import Rx, { Observable } from 'rxjs';
import { BEHAVIOR, ENTITIES, RAD } from './enums';
import Store from './store';

const random = {
    bool: (weight) => Math.random() < (weight || 0.5),
    color: () => `rgb(
        ${Math.floor(Math.random() * 170)},
        ${Math.floor(Math.random() * 170)},
        ${Math.floor(Math.random() * 170)}
    )`,
    id: () => String.fromCharCode(
        random.num(65, 90), random.num(97, 122), random.num(97, 122),
        random.num(97, 122), random.num(97, 122), random.num(97, 122)
    ),
    num: (min, max) => min + Math.round(Math.random() * (max - min)),
}

// ===== Constructor =====

function Particle(parent, bounds, config, globalGrid) {
    Object.defineProperty(this, 'config', {
        value: Object.assign({}, {
            behavior: BEHAVIOR.COHESION,
            bounds,
            color: random.color(),
            gridSize: 10,
            randomize: true,
            showMovementCircle: false,
            showVisionGrid: false,
            speed: 4,
            visionRadius: 200
        }, config)
    });

    Object.defineProperty(this, 'grids', {
        value: {
            global: globalGrid || {},
            vision: createVisionGrid(this.config)
        }
    });

    Object.defineProperty(this, 'id', {
        value: random.id(6)
    });

    Object.defineProperty(this, 'nodes', {
        value: {
            body: createBodyNode(this.config),
            circle: undefined,
            container: createContainerNode(this.config, this.id),
            parent,
            visionGrid: undefined,
        }
    });

    // TODO encapsulate better
    this.isLeader = false;
    this.leader = null;

    this.nodes.container.appendChild(this.nodes.body);
    parent.appendChild(this.nodes.container);

    this.arc = createArc(bounds, this.grids);
    this.updateConfig(this.config);
    this.nextFrame(globalGrid);
};

// ===== PROTOTYPE =====

Particle.prototype.remove = function() {
    this.nodes.parent.removeChild(this.nodes.container);
    return this;
}

Particle.prototype.nextFrame = function(globalGrid) {
    // Randomly change radius and rotation direction.
    if (this.arc.length <= 0 && this.config.randomize) {
        this.arc = randomizeArc(this.arc);
    }

    this.arc = step(this.arc, this.config);

    if (this.leader !== null) {
        this.arc = followArc(this.arc, this.leader.arc);
    }

    this.grids.global = globalGrid;
    this.grids.vision = updateVisionGrid(this.arc, this.config, this.grids);

    const { hazards, particles } = look(this.arc, this.grids);

    if (this.leader === null && particles.length > 0) {
        const candidates = particles
            .filter(v => v.leader ? (v.leader.id !== this.id) : true);

        const leader = candidates.find(v => v.isLeader) || candidates[0];

        if (leader !== undefined) {
            leader.isLeader = true;

            console.warn(`${particles[0].id} is now a leader`);
            console.log(`${this.id} is now following ${leader.id}`);

            this.isLeader = false;
            this.leader = leader;
        }
    }

    // if (hazards.length) {
        // this.arc = evade(this.arc, this.grids.vision);
    // }

    repaintContainer(this.nodes.container, this.arc);
    repaintBody(this.nodes.body, this.arc, this.isLeader);
    repaintCircle(this.nodes.circle, this.arc);
    repaintVisionGrid(this.nodes.visionGrid, this.arc, this.grids);
}

Particle.prototype.updateConfig = function(config) {
    Object.assign(this.config, config);

    const { showMovementCircle, showVisionGrid } = this.config;

    if (showMovementCircle === true && this.nodes.circle === undefined) {
        this.nodes.circle = createCircleNode(config);
        this.nodes.container.appendChild(this.nodes.circle);
    }

    if (showMovementCircle === false && this.nodes.circle !== undefined) {
        this.nodes.container.removeChild(this.nodes.circle);
        delete this.nodes.circle;
    }

    if (showVisionGrid === true && this.nodes.visionGrid === undefined) {
        this.nodes.visionGrid = createVisionGridNodes(this.config, this.grids, this.nodes);
    }

    if (showVisionGrid === false && this.nodes.visionGrid !== undefined) {
        delete this.nodex.visionGrid;
    }
}

// ===== CREATION =====

function createArc(bounds, grids) {
    let arc = {
        centerX: random.num(0, bounds.width),
        centerY: random.num(0, bounds.height),
        clockwise: random.bool(),
        endX: 0,
        endY: 0,
        length: random.num(RAD.t90, RAD.t360),
        radius: random.num(100, 200),
        theta: random.num(RAD.t90, RAD.t360),
    };

    arc.endX = arc.centerX + arc.radius * Math.cos(arc.theta);
    arc.endY = arc.centerY - arc.radius * Math.sin(arc.theta);

    arc = overflowArc(arc, bounds);

    const x = arc.endX - arc.endX % 5;
    const y = arc.endY - arc.endY % 5;

    // If starting in a hazard, recurse.
    if (grids.global[x] !== undefined && grids.global[x][y] !== undefined) {
        arc = createArc(bounds, grids);
    }

    return arc;
}

function createBodyNode(config) {
    const node = document.createElement('div');
    node.className = 'particle-body';
    node.style.backgroundColor = config.color;
    return node;
}

function createCircleNode(config) {
    if (config.showMovementCircle === false) {
        return undefined;
    }

    const node = document.createElement('div');
    node.className = 'particle-movement-circle';
    node.style.borderColor = config.color;
    return node;
}

function createContainerNode(config, id) {
    const node = document.createElement('div');
    node.className = 'particle-container';
    node.id = id;
    return node;
}

function createVisionGrid(config) {
    const { gridSize: side, visionRadius: radius } = config;
    const r0 = radius;
    const r1 = 20;

    const points = [];

    for (let x = -radius; x <= radius; x += side) {
        for (let y = -radius; y <= radius; y += side) {
            // Omit large slices of unused circle
            if (x > y || x < -y) {
                continue;
            }

            // Include vision band
            const r = Math.pow(Math.pow(x, 2) + Math.pow(y, 2), 0.5);
            if (r > r0 || r < r1) {
                continue;
            }

            let alpha = Math.atan(y / x);
            if (x < 0) {
                alpha += RAD.t180;
            }

            points.push({ x, y, r, alpha, touch: false });
        }
    }

    return points;
}

function createVisionGridNodes(config, grids, nodes) {
    if (config.showVisionGrid === false) {
        return undefined;
    }

    return grids.vision.reduce((acc, { x, y }) => {
        const div = document.createElement('div');
        div.className = 'particle-vision-dot';
        div.style.backgroundColor = config.color;
        nodes.container.appendChild(div);

        acc.push(div);

        return acc;
    }, []);
}

// ===== CALCULATIONS =====

function step(arc, { bounds, speed }) {
    // Ensure constant velocity and theta between 0 and 2π.
    const delta = speed / arc.radius;
    arc.length -= delta;

    arc.theta += (arc.clockwise ? -delta : +delta);
    arc.theta = (arc.theta > 0 ? arc.theta % RAD.t360 : RAD.t360 + arc.theta);

    arc.endX = arc.centerX + arc.radius * Math.cos(arc.theta); // TODO perf here
    arc.endY = arc.centerY - arc.radius * Math.sin(arc.theta); // TODO perf here

    // Overflow.
    arc = overflowArc(arc, bounds);

    return arc;
}

function randomizeArc(arc) {
    arc.length = random.num(RAD.t90, RAD.t360);

    arc = moveArc(arc, random.num(100, 200));

    if (random.bool(0.8)) {
        arc = reverseArc(arc);
    }

    return arc;
}

function overflowArc(arc, bounds) {
    if (arc.endX < 0) {
        arc.endX += bounds.width;
        arc.centerX += bounds.width
    } else if (arc.endX > bounds.width) {
        arc.endX -= bounds.width;
        arc.centerX -= bounds.width
    }

    if (arc.endY < 0) {
        arc.endY += bounds.height;
        arc.centerY += bounds.height
    } else if (arc.endY > bounds.height) {
        arc.endY -= bounds.height;
        arc.centerY -= bounds.height
    }

    return arc;
}

function moveArc(arc, newRadius) {
    const r0 = arc.radius;
    const r1 = newRadius;

    // Moves arc center to new radius while keeping theta constant.
    arc.centerX -= (r1 - r0) * Math.cos(arc.theta); // TODO perf here
    arc.centerY += (r1 - r0) * Math.sin(arc.theta); // TODO perf here
    arc.radius = r1;

    return arc;
}

function reverseArc(arc) {
    arc.clockwise = !arc.clockwise;

    arc.theta = (arc.theta + RAD.t180) % RAD.t360;

    arc.centerX -= (2 * arc.radius) * Math.cos(arc.theta); // TODO perf here
    arc.centerY += (2 * arc.radius) * Math.sin(arc.theta); // TODO perf here

    return arc;
}

function followArc(arc, arcToFollow) {
    if (arc.clockwise !== arcToFollow.clockwise) {
        arc = reverseArc(arc);
    }

    // if (Math.abs(arc.theta - arcToFollow.theta) > 0.1) {
    //     arc = moveArc(arc, 20);
    // } else {
    //     arc = moveArc(arc, arcToFollow.radius);
    // }

    return arc;
}

function updateVisionGrid(arc, config, grids) {
    const { global, vision } = grids;

    return vision.reduce((acc, point) => {
        const rad = arc.clockwise
            ? point.alpha - arc.theta
            : point.alpha - arc.theta + RAD.t180;

        point.x = point.r * Math.cos(rad);
        point.y = point.r * Math.sin(rad);

        return acc.concat(point);
    }, []);
}

// ===== ACTIONS =====
function look(arc, grids) {
    const { global, vision } = grids;

    return vision.reduce((acc, point) => {
        const x = arc.endX + point.x;
        const y = arc.endY + point.y;
        const p = global.getPoint({ x, y, type: ENTITIES.PARTICLE });

        if (p) {
            acc.particles.push(p);
        }

        // if (global.getPoint({ x, y, type: ENTITIES.HAZARD })) {
        //     acc.hazards.push({ x, y });
        // }

        return acc;
    }, { hazards: [], particles: [] });
}

function evade(arc, visionGrid) {
    // const danger = visionGrid.reduce((acc, v) => acc || v.touch, false);
    //
    // if (danger === false) {
    //     return arc;
    // }
    //
    // const evasionArc = moveArc(arc, 20);
    // evasionArc.length = 1;
    //
    // return evasionArc;
}

// ===== RENDERING =====
function repaintContainer(node, arc) {
    node.style.left = `${arc.endX}px`;
    node.style.top = `${arc.endY}px`;
}

function repaintBody(node, arc, isLeader) {
    const rad = arc.clockwise
        ? RAD.t180 - arc.theta
        : RAD.t360 - arc.theta;

    node.style.transform = `rotate(${rad + RAD.t45}rad)`;

    isLeader ? node.style.outline = '1px solid red' : node.style.outline = '';
}

function repaintCircle(node, arc) {
    if (node === undefined) {
        return;
    }

    node.style.width = `${2 * arc.radius}px`;
    node.style.height = `${2 * arc.radius}px`;

    node.style.left = `-${arc.radius + arc.radius * Math.cos(arc.theta)}px`;  // TODO perf here
    node.style.top = `-${arc.radius - arc.radius * Math.sin(arc.theta)}px`;   // TODO perf here

    node.style.borderRadius = `${arc.radius}px`;
}

function repaintVisionGrid(nodes, arc, grids) {
    if (nodes === undefined) {
        return;
    }

    grids.vision.forEach(({ x, y, touch }, i) => {
        nodes[i].style.left = `${x}px`;
        nodes[i].style.top = `${y}px`;

        nodes[i].style.border = (touch ? '2px solid red' : '0');
    });
}

export default Particle;