package ssh

import (
	"testing"
)

func TestParse_BareHostname(t *testing.T) {
	got := Parse([]string{"myhost"})
	assertParsed(t, got, "myhost", "", 0)
}

func TestParse_UserAtHost(t *testing.T) {
	got := Parse([]string{"admin@myhost"})
	assertParsed(t, got, "myhost", "admin", 0)
}

func TestParse_PortFlag_Separated(t *testing.T) {
	got := Parse([]string{"-p", "2222", "myhost"})
	assertParsed(t, got, "myhost", "", 2)
}

func TestParse_PortFlag_Attached(t *testing.T) {
	got := Parse([]string{"-p2222", "myhost"})
	assertParsed(t, got, "myhost", "", 1)
}

func TestParse_IdentityFlag(t *testing.T) {
	got := Parse([]string{"-i", "/path/to/key", "user@myhost", "ls"})
	assertParsed(t, got, "myhost", "user", 2)
}

func TestParse_VerboseFlag(t *testing.T) {
	got := Parse([]string{"-v", "myhost"})
	assertParsed(t, got, "myhost", "", 1)
}

func TestParse_OptionFlag(t *testing.T) {
	got := Parse([]string{"-o", "StrictHostKeyChecking=no", "myhost"})
	assertParsed(t, got, "myhost", "", 2)
}

func TestParse_JumpHost(t *testing.T) {
	got := Parse([]string{"-J", "jumphost", "-p", "22", "target"})
	assertParsed(t, got, "target", "", 4)
}

func TestParse_MultipleFlags(t *testing.T) {
	got := Parse([]string{"-v", "-p", "22", "-i", "key", "root@host", "uptime"})
	assertParsed(t, got, "host", "root", 5)
}

func TestParse_DoubleDash(t *testing.T) {
	got := Parse([]string{"--", "myhost"})
	assertParsed(t, got, "myhost", "", 1)
}

func TestParse_DoubleDash_WithFlags(t *testing.T) {
	// flags after -- should be treated as destination
	got := Parse([]string{"-v", "--", "-not-a-flag"})
	assertParsed(t, got, "-not-a-flag", "", 2)
}

func TestParse_NoDestination(t *testing.T) {
	got := Parse([]string{"-v", "-p", "2222"})
	if got != nil {
		t.Errorf("expected nil for args without destination, got %+v", got)
	}
}

func TestParse_EmptyArgs(t *testing.T) {
	got := Parse([]string{})
	if got != nil {
		t.Error("empty args should return nil")
	}
}

func TestParse_OnlyDoubleDash(t *testing.T) {
	got := Parse([]string{"--"})
	if got != nil {
		t.Error("only -- with no destination should return nil")
	}
}

func TestReplaceHost_PlainHost(t *testing.T) {
	args := []string{"myhost"}
	result := ReplaceHost(args, 0, "10.0.0.1")
	if result[0] != "10.0.0.1" {
		t.Errorf("got %q, want %q", result[0], "10.0.0.1")
	}
}

func TestReplaceHost_PreservesUserPrefix(t *testing.T) {
	args := []string{"-p", "22", "admin@myhost", "ls"}
	result := ReplaceHost(args, 2, "10.0.0.1")
	if result[2] != "admin@10.0.0.1" {
		t.Errorf("got %q, want %q", result[2], "admin@10.0.0.1")
	}
}

func TestReplaceHost_DoesNotMutateOriginal(t *testing.T) {
	args := []string{"myhost"}
	_ = ReplaceHost(args, 0, "10.0.0.1")
	if args[0] != "myhost" {
		t.Error("ReplaceHost must not mutate the original slice")
	}
}

func TestReplaceHost_OtherArgsUnchanged(t *testing.T) {
	args := []string{"-p", "22", "myhost"}
	result := ReplaceHost(args, 2, "10.0.0.1")
	if result[0] != "-p" || result[1] != "22" {
		t.Errorf("other args should be unchanged: %v", result)
	}
}

func TestHasUserFlag_FlagSeparated(t *testing.T) {
	if !HasUserFlag([]string{"-l", "admin", "host"}) {
		t.Error("should detect -l <user>")
	}
}

func TestHasUserFlag_FlagAttached(t *testing.T) {
	if !HasUserFlag([]string{"-ladmin", "host"}) {
		t.Error("should detect -l<user> (attached form)")
	}
}

func TestHasUserFlag_NotPresent(t *testing.T) {
	if HasUserFlag([]string{"-p", "22", "host"}) {
		t.Error("should not detect user flag when absent")
	}
}

func TestHasUserFlag_EmptyArgs(t *testing.T) {
	if HasUserFlag([]string{}) {
		t.Error("empty args should return false")
	}
}

func TestHasUserFlag_LFlagAtEnd(t *testing.T) {
	// -l at the very end with no value — should not panic
	if HasUserFlag([]string{"-l"}) {
		t.Error("-l with no value should return false")
	}
}

func assertParsed(t *testing.T, got *ParsedArgs, host, user string, destIdx int) {
	t.Helper()
	if got == nil {
		t.Fatal("Parse returned nil")
	}
	if got.Host != host {
		t.Errorf("host: got %q, want %q", got.Host, host)
	}
	if got.User != user {
		t.Errorf("user: got %q, want %q", got.User, user)
	}
	if got.DestIdx != destIdx {
		t.Errorf("destIdx: got %d, want %d", got.DestIdx, destIdx)
	}
}