package roomversion

import (
	"errors"
	"strings"
	"testing"
)

func TestGet(t *testing.T) {
	t.Run("a supported version", func(t *testing.T) {
		rules, err := Get(V11)
		if err != nil {
			t.Fatalf("Get(11): %v", err)
		}
		if rules.Version != V11 {
			t.Errorf("Version = %q, want 11", rules.Version)
		}
		if !rules.Supported {
			t.Error("the rules we were handed say they are not supported")
		}
	})

	t.Run("a known but unsupported version", func(t *testing.T) {
		_, err := Get(V1)
		if !errors.Is(err, ErrUnsupportedVersion) {
			t.Errorf("Get(1) = %v, want ErrUnsupportedVersion", err)
		}
	})

	t.Run("an unknown version", func(t *testing.T) {
		_, err := Get("99")
		if !errors.Is(err, ErrUnknownVersion) {
			t.Errorf("Get(99) = %v, want ErrUnknownVersion", err)
		}
	})
}

func TestMustGetPanicsOnAnUnsupportedVersion(t *testing.T) {
	defer func() {
		if recover() == nil {
			t.Error("MustGet did not panic on an unsupported version")
		}
	}()
	MustGet(V1)
}

func TestDefaultIsSupported(t *testing.T) {
	if _, err := Get(Default); err != nil {
		t.Fatalf("the default room version %q is not usable: %v", Default, err)
	}
	if !IsSupported(Default) {
		t.Errorf("IsSupported(%q) = false", Default)
	}
}

func TestSupported(t *testing.T) {
	supported := Supported()
	if len(supported) == 0 {
		t.Fatal("no room versions are supported")
	}
	for _, v := range supported {
		if !IsSupported(v) {
			t.Errorf("Supported() lists %q but IsSupported says no", v)
		}
	}
	for _, v := range []Version{V1, V2} {
		if IsSupported(v) {
			t.Errorf("IsSupported(%q) = true, but the event format for it is not implemented", v)
		}
	}
	if s := SupportedString(); !strings.Contains(s, string(Default)) {
		t.Errorf("SupportedString() = %q, want it to include the default", s)
	}
}

func TestKnownListsEveryVersion(t *testing.T) {
	known := Known()
	if len(known) < 12 {
		t.Errorf("Known() returned %d versions, want every version from 1 to 12", len(known))
	}
	// Known hands out a copy, so a caller cannot edit the registry.
	known[0].Supported = !known[0].Supported
	if Known()[0].Supported == known[0].Supported {
		t.Error("Known() returns the registry itself rather than a copy")
	}
}

// TestFlagsAreMonotonic checks the flags that a later room version never
// takes back. Each of these was added once and kept, so a version where
// one is off after a version where it is on is a transcription error in
// the table — the kind of mistake that would otherwise only show up as a
// room whose history stops verifying.
func TestFlagsAreMonotonic(t *testing.T) {
	flags := map[string]func(Rules) bool{
		"StrictCanonicalJSON":                        func(r Rules) bool { return r.StrictCanonicalJSON },
		"EnforceSigningKeyValidity":                  func(r Rules) bool { return r.EnforceSigningKeyValidity },
		"KnockJoinRule":                              func(r Rules) bool { return r.KnockJoinRule },
		"RestrictedJoinRule":                         func(r Rules) bool { return r.RestrictedJoinRule },
		"KnockRestrictedJoinRule":                    func(r Rules) bool { return r.KnockRestrictedJoinRule },
		"RequireIntegerPowerLevels":                  func(r Rules) bool { return r.RequireIntegerPowerLevels },
		"RedactsInContent":                           func(r Rules) bool { return r.RedactsInContent },
		"RedactionKeepsWholeCreateContent":           func(r Rules) bool { return r.RedactionKeepsWholeCreateContent },
		"RedactionKeepsRedacts":                      func(r Rules) bool { return r.RedactionKeepsRedacts },
		"RedactionKeepsPowerLevelsInvite":            func(r Rules) bool { return r.RedactionKeepsPowerLevelsInvite },
		"RedactionKeepsThirdPartyInviteSigned":       func(r Rules) bool { return r.RedactionKeepsThirdPartyInviteSigned },
		"RedactionKeepsJoinAuthorisedViaUsersServer": func(r Rules) bool { return r.RedactionKeepsJoinAuthorisedViaUsersServer },
		"RedactionKeepsJoinRulesAllow":               func(r Rules) bool { return r.RedactionKeepsJoinRulesAllow },
		"RoomIDIsCreateEventID":                      func(r Rules) bool { return r.RoomIDIsCreateEventID },
		"CreateEventExcludedFromAuthEvents":          func(r Rules) bool { return r.CreateEventExcludedFromAuthEvents },
		"CreatorsHaveInfinitePower":                  func(r Rules) bool { return r.CreatorsHaveInfinitePower },
		"AdditionalCreators":                         func(r Rules) bool { return r.AdditionalCreators },
	}

	known := Known()
	for name, get := range flags {
		seen := false
		for _, rules := range known {
			if get(rules) {
				seen = true
				continue
			}
			if seen {
				t.Errorf("%s is on before room version %s and off again at it", name, rules.Version)
				break
			}
		}
		if !seen {
			t.Errorf("%s is never on in any room version", name)
		}
	}
}

// TestFlagsThatWereDropped covers the other direction: the four pieces of
// behaviour a later room version took away.
func TestFlagsThatWereDropped(t *testing.T) {
	cases := []struct {
		name      string
		get       func(Rules) bool
		lastOnFor Version
	}{
		{"AliasesEventAuth", func(r Rules) bool { return r.AliasesEventAuth }, V5},
		{"RedactionKeepsAliases", func(r Rules) bool { return r.RedactionKeepsAliases }, V5},
		{"CreateEventRequiresCreator", func(r Rules) bool { return r.CreateEventRequiresCreator }, V10},
		{"RedactionProtectsLegacyKeys", func(r Rules) bool { return r.RedactionProtectsLegacyKeys }, V10},
	}

	known := Known()
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			past := false
			for _, rules := range known {
				want := !past
				if got := tc.get(rules); got != want {
					t.Errorf("room version %s has %s = %v, want %v", rules.Version, tc.name, got, want)
				}
				if rules.Version == tc.lastOnFor {
					past = true
				}
			}
		})
	}
}

func TestEventIDFormatByVersion(t *testing.T) {
	cases := map[Version]EventIDFormat{
		V1:  EventIDFormatExplicit,
		V2:  EventIDFormatExplicit,
		V3:  EventIDFormatSHA256,
		V4:  EventIDFormatSHA256URLSafe,
		V11: EventIDFormatSHA256URLSafe,
		V12: EventIDFormatSHA256URLSafe,
	}
	for _, rules := range Known() {
		want, ok := cases[rules.Version]
		if !ok {
			continue
		}
		if rules.EventIDFormat != want {
			t.Errorf("room version %s has event ID format %d, want %d", rules.Version, rules.EventIDFormat, want)
		}
	}
}

func TestStateResByVersion(t *testing.T) {
	cases := map[Version]StateResVersion{
		V1:  StateResV1,
		V2:  StateResV2,
		V11: StateResV2,
		V12: StateResV2Subgraph,
	}
	for _, rules := range Known() {
		want, ok := cases[rules.Version]
		if !ok {
			continue
		}
		if rules.StateRes != want {
			t.Errorf("room version %s uses state resolution %d, want %d", rules.Version, rules.StateRes, want)
		}
	}
}

func TestValidate(t *testing.T) {
	valid := []string{"1", "11", "12", "org.example.room-version.1", "a.b-c", strings.Repeat("a", 32)}
	for _, s := range valid {
		if err := Validate(s); err != nil {
			t.Errorf("Validate(%q) = %v, want it to be accepted", s, err)
		}
	}

	invalid := map[string]string{
		"":                      "empty",
		strings.Repeat("a", 33): "the limit is",
		"V11":                   "contains",
		"11_beta":               "contains",
		"org.example/room":      "contains",
		"room version 11":       "contains",
	}
	for s, want := range invalid {
		err := Validate(s)
		if err == nil {
			t.Errorf("Validate(%q) was accepted, want an error", s)
			continue
		}
		if !strings.Contains(err.Error(), want) {
			t.Errorf("Validate(%q) = %q, want it to mention %q", s, err, want)
		}
	}
}

func TestRulesString(t *testing.T) {
	if got := MustGet(V11).String(); got != "11" {
		t.Errorf("String() = %q, want 11", got)
	}
}