package testkit_test

import (
	"bytes"
	"encoding/hex"
	"encoding/json"
	"os"
	"path/filepath"
	"reflect"
	"slices"
	"testing"

	"filippo.io/age"

	"g.activething.com/go/DateKeys/internal/pathrule"
	"g.activething.com/go/DateKeys/internal/testkit"
	"g.activething.com/go/DateKeys/profile"
)

func TestEdits(t *testing.T) {
	base := []byte("0123456789")
	long := "0123456789abcdefghijklmnopqrstuvwxyz"
	for _, tc := range []struct {
		base string
		out  string
		want string // JSON of Splice(base, out)
	}{
		{"", "0123456789", `[]`},
		{"", "01X3456789", `[[2,1,"58"]]`},
		{"", "012", `[[3,7,""]]`},
		{"", "", `[[0,10,""]]`},
		{"", "01234567890", `[[10,0,"30"]]`},
		{"", "0123XY456789", `[[4,0,"5859"]]`},
		// Runs 16 or more equal bytes apart are edits of their own; closer
		// ones are merged.
		{long, "0X23456789abcdefghijklmnopqrstuvwxYz", `[[1,1,"58"],[34,1,"59"]]`},
		{long, "0X23456789aXcdefghijklmnopqrstuvwxyz", `[[1,11,"5832333435363738396158"]]`},
		// A change and a cut: an edit and a deletion.
		{long, "0X23456789abcdefghijklmnopqrst", `[[1,1,"58"],[30,6,""]]`},
		// A change and more bytes: an edit and an insertion.
		{long, "0X23456789abcdefghijklmnopqrstuvwxyz!!", `[[1,1,"58"],[36,0,"2121"]]`},
	} {
		base := base
		if tc.base != "" {
			base = []byte(tc.base)
		}
		edits := testkit.Splice(base, []byte(tc.out))
		if edits == nil {
			edits = []testkit.Edit{}
		}
		b, err := json.Marshal(edits)
		if err != nil || string(b) != tc.want {
			t.Errorf("Splice(%q) = %s, %v; want %s", tc.out, b, err, tc.want)
		}
		var back []testkit.Edit
		if err := json.Unmarshal(b, &back); err != nil {
			t.Fatal(err)
		}
		out, err := testkit.ApplyEdits(base, back)
		if err != nil || string(out) != tc.out {
			t.Errorf("ApplyEdits(%s) = %q, %v; want %q", b, out, err, tc.out)
		}
	}
	// Several edits refer to offsets of the base.
	out, err := testkit.ApplyEdits(base, []testkit.Edit{{At: 1, Delete: 1, Insert: []byte("ab")}, {At: 5, Delete: 2}, {At: 10, Insert: []byte("!")}})
	if err != nil || string(out) != "0ab234789!" {
		t.Fatalf("got %q, %v", out, err)
	}
	for _, bad := range [][]testkit.Edit{
		{{At: 5, Delete: 1}, {At: 2, Delete: 1}}, // out of order
		{{At: 2, Delete: 3}, {At: 4, Delete: 1}}, // overlapping
		{{At: 9, Delete: 2}},                     // beyond the base
		{{At: -1}},
	} {
		if _, err := testkit.ApplyEdits(base, bad); err == nil {
			t.Errorf("ApplyEdits accepted %v", bad)
		}
	}
	for _, bad := range []string{`[1,2]`, `[1,2,"zz"]`, `["1",2,""]`, `{}`} {
		var e testkit.Edit
		if err := json.Unmarshal([]byte(bad), &e); err == nil {
			t.Errorf("Edit accepted %s", bad)
		}
	}
}

// The re-encodings of the point mutations (spec §12.2) change only what their
// names say, and x + p fits for XPlusPRound only among the known rounds.
func TestPointReencodings(t *testing.T) {
	sig := testkit.Release(testkit.XPlusPRound).Signature
	xp, err := testkit.AddModulus(sig, 0)
	if err != nil {
		t.Fatal(err)
	}
	if xp[0]&0xe0 != sig[0]&0xe0 || bytes.Equal(xp, sig) || !bytes.Equal(testkit.ReduceCoordinate(xp, 0), sig) {
		t.Fatalf("x + p of %x is %x", sig, xp)
	}
	for _, r := range testkit.Rounds {
		if _, err := testkit.AddModulus(testkit.Release(r).Signature, 0); (err == nil) != (r == testkit.XPlusPRound) {
			t.Errorf("round %d: x + p fits: %v", r, err == nil)
		}
	}
	key := profile.Quicknet().PublicKey
	for _, at := range []int{0, testkit.CoordinateLen} {
		k, err := testkit.AddModulus(key, at)
		if err != nil {
			t.Fatalf("coordinate at %d of the Quicknet key: %v", at, err)
		}
		other := testkit.CoordinateLen - at
		if !bytes.Equal(k[other:other+testkit.CoordinateLen], key[other:other+testkit.CoordinateLen]) || !bytes.Equal(testkit.ReduceCoordinate(k, at), key) {
			t.Fatalf("coordinate at %d: %x", at, k)
		}
	}
	for _, at := range []int{-48, 1, testkit.CoordinateLen} {
		if _, err := testkit.AddModulus(sig, at); err == nil {
			t.Errorf("offset %d of a G1 point accepted", at)
		}
	}
	if n := testkit.Negated(sig); n[0]^sig[0] != testkit.FlagSort || !bytes.Equal(n[1:], sig[1:]) || !bytes.Equal(testkit.Negated(n), sig) {
		t.Fatalf("negated %x", n)
	}
	if i := testkit.InfinityWithPayload(sig); i[0] != 0xc0|sig[0]&0x1f || !bytes.Equal(i[1:], sig[1:]) {
		t.Fatalf("infinity with payload %x", i)
	}
	if i := testkit.Infinity(96); len(i) != 96 || i[0] != 0xc0 || !bytes.Equal(i[1:], make([]byte, 95)) {
		t.Fatalf("infinity %x", i)
	}
}

// The schema vectors of testdata/vectors/cbor.json replay: the decoder of each
// schema gives exactly the recorded result.
func TestSchemaVectors(t *testing.T) {
	var f testkit.CBORVectorFile
	if err := testkit.ReadJSON("../../testdata/vectors/cbor.json", &f); err != nil {
		t.Fatal(err)
	}
	blocks := map[string]int{}
	for _, v := range f.Schemas {
		b, err := hex.DecodeString(v.Hex)
		if err != nil {
			t.Fatal(err)
		}
		if got := testkit.Result(testkit.DecodeSchema(v.Schema, b, v.Format)); got != v.Result {
			t.Errorf("%s %q: got %s, want %s", v.Block, v.Name, got, v.Result)
		}
		blocks[v.Block]++
	}
	for _, b := range []string{testkit.SchemaProfile, testkit.SchemaHeader, testkit.SchemaControl, testkit.SchemaDKKBody, "verification_metadata", "extension"} {
		if blocks[b] < 5 {
			t.Errorf("block %s has %d vectors", b, blocks[b])
		}
	}
	if err := testkit.DecodeSchema("nope", nil, 0); err == nil {
		t.Error("unknown schema accepted")
	}
}

// The vectors of format 3 replay: each path, tree, key, head and security
// area of the committed files gets its recorded result from the
// implementation, with the tables the files name (spec §29.3 to §29.7).
func TestFormat3VectorFiles(t *testing.T) {
	const dir = "../../testdata/vectors/"
	var paths testkit.PathVectorFile
	if err := testkit.ReadJSON(dir+"paths.json", &paths); err != nil {
		t.Fatal(err)
	}
	var fold testkit.PathFoldFile
	if err := testkit.ReadJSON(dir+"path_fold.json", &fold); err != nil {
		t.Fatal(err)
	}
	for _, f := range []struct{ version, digest string }{{paths.UnicodeVersion, paths.TablesDigest}, {fold.UnicodeVersion, fold.TablesDigest}} {
		if f.version != pathrule.UnicodeVersion || f.digest != pathrule.TablesDigest {
			t.Fatalf("vectors of Unicode %s and tables %s", f.version, f.digest)
		}
	}
	for _, v := range paths.Paths {
		if got := testkit.PathResult(v.Path); got != v.Result {
			t.Errorf("path %q: %q, want %q", v.Name, got, v.Result)
		}
	}
	for _, v := range paths.Trees {
		b, err := testkit.TreeHead(v.Paths)
		if err != nil {
			t.Fatal(err)
		}
		if got, detail := testkit.HeadResult(b); got != v.Result || detail != v.Detail {
			t.Errorf("tree %q: %s %q, want %s %q", v.Name, got, detail, v.Result, v.Detail)
		}
	}
	for _, v := range fold.Keys {
		if pathrule.NFD(v.Segment) != v.NFD || pathrule.Key(v.Segment) != v.Key {
			t.Errorf("key %q: NFD %+q, key %+q", v.Name, pathrule.NFD(v.Segment), pathrule.Key(v.Segment))
		}
	}
	var heads testkit.HeadSchemaFile
	if err := testkit.ReadJSON(dir+"head_schema.json", &heads); err != nil {
		t.Fatal(err)
	}
	for _, v := range heads.Heads {
		b, err := hex.DecodeString(v.Hex)
		if err != nil {
			t.Fatal(err)
		}
		if got, detail := testkit.HeadResult(b); got != v.Result || detail != v.Detail {
			t.Errorf("head %q: %s %q, want %s %q", v.Name, got, detail, v.Result, v.Detail)
		}
	}
	var security testkit.SecurityVectorFile
	if err := testkit.ReadJSON(dir+"security.json", &security); err != nil {
		t.Fatal(err)
	}
	c, err := testkit.SecurityContextOf(security.Context)
	if err != nil {
		t.Fatal(err)
	}
	verdicts := map[string]bool{}
	for _, v := range security.Vectors {
		b, err := hex.DecodeString(v.Hex)
		if err != nil {
			t.Fatal(err)
		}
		if sig, seal, lines := testkit.SecurityResultIn(b, c); sig != v.Signature || seal != v.Seal || !slices.Equal(lines, v.Lines) {
			t.Errorf("security %q: %s %s %q, want %s %s %q", v.Name, sig, seal, lines, v.Signature, v.Seal, v.Lines)
		}
		verdicts[v.Signature], verdicts[v.Seal] = true, true
	}
	// Every verdict that needs no certificate has a vector here; those of
	// alg 2 and seal_type 2 are in security_cms.json.
	for _, v := range []string{"X", "F0", "F1", "F2", "F4", "S0", "S1", "S2"} {
		if !verdicts[v] {
			t.Errorf("no vector gives %s", v)
		}
	}
}

// The committed vector files are what the generators compute now.
func TestVectorFilesAreCurrent(t *testing.T) {
	cbor, err := testkit.CBORVectors()
	if err != nil {
		t.Fatal(err)
	}
	padding, err := testkit.PaddingVectors()
	if err != nil {
		t.Fatal(err)
	}
	paths, err := testkit.PathVectors()
	if err != nil {
		t.Fatal(err)
	}
	fold, err := testkit.PathFoldVectors()
	if err != nil {
		t.Fatal(err)
	}
	heads, err := testkit.HeadSchemaVectors()
	if err != nil {
		t.Fatal(err)
	}
	security, err := testkit.SecurityVectors()
	if err != nil {
		t.Fatal(err)
	}
	strict, err := testkit.Ed25519StrictVectors()
	if err != nil {
		t.Fatal(err)
	}
	note, err := testkit.NoteVectors()
	if err != nil {
		t.Fatal(err)
	}
	words, err := testkit.WordKeyVectors()
	if err != nil {
		t.Fatal(err)
	}
	resolved, err := testkit.ResolvedIPVectors()
	if err != nil {
		t.Fatal(err)
	}
	steps, err := testkit.TlockStepVectors()
	if err != nil {
		t.Fatal(err)
	}
	releases, err := testkit.ReleaseVectors()
	if err != nil {
		t.Fatal(err)
	}
	files, err := testkit.ReleaseFiles()
	if err != nil {
		t.Fatal(err)
	}
	for name, want := range files {
		got, err := os.ReadFile("../../testdata/releases/" + name)
		if err != nil || !bytes.Equal(got, want) {
			t.Errorf("testdata/releases/%s is stale: run go run ./internal/testkit/genfixtures -out testdata", name)
		}
	}
	// The generator never deletes: a file it no longer writes is stale.
	entries, err := os.ReadDir("../../testdata/releases")
	if err != nil {
		t.Fatal(err)
	}
	for _, e := range entries {
		if _, ok := files[e.Name()]; !ok {
			t.Errorf("testdata/releases/%s is not generated: remove it", e.Name())
		}
	}
	for _, v := range []struct {
		file string
		want any
		got  any
	}{
		{"cbor.json", cbor, &testkit.CBORVectorFile{}},
		{"padding.json", padding, &testkit.PaddingVectorFile{}},
		{"paths.json", paths, &testkit.PathVectorFile{}},
		{"path_fold.json", fold, &testkit.PathFoldFile{}},
		{"head_schema.json", heads, &testkit.HeadSchemaFile{}},
		{"security.json", security, &testkit.SecurityVectorFile{}},
		{"ed25519_strict.json", strict, &testkit.Ed25519StrictFile{}},
		{"note.json", note, &testkit.NoteVectorFile{}},
		{"wordkey.json", words, &testkit.WordKeyVectorFile{}},
		{"resolved_ip.json", resolved, &testkit.ResolvedIPVectorFile{}},
		{"tlock_steps.json", steps, &testkit.TlockStepsFile{}},
		{"release.json", releases, &testkit.ReleaseVectorFile{}},
	} {
		if err := testkit.ReadJSON("../../testdata/vectors/"+v.file, v.got); err != nil {
			t.Fatal(err)
		}
		a, _ := json.Marshal(v.want)
		b, _ := json.Marshal(v.got)
		if !bytes.Equal(a, b) {
			t.Errorf("testdata/vectors/%s is stale: run go run ./internal/testkit/genfixtures -out testdata", v.file)
		}
	}
}

// The tools that seal age files again with known keys reproduce the official
// fixtures byte for byte when nothing is edited: their STREAM, header MAC and
// PRELUDE are those of age and of the reference, so that the format 2
// mutations derived with them differ only where they are edited.
func TestResealReproducesFixtures(t *testing.T) {
	const dir = "../../testdata/fixtures"
	to, err := testkit.LoadFixture(dir, "format2_time_only")
	if err != nil {
		t.Fatal(err)
	}
	same, err := to.WithControl(func(map[uint64]any) {})
	if err != nil || !bytes.Equal(same.DKC, to.DKC) {
		t.Fatalf("WithControl without an edit changes the capsule: %v", err)
	}
	content, err := os.ReadFile(filepath.Join(dir, to.PlaintextFile))
	if err != nil {
		t.Fatal(err)
	}
	padded := append(content, make([]byte, to.PaddedLength-to.PayloadLength)...)
	same, err = to.WithPayloadPlaintext(padded)
	if err != nil || !bytes.Equal(same.DKC, to.DKC) {
		t.Fatalf("WithPayloadPlaintext of the same plaintext changes the capsule: %v", err)
	}
	tk, err := testkit.LoadFixture(dir, "format2_time_and_key_portable")
	if err != nil {
		t.Fatal(err)
	}
	same, err = tk.WithInnerStanzas(func(_ []byte, s []*age.Stanza) ([]*age.Stanza, error) { return s, nil })
	if err != nil || !bytes.Equal(same.DKC, tk.DKC) || same.DKK != nil || len(same.Identities) != 1 {
		t.Fatalf("WithInnerStanzas without an edit changes the capsule: %v", err)
	}
	if testkit.StreamLen(0) != 16 || testkit.StreamLen(65536) != 65552 || testkit.StreamLen(65537) != 65569 {
		t.Fatal("StreamLen")
	}
}

// FixedX25519Stanza builds the stanza age builds, with a chosen ephemeral:
// the identity of the recipient unwraps the file key, and the same seed gives
// the same stanza.
func TestFixedX25519Stanza(t *testing.T) {
	id, _ := age.GenerateX25519Identity()
	fk := bytes.Repeat([]byte{7}, 16)
	s, err := testkit.FixedX25519Stanza(fk, id.Recipient(), "seed")
	if err != nil {
		t.Fatal(err)
	}
	got, err := id.Unwrap([]*age.Stanza{s})
	if err != nil || !bytes.Equal(got, fk) {
		t.Fatalf("unwrap: %v", err)
	}
	again, _ := testkit.FixedX25519Stanza(fk, id.Recipient(), "seed")
	other, _ := testkit.FixedX25519Stanza(fk, id.Recipient(), "other seed")
	if !reflect.DeepEqual(s, again) || reflect.DeepEqual(s, other) {
		t.Fatal("the stanza does not depend on the seed alone")
	}
}