/** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */

import { base } from '../geo/base.js';
import { newPolygon } from './polygon.js';

const { config } = base;
const factor = config.clipper;

export const wasm_ctrl = {
    enable,
    disable,
    count: {
        offset: 0,
        union: 0,
        diff: 0
    }
};

function log() {
    console.log(...arguments);
}

function writePolys(view, polys) {
    let pcount = 0;
    for (let poly of polys) {
        pcount += writePoly(view, poly);
    }
    return pcount;
}

function writePoly(view, poly, inner) {
    if (inner) {
        poly.setCounterClockwise();
    } else {
        poly.setClockwise();
    }
    let count = 1;
    let points = poly.points;
    let inners = poly.inner;
    view.writeU16(points.length, true);
    for (let i=0, il=points.length; i<il; i++) {
        let point = points[i];
        view.writeI32((point.x * factor)|0, true);
        view.writeI32((point.y * factor)|0, true);
    }
    if (inners) {
        for (let i=0, il=inners.length; i<il; i++) {
            count += writePoly(view, inners[i], true);
        }
    }
    return count;
}

function readPoly(view, z) {
    let points = view.readU16(true);
    if (points === 0) return;
    let poly = newPolygon();
    while (points-- > 0) {
        poly.add(view.readI32(true)/factor, view.readI32(true)/factor, z || 0);
    }
    return poly;
}

function readPolys(view, z, out = []) {
    for (;;) {
        let poly = readPoly(view, z);
        if (poly) {
            out.push(poly);
        } else {
            break;
        }
    }
    return out;
}

export function polyOffset(polys, offset, z, clean, simple) {
    wasm_ctrl.count.offset++;
    let wasm = base.wasm,
        buffer = wasm.shared,
        pcount = writePolys(new DataWriter(wasm.heap, buffer), polys),
        resat = wasm.fn.offset(buffer, pcount, offset * factor, clean, simple),
        out = readPolys(new DataReader(wasm.heap, resat), z);
    return polyNest(out);
}

export function polyUnion(polys, z) {
    wasm_ctrl.count.union++;
    let wasm = base.wasm,
        buffer = wasm.shared,
        pcount = writePolys(new DataWriter(wasm.heap, buffer), polys),
        resat = wasm.fn.union(buffer, pcount),
        out = readPolys(new DataReader(wasm.heap, resat), z);
    return polyNest(out);
}

export function polyDiff(polysA, polysB, z, AB, BA) {
    wasm_ctrl.count.diff++;
    let wasm = base.wasm,
        buffer = wasm.shared,
        writer = new DataWriter(wasm.heap, buffer),
        pcountA = writePolys(writer, polysA),
        pcountB = writePolys(writer, polysB),
        resat = wasm.fn.diff(buffer, pcountA, pcountB, AB?1:0, BA?1:0, config.clipperClean),
        reader = new DataReader(wasm.heap, resat);
    if (AB) {
        AB.appendAll(polyNest(readPolys(reader, z)));
    }
    if (BA) {
        BA.appendAll(polyNest(readPolys(reader, z)));
    }
}

// nest closed polygons without existing parent / child relationships
function polyNest(polys) {
    polys.sort((a,b) => {
        return b.bounds.minx - a.bounds.minx;
    });
    // from smallest to largest, check for enclosing bounds and nest
    for (let i=0, il=polys.length; i<il; i++) {
        let smaller = polys[i];
        // prevent parent poly from being consumed
        if (smaller.inner) continue;
        for (let j=i+1; j<il; j++) {
            let larger = polys[j];
            if (larger.bounds.contains(smaller.bounds)) {
                larger.addInner(smaller);
                break;
            }
        }
    }
    let tops = [];
    for (let i=0, il=polys.length; i<il; i++) {
        let poly = polys[i];
        if (!poly.parent) {
            tops.push(poly);
        }
    }
    return tops;
}

function readString(pos, len) {
    let view = new DataReader(base.wasm.heap, pos);
    let out = [];
    while (len-- > 0) {
        out.push(String.fromCharCode(view.readU8()));
    }
    return out.join('');
}

export function enable() {
    if (base.wasm || base._wasm) {
        return;
    }
    base._wasm = 'loading';
    fetch('/wasm/kiri-geo.wasm')
        .then(response => response.arrayBuffer())
        .then(bytes => WebAssembly.instantiate(bytes, {
            env: {
                debug_string: (len, ptr) => { console.log('wasm', readString(ptr, len)) }
            },
            wasi_snapshot_preview1: {
                // args_get: (count,bufsize) => { return 0 },
                // args_sizes_get: (count,bufsize) => { },
                // environ_get: (count,bufsize) => { return 0 },
                // environ_sizes_get: (count,bufsize) => { },
                proc_exit: (code) => { return code }
            }
        }))
        .then(results => {
            // console.log({enabled: base.wasm});
            delete base._wasm;
            let { module, instance } = results;
            let { exports } = instance;
            let heap = new DataView(exports.memory.buffer);
            let wasm = base.wasm = {
                heap,
                exports,
                memory: exports.memory,
                memmax: exports.memory.buffer.byteLength,
                malloc: exports.mem_get,
                free: exports.mem_clr
            };
            wasm.shared = wasm.malloc(1024 * 1024 * 30),
            wasm.fn = {
                diff: exports.poly_diff,
                union: exports.poly_union,
                offset: exports.poly_offset
            };
            wasm.js = {
                diff: polyDiff,
                union: polyUnion,
                offset: polyOffset
            };
        });
}

export function disable() {
    if (base.wasm) {
        base.wasm.free(base.wasm.shared);
        delete base.wasm;
    }
}