package roomserver_test

import (
	"encoding/json"
	"errors"
	"testing"

	"github.com/dariuszjaniak/warp/server/internal/matrix/event"
	"github.com/dariuszjaniak/warp/server/internal/roomserver"
	"github.com/dariuszjaniak/warp/server/internal/storage"
)

// contentOf reads a stored event's content as a map.
func (f *fixture) contentOf(roomID, eventID string) map[string]any {
	f.t.Helper()
	stored, err := f.store.Event(f.t.Context(), roomID, eventID)
	if err != nil {
		f.t.Fatalf("Event: %v", err)
	}
	var body struct {
		Content map[string]any `json:"content"`
	}
	if err := json.Unmarshal(stored.JSON, &body); err != nil {
		f.t.Fatalf("the stored event is not an object: %v", err)
	}
	return body.Content
}

func TestRedactOwnEvent(t *testing.T) {
	f := newFixture(t, nil)
	resp := f.createRoom(roomserver.CreateRoomRequest{Preset: roomserver.PresetPublicChat})

	target, err := f.sendMessage(resp.RoomID, alice, "something regrettable", "m1")
	if err != nil {
		t.Fatalf("sending the message: %v", err)
	}
	if body := f.contentOf(resp.RoomID, target); body["body"] == nil {
		t.Fatal("the message was stored without its body")
	}

	redaction, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID:  resp.RoomID,
		Sender:  alice,
		EventID: target,
		Reason:  "a mistake",
	})
	if err != nil {
		t.Fatalf("Redact: %v", err)
	}

	// The event is stripped in place, and still has its original ID: the
	// ID is the reference hash of the redacted form, so redacting an event
	// does not rename it.
	stored, err := f.store.Event(t.Context(), resp.RoomID, target)
	if err != nil {
		t.Fatalf("Event: %v", err)
	}
	if stored.RedactedBy != redaction {
		t.Errorf("redacted_by = %q, want %q", stored.RedactedBy, redaction)
	}
	if body := f.contentOf(resp.RoomID, target); len(body) != 0 {
		t.Errorf("the redacted event still has content: %v", body)
	}

	// A client reading it back is told why it is empty.
	clientEvent, err := f.api.Event(t.Context(), resp.RoomID, alice, target)
	if err != nil {
		t.Fatalf("Event: %v", err)
	}
	var unsigned struct {
		RedactedBecause struct {
			EventID string `json:"event_id"`
		} `json:"redacted_because"`
	}
	if err := json.Unmarshal(clientEvent.Unsigned, &unsigned); err != nil {
		t.Fatalf("the unsigned block is not an object: %v", err)
	}
	if unsigned.RedactedBecause.EventID != redaction {
		t.Errorf("unsigned.redacted_because names %q, want %q",
			unsigned.RedactedBecause.EventID, redaction)
	}
}

// TestRedactAnotherUsersEvent checks the second half of the spec's test
// under "Handling redactions", which is the one that actually fires on a
// server with no federation: a redaction applies when it comes from the
// same server as the event it redacts, whatever the sender's power level,
// because a server may always take back its own users' events.
//
// Every user here is on one server, so that rule covers every pair of them
// and the power-level branch cannot be reached. Exercising that branch
// needs an event from another server, which is Phase 5; the branch itself
// is tested in internal/matrix/auth.
func TestRedactAnotherUsersEvent(t *testing.T) {
	f := newFixture(t, nil)
	resp := f.createRoom(roomserver.CreateRoomRequest{
		Preset: roomserver.PresetPublicChat,
		// carol is an ordinary member with no redact power, so if the
		// redaction applies it is the same-server rule that did it.
		PowerLevelContentOverride: json.RawMessage(
			`{"users":{"` + alice + `":100},"redact":50}`),
	})
	for _, user := range []string{bob, carol} {
		if _, err := f.api.JoinRoom(t.Context(), roomserver.JoinRequest{
			RoomID: resp.RoomID, User: user,
		}); err != nil {
			t.Fatalf("%s joining: %v", user, err)
		}
	}

	target, err := f.sendMessage(resp.RoomID, bob, "bob's message", "m1")
	if err != nil {
		t.Fatalf("sending the message: %v", err)
	}

	redaction, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: carol, EventID: target,
	})
	if err != nil {
		t.Fatalf("Redact: %v", err)
	}
	stored, err := f.store.Event(t.Context(), resp.RoomID, target)
	if err != nil {
		t.Fatalf("Event: %v", err)
	}
	if stored.RedactedBy != redaction {
		t.Errorf("redacted_by = %q, want %q", stored.RedactedBy, redaction)
	}
	if body := f.contentOf(resp.RoomID, target); len(body) != 0 {
		t.Errorf("the redacted event still has content: %v", body)
	}

	// A second redaction has nothing left to remove and must not rewrite
	// which redaction stripped the event.
	if _, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: alice, EventID: target,
	}); err != nil {
		t.Fatalf("redacting twice: %v", err)
	}
	stored, err = f.store.Event(t.Context(), resp.RoomID, target)
	if err != nil {
		t.Fatalf("Event: %v", err)
	}
	if stored.RedactedBy != redaction {
		t.Errorf("a second redaction took over: redacted_by = %q, want %q",
			stored.RedactedBy, redaction)
	}
}

// TestRedactStateEventKeepsItsKeys is what the redaction algorithm is for:
// stripping a membership event must not strip the membership, or the room
// would forget who is in it.
func TestRedactStateEventKeepsItsKeys(t *testing.T) {
	f := newFixture(t, nil)
	resp := f.createRoom(roomserver.CreateRoomRequest{Preset: roomserver.PresetPublicChat})

	if _, err := f.api.JoinRoom(t.Context(), roomserver.JoinRequest{
		RoomID: resp.RoomID, User: bob,
	}); err != nil {
		t.Fatalf("bob joining: %v", err)
	}
	memberEvent := f.memberEventID(resp.RoomID, bob)

	if _, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: alice, EventID: memberEvent,
	}); err != nil {
		t.Fatalf("Redact: %v", err)
	}

	body := f.contentOf(resp.RoomID, memberEvent)
	if body["membership"] != event.MembershipJoin {
		t.Errorf("the redacted membership event lost its membership: %v", body)
	}
	// The display name is not protected, so it goes.
	if body["displayname"] != nil {
		t.Errorf("the redacted membership event kept its display name: %v", body)
	}
	// Bob is still in the room.
	if got := f.membership(resp.RoomID, bob); got != event.MembershipJoin {
		t.Errorf("bob's membership after the redaction is %q, want join", got)
	}
}

func TestRedactRefusals(t *testing.T) {
	f := newFixture(t, nil)
	resp := f.createRoom(roomserver.CreateRoomRequest{})

	// An event that does not exist is a 404, not an event in the room
	// that refers to nothing.
	_, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: alice, EventID: "$nope",
	})
	if !errors.Is(err, roomserver.ErrNoSuchEvent) {
		t.Errorf("redacting an unknown event = %v, want ErrNoSuchEvent", err)
	}

	// A non-member cannot send a redaction at all.
	target, err := f.sendMessage(resp.RoomID, alice, "hello", "m1")
	if err != nil {
		t.Fatalf("sending the message: %v", err)
	}
	_, err = f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: bob, EventID: target,
	})
	if !errors.Is(err, roomserver.ErrRejected) {
		t.Errorf("a stranger redacting = %v, want ErrRejected", err)
	}
}

func TestRedactIsIdempotentPerTransaction(t *testing.T) {
	f := newFixture(t, nil)
	resp := f.createRoom(roomserver.CreateRoomRequest{})

	target, err := f.sendMessage(resp.RoomID, alice, "hello", "m1")
	if err != nil {
		t.Fatalf("sending the message: %v", err)
	}

	ref := &storage.TransactionRef{Localpart: "alice", DeviceID: "DEV", TxnID: "r1"}
	first, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: alice, EventID: target, Transaction: ref,
	})
	if err != nil {
		t.Fatalf("first redaction: %v", err)
	}
	again, err := f.api.Redact(t.Context(), roomserver.RedactRequest{
		RoomID: resp.RoomID, Sender: alice, EventID: target, Transaction: ref,
	})
	if err != nil {
		t.Fatalf("retried redaction: %v", err)
	}
	if again != first {
		t.Errorf("a retried redaction produced a second event: %q then %q", first, again)
	}
}