Hooks.on('renderTokenHUD', (app, html, data) => {
    const token = app.object;
    if (!token?.combatant) return;

    const viewedCombat = ui.combat?.viewed;
    if (!viewedCombat) return;

    // In Daggerheart, the combatant with the spotlight is the one whose turn it currently is.
    const hasSpotlight = viewedCombat.combatant?.id === token.combatant.id;
    const isRequesting = token.combatant.system?.spotlight?.requesting;

    // Determine icon and classes based on spotlight state
    let iconClass = "fa-regular fa-hand-sparkles";
    let activeClass = "";
    if (hasSpotlight) {
        iconClass = "fa-solid fa-hand-sparkles dh-spotlight-glow";
        activeClass = "active";
    } else if (isRequesting) {
        iconClass = "fa-solid fa-hand-sparkles dh-spotlight-request";
        activeClass = "active";
    }
    
    let tooltipText = "";
    if (game.user.isGM) {
        tooltipText = hasSpotlight ? "Take Spotlight" : "Grant Spotlight";
    } else {
        tooltipText = hasSpotlight ? "Remove Spotlight" : (isRequesting ? "Cancel Spotlight Request" : "Request Spotlight");
    }

    const buttonHtml = `
        <div class="control-icon ${activeClass}" data-action="toggle-spotlight" title="${tooltipText}">
            <i class="${iconClass}"></i>
        </div>
    `;

    // Append to the right column of the Token HUD
    const colRight = $(html).find('.col.right');
    colRight.append(buttonHtml);

    // Add click listener
    $(html).find('[data-action="toggle-spotlight"]').click(async event => {
        event.preventDefault();
        event.stopPropagation();
        
        if (ui.combat) {
            const btn = $(event.currentTarget);
            const icon = btn.find('i');
            const wasActive = btn.hasClass('active');
            const isRequestingMsg = icon.hasClass('dh-spotlight-request');
            
            if (game.user.isGM) {
                if (typeof ui.combat.setCombatantSpotlight === "function") {
                    // Optimistic UI update for GM
                    if (wasActive && !isRequestingMsg) {
                        btn.removeClass('active');
                        icon.removeClass('fa-solid dh-spotlight-glow').addClass('fa-regular');
                    } else {
                        btn.addClass('active');
                        icon.removeClass('fa-regular dh-spotlight-request').addClass('fa-solid dh-spotlight-glow');
                    }
                    await ui.combat.setCombatantSpotlight(token.combatant.id);
                }
            } else {
                // Players request the spotlight
                const combat = ui.combat.viewed;
                if (!combat) return;
                
                const characters = combat.turns?.filter(x => !x.isNPC) ?? [];
                // Fallback to maxRequestIndex = 0 if necessary
                const orderValues = characters.map(c => c.system?.spotlight?.requestOrderIndex || 0);
                const maxRequestIndex = orderValues.length > 0 ? Math.max(...orderValues) : 0;
                
                const currentlyRequesting = !!token.combatant.system?.spotlight?.requesting;
                
                // Optimistic UI update for Player
                if (currentlyRequesting) {
                    btn.removeClass('active');
                    icon.removeClass('fa-solid dh-spotlight-request').addClass('fa-regular');
                } else {
                    btn.addClass('active');
                    icon.removeClass('fa-regular').addClass('fa-solid dh-spotlight-request');
                }
                
                await token.combatant.update({
                    'system.spotlight': {
                        requesting: !currentlyRequesting,
                        requestOrderIndex: !currentlyRequesting ? maxRequestIndex + 1 : 0
                    }
                });
            }
        } else {
            ui.notifications.warn("System does not support spotlight or combat is not initialized.");
        }
    });
});