using System.Numerics;
using Content.Shared.TextScreen;
using Robust.Client.GameObjects;
using Robust.Shared.Timing;
using Robust.Shared.Utility;

namespace Content.Client.TextScreen;

/// <summary>
///     The TextScreenSystem draws text in the game world using 3x5 sprite states for each character.
/// </summary>
public sealed class TextScreenSystem : VisualizerSystem<TextScreenVisualsComponent>
{
    [Dependency] private readonly IGameTiming _gameTiming = default!;

    /// <summary>
    ///     Contains char/state Key/Value pairs. <br/>
    ///     The states in Textures/Effects/text.rsi that special character should be replaced with.
    /// </summary>
    private static readonly Dictionary<char, string> CharStatePairs = new()
        {
            { ':', "colon" },
            { '!', "exclamation" },
            { '?', "question" },
            { '*', "star" },
            { '+', "plus" },
            { '-', "dash" },
            { ' ', "blank" }
        };

    private const string DefaultState = "blank";

    /// <summary>
    ///     A string prefix for all text layers.
    /// </summary>
    private const string TextScreenLayerMapKey = "textScreenLayerMapKey";

    public override void Initialize()
    {
        base.Initialize();

        SubscribeLocalEvent<TextScreenVisualsComponent, ComponentInit>(OnInit);
    }

    private void OnInit(EntityUid uid, TextScreenVisualsComponent component, ComponentInit args)
    {
        if (!TryComp(uid, out SpriteComponent? sprite))
            return;

        ResetTextLength(uid, component, sprite);
        PrepareLayerStatesToDraw(uid, component, sprite);
        UpdateLayersToDraw(uid, component, sprite);
    }

    /// <summary>
    ///     Resets all TextScreenComponent sprite layers, through removing them and then creating new ones.
    /// </summary>
    public void ResetTextLength(EntityUid uid, TextScreenVisualsComponent component, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref sprite))
            return;

        foreach (var (key, _) in component.LayerStatesToDraw)
        {
            sprite.RemoveLayer(key);
        }

        component.LayerStatesToDraw.Clear();

        var length = component.TextLength;
        component.TextLength = 0;
        SetTextLength(uid, component, length, sprite);
    }

    /// <summary>
    ///     Sets <see cref="TextScreenVisualsComponent.TextLength"/>, adding or removing sprite layers if necessary.
    /// </summary>
    public void SetTextLength(EntityUid uid, TextScreenVisualsComponent component, int newLength, SpriteComponent? sprite = null)
    {
        if (newLength == component.TextLength)
            return;

        if (!Resolve(uid, ref sprite))
            return;

        if (newLength > component.TextLength)
        {
            for (var i = component.TextLength; i < newLength; i++)
            {
                sprite.LayerMapReserveBlank(TextScreenLayerMapKey + i);
                component.LayerStatesToDraw.Add(TextScreenLayerMapKey + i, null);
                sprite.LayerSetRSI(TextScreenLayerMapKey + i, new ResPath("Effects/text.rsi"));
                sprite.LayerSetColor(TextScreenLayerMapKey + i, component.Color);
                sprite.LayerSetState(TextScreenLayerMapKey + i, DefaultState);
            }
        }
        else
        {
            for (var i = component.TextLength; i > newLength; i--)
            {
                sprite.LayerMapGet(TextScreenLayerMapKey + (i - 1));
                component.LayerStatesToDraw.Remove(TextScreenLayerMapKey + (i - 1));
                sprite.RemoveLayer(TextScreenLayerMapKey + (i - 1));
            }
        }

        UpdateOffsets(uid, component, sprite);

        component.TextLength = newLength;
    }

    /// <summary>
    ///     Updates the layers offsets based on the text length, so it is drawn correctly.
    /// </summary>
    public void UpdateOffsets(EntityUid uid, TextScreenVisualsComponent component, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref sprite))
            return;

        for (var i = 0; i < component.LayerStatesToDraw.Count; i++)
        {
            var offset = i - (component.LayerStatesToDraw.Count - 1) / 2.0f;
            sprite.LayerSetOffset(TextScreenLayerMapKey + i, new Vector2(offset * TextScreenVisualsComponent.PixelSize * 4f, 0.0f) + component.TextOffset);
        }
    }

    protected override void OnAppearanceChange(EntityUid uid, TextScreenVisualsComponent component, ref AppearanceChangeEvent args)
    {
        UpdateAppearance(uid, component, args.Component, args.Sprite);
    }

    public void UpdateAppearance(EntityUid uid, TextScreenVisualsComponent component, AppearanceComponent? appearance = null, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref appearance, ref sprite))
            return;

        if (AppearanceSystem.TryGetData(uid, TextScreenVisuals.On, out bool on, appearance))
        {
            component.Activated = on;
            UpdateVisibility(uid, component, sprite);
        }

        if (AppearanceSystem.TryGetData(uid, TextScreenVisuals.Mode, out TextScreenMode mode, appearance))
        {
            component.CurrentMode = mode;
            if (component.CurrentMode == TextScreenMode.Timer)
                EnsureComp<TextScreenTimerComponent>(uid);
            else
                RemComp<TextScreenTimerComponent>(uid);

            UpdateText(component);
        }

        if (AppearanceSystem.TryGetData(uid, TextScreenVisuals.TargetTime, out TimeSpan time, appearance))
        {
            component.TargetTime = time;
        }

        if (AppearanceSystem.TryGetData(uid, TextScreenVisuals.ScreenText, out string text, appearance))
        {
            component.Text = text;
        }

        UpdateText(component);
        PrepareLayerStatesToDraw(uid, component, sprite);
        UpdateLayersToDraw(uid, component, sprite);
    }

    /// <summary>
    ///     If currently in <see cref="TextScreenMode.Text"/> mode: <br/>
    ///     Sets <see cref="TextScreenVisualsComponent.TextToDraw"/> to the value of <see cref="TextScreenVisualsComponent.Text"/>
    /// </summary>
    public static void UpdateText(TextScreenVisualsComponent component)
    {
        if (component.CurrentMode == TextScreenMode.Text)
            component.TextToDraw = component.Text;
    }

    /// <summary>
    ///     Sets visibility of text to <see cref="TextScreenVisualsComponent.Activated"/>.
    /// </summary>
    public void UpdateVisibility(EntityUid uid, TextScreenVisualsComponent component, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref sprite))
            return;

        foreach (var (key, _) in component.LayerStatesToDraw)
        {
            sprite.LayerSetVisible(key, component.Activated);
        }
    }

    /// <summary>
    ///     Sets the states in the <see cref="TextScreenVisualsComponent.LayerStatesToDraw"/> to match the component <see cref="TextScreenVisualsComponent.TextToDraw"/> string.
    /// </summary>
    /// <remarks>
    ///     Remember to set <see cref="TextScreenVisualsComponent.TextToDraw"/> to a string first.
    /// </remarks>
    public void PrepareLayerStatesToDraw(EntityUid uid, TextScreenVisualsComponent component, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref sprite))
            return;

        for (var i = 0; i < component.TextLength; i++)
        {
            if (i >= component.TextToDraw.Length)
            {
                component.LayerStatesToDraw[TextScreenLayerMapKey + i] = DefaultState;
                continue;
            }
            component.LayerStatesToDraw[TextScreenLayerMapKey + i] = GetStateFromChar(component.TextToDraw[i]);
        }
    }

    /// <summary>
    ///     Iterates through <see cref="TextScreenVisualsComponent.LayerStatesToDraw"/>, setting sprite states to the appropriate layers.
    /// </summary>
    public void UpdateLayersToDraw(EntityUid uid, TextScreenVisualsComponent component, SpriteComponent? sprite = null)
    {
        if (!Resolve(uid, ref sprite))
            return;

        foreach (var (key, state) in component.LayerStatesToDraw)
        {
            if (state == null)
                continue;
            sprite.LayerSetState(key, state);
        }
    }

    public override void Update(float frameTime)
    {
        base.Update(frameTime);

        var query = EntityQueryEnumerator<TextScreenVisualsComponent, TextScreenTimerComponent>();
        while (query.MoveNext(out var uid, out var comp, out _))
        {
            // Basically Abs(TimeSpan, TimeSpan) -> Gives the difference between the current time and the target time.
            var timeToShow = _gameTiming.CurTime > comp.TargetTime ? _gameTiming.CurTime - comp.TargetTime : comp.TargetTime - _gameTiming.CurTime;
            comp.TextToDraw = TimeToString(timeToShow, false);
            PrepareLayerStatesToDraw(uid, comp);
            UpdateLayersToDraw(uid, comp);
        }
    }

    /// <summary>
    ///     Returns the <paramref name="timeSpan"/> converted to a string in either HH:MM, MM:SS or potentially SS:mm format.
    /// </summary>
    /// <param name="timeSpan">TimeSpan to convert into string.</param>
    /// <param name="getMilliseconds">Should the string be ss:ms if minutes are less than 1?</param>
    public static string TimeToString(TimeSpan timeSpan, bool getMilliseconds = true)
    {
        string firstString;
        string lastString;

        if (timeSpan.TotalHours >= 1)
        {
            firstString = timeSpan.Hours.ToString("D2");
            lastString = timeSpan.Minutes.ToString("D2");
        }
        else if (timeSpan.TotalMinutes >= 1 || !getMilliseconds)
        {
            firstString = timeSpan.Minutes.ToString("D2");
            // It's nicer to see a timer set at 5 seconds actually start at 00:05 instead of 00:04.
            var seconds = timeSpan.Seconds + (timeSpan.Milliseconds > 500 ? 1 : 0);
            lastString = seconds.ToString("D2");
        }
        else
        {
            firstString = timeSpan.Seconds.ToString("D2");
            var centiseconds = timeSpan.Milliseconds / 10;
            lastString = centiseconds.ToString("D2");
        }

        return firstString + ':' + lastString;
    }

    /// <summary>
    ///     Returns the Effects/text.rsi state string based on <paramref name="character"/>, or null if none available.
    /// </summary>
    public static string? GetStateFromChar(char? character)
    {
        if (character == null)
            return null;

        // First checks if its one of our special characters
        if (CharStatePairs.ContainsKey(character.Value))
            return CharStatePairs[character.Value];

        // Or else it checks if its a normal letter or digit
        if (char.IsLetterOrDigit(character.Value))
            return character.Value.ToString().ToLower();

        return null;
    }
}