const edgeSize = 4; //min=2 max=30 step=1
const orientation = 20; //min=0 max=360 step=1
const rings = 19; //min=0 max=30 step=1
const vBorder = 0; //min=0 max=100 step=1
const hBorder = 42; //min=0 max=100 step=1

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(.7);

// Global code will be evaluated once.
const turtle = new Turtle();
const polygons = new Polygons();
turtle.radians();

const show = 6;
const loopMode = 0;
const drawEdges = 0;
const clockwise = 0;
const rotation = (orientation / 180) * Math.PI;
const clockwiseIndex = clockwise == 1;

turtle.seth(rotation);

class HexGrid {
    innerRVectors = []; // list of downright, upright, up, upleft, downleft, down vectors
    offsetModifiers = [
        [ 1, (column) => column % 2 == 0? 0: 1 ], // downright
        [ 1, (column) => column % 2 == 0? -1: 0 ], //upright
        [ 0, (column) => -1 ], //up 
        [-1, (column) => column % 2 == 0? -1: 0 ], //upleft
        [-1, (column) => column % 2 == 0? 0: 1 ], //downleft
        [ 0, (column) => 1 ] //down
    ];

    cubeModifiers = [[1,0,-1],[1,-1, 0],[0,-1,1],[-1,0,1],[-1,1,0],[0,1,-1]];
    
    iterator = null;
    
    currentOffset = [0,0];
    currentIndex = 0;
    currentCube = [0,0,0];
    currentDouble = [0,0];
    currentRing = 0;
    
    constructor(edgeSize, spiral = false, rotation = 0, clockwise = false) {
        this.edgeSize = edgeSize;
        this.innerSize = Math.sqrt(.75) * edgeSize;
        this.spiral = spiral;
        this.rotation = rotation;
        this.clockwise = clockwise
    }
    setInnerRVectors() {
        for(let i = 1; i <= 6; i++) {
            this.innerRVectors.push(trans2(rot2(((Math.PI / 3) * i * (this.clockwise? -1: 1)) - this.rotation), [0, this.innerSize * 2]));
        }
    }
    updateCoordination(index) {
        this.currentOffset = add2(this.currentOffset, [this.offsetModifiers[index][0], this.offsetModifiers[index][1](this.currentOffset[0])]);
        this.currentDouble = [this.currentOffset[0], this.currentOffset[1] + this.currentOffset[1] + (this.currentOffset[0] % 2 == 0? 0:1)];
        this.currentCube = add3(this.currentCube, this.cubeModifiers[index]);
        this.currentIndex++;
    }
    *spiralCellPositions() {
        let position = turtle.pos();

        yield this.yieldCell(position);
        while(this.currentRing++ !== false) {
            position = add2(position, this.innerRVectors[5]);
            this.updateCoordination(5);
            yield this.yieldCell(position);
            
            for(let j = 0; j < 6; j++) {
                for(let i = 0; i < this.currentRing - (j == 0? 1: 0); i++) {
                    position = add2(position, this.innerRVectors[j]);

                    this.updateCoordination(j);

                    yield this.yieldCell(position);
                }
            }
        }
    }
    *ringCellPositions() {
        let position = turtle.pos();
        
        yield this.yieldCell(position);
        while(this.currentRing++ !== false) {
            let rPosition = add2(position, scale2(this.innerRVectors[5], this.currentRing));

            this.currentOffset = [0, this.currentRing];
            this.currentDouble = [this.currentOffset[0], this.currentOffset[1] + this.currentOffset[1] + (this.currentOffset[0] % 2 == 0? 0:1)];
            this.currentCube = [0, this.currentRing, -this.currentRing];
            this.currentIndex++;

            yield this.yieldCell(rPosition);
            for(let i = 1; i <= 6; i++) {
                for(let n = 0; n < (i == 6? this.currentRing - 1: this.currentRing); n++) {
                    rPosition = add2(rPosition, this.innerRVectors[i % 6]);
                    this.updateCoordination(i % 6);
                    yield this.yieldCell(rPosition);
                }
            }
        }
    }
    yieldCell(position) {
        return new HexCell(this.edgeSize, position, this.currentIndex, this.currentOffset, this.currentCube, this.currentDouble, this.currentRing, this.rotation);
    }
    nextCell() {
        if(this.iterator == null) {
            this.setInnerRVectors();
            this.iterator = this.spiral? this.spiralCellPositions(): this.ringCellPositions();
            this.index = 0;
        }
        return this.iterator.next().value;
    }
}

class HexCell {
    constructor(size, position, index, offset, cube, double, ring, rotation) {
        this.position = position;
        this.index = index;
        this.offset = offset;
        this.cube = cube;
        this.double = double;
        this.ring = ring;
        this.size = size;
        this.rotation = rotation;
    }
    getBorderPoints(turtle, borderSize = null) {
        let isDown = turtle.isdown();
        turtle.up();

        if(borderSize == null) {
            borderSize = this.size;
        }

        turtle.forward(borderSize);
        turtle.right(turtle._fullCircle / 3);

        let points = [];
        for(let i = 0; i < 6; i++) {
            points.push(turtle.pos());
            turtle.forward(borderSize);
            turtle.right(turtle._fullCircle / 6);
        }

        turtle.left(turtle._fullCircle / 3);
        turtle.forward(-borderSize);

        if(isDown) { turtle.down(); }

        return points;
    }
    drawBorder(turtle, borderSize = null) {
        let points = this.getBorderPoints(turtle, borderSize);
        turtle.jump(points[0]);
        for(let i = 1; i < points.length; i++) {
            turtle.goto(points[i]);
        }
        turtle.goto(points[0]);
        turtle.jump(this.position);
    }
    decorate(turtle) {
        if( Math.abs(this.position[1]) - (100 - hBorder) - this.size > 0 || Math.abs(this.position[0]) - (100 - vBorder) - this.size > 0) {
            return;
        }
        let x = this.position[0];
        let y = this.position[1];
        let scale = this.size;
        let lineWidth = .28;
        let rotation = this.rotation;
        let t = turtle;
        
        const h0 = Math.sqrt(3)/2;
        const h1 = 1/2;
    
        const poly = new Polygons();
        
        // 2 transform functions: translate-scale (for background hatching), and rotate-translate-scale
        const ts  = p => [(scale*p[0])+x,(scale*p[1])+y];
        const rts = (p, a) => ts([Math.cos(a)*p[0]+Math.sin(a)*p[1], Math.cos(a)*p[1]-Math.sin(a)*p[0]]);

        // vec2 helper functions
        const add = (a, b) => [a[0]+b[0], a[1]+b[1]];
        const sub = (a, b) => [a[0]-b[0], a[1]-b[1]];
        const scl = (a, b) => [a[0]*b, a[1]*b];
        
        const rm = [Math.cos(-rotation), -Math.sin(-rotation), Math.sin(-rotation), Math.cos(-rotation)];
        const rotate = (a) => [rm[0]*a[0]+rm[2]*a[1], rm[1]*a[0]+rm[3]*a[1]];
    
        // 2 methods to create lines in a tile
        const circle = (c, r, s, e, fill) => { // circle around c, from angle s to e with radius r
            const p = poly.create(), c0 =[ts(c)], f=10;
            for (let i=0; i<=f; i++) {
                c0.push(ts(add(c, [Math.cos(s+(e-s)*i/f)*r, Math.sin(s+(e-s)*i/f)*r])));
            }
            p.addPoints(...c0);
            if(fill) {
                p.addHatching(0, .15);
            }
            return p;
        }
        const polygon = (points, fill) => {
            const p = poly.create();
            p.addPoints(...points);
            if(fill) {
                p.addHatching(0, .15);
            }
            return p;
        }
        
        // six corners of hexagon
        const c = [];
        for (let i=0; i<6; i++) {
            c.push([Math.cos((i*Math.PI/3) + rotation), Math.sin((i*Math.PI/3) + rotation)]);
        }
        
        // generate lines in tile
        const l = [];//, tileType = (Math.random()*5)|0; // 5 different tile types

        let tileType = 0;
        if(Math.random() < .7) {
            tileType = 3 + ((Math.random() * 2)|0);
        } else {
            tileType = ((Math.random() * 3)|0)
        }


        switch (tileType) {
            case 0:  l.push(circle(c[3], h1, -Math.PI/3 + rotation, Math.PI/3 + rotation));
                     l.push(circle(c[0], h1, Math.PI-Math.PI/3 + rotation, Math.PI+Math.PI/3 + rotation, true));
                     l.push(polygon([[0,-h0], [0, h0], [-h1, h0], [-2*h1, 0], [-h1, -h0]].map(p => rts(p, 0 - rotation)), true))
                     l.push(polygon(c.map(p => rts(p, 0))))
                     break;
            case 1:  l.push(circle(c[1], h1, Math.PI + rotation, 5*Math.PI/3 + rotation));
                     l.push(circle(c[4], h1, rotation, 2*Math.PI/3 + rotation, true));
                     l.push(polygon([[0,-h0], [0, h0], [-h1, h0], [-2*h1, 0], [-h1, -h0]].map(p => rts(p, Math.PI / 1.5 - rotation)), true))
                     l.push(polygon(c.map(p => rts(p, 0))))
                     break;
            case 2:  l.push(circle(c[5], h1, Math.PI + rotation, Math.PI/3 + rotation));
                     l.push(circle(c[2], h1, rotation, -2*Math.PI/3 + rotation, true));
                     l.push(polygon([[0,-h0], [0, h0], [-h1, h0], [-2*h1, 0], [-h1, -h0]].map(p => rts(p, Math.PI / .75 - rotation)), true))
                     l.push(polygon(c.map(p => rts(p, 0))))
                     break;
            case 3:  l.push(circle(c[0], h1, Math.PI-Math.PI/3 + rotation, Math.PI+Math.PI/3 + rotation, true)); // 3 arcs #1
                     l.push(circle(c[2], h1, -2*Math.PI/3 + rotation, 0 + rotation, true));
                     l.push(circle(c[4], h1, 0 + rotation, 2*Math.PI/3 + rotation, true));
                     l.push(polygon(c.map(p => ts(p))))
                     break;
            case 4:  l.push(circle(c[1], h1, Math.PI + rotation, Math.PI+Math.PI/1.5 + rotation)); // 3 arcs #1
                     l.push(circle(c[3], h1, -Math.PI/3 + rotation, Math.PI/3 + rotation));
                     l.push(circle(c[5], h1, Math.PI/3 + rotation, 3*Math.PI/3 + rotation));
                     l.push(polygon(c.map(p => ts(p)), true))
                     break;
        }
    
        // shuffle lines and draw
//        l.sort((a,b) => Math.random()-.5);
        l.map(p => poly.draw(t, p));
    }
}

let hg = new HexGrid(edgeSize, loopMode === 0, rotation, clockwiseIndex);

// The walk function will be called until it returns false.
function walk(i) {
    let cell = hg.nextCell();
    turtle.jump(cell.position);

    cell.decorate(turtle);

    return i < (nthTriangular(rings) * 6);
}

function nthTriangular(n) { return ((n * n) + n) / 2; }

// 
// Vector math
//

function rot2(a) { return [Math.cos(a), -Math.sin(a), Math.sin(a), Math.cos(a)]; }
function trans2(m, a) { return [m[0]*a[0]+m[2]*a[1], m[1]*a[0]+m[3]*a[1]]; }
function scale2(a,b) { return [a[0]*b,a[1]*b]; }
function add2(a,b) { return [a[0]+b[0],a[1]+b[1]]; }
function add3(a,b) { return [a[0]+b[0],a[1]+b[1],a[2]+b[2]]; }

////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// (Polygon binning by Lionel Lemarie 2021)
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////
function Polygons(){const t=[],s=25,e=Array.from({length:s**2},t=>[]),n=class{constructor(){this.cp=[],this.dp=[],this.aabb=[]}addPoints(...t){let s=1e5,e=-1e5,n=1e5,h=-1e5;(this.cp=[...this.cp,...t]).forEach(t=>{s=Math.min(s,t[0]),e=Math.max(e,t[0]),n=Math.min(n,t[1]),h=Math.max(h,t[1])}),this.aabb=[s,n,e,h]}addSegments(...t){t.forEach(t=>this.dp.push(t))}addOutline(){for(let t=0,s=this.cp.length;t<s;t++)this.dp.push(this.cp[t],this.cp[(t+1)%s])}draw(t){for(let s=0,e=this.dp.length;s<e;s+=2)t.jump(this.dp[s]),t.goto(this.dp[s+1])}addHatching(t,s){const e=new n;e.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);const h=Math.sin(t)*s,o=Math.cos(t)*s,a=200*Math.sin(t),i=200*Math.cos(t);for(let t=.5;t<150/s;t++)e.dp.push([h*t+i,o*t-a],[h*t-i,o*t+a]),e.dp.push([-h*t+i,-o*t-a],[-h*t-i,-o*t+a]);e.boolean(this,!1),this.dp=[...this.dp,...e.dp]}inside(t){let s=0;for(let e=0,n=this.cp.length;e<n;e++)this.segment_intersect(t,[.1,-1e3],this.cp[e],this.cp[(e+1)%n])&&s++;return 1&s}boolean(t,s=!0){const e=[];for(let n=0,h=this.dp.length;n<h;n+=2){const h=this.dp[n],o=this.dp[n+1],a=[];for(let s=0,e=t.cp.length;s<e;s++){const n=this.segment_intersect(h,o,t.cp[s],t.cp[(s+1)%e]);!1!==n&&a.push(n)}if(0===a.length)s===!t.inside(h)&&e.push(h,o);else{a.push(h,o);const n=o[0]-h[0],i=o[1]-h[1];a.sort((t,s)=>(t[0]-h[0])*n+(t[1]-h[1])*i-(s[0]-h[0])*n-(s[1]-h[1])*i);for(let n=0;n<a.length-1;n++)(a[n][0]-a[n+1][0])**2+(a[n][1]-a[n+1][1])**2>=.001&&s===!t.inside([(a[n][0]+a[n+1][0])/2,(a[n][1]+a[n+1][1])/2])&&e.push(a[n],a[n+1])}}return(this.dp=e).length>0}segment_intersect(t,s,e,n){const h=(n[1]-e[1])*(s[0]-t[0])-(n[0]-e[0])*(s[1]-t[1]);if(0===h)return!1;const o=((n[0]-e[0])*(t[1]-e[1])-(n[1]-e[1])*(t[0]-e[0]))/h,a=((s[0]-t[0])*(t[1]-e[1])-(s[1]-t[1])*(t[0]-e[0]))/h;return o>=0&&o<=1&&a>=0&&a<=1&&[t[0]+o*(s[0]-t[0]),t[1]+o*(s[1]-t[1])]}};return{list:()=>t,create:()=>new n,draw:(n,h,o=!0)=>{reducedPolygonList=function(n){const h={},o=200/s;for(var a=0;a<s;a++){const c=a*o-100,r=[0,c,200,c+o];if(!(n[3]<r[1]||n[1]>r[3]))for(var i=0;i<s;i++){const c=i*o-100;r[0]=c,r[2]=c+o,n[0]>r[2]||n[2]<r[0]||e[i+a*s].forEach(s=>{const e=t[s];n[3]<e.aabb[1]||n[1]>e.aabb[3]||n[0]>e.aabb[2]||n[2]<e.aabb[0]||(h[s]=1)})}}return Array.from(Object.keys(h),s=>t[s])}(h.aabb);for(let t=0;t<reducedPolygonList.length&&h.boolean(reducedPolygonList[t]);t++);h.draw(n),o&&function(n){t.push(n);const h=t.length-1,o=200/s;e.forEach((t,e)=>{const a=e%s*o-100,i=(e/s|0)*o-100,c=[a,i,a+o,i+o];c[3]<n.aabb[1]||c[1]>n.aabb[3]||c[0]>n.aabb[2]||c[2]<n.aabb[0]||t.push(h)})}(h)}}}