// derived from https://cs.uwaterloo.ca/~csk/spectre/spectre.js


const {PI, cos, sin} = Math;

function radians(degrees) {
    return degrees * PI / 180;
}

let num_pieces = 0;

class Point {
    constructor(x,y) {
        this.x = x;
        this.y = y;
    }

    add(q) {
        return { x : this.x + q.x, y : this.y + q.y };
    }

    sub(q) {
        return { x : this.x - q.x, y : this.y - q.y };
    }

    frame(p, q, a, b) {
        return{ x : this.x + a*p.x + b*q.x, y : this.y + a*p.y + b*q.y };
    }

}

class Matrix {
    constructor(mat) {
        this.mat = mat;
    }

    determinant() {
        const T = this.mat;
        const det = T[0]*T[4] - T[1]*T[3];
    }

    inverse() {
        const T = this.mat;
        const det = this.determinant();
        return new Matrix([
            T[4]/det,
            -T[1]/det,
            (T[1]*T[5]-T[2]*T[4])/det,
            -T[3]/det,
            T[0]/det,
            (T[2]*T[3]-T[0]*T[5])/det
        ]);
    }

    mul(other) {
        const A = this.mat;
        const B = other.mat;
        return new Matrix([
            A[0]*B[0] + A[1]*B[3], 
            A[0]*B[1] + A[1]*B[4],
            A[0]*B[2] + A[1]*B[5] + A[2],

            A[3]*B[0] + A[4]*B[3], 
            A[3]*B[1] + A[4]*B[4],
            A[3]*B[2] + A[4]*B[5] + A[5]
        ]);
    }

    // Rotation matrix
    static rotation(ang) {
        const c = cos(ang);
        const s = sin(ang);
        return new Matrix([c, -s, 0, s, c, 0]);
    }

    static scale(x,y) {
        return new Matrix([x,0,0,0,y,0]);
    }

    static translate(tx, ty) {
        return new Matrix([1, 0, tx, 0, 1, ty]);
    }

    // Translation matrix moving p to q
    static translateTo(p, q) {
        return Matrix.translate(q.x - p.x, q.y - p.y);
    }

    transform(P) {
        const M = this.mat;
        return new Point(M[0]*P.x + M[1]*P.y + M[2], M[3]*P.x + M[4]*P.y + M[5]);
    }

}

const ident = new Matrix([1,0,0,0,1,0]);

const spectre = [
    new Point(0, 0),
    new Point(1.0, 0.0),
    new Point(1.5, -0.8660254037844386),
    new Point(2.366025403784439, -0.36602540378443865),
    new Point(2.366025403784439, 0.6339745962155614),
    new Point(3.366025403784439, 0.6339745962155614),
    new Point(3.866025403784439, 1.5),
    new Point(3.0, 2.0),
    new Point(2.133974596215561, 1.5),
    new Point(1.6339745962155614, 2.3660254037844393),
    new Point(0.6339745962155614, 2.3660254037844393),
    new Point(-0.3660254037844386, 2.3660254037844393),
    new Point(-0.866025403784439, 1.5),
    new Point(0.0, 1.0) 
];

const base_quad = [spectre[3], spectre[5], spectre[7], spectre[11]];

function getsvg(event) {
    let t = event.target;
    while(t && t.tagName.toLowerCase()!='svg') {
        t = t.parentElement;
    }
    return t;
}

function getcoords(event) {
    const t = getsvg(event);
    if(!t) {
        return;
    }
    const point = t.createSVGPoint()
    point.x = event.clientX
    point.y = event.clientY
    const position = point.matrixTransform(t.getScreenCTM().inverse())                
    return position;
}

class Tile {
    constructor(pts, quad) {
        this.pts = pts;
        this.quad = quad;

        this.pts = [pts[pts.length-1]];
        for(const p of pts) {
            const prev = this.pts[this.pts.length-1];
            const v = p.sub(prev);
            const w = new Point(-v.y, v.x);
            this.pts.push(prev.frame(v, w, 0.5, -0.3));
            this.pts.push(prev.frame(v, w, 0.5, 0.3));
            this.pts.push(p);
        }
    }

    streamSVG(S, stream) {
        const tpts = this.pts.map(p => S.transform(p));

        const [a,c,e,b,d,f] = S.mat;
        const matS = [a,b,c,d,e,f].map(p=>p.toFixed(3));
        num_pieces += 1;
        stream.push(`<g class="tile">
    <use href="#spectre" transform="matrix(${matS.join(',')}) "/>
    <text font-size="0.5" dominant-baseline="middle" text-anchor="middle" transform="matrix(${matS.join(',')}) translate(1 1.6)">${num_pieces}</text>
    <text font-size="1" dominant-baseline="middle" text-anchor="middle" transform="matrix(${matS.join(',')}) translate(1 1)">↑</text>
</g>`);
    }

}

class Metatile {
    constructor() {
        this.geoms = [];
        this.quad = [];
    }

    addChild(g, T) {
        this.geoms.push({ geom : g, xform: T });
    }

    streamSVG(S, stream) {
        for(let g of this.geoms) {
            g.geom.streamSVG(S.mul(g.xform), stream);
        }

    }
}

function tiles(level, label) {
    let quad;
    let out = [];
    let transform;
    if(level == 0) {
        transform = ident;
        quad = base_quad;
        switch(label) {
            case 'Delta':
            case 'Theta':
            case 'Lambda':
            case 'Xi':
            case 'Pi':
            case 'Sigma':
            case 'Phi':
            case 'Psi':
                out.push(ident);
            case 'Gamma':
                const mystic = new Metatile();
                out.push(ident);
                out.push(Matrix.translate(spectre[8].x, spectre[8].y).mul(Matrix.rotation(PI / 6)));
        }
    } else {
        /*
         * Each of the subtiles is identical, but rotated and translated.
         *
         * Produce transformation matrices Ts for each of the subtiles: they're formed by rotating the quad and then matching up a pair of points.
         *
         * The whole thing is then reflected.
         *
         * The layout of subtiles depends on the larger tile.
         *
         */
        const labels = [
            'Delta',
            'Theta',
            'Lambda',
            'Xi', 
            'Pi',
            'Sigma',
            'Phi',
            'Psi'
        ];

        const sublevels = Object.fromEntries(labels.map(label => tiles(level-1, label)));
        const subquad = sublevels['Delta'].quad;

        const reflection = Matrix.scale(-1,1);


        // How to get from each subtile to the next.
        const t_rules = [
            [60, 3, 1],
            [0, 2, 0],
            [60, 3, 1],
            [60, 3, 1],
            [0, 2, 0],
            [60, 3, 1],
            [-120, 3, 3]
        ];


        let Ts = [ident];
        let total_ang = 0;
        let rot = ident;
        let tquad = [...subquad];
        for(const [ang,from,to] of t_rules) {
            total_ang += ang;
            if(ang != 0) {
                rot = Matrix.rotation(radians(total_ang));
                tquad = subquad.map(q => rot.transform(q));
            }

            const ttt = Matrix.translateTo(tquad[to], Ts[Ts.length-1].transform(subquad[from]));
            Ts.push(ttt.mul(rot));
        }

        Ts = Ts.map(t => mul(reflection, t));


        // Now build the actual supertiles, labelling appropriately.
        const super_rules = {
            'Gamma' :  ['Pi','Delta','null','Theta','Sigma','Xi','Phi','Gamma'],
            'Delta' :  ['Xi','Delta','Xi','Phi','Sigma','Pi','Phi','Gamma'],
            'Theta' :  ['Psi','Delta','Pi','Phi','Sigma','Pi','Phi','Gamma'],
            'Lambda' : ['Psi','Delta','Xi','Phi','Sigma','Pi','Phi','Gamma'],
            'Xi' :     ['Psi','Delta','Pi','Phi','Sigma','Psi','Phi','Gamma'],
            'Pi' :     ['Psi','Delta','Xi','Phi','Sigma','Psi','Phi','Gamma'],
            'Sigma' :  ['Xi','Delta','Xi','Phi','Sigma','Pi','Lambda','Gamma'],
            'Phi' :    ['Psi','Delta','Psi','Phi','Sigma','Pi','Phi','Gamma'],
            'Psi' :    ['Psi','Delta','Psi','Phi','Sigma','Psi','Phi','Gamma']
        };
        const super_quad = [
            Ts[6].transform(subquad[2]),
            Ts[5].transform(subquad[1]),
            Ts[3].transform(subquad[2]),
            Ts[0].transform(subquad[1]) ]; 
    }
    return {quad, tiles: out};
}


let last_num_iterations;

function get_settings() {
    return Object.fromEntries(
        Array.from(document.querySelectorAll('input,textarea')).map(i => [i.id, i.type=='number' ? i.valueAsNumber : i.value])
    );
}

class Builder {
    constructor(settings) {
        this.settings = settings;
    }

    build() {
        const {settings} = this;

        num_pieces = 0;

        let sys = this.buildSpectreBase();

        for(let i=0;i<settings.num_iterations;i++) {
            sys = this.buildSupertiles(sys);	
        }

        sys = sys['Delta'];

        this.sys = sys;
    }

    buildSpectreBase() {
        const ret = {};

        for(let lab of ['Delta', 'Theta', 'Lambda', 'Xi', 
            'Pi', 'Sigma', 'Phi', 'Psi']) {
            ret[lab] = new Tile(spectre, base_quad, lab);
        }

        const mystic = new Metatile();
        mystic.addChild(new Tile(spectre, base_quad, 'Gamma1'), ident);
        mystic.addChild(new Tile(spectre, base_quad, 'Gamma2'),
            Matrix.translate(spectre[8].x, spectre[8].y).mul(Matrix.rotation(PI / 6)));
        mystic.quad = base_quad;
        ret['Gamma'] = mystic;

        return ret;
    }

    buildSupertiles(sys) {
        // First, use any of the nine-unit tiles in sys to obtain
        // a list of transformation matrices for placing tiles within
        // supertiles.

        const quad = sys['Delta'].quad;
        const R = new Matrix([-1,0,0,0,1,0]);

        const t_rules = [
            [60, 3, 1], [0, 2, 0], [60, 3, 1], [60, 3, 1],
            [0, 2, 0], [60, 3, 1], [-120, 3, 3] ];  

        const Ts = [ident];
        let total_ang = 0;
        let rot = ident;
        const tquad = [...quad];
        for(const [ang,from,to] of t_rules) {
            total_ang += ang;
            if(ang != 0) {
                rot = Matrix.rotation(radians(total_ang));
                for(let i = 0; i < 4; ++i) {
                    tquad[i] = rot.transform(quad[i]);
                }
            }

            const ttt = Matrix.translateTo(tquad[to], 
                Ts[Ts.length-1].transform(quad[from]));
            Ts.push(ttt.mul(rot));
        }

        for(let idx = 0; idx < Ts.length; ++idx) {
            Ts[idx] = R.mul(Ts[idx]);
        }

        // Now build the actual supertiles, labelling appropriately.
        const super_rules = {
            'Gamma' :  ['Pi','Delta','null','Theta','Sigma','Xi','Phi','Gamma'],
            'Delta' :  ['Xi','Delta','Xi','Phi','Sigma','Pi','Phi','Gamma'],
            'Theta' :  ['Psi','Delta','Pi','Phi','Sigma','Pi','Phi','Gamma'],
            'Lambda' : ['Psi','Delta','Xi','Phi','Sigma','Pi','Phi','Gamma'],
            'Xi' :     ['Psi','Delta','Pi','Phi','Sigma','Psi','Phi','Gamma'],
            'Pi' :     ['Psi','Delta','Xi','Phi','Sigma','Psi','Phi','Gamma'],
            'Sigma' :  ['Xi','Delta','Xi','Phi','Sigma','Pi','Lambda','Gamma'],
            'Phi' :    ['Psi','Delta','Psi','Phi','Sigma','Pi','Phi','Gamma'],
            'Psi' :    ['Psi','Delta','Psi','Phi','Sigma','Psi','Phi','Gamma'] };
        const super_quad = [
            Ts[6].transform(quad[2]),
            Ts[5].transform(quad[1]),
            Ts[3].transform(quad[2]),
            Ts[0].transform(quad[1]) ]; 

        const ret = {};

        for(const [lab, subs] of Object.entries(super_rules)) {
            const sup = new Metatile();
            for(let idx = 0; idx < 8; ++idx) {
                if(subs[idx] == 'null') {
                    continue;
                }
                sup.addChild(sys[subs[idx]], Ts[idx]);
            }
            sup.quad = super_quad;

            ret[lab] = sup;
        }

        return ret;
    }


    draw() {
        const {sys} = this;

        const drawing = [];

        const svg = document.querySelector('svg');

        const board = svg.querySelector('#board');
        board.innerHTML = '';
        const R = new Matrix([-1,0,0,0,1,0]);
        const m = this.settings.num_iterations % 2 == 0 ? ident : R;
        sys.streamSVG(m, drawing);
        board.innerHTML = drawing.join(' ');

        const viewbox = svg.getBoundingClientRect();
        function visit(g, t) {
            for(let c of g.children) {
                visit(c, t+Math.random()*10-5);
            }
            if(g.tagName=='path') {
                const b = g.getBoundingClientRect();
                const x = (b.x - viewbox.x) / viewbox.width;
                const y = (b.y - viewbox.y) / viewbox.height;
                g.style.color = '#ccc';
            }
        }
        visit(board,50);

        svg.addEventListener('click', e => {
            if(!last_click) {
                return;
            }
            let tile = e.target;
            while(tile && !tile.classList.contains('tile')) {
                tile = tile.parentElement;
            }
            if(!tile) {
                return;
            }

            for(let el of svg.querySelectorAll('.highlight')) {
                el.classList.remove('highlight');
            }
            tile.classList.add('highlight');
        });
    }
}

function update_display() {
    const settings = get_settings();
    const svg = document.querySelector('svg');
    svg.setAttribute('viewBox',`${-settings.scale/2} ${-settings.scale/2} ${settings.scale} ${settings.scale}`);
    const mx = spectre.map(p=>p.x).reduce((a,b)=>a+b)/spectre.length;
    const my = spectre.map(p=>p.y).reduce((a,b)=>a+b)/spectre.length;
    document.getElementById('spectre').setAttribute('transform',`translate(${mx},${my}) translate(${-mx},${-my})`);

    if(settings.num_iterations != last_num_iterations) {
        const builder = new Builder(settings);
        builder.build();
        builder.draw();
        last_num_iterations = settings.num_iterations;
    }
}

for(let i of document.querySelectorAll('input')) {
    i.addEventListener('input', update_display);
    i.addEventListener('change', update_display)
}

update_display();

let opos;
let dragging;
let pan = {x:0, y:0};
let npan = pan;
let last_click = false;

const svg = document.querySelector('svg');
svg.addEventListener('pointerdown', e => {
    opos = getcoords(e);
    dragging = true;
});

svg.addEventListener('pointermove', e => {
    if(!dragging) {
        return;
    }
    const pos = getcoords(e);
    npan = {x: pan.x + pos.x - opos.x, y: pan.y + pos.y - opos.y};
    document.getElementById('board').setAttribute('transform', `translate(${npan.x} ${npan.y})`);
});

svg.addEventListener('pointerup', e => {
    dragging = false;
    const [dx,dy] = [npan.x - pan.x, npan.y - pan.y];
    const d = Math.sqrt(dx*dx + dy*dy);
    last_click = d < 0.5;
    pan = npan;
});