
	}

	// The lines are fixed, so every computation of it agrees: pinned here.
	want := "named:" + sha256Of("manifest "+manifest+"\npath package.json "+strings.Repeat("b", 40)+"\npath src "+strings.Repeat("a", 40))
	if v != want {
		t.Fatalf("NamedTree = %q, want %q", v, want)
	}
}

func TestTheNamedTreeRefusesWhatItCannotPin(t *testing.T) {
	manifest := sha256Of("{}")
	for _, c := range []struct {
		manifest string
		paths    map[string]string
		says     string
	}{
		{manifest, nil, "names no path"},
		{manifest, map[string]string{"src": ""}, `the named path "src" has no git object`},
		{"abc", map[string]string{"src": "x"}, "not a manifest digest"},
		{manifest, map[string]string{"src/../x": "x"}, "is not a clean path"},
		{manifest, map[string]string{"": "x"}, "is not a clean path"},
		{manifest, map[string]string{"/src": "x"}, "is not a clean path"},
	} {
		if _, err := NamedTree(c.manifest, c.paths); err == nil || !strings.Contains(err.Error(), c.says) {
			t.Errorf("NamedTree(%q, %v) = %v, wanted a refusal saying %q", c.manifest, c.paths, err, c.says)
		}
	}
}