package capsule_test

import (
	"bytes"
	"context"
	"errors"
	"strings"
	"testing"

	datekeys "g.activething.com/go/DateKeys"
	"g.activething.com/go/DateKeys/capsule"
	"g.activething.com/go/DateKeys/extension"
	"g.activething.com/go/DateKeys/internal/testkit"
)

// Spec v0.11 §24.1, §62.1 rule 23: the public note is in PUBLIC_HEADER, in
// clear, and header_binding ties it to the control: changing it makes step 15
// fail.
func TestPublicNote(t *testing.T) {
	opts := files3(t)
	opts.PublicNote = "Cartas del viaje a Lisboa"
	var dkc bytes.Buffer
	if _, err := capsule.EncryptFiles(&dkc, []capsule.Source{source("nota.txt", "Hola.\n")}, opts); err != nil {
		t.Fatal(err)
	}
	in, err := capsule.Inspect(bytes.NewReader(dkc.Bytes()), capsule.InspectOptions{Registry: testkit.Registry()})
	if err != nil {
		t.Fatal(err)
	}
	if note, ok := in.Header.PublicNote(); !ok || note != "Cartas del viaje a Lisboa" {
		t.Errorf("the note: %q %v", note, ok)
	}
	// The same bytes with another letter in the note: it still inspects, and
	// Open fails at step 15 with ERR_HEADER_BINDING.
	changed := bytes.Replace(dkc.Bytes(), []byte("Lisboa"), []byte("Lisbon"), 1)
	if bytes.Equal(changed, dkc.Bytes()) {
		t.Fatal("the note is not in clear in the capsule")
	}
	o := defaultOpen(1000)
	o.Sink = &testkit.MemorySink{}
	if _, err := capsule.Open(context.Background(), nil, bytes.NewReader(changed), o); !errors.Is(err, datekeys.ErrHeaderBinding) {
		t.Errorf("a note changed: %v", err)
	}
	if _, err := capsule.Open(context.Background(), nil, bytes.NewReader(dkc.Bytes()), o); err != nil {
		t.Errorf("the capsule with its note: %v", err)
	}
}

func TestPublicNoteRules(t *testing.T) {
	for name, text := range map[string]string{
		"a tab":                "a\tb",
		"a line feed":          "a\nb",
		"a space at the end":   "a ",
		"a space at the start": " a",
		"too long":             strings.Repeat("a", extension.MaxNoteLen+1),
		"not UTF-8":            "\xff",
	} {
		if err := extension.CheckNote(text); err == nil {
			t.Errorf("%s: accepted", name)
		}
		opts := files3(t)
		opts.PublicNote = text
		if _, err := capsule.EncryptFiles(&bytes.Buffer{}, []capsule.Source{source("a", "x")}, opts); err == nil {
			t.Errorf("%s: written", name)
		}
	}
	if err := extension.CheckNote(strings.Repeat("a", extension.MaxNoteLen)); err != nil {
		t.Errorf("1024 bytes: %v", err)
	}
	// An unusable note shows nothing.
	if _, ok := extension.Note([]extension.Extension{{ID: extension.NoteID, Version: 1, Data: []byte("a\nb")}}); ok {
		t.Error("an unusable note was shown")
	}
	// The registry knows it only in PUBLIC_HEADER, noncritical.
	var reg extension.Standard
	if !extension.KnownIn(reg, extension.NoteID, 1, extension.PublicHeader, extension.Noncritical) ||
		extension.KnownIn(reg, extension.NoteID, 1, extension.Control, extension.Noncritical) ||
		extension.KnownIn(reg, extension.NoteID, 1, extension.PublicHeader, extension.Critical) ||
		extension.KnownIn(reg, extension.NoteID, 2, extension.PublicHeader, extension.Noncritical) {
		t.Error("registration of datekeys.note")
	}
	if us := extension.CheckNoncriticalIn(extension.PublicHeader, []extension.Extension{{ID: extension.NoteID, Version: 1, Data: []byte("a\tb")}}, reg); len(us) != 1 {
		t.Errorf("the note with a tab is not unusable: %v", us)
	}
}

// Review: spec §72 forbids an encoder to write a registered extension where
// it is not registered. A note given as an extension is checked like
// PublicNote, and no array of a capsule but the noncritical one of
// PUBLIC_HEADER takes it. In CONTROL_CBOR, critical, it would have inspected
// well and failed after the date at step 14. datekeys.capsule goes in none.
func TestRegisteredExtensionsWhereRegistered(t *testing.T) {
	note := extension.Extension{ID: extension.NoteID, Version: 1, Data: []byte("Cartas")}
	tab := extension.Extension{ID: extension.NoteID, Version: 1, Data: []byte("a\tb")}
	capsuleExt := extension.Extension{ID: extension.CapsuleID, Version: 1, Data: []byte{0xa0}}
	for name, set := range map[string]func(*capsule.EncryptOptions){
		"a note with a tab":               func(o *capsule.EncryptOptions) { o.Noncritical = []extension.Extension{tab} },
		"a note in critical":              func(o *capsule.EncryptOptions) { o.Critical = []extension.Extension{note} },
		"a note in the control":           func(o *capsule.EncryptOptions) { o.ControlNoncritical = []extension.Extension{note} },
		"a note in the control, critical": func(o *capsule.EncryptOptions) { o.ControlCritical = []extension.Extension{note} },
		"a note in the head":              func(o *capsule.EncryptOptions) { o.HeadNoncritical = []extension.Extension{note} },
		"datekeys.capsule":                func(o *capsule.EncryptOptions) { o.Noncritical = []extension.Extension{capsuleExt} },
	} {
		opts := files3(t)
		set(&opts)
		if _, err := capsule.EncryptFiles(&bytes.Buffer{}, []capsule.Source{source("a", "x")}, opts); err == nil {
			t.Errorf("%s: written", name)
		}
	}
	opts := files3(t)
	opts.Noncritical = []extension.Extension{note}
	var dkc bytes.Buffer
	if _, err := capsule.EncryptFiles(&dkc, []capsule.Source{source("a", "x")}, opts); err != nil {
		t.Fatalf("a valid note as an extension: %v", err)
	}
}

// Review: a reader tells a note that breaks the rules of §24.1 from no note,
// so that it can say that it does not show one.
func TestUnusableNote(t *testing.T) {
	for _, c := range []struct {
		exts []extension.Extension
		want bool
	}{
		{nil, false},
		{[]extension.Extension{{ID: extension.NoteID, Version: 1, Data: []byte("Cartas")}}, false},
		{[]extension.Extension{{ID: extension.NoteID, Version: 1, Data: []byte("a\tb")}}, true},
		{[]extension.Extension{{ID: extension.NoteID, Version: 2, Data: []byte("a\tb")}}, false},
	} {
		h := &capsule.Header{Noncritical: c.exts}
		if got := h.UnusableNote(); got != c.want {
			t.Errorf("%+v: %v, want %v", c.exts, got, c.want)
		}
	}
}