/*
The interface is like a flywheel.
*/
export class Flywheel {
    constructor() {
        this.value = 0.; // start at 0 - gradual meter
        this.stage = 0.; // start at 0 - the various stages

        this.f_falloff = (value) => value / 20; // value at which it reduces per second
        this.f_stage = (value) => 5 * Math.log10(value); // value to stage calculation

        this.value_min = 0;
        this.value_max = 100; // gives stage 0-9

        // this.interval = window.setInterval(this.step, 50)
        this.time = null;
        window.requestAnimationFrame(this.step.bind(this));
        // TODO: once/twice per second should be enough! + on release (add())

        this.effects = {
            'shape': new ShapeEffect(),
            'video': new VideoEffect(),
        }
    }

    step(time) {
        if (this.time === null) {
            // first run
            this.time = time;
            window.requestAnimationFrame(this.step.bind(this));
            return;
        }

        if (time - this.time < 500) {
            window.requestAnimationFrame(this.step.bind(this));
            return;
        }

        const dt = time - this.time;
        this.time = time;

        this.value -= this.f_falloff(this.value) * dt / 1000; // linear falloff

        if (this.value < 0) {
            this.value = 0;
        }
        // console.log(this.value,this.falloff, dt,this.time);

        // TODO: check if this should be different

        const stage = Math.max(0, Math.floor(this.f_stage(this.value)));
        if (stage != this.stage) {
            this.changeStage(stage);
        }

        window.requestAnimationFrame(this.step.bind(this));
    }

    add(increment) {
        this.value += typeof increment == 'undefined' ? 1 : increment;
        // cap:
        if (this.value > this.value_max) this.value = this.value_max;
    }

    changeStage(stage) {
        this.stage = stage;
        console.log('stage now at', this.stage);
        for (let fx of Object.values(this.effects)) {
            fx.setStageHandler(this.stage);
        }
    }
}

function effect(start_stage, end_stage) {
    return class Effect {
        constructor() {
            this.enabled = false;
            this.start_stage = start_stage;
            this.end_stage = end_stage;
            this.intensity = 0;
            this.intensity_easing = (t) => t; // 0 < t <= 1: use this to make effect eg. more eased 
        }

        setStageHandler(stage) {
            if (stage < this.start_stage || stage > this.end_stage) {
                this.disable(stage);
            } else {
                this.enable(stage);
            }
        }

        enable(stage) {
            if (!this.enabled) {
                this.enabled = true;
                this.enableHandler();
            }

            const ds = this.end_stage - this.start_stage + 1;
            if (ds === 1) {
                this.setIntensity(1);
            } else {
                const s = stage - this.start_stage + 1;
                const t = s / ds;
                this.setIntensity(this.intensity_easing(t));
            }
        }

        disable(stage) {
            if (this.enabled) {
                this.enabled = false;
                this.disableHandler();
            }
        }

        setIntensity(intensity) {
            if (intensity !== this.intensity) {
                this.intensity = intensity;
                this.intensityHandler();
            }
        }

        enableHandler() {/* to override */ }
        disableHandler() {/* to override */ }
        intensityHandler() {/* to override */ }
    }


}

class ShapeEffect extends effect(3, 10) {
    getAngles() {
        if (!this.enabled) {
            return 4;
        }
        if (this.intensity < .3) {
            return 3;
        } else if (this.intensity < .7) {
            return 5;
        } else {
            // random pick
            const corners = [3, 4, 5, 7]
            return corners[Math.floor(Math.random() * corners.length)];
        }
    }
}
class VideoEffect extends effect(3, 10) {
    // override enable instead of using handler to apply it gradually
    disableHandler() {
        document.getElementById('video_background').style.opacity = 0;
    }

    intensityHandler() {
        document.getElementById('video_background').style.opacity = this.intensity;
    }


}