import PanelSlider from 'panel-slider'

const slider = PanelSlider({
	// The root element containing all panels
	element: document.querySelector('.my-panel-slider'),
	// Number of equal-sized panels
	numPanels: 3,
	// Starting panel
	initialPanel: 0
})

interface PanelSliderOptions {
	/** The root element to use */
	element: HTMLElement
	/** Number of panels the root element is divided into */
	numPanels: number
	/** Starting panel */
	initialPanel?: number
	/** Duration of slide animation on release (default 500ms) */
	slideDuration?: number
	/** Horizontal distance threshold to initiate drag (default 12px) */
	dragThreshold?: number
	/** Minimum required horizontal:vertical ratio to initiate drag (default 1.5) */
	dragRatio?: number
	/** Input devices to enable (default ['mouse', 'touch']) */
	devices?: ('mouse' | 'touch')[]
	/**
	 * Optional custom animation interpolation function
	 * @param x0 Start coordinate
	 * @param x1 End coordinate
	 * @param t Time (0..1)
	 */
	terp?(x0: number, x1: number, t: number): number
}

interface PanelSlider {
	/** Add a listener that fires when drag starts */
	on(eventType: 'dragstart', cb: (d: Drag) => void): void
	/** Remove dragstart listener */
	off(eventType: 'dragstart', cb: (d: Drag) => void): void
	/** Add a listener that fires every move event while dragging */
	on(eventType: 'drag', cb: (d: Drag) => void): void
	/** Remove drag listener */
	off(eventType: 'drag', cb: (d: Drag) => void): void
	/** Add a listener that fires when drag ended */
	on(eventType: 'dragend', cb: (d: Drag) => void): void
	/** Remove dragend listener */
	off(eventType: 'dragend', cb: (d: Drag) => void): void
	/** Add a listener that fires when drag canceled */
	on(eventType: 'dragcancel', cb: (d: Drag) => void): void
	/** Remove dragcancel listener */
	off(eventType: 'dragcancel', cb: (d: Drag) => void): void
	/** Add a listener that fires every frame the panel moves */
	on(eventType: 'animate', cb: (panelFraction: number) => void): void
	/** Remove animate listener */
	off(eventType: 'animate', cb: (panelFraction: number) => void): void
	/** Add a listener that fires when animation starts or ends */
	on(eventType: 'animationstatechange', cb: (animating: boolean) => void): void
	/** Remove animationstatechange listener */
	off(eventType: 'animationstatechange', cb: (animating: boolean) => void): void
	/** Add a listener that fires when current panel has changed */
	on(eventType: 'panelchange', cb: (panelId: number) => void): void
	/** Remove panelchange listener */
	off(eventType: 'panelchange', cb: (panelId: number) => void): void
	/** Sets the current panel - animates to position */
	setPanel(panelId: number, done?: (panelId: number) => void): void
	/** Gets the current panel */
	getPanel(): number
	/** Gets the current root element & panel sizes */
	getSizes(): {fullWidth: number, panelWidth: number}
	/** Returns whether panels are currently being dragged or not */
	isDragging(): boolean
	/** Returns whether panels are currently animating or not */
	isAnimating(): boolean
	/** Destroy & cleanup resources */
	destroy(): void
}

export interface Drag {
	/** Horizontal amount dragged from start (in pixels) */
	x: number
	/** Current horizontal velocity */
	v: number
}