// PoseTrigger.cs
// Two players pose together, here a handshake. While two or more players are inside this trigger area, each of them
// gets an action button (F on desktop). Walk up to another player in the area and press it: they get a dialog asking
// whether they want to shake hands. If they say yes while you are both still in the area, the two of you are placed
// facing each other, lined up for the pose, and both play the emote at the same time.
//
//  • You can ask several people at once, but each of them only once at a time (no spamming one player).
//  • Each player does one pose at a time. If more people say yes, those poses wait in line and play one after the
//    other as soon as both players in each are free.
//  • Leaving the area quietly cancels every request to or from you (and a pose you are in).
//  • The emote is not the handshake only: pick any two-person emote. Both players can play the same one (a handshake
//    facing each other) or each side its own (EmoteReceiver: a hug and a hug back, a high five and a catch, a bow and a
//    curtsy...). Distance and Side Offset line the two avatars up the way the emote was animated.
//
// Set up:
//  1. Make a box (or any shape) covering the area, give it a Collider with "Is Trigger" on, and put this script on it.
//     (Or put the script anywhere and drag the area into TriggerArea.) A see-through material shows people where it is.
//  2. Pick the emote in EmoteRequester (upload it in the Avatar Editor first). Leave EmoteReceiver empty for the same one.
//  3. Play it with a second player and adjust Distance / Side Offset until the hands meet.
//
// Lining up an emote: Distance and SideOffset come from where the emote puts the hand at the moment of the pose,
// measured from where the character stood when it started (emotes that step in move the body too):
//     Distance   = forward reach of the requester's emote + forward reach of the receiver's emote (+ a palm each)
//     SideOffset = (sideways reach of one + sideways reach of the other) / 2   (to the right = plus)
// "Reach" here is the wrist (the hand bone). For hands that hold each other add about a palm each to Distance (the palm
// centre is ~5 cm past the wrist), and move each player ~1.75 cm right (SideOffset minus that): the two right palms face
// each other, so the hands sit side by side instead of in one another.
// Measure it on the platform's avatars, not on the character the emote was made with: the same animation reaches less
// far with shorter arms. The defaults are for Mixamo's "Shaking Hands" (Shaking_Hands_1) on both sides, played on the
// standard avatars (Female1 / Male1): it steps in and the right wrist ends 66 cm in front of where the player stood,
// 1.5 cm left of their middle; with a palm each that is Distance 1.32 + 0.10 = 1.42 and SideOffset -0.015 - 0.0175
// = -0.03. (On Mixamo's own, taller character the same clip reaches 69 cm, 9 cm to the right.)
using System.Collections;
using System.Collections.Generic;
using IHXR.Simulation;

public class PoseTrigger : ScriptBase
{
    [Header("Where")]
    [Tooltip("The trigger area (a Collider with Is Trigger on). Empty = the object this script is on.")]
    public SceneObject TriggerArea;

    [Header("The pose")]
    [Tooltip("What it is called in the button and the dialog, e.g. \"Shake hands\" / \"shake hands with you\".")]
    public string ButtonLabel = "Shake hands";
    public string RequestText = "would like to shake hands with you.";
    [Tooltip("The emote the player who asked plays.")]
    public Emote EmoteRequester;
    [Tooltip("The emote the player who said yes plays. Empty = the same as EmoteRequester.")]
    public Emote EmoteReceiver;
    [Tooltip("How long the pose lasts, in seconds (the emote's length). Then both are free again.")]
    public float PoseSeconds = 4.4f;

    [Header("Lining up")]
    [Tooltip("Metres between where the two players stand when the emote starts (their feet). Emotes that step in close the gap themselves. 1.42 = Mixamo Shaking Hands on both sides, on the standard avatars.")]
    public float Distance = 1.42f;
    [Tooltip("Metres each player is moved sideways, to their own left (minus = right). Use the sideways reach of the emote's hand, as played on the avatars (-0.03 = Mixamo Shaking Hands on the standard avatars).")]
    public float SideOffset = -0.03f;
    [Tooltip("Degrees each player turns away from facing the other straight on (plus = clockwise seen from above).")]
    public float TurnOffset = 0.0f;

    [Header("Asking")]
    [Tooltip("How close (metres) another player must be to ask them. The one in front of you is picked first.")]
    public float AskRange = 2.5f;
    [Tooltip("The desktop key for the button (phones and VR get the button itself / the right stick click).")]
    public string Key = "F";

    const string ButtonId = "pose-trigger-ask";

    readonly HashSet<string> inside = new HashSet<string>();
    // Asked but not answered yet: "from|to".
    readonly HashSet<string> pending = new HashSet<string>();
    // Said yes, waiting for both players to be free: in the order they were accepted.
    readonly List<string[]> queue = new List<string[]>();
    // Players posing right now.
    readonly HashSet<string> busy = new HashSet<string>();

    public override void Start()
    {
        var area = TriggerArea != null && !TriggerArea.IsNull ? TriggerArea : null;
        if (area != null) RegisterTrigger(area, OnEnter, OnExit); else RegisterTrigger(OnEnter, OnExit);
        ListenForActionButton(ButtonId, OnButton);
        if (EmoteRequester == null || EmoteRequester.IsNull) LogWarning("[PoseTrigger] Pick an emote in EmoteRequester.");
    }

    // ---------------------------------------------------------------- who is in the area
    void OnEnter(TriggerInfo info)
    {
        if (!info.IsPlayer || string.IsNullOrEmpty(info.Username)) return;
        inside.Add(info.Username);
        UpdateButtons();
    }

    void OnExit(TriggerInfo info)
    {
        if (!info.IsPlayer || string.IsNullOrEmpty(info.Username)) return;
        Leave(info.Username);
    }

    public override void OnUserPart(UserInfo user) => Leave(user.Username);

    void Leave(string username)
    {
        if (!inside.Remove(username)) return;
        HideActionButton(username, ButtonId);
        // Everything to or from them is quietly dropped (and a pose they are in ends).
        pending.RemoveWhere(key => key.StartsWith(username + "|") || key.EndsWith("|" + username));
        queue.RemoveAll(pair => pair[0] == username || pair[1] == username);
        UpdateButtons();
    }

    // The button is there only while someone else is in the area to ask.
    void UpdateButtons()
    {
        bool show = inside.Count >= 2;
        foreach (var username in inside)
            if (show) ShowActionButton(username, ButtonId, ButtonLabel, Key);
            else HideActionButton(username, ButtonId);
    }

    // ---------------------------------------------------------------- asking
    void OnButton(ActionButtonInfo info)
    {
        if (info.State != ActionButtonState.Down) return;
        string from = info.Username;
        if (!inside.Contains(from)) return;
        string to = PickPartner(from);
        if (to == null) { ShowToast(from, null, ButtonLabel, "Walk up to someone in the area first."); return; }
        string key = from + "|" + to;
        if (pending.Contains(key) || IsQueued(from, to)) { ShowToast(from, null, ButtonLabel, "Still waiting for " + to + "."); return; }
        pending.Add(key);
        ShowToast(from, null, ButtonLabel, "Asked " + to + ".");
        ShowDialog(ButtonLabel, from + " " + RequestText, ModalDialogIcon.Info, ModalDialogButtons.YesNo, result =>
        {
            // Only when the request still stands: both still here, nobody cancelled it.
            if (!pending.Remove(key)) return;
            if (result != ModalDialogResult.Yes) return;
            if (!inside.Contains(from) || !inside.Contains(to)) return;
            queue.Add(new[] { from, to });
            RunQueue();
        }, to);
    }

    // The player you face within AskRange (the nearest one if nobody is in front of you).
    string PickPartner(string from)
    {
        var me = GetUser(from);
        if (me == null) return null;
        string best = null; float bestScore = float.MaxValue;
        foreach (var other in inside)
        {
            if (other == from) continue;
            var them = GetUser(other);
            if (them == null) continue;
            var gap = them.Position - me.Position; gap.y = 0;
            float distance = gap.magnitude;
            if (distance > AskRange) continue;
            float facing = distance > 0.01f ? Vector3.Dot(me.Forward, gap / distance) : 1f;
            float score = distance * (facing > 0.3f ? 1f : 3f);   // in front of you counts as three times closer
            if (score < bestScore) { bestScore = score; best = other; }
        }
        return best;
    }

    bool IsQueued(string a, string b)
    {
        foreach (var pair in queue) if ((pair[0] == a && pair[1] == b) || (pair[0] == b && pair[1] == a)) return true;
        return false;
    }

    // ---------------------------------------------------------------- posing, one at a time per player
    void RunQueue()
    {
        for (int i = 0; i < queue.Count; i++)
        {
            var pair = queue[i];
            if (busy.Contains(pair[0]) || busy.Contains(pair[1])) continue;
            queue.RemoveAt(i); i--;
            if (!inside.Contains(pair[0]) || !inside.Contains(pair[1])) continue;
            StartCoroutine(Pose(pair[0], pair[1]));
        }
    }

    IEnumerator Pose(string a, string b)
    {
        var ua = GetUser(a); var ub = GetUser(b);
        if (ua == null || ub == null) yield break;
        busy.Add(a); busy.Add(b);

        // Facing each other across the middle point of where they stand, Distance apart.
        var middle = (ua.Position + ub.Position) * 0.5f;
        var across = ub.Position - ua.Position; across.y = 0;
        if (across.sqrMagnitude < 0.0001f) across = ua.Forward;
        across = across.normalized;
        // Each player's own left (y up): A faces +across, B faces -across.
        var leftOfA = new Vector3(-across.z, 0, across.x);
        var spotA = middle - across * (Distance * 0.5f) + leftOfA * SideOffset;
        var spotB = middle + across * (Distance * 0.5f) - leftOfA * SideOffset;
        spotA.y = ua.Position.y; spotB.y = ub.Position.y;
        float yawA = FacingYaw(across) + TurnOffset, yawB = FacingYaw(-across) + TurnOffset;
        TeleportPlayer(a, spotA, new Vector3(0, yawA, 0), true);
        TeleportPlayer(b, spotB, new Vector3(0, yawB, 0), true);
        yield return new WaitForSeconds(0.2f);   // both in place before the emote starts

        var emoteA = EmoteRequester; var emoteB = EmoteReceiver != null && !EmoteReceiver.IsNull ? EmoteReceiver : EmoteRequester;
        if (emoteA != null && !emoteA.IsNull) { PlayPlayerEmote(a, emoteA); PlayPlayerEmote(b, emoteB); }

        // Until the emote is over, or one of them leaves the area.
        float until = Time.time + PoseSeconds;
        while (Time.time < until && inside.Contains(a) && inside.Contains(b)) yield return new WaitForSeconds(0.1f);
        StopPlayerEmote(a); StopPlayerEmote(b);

        busy.Remove(a); busy.Remove(b);
        RunQueue();   // their next pose in line, if any
    }

    // TeleportPlayer's facing: degrees, 0 = toward -Z, 90 = toward +X.
    static float FacingYaw(Vector3 direction) => (float)(System.Math.Atan2(direction.x, -direction.z) * 180.0 / System.Math.PI);
}