/** 
based on framer-motion@4.0.3,
Copyright (c) 2018 Framer B.V.
*/
import {fixed} from '../utils/fix-process-env';
import { isMouseEvent, isTouchEvent } from './utils/event-type.js';
import { extractEventInfo } from '../events/event-info.js';
import sync, { getFrameData, cancelSync } from 'framesync';
import { secondsToMilliseconds } from '../utils/time-conversion.js';
import { addPointerEvent } from '../events/use-pointer-event.js';
import { distance, pipe } from 'popmotion';

/**
 * @internal
 */
var PanSession = /** @class */ (function () {
    function PanSession(event, handlers, _a) {
        var _this = this;
        var _b = _a === void 0 ? {} : _a, transformPagePoint = _b.transformPagePoint;
        /**
         * @internal
         */
        this.startEvent = null;
        /**
         * @internal
         */
        this.lastMoveEvent = null;
        /**
         * @internal
         */
        this.lastMoveEventInfo = null;
        /**
         * @internal
         */
        this.handlers = {};
        this.updatePoint = function () {
            if (!(_this.lastMoveEvent && _this.lastMoveEventInfo))
                return;
            var info = getPanInfo(_this.lastMoveEventInfo, _this.history);
            var isPanStarted = _this.startEvent !== null;
            // Only start panning if the offset is larger than 3 pixels. If we make it
            // any larger than this we'll want to reset the pointer history
            // on the first update to avoid visual snapping to the cursoe.
            var isDistancePastThreshold = distance(info.offset, { x: 0, y: 0 }) >= 3;
            if (!isPanStarted && !isDistancePastThreshold)
                return;
            var point = info.point;
            var timestamp = getFrameData().timestamp;
            _this.history.push(Object.assign(Object.assign({}, point), { timestamp: timestamp }));
            var _a = _this.handlers, onStart = _a.onStart, onMove = _a.onMove;
            if (!isPanStarted) {
                onStart && onStart(_this.lastMoveEvent, info);
                _this.startEvent = _this.lastMoveEvent;
            }
            onMove && onMove(_this.lastMoveEvent, info);
        };
        this.handlePointerMove = function (event, info) {
            _this.lastMoveEvent = event;
            _this.lastMoveEventInfo = transformPoint(info, _this.transformPagePoint);
            // Because Safari doesn't trigger mouseup events when it's above a `<select>`
            if (isMouseEvent(event) && event.buttons === 0) {
                _this.handlePointerUp(event, info);
                return;
            }
            // Throttle mouse move event to once per frame
            sync.update(_this.updatePoint, true);
        };
        this.handlePointerUp = function (event, info) {
            _this.end();
            var _a = _this.handlers, onEnd = _a.onEnd, onSessionEnd = _a.onSessionEnd;
            var panInfo = getPanInfo(transformPoint(info, _this.transformPagePoint), _this.history);
            if (_this.startEvent && onEnd) {
                onEnd(event, panInfo);
            }
            onSessionEnd && onSessionEnd(event, panInfo);
        };
        // If we have more than one touch, don't start detecting this gesture
        if (isTouchEvent(event) && event.touches.length > 1)
            return;
        this.handlers = handlers;
        this.transformPagePoint = transformPagePoint;
        var info = extractEventInfo(event);
        var initialInfo = transformPoint(info, this.transformPagePoint);
        var point = initialInfo.point;
        var timestamp = getFrameData().timestamp;
        this.history = [Object.assign(Object.assign({}, point), { timestamp: timestamp })];
        var onSessionStart = handlers.onSessionStart;
        onSessionStart &&
            onSessionStart(event, getPanInfo(initialInfo, this.history));
        this.removeListeners = pipe(addPointerEvent(window, "pointermove", this.handlePointerMove), addPointerEvent(window, "pointerup", this.handlePointerUp), addPointerEvent(window, "pointercancel", this.handlePointerUp));
    }
    PanSession.prototype.updateHandlers = function (handlers) {
        this.handlers = handlers;
    };
    PanSession.prototype.end = function () {
        this.removeListeners && this.removeListeners();
        cancelSync.update(this.updatePoint);
    };
    return PanSession;
}());
function transformPoint(info, transformPagePoint) {
    return transformPagePoint ? { point: transformPagePoint(info.point) } : info;
}
function subtractPoint(a, b) {
    return { x: a.x - b.x, y: a.y - b.y };
}
function getPanInfo(_a, history) {
    var point = _a.point;
    return {
        point: point,
        delta: subtractPoint(point, lastDevicePoint(history)),
        offset: subtractPoint(point, startDevicePoint(history)),
        velocity: getVelocity(history, 0.1),
    };
}
function startDevicePoint(history) {
    return history[0];
}
function lastDevicePoint(history) {
    return history[history.length - 1];
}
function getVelocity(history, timeDelta) {
    if (history.length < 2) {
        return { x: 0, y: 0 };
    }
    var i = history.length - 1;
    var timestampedPoint = null;
    var lastPoint = lastDevicePoint(history);
    while (i >= 0) {
        timestampedPoint = history[i];
        if (lastPoint.timestamp - timestampedPoint.timestamp >
            secondsToMilliseconds(timeDelta)) {
            break;
        }
        i--;
    }
    if (!timestampedPoint) {
        return { x: 0, y: 0 };
    }
    var time = (lastPoint.timestamp - timestampedPoint.timestamp) / 1000;
    if (time === 0) {
        return { x: 0, y: 0 };
    }
    var currentVelocity = {
        x: (lastPoint.x - timestampedPoint.x) / time,
        y: (lastPoint.y - timestampedPoint.y) / time,
    };
    if (currentVelocity.x === Infinity) {
        currentVelocity.x = 0;
    }
    if (currentVelocity.y === Infinity) {
        currentVelocity.y = 0;
    }
    return currentVelocity;
}

export { PanSession };
