package id

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

func TestSplitUserID(t *testing.T) {
	cases := []struct {
		in         string
		localpart  string
		serverName string
	}{
		{"@alice:warp.test", "alice", "warp.test"},
		{"@alice:warp.test:8448", "alice", "warp.test:8448"},
		// Historical IDs: characters the current grammar forbids still have
		// to be accepted, because rooms are full of them.
		{"@Alice:warp.test", "Alice", "warp.test"},
		{"@a b:warp.test", "a b", "warp.test"},
		{"@😀:warp.test", "😀", "warp.test"},
	}
	for _, tc := range cases {
		localpart, serverName, err := SplitUserID(tc.in)
		if err != nil {
			t.Errorf("SplitUserID(%q) = %v", tc.in, err)
			continue
		}
		if localpart != tc.localpart || serverName != tc.serverName {
			t.Errorf("SplitUserID(%q) = %q, %q; want %q, %q",
				tc.in, localpart, serverName, tc.localpart, tc.serverName)
		}
	}
}

func TestValidateUserIDRejects(t *testing.T) {
	cases := map[string]string{
		"":                             "must not be empty",
		"alice:warp.test":              "does not start with",
		"#alice:warp.test":             "does not start with",
		"@alice":                       "no server name",
		"@:warp.test":                  "empty localpart",
		"@alice:":                      "empty server name",
		"@alice\x00:warp.test":         "NUL",
		"@" + strings.Repeat("a", 255): "the limit is",
	}
	for in, want := range cases {
		err := ValidateUserID(in)
		if err == nil {
			t.Errorf("ValidateUserID(%q) was accepted, want an error", in)
			continue
		}
		if !strings.Contains(err.Error(), want) {
			t.Errorf("ValidateUserID(%q) = %q, want it to mention %q", in, err, want)
		}
		if !errors.Is(err, ErrInvalidID) {
			t.Errorf("ValidateUserID(%q) does not wrap ErrInvalidID: %v", in, err)
		}
	}
}

func TestUserIDLengthLimit(t *testing.T) {
	// Exactly at the limit is allowed; one byte over is not.
	atLimit := "@" + strings.Repeat("a", MaxLength-len("@:warp.test")) + ":warp.test"
	if len(atLimit) != MaxLength {
		t.Fatalf("the test built a %d-byte ID, want %d", len(atLimit), MaxLength)
	}
	if err := ValidateUserID(atLimit); err != nil {
		t.Errorf("a %d-byte user ID was rejected: %v", MaxLength, err)
	}
	if err := ValidateUserID(atLimit + "a"); err == nil {
		t.Error("a user ID one byte over the limit was accepted")
	}
}

func TestServerNameOf(t *testing.T) {
	got, err := ServerNameOf("@alice:warp.test")
	if err != nil {
		t.Fatal(err)
	}
	if got != "warp.test" {
		t.Errorf("ServerNameOf = %q, want warp.test", got)
	}
	if _, err := ServerNameOf("nonsense"); err == nil {
		t.Error("ServerNameOf accepted a string that is not a user ID")
	}
}

func TestSameServer(t *testing.T) {
	cases := []struct {
		a, b string
		want bool
	}{
		{"@alice:warp.test", "@bob:warp.test", true},
		{"@alice:warp.test", "@alice:warp.test", true},
		{"@alice:warp.test", "@bob:other.test", false},
		// Server names are case-sensitive by spec, and the rules that turn
		// on a domain match must not be widened by a capital letter.
		{"@alice:warp.test", "@bob:Warp.test", false},
		{"@alice:warp.test", "not-a-user-id", false},
		{"", "", false},
	}
	for _, tc := range cases {
		if got := SameServer(tc.a, tc.b); got != tc.want {
			t.Errorf("SameServer(%q, %q) = %v, want %v", tc.a, tc.b, got, tc.want)
		}
	}
}

func TestValidateRoomID(t *testing.T) {
	valid := []string{
		"!abc:warp.test",
		// From room version 12 a room ID is a hash with no domain at all.
		"!Nhcu5BS-UMnFX7hBVfVSoXiD7OgH6iRT-xyIuqDnpYQ",
	}
	for _, s := range valid {
		if err := ValidateRoomID(s); err != nil {
			t.Errorf("ValidateRoomID(%q) = %v", s, err)
		}
	}

	invalid := map[string]string{
		"":                             "must not be empty",
		"abc:warp.test":                "does not start with",
		"@abc:warp.test":               "does not start with",
		"!":                            "only a sigil",
		"!abc\x00:warp.test":           "NUL",
		"!" + strings.Repeat("a", 255): "the limit is",
	}
	for s, want := range invalid {
		err := ValidateRoomID(s)
		if err == nil {
			t.Errorf("ValidateRoomID(%q) was accepted, want an error", s)
			continue
		}
		if !strings.Contains(err.Error(), want) {
			t.Errorf("ValidateRoomID(%q) = %q, want it to mention %q", s, err, want)
		}
	}
}

func TestServerNameOfRoomID(t *testing.T) {
	got, err := ServerNameOfRoomID("!abc:warp.test")
	if err != nil {
		t.Fatal(err)
	}
	if got != "warp.test" {
		t.Errorf("ServerNameOfRoomID = %q, want warp.test", got)
	}

	// A version 12 room ID names no server, and saying so is the point:
	// the caller must only ask in the versions where there is an answer.
	if _, err := ServerNameOfRoomID("!Nhcu5BS-UMnFX7hBVfVSoXiD7OgH6iRT"); err == nil {
		t.Error("ServerNameOfRoomID found a server in a room ID that has none")
	}
}

func TestValidateEventID(t *testing.T) {
	valid := []string{"$Rqnc-F-dvnEYJTyHq_iKxU2bZ1CI92-kuZq3a5lr5Zg", "$abc:warp.test"}
	for _, s := range valid {
		if err := ValidateEventID(s); err != nil {
			t.Errorf("ValidateEventID(%q) = %v", s, err)
		}
	}

	invalid := map[string]string{
		"":                             "must not be empty",
		"abc":                          "does not start with",
		"!abc":                         "does not start with",
		"$":                            "only a sigil",
		"$abc\x00":                     "NUL",
		"$" + strings.Repeat("a", 255): "the limit is",
	}
	for s, want := range invalid {
		err := ValidateEventID(s)
		if err == nil {
			t.Errorf("ValidateEventID(%q) was accepted, want an error", s)
			continue
		}
		if !strings.Contains(err.Error(), want) {
			t.Errorf("ValidateEventID(%q) = %q, want it to mention %q", s, err, want)
		}
	}
}