"use strict";

const PerimeterWarningSound = (function(){

    return function(audio_ctx, output_node, volume_multiplier = 1.0){
        const now = audio_ctx.currentTime;
        const duration = 0.14;

        const preset_bus = audio_ctx.createGain();
        preset_bus.gain.setValueAtTime(volume_multiplier * 0.5, now);

        // Envolvente seca estilo sonar
        const env = audio_ctx.createGain();
        env.gain.setValueAtTime(0.001, now);
        env.gain.linearRampToValueAtTime(0.85, now + 0.01);
        env.gain.exponentialRampToValueAtTime(0.001, now + duration);

        // Tono puro resonante de telemetría militar (960Hz descendiendo a 820Hz)
        const osc = audio_ctx.createOscillator();
        osc.type = "sine";
        osc.frequency.setValueAtTime(960, now);
        osc.frequency.exponentialRampToValueAtTime(820, now + duration);

        // Armónico metálico sutil
        const harm = audio_ctx.createOscillator();
        const harm_gain = audio_ctx.createGain();
        harm.type = "triangle";
        harm.frequency.setValueAtTime(1920, now);
        harm_gain.gain.setValueAtTime(0.2, now);

        // Filtro de mampara
        const filter = audio_ctx.createBiquadFilter();
        filter.type = "bandpass";
        filter.frequency.setValueAtTime(900, now);
        filter.Q.setValueAtTime(2.5, now);

        osc.connect(env);
        harm.connect(harm_gain);
        harm_gain.connect(env);

        env.connect(filter);
        filter.connect(preset_bus);
        preset_bus.connect(output_node);

        osc.start(now);
        harm.start(now);
        osc.stop(now + duration);
        harm.stop(now + duration);
    };

})();