/// <reference path="../../scripts/jquery-3.5.1.min.js"/>
/// <reference path="../../_shared/math/vec2.js" />
/// <reference path="../../_shared/math/mat4.js" />
/// <reference path="../../_shared/2d/shader.js" />
/// <reference path="../../_shared/math/rectangle.js" />
/// <reference path="../../_shared/math/line2.js" />
/// <reference path="../../_shared/math/collision.js" />
/// <reference path="../../_shared/2d/program_common.js" />

(function() {
    var programContext,
        rectangleObject,
        lineObjectList,
        programInfo,
        exitRequestFunc;

    function main() {
        programContext = getContext('#rectangle_line_collision');
    
        if (programContext.gl === null) {
            console.error('Unable to initialize WebGL. Your browser or machine may not support it.');
            return;
        }
    
        programContext.gl.clearColor(0.1, 0.15, 0.2, 1.0);
        programContext.gl.clear(programContext.gl.COLOR_BUFFER_BIT);
        programContext.playButton.on('click', run);
    }
    
    function run() {
        console.log('Running Rectangle-Line Collisions');
        programContext.load().then(function(pProgramInfo) {
            programInfo = pProgramInfo;

            rectangleObject = rectangle(programContext.gl, { 
                width: 50, 
                height: 50, 
                mass: 1,
                color: { x: 0.3, y: 0.5, z: 0.1, w: 0.7 },
                position: vec2(programContext.width / 2.0 - 100, programContext.height / 2.0 + 100)
            });
            rectangleObject.velocity = vec2(0, -50);

            lineObjectList = [];
            
            lineObjectList.push(line2({ x: 100, y: 100 }, { x: programContext.width - 100, y: 200 }, programContext.gl,
                { x: 1, y: 0, z: 0, w: 1 }, 10000000.0));

            lineObjectList.push(line2({ x: 100, y: 200 }, { x: programContext.width - 100, y: 100 }, programContext.gl,
                { x: 1, y: 1, z: 0, w: 1 }, 10000000.0));

            lineObjectList.push(line2({ x: 100, y: 0 }, { x: 100, y: programContext.height }, programContext.gl,
                { x: 0, y: 1, z: 0, w: 1 }, 10000000.0));

            lineObjectList.push(line2({ x: programContext.width - 100, y: 0 }, { x: programContext.width - 100, y: programContext.height }, programContext.gl,
                { x: 0, y: 1, z: 0, w: 1 }, 10000000.0));
            

            exitRequestFunc = requestUpdateLoop(update, cleanup);
            programContext.stopButton.on('click', reset);
        });
    }

    function update(pDeltaTimeSeconds) {
        pDeltaTimeSeconds = pDeltaTimeSeconds;
        updateRigidBody2(rectangleObject, pDeltaTimeSeconds);
        collision(pDeltaTimeSeconds);
        render();
    }

    function collision(pDeltaTimeSeconds) {
        for (var lineIdx = 0; lineIdx < lineObjectList.length; lineIdx++) {
            var lLine = lineObjectList[lineIdx];
            
            if (areIntersecting(rectangleObject, lLine, pDeltaTimeSeconds)) {
                break;
            }
        }
    }
    
    function doesPointIntersect(pPoint, pLine) {
        const EPSILON = 0.98;
        return distanceFromPoint2ToLine2(pPoint, pLine) <= EPSILON;
    }

    function getIntersectionInformation(pRectangle, pCollisionPoint, pLine) {
        var lCollisionNormal = pLine.normal,
            lRectCollisionPoint_WorldCoords = multMat4ByVec2(pRectangle.model, pCollisionPoint),
            lRectPosition = pRectangle.position,
            lTrueRectCollisionPoint = normalize2(subVec2(lRectPosition, lRectCollisionPoint_WorldCoords));

        console.log(lTrueRectCollisionPoint);

        return {
            relativeVelocity:           subVec2(pRectangle.velocity, pLine.velocity),
            collisionNormal:            lCollisionNormal,
            rectangleCollisionPoint:    lTrueRectCollisionPoint
        }
    }

    function areIntersecting(pRectangle, pLine, pDeltaTimeSeconds) {
        var lCollisionPoint = undefined,
            lCheckCollision = function(pRectangle) {
                var lLowerLeft      = multMat4ByVec2(pRectangle.model, vec2(-pRectangle.width / 2.0, -pRectangle.height / 2.0)),
                    lUpperLeft      = multMat4ByVec2(pRectangle.model, vec2(-pRectangle.width / 2.0, pRectangle.height / 2.0)),
                    lUpperRight     = multMat4ByVec2(pRectangle.model, vec2(pRectangle.width / 2.0, pRectangle.height / 2.0)),
                    lLowerRight     = multMat4ByVec2(pRectangle.model, vec2(pRectangle.width / 2.0, -pRectangle.height / 2.0));

                if (doesPointIntersect(lLowerLeft, pLine)) {
                    lCollisionPoint = vec2(-pRectangle.width / 2.0, -pRectangle.height / 2.0);
                    return true;
                } else if (doesPointIntersect(lUpperLeft, pLine)) {
                    lCollisionPoint = vec2(-pRectangle.width / 2.0, pRectangle.height / 2.0);
                    return true;
                } else if (doesPointIntersect(lUpperRight, pLine)) {
                    lCollisionPoint = vec2(pRectangle.width / 2.0, pRectangle.height / 2.0);
                    return true;
                } else if (doesPointIntersect(lLowerRight, pLine)) {
                    lCollisionPoint = vec2(pRectangle.width / 2.0, -pRectangle.height / 2.0);
                    return true;
                }

                return false;
            };

        if (!lCheckCollision(pRectangle)) {
            return;
        }

        // Subdivide until we find the exact moment where we intersected
        var lSubdividedDeltaTime = pDeltaTimeSeconds,
            lSubRectangle = undefined;
        do {
            lSubRectangle = JSON.parse(JSON.stringify(pRectangle));
            lSubRectangle.position = {...pRectangle.prevPos};
            lSubRectangle.velocity = {...pRectangle.prevVelocity};
            lSubRectangle.getMomentOfInertia = pRectangle.getMomentOfInertia;
            lSubdividedDeltaTime = lSubdividedDeltaTime / 2.0;
            updateRigidBody2(lSubRectangle, lSubdividedDeltaTime);
            if (lSubdividedDeltaTime === 0) {
                console.error('This should NOT be happening');
                break;
            }
        } while (lCheckCollision(lSubRectangle)); 
        
        var lIntersectionResult = getIntersectionInformation(lSubRectangle, lCollisionPoint, pLine),
            lRelativeVelocity   = lIntersectionResult.relativeVelocity,
            lCollisionNormal    = lIntersectionResult.collisionNormal,
            lRectPerp           = getPerp2(lIntersectionResult.rectangleCollisionPoint);

        const lNumerator = dot2(scaleVec2(lRelativeVelocity, -(1.0 + 1.0)), lCollisionNormal);
        const lLinearDenomPart = dot2(lCollisionNormal, (scaleVec2(lCollisionNormal, 1.0 / pRectangle.mass)));
        const lRotationalDenomPart = (Math.pow(dot2(lRectPerp, lCollisionNormal), 2) / pRectangle.getMomentOfInertia());

        const lImpulseMagnitude = lNumerator / (lLinearDenomPart + lRotationalDenomPart);

        pRectangle.position = lSubRectangle.position;
        pRectangle.velocity = addVec2(lSubRectangle.velocity, scaleVec2(lCollisionNormal, lImpulseMagnitude / pRectangle.mass));
        pRectangle.rotationVelocity = lSubRectangle.rotationVelocity + dot2(lRectPerp, scaleVec2(lCollisionNormal, lImpulseMagnitude)) / pRectangle.getMomentOfInertia();

        updateRigidBody2(pRectangle, pDeltaTimeSeconds - lSubdividedDeltaTime);
        return true;
    }

    function render() {
        programContext.gl.clearColor(0.1, 0.15, 0.2, 1.0);
        programContext.gl.clearDepth(1.0);
        programContext.gl.enable(programContext.gl.DEPTH_TEST);
        programContext.gl.depthFunc(programContext.gl.LEQUAL);
        programContext.gl.clear(programContext.gl.COLOR_BUFFER_BIT | programContext.gl.DEPTH_BUFFER_BIT);
        programContext.gl.useProgram(programInfo.program);
        programContext.gl.uniformMatrix4fv(programInfo.uniformLocations.projection, false, programContext.perspective);

        programInfo.renderShape(rectangleObject);
        lineObjectList.forEach(function(lineObject) {
            renderLine2(programContext.gl, programInfo, lineObject);
        });
    }

    function cleanup() {
        programContext.gl.deleteBuffer(rectangleObject.buffer);
        lineObjectList.forEach(function(lineObject) {
            programContext.gl.deleteBuffer(lineObject.buffer);
        });
        programContext.gl.deleteProgram(programInfo.program);
        programContext.gl.clearColor(0.1, 0.15, 0.2, 1.0);
        programContext.gl.clear(programContext.gl.COLOR_BUFFER_BIT);
    }

    function reset() {
        exitRequestFunc();
        programContext.reset();
    }
    
    $(document).ready(main);
})()