using AcDream.UI.Abstractions.Panels.Chat;

namespace AcDream.UI.Abstractions.Tests.Panels.Chat;

/// <summary>
/// TDD coverage for <see cref="ChatInputParser.Parse"/>. Pure function:
/// no fakes, no setup. Each prefix in the holtburger
/// <c>chat.rs</c> alias table gets at least one round-trip test plus
/// every documented edge case.
/// </summary>
public sealed class ChatInputParserTests
{
    // -- Default channel (no prefix / explicit /say) --------------------

    [Fact]
    public void NoPrefix_UsesDefaultChannelLiteral()
    {
        var parsed = ChatInputParser.Parse("hello world", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
        Assert.Null(parsed.Value.TargetName);
        Assert.Equal("hello world", parsed.Value.Text);
    }

    [Fact]
    public void SayPrefix_StripsTheSlashSay()
    {
        var parsed = ChatInputParser.Parse("/say hi there", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
        Assert.Null(parsed.Value.TargetName);
        Assert.Equal("hi there", parsed.Value.Text);
    }

    // -- Tell aliases ----------------------------------------------------

    [Fact]
    public void TellPrefix_FullForm_ParsesTargetAndMessage()
    {
        var parsed = ChatInputParser.Parse("/tell Bestie hi there", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Tell, parsed!.Value.Channel);
        Assert.Equal("Bestie", parsed.Value.TargetName);
        Assert.Equal("hi there", parsed.Value.Text);
    }

    [Fact]
    public void TellPrefix_ShortForm_ParsesTargetAndMessage()
    {
        var parsed = ChatInputParser.Parse("/t Bestie hi", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Tell, parsed!.Value.Channel);
        Assert.Equal("Bestie", parsed.Value.TargetName);
        Assert.Equal("hi", parsed.Value.Text);
    }

    [Fact]
    public void TellPrefix_MultiWordTarget_ChompsFirstTokenAsTarget()
    {
        // Holtburger split_once on whitespace: first token is target.
        // "/t Sir Lancelot hello" -> target="Sir", text="Lancelot hello".
        var parsed = ChatInputParser.Parse("/t Sir Lancelot hello", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Tell, parsed!.Value.Channel);
        Assert.Equal("Sir", parsed.Value.TargetName);
        Assert.Equal("Lancelot hello", parsed.Value.Text);
    }

    // -- Reply aliases ---------------------------------------------------

    [Fact]
    public void ReplyPrefix_UsesLastIncomingTellSenderAsTarget()
    {
        var parsed = ChatInputParser.Parse("/r back at you", ChatChannelKind.Say, lastTellSender: "Bestie");

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Tell, parsed!.Value.Channel);
        Assert.Equal("Bestie", parsed.Value.TargetName);
        Assert.Equal("back at you", parsed.Value.Text);
    }

    [Fact]
    public void ReplyPrefix_NoLastSender_ReturnsNull()
    {
        var parsed = ChatInputParser.Parse("/r hi", ChatChannelKind.Say, lastTellSender: null);

        Assert.Null(parsed);
    }

    // -- Channel aliases (single-message) -------------------------------

    [Theory]
    [InlineData("/g raid time",       ChatChannelKind.General,    "raid time")]
    [InlineData("/f buff up",         ChatChannelKind.Fellowship, "buff up")]
    [InlineData("/a swearing in",     ChatChannelKind.Allegiance, "swearing in")]
    [InlineData("/m monarch broadcast", ChatChannelKind.Monarch, "monarch broadcast")]
    [InlineData("/p patron only",     ChatChannelKind.Patron,     "patron only")]
    [InlineData("/v vassals only",    ChatChannelKind.Vassals,    "vassals only")]
    [InlineData("/cv covassals only", ChatChannelKind.CoVassals,  "covassals only")]
    [InlineData("/lfg need 3 more",   ChatChannelKind.Lfg,        "need 3 more")]
    [InlineData("/trade wts gem",     ChatChannelKind.Trade,      "wts gem")]
    [InlineData("/role *waves*",      ChatChannelKind.Roleplay,   "*waves*")]
    [InlineData("/society olthoi raid", ChatChannelKind.Society,  "olthoi raid")]
    [InlineData("/olthoi for the queen", ChatChannelKind.Olthoi,  "for the queen")]
    public void ChannelPrefixes_RouteToTheirChannel(string raw, ChatChannelKind expectedChannel, string expectedText)
    {
        var parsed = ChatInputParser.Parse(raw, ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(expectedChannel, parsed!.Value.Channel);
        Assert.Null(parsed.Value.TargetName);
        Assert.Equal(expectedText, parsed.Value.Text);
    }

    // -- Edge cases: empty / whitespace / no-message --------------------

    [Fact]
    public void Empty_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("", ChatChannelKind.Say, lastTellSender: null));
    }

    [Fact]
    public void WhitespaceOnly_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("   \t  ", ChatChannelKind.Say, lastTellSender: null));
    }

    [Fact]
    public void SayWithNoMessage_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("/say", ChatChannelKind.Say, lastTellSender: null));
        Assert.Null(ChatInputParser.Parse("/say   ", ChatChannelKind.Say, lastTellSender: null));
    }

    [Fact]
    public void TellWithNoTargetNoMessage_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("/t", ChatChannelKind.Say, lastTellSender: null));
        Assert.Null(ChatInputParser.Parse("/tell", ChatChannelKind.Say, lastTellSender: null));
    }

    [Fact]
    public void TellWithTargetButNoMessage_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("/t Bestie", ChatChannelKind.Say, lastTellSender: null));
        Assert.Null(ChatInputParser.Parse("/tell Bestie   ", ChatChannelKind.Say, lastTellSender: null));
    }

    [Fact]
    public void ReplyWithNoMessage_ReturnsNull_EvenWithLastSender()
    {
        Assert.Null(ChatInputParser.Parse("/r", ChatChannelKind.Say, lastTellSender: "Bestie"));
        Assert.Null(ChatInputParser.Parse("/r   ", ChatChannelKind.Say, lastTellSender: "Bestie"));
    }

    [Fact]
    public void ChannelPrefixWithNoMessage_ReturnsNull()
    {
        Assert.Null(ChatInputParser.Parse("/g", ChatChannelKind.Say, lastTellSender: null));
        Assert.Null(ChatInputParser.Parse("/f   ", ChatChannelKind.Say, lastTellSender: null));
        Assert.Null(ChatInputParser.Parse("/a", ChatChannelKind.Say, lastTellSender: null));
    }

    // -- Unknown slash command: holtburger fall-through to Talk(literal)
    // ("/wave hello" → Talk("/wave hello") + treat-as-Say). See
    // chat.rs::handle_slash_command default arm at line ~744.
    [Fact]
    public void UnknownSlashCommand_FallsBackToDefaultChannelWithLiteralText()
    {
        var parsed = ChatInputParser.Parse("/xyz hello", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
        Assert.Null(parsed.Value.TargetName);
        Assert.Equal("/xyz hello", parsed.Value.Text);
    }

    // -- Default-channel parameter is honoured when no prefix is given --

    [Fact]
    public void NoPrefix_HonoursAlternateDefaultChannel()
    {
        // If the panel ever defaults to e.g. Fellowship channel input,
        // the parser must use that for unprefixed text.
        var parsed = ChatInputParser.Parse("hi gang", ChatChannelKind.Fellowship, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Fellowship, parsed!.Value.Channel);
        Assert.Null(parsed.Value.TargetName);
        Assert.Equal("hi gang", parsed.Value.Text);
    }

    // -- The verb itself must be exact: prefix-of-other-word doesn't count --

    [Fact]
    public void PrefixSubstring_IsNotAVerbMatch()
    {
        // "/general" (no leading "/g " token) is NOT /g; it's just text.
        // Must not be misclassified as /g + "eneral".
        var parsed = ChatInputParser.Parse("/general public", ChatChannelKind.Say, lastTellSender: null);

        Assert.NotNull(parsed);
        Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
        Assert.Equal("/general public", parsed.Value.Text);
    }
}