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

import { util } from '../../geo/base.js';
import { slicer } from '../../geo/slicer.js';
import { newPolygon } from '../../geo/polygon.js';
import { polygons as POLY } from '../../geo/polygons.js';
import { newSlice, newTop } from '../../kiri/slice.js';
import { doShells, doDiff, projectFlats, projectBridges } from '../fdm/slice.js';
import { PNG } from '../../ext/pngjs.esm.js';
import { SLA } from './driver.js';

const tracker = util.pwait;

let fill_cache;

/**
 * DRIVER CONTRACT - runs in worker
 * @param {Object} settings
 * @param {Widget} Widget
 * @param {Function} onupdate (called with % complete and optional message)
 * @param {Function} ondone (called when complete with an array of Slice objects)
 */
export function sla_slice(settings, widget, onupdate, ondone) {
    let { minions } = self.kiri_worker,
        { process, device, controller } = settings,
        isConcurrent = controller.threaded && minions.concurrent,
        work_total,
        work_remain;

    if (SLA.legacy && !self.OffscreenCanvas) {
        return ondone("browser lacks support for OffscreenCanvas",true);
    }

    // calculate % complete and call onupdate()
    function doupdate(work, msg) {
        onupdate(0.25 + ((work_total - work_remain) / work_total) * 0.75, msg);
        work_remain -= work;
    }

    // for each slice, perform a function and call doupdate()
    function forSlices(slices, work, fn, msg) {
        slices.forEach(function(slice,index) {
            fn(slice,index);
            doupdate(work / slices.length, msg)
        });
    }

    let smallDims = { x: 200, y: 125 };
    let largeDims = { x: 400, y: 300 };

    switch (device.deviceName) {
        case 'Anycubic.Photon':
        case 'Anycubic.Photon.S':
            // defaults above
            break;
        case 'Creality.Halot.One':
        case 'Creality.Halot.Max':
        case 'Creality.Halot.Sky':
            smallDims = { x: 116, y: 116 };
            largeDims = { x: 290, y: 290 };
            break;
    }

    let sws = self.kiri_worker.current.snap.url;
    let b64 = atob(sws.substring(sws.indexOf(',') + 1));
    let bin = Uint8Array.from(b64, c => c.charCodeAt(0));
    let img = new PNG();
    img.parse(bin, (err, data) => {
        SLA.preview = img;
        SLA.previewSmall = samplePNG(img, smallDims.x, smallDims.y);
        SLA.previewLarge = samplePNG(img, largeDims.x, largeDims.y);
    });
    let height = process.slaSlice || 0.05;

    async function onSliceDone(slices) {
        // remove empty slices
        slices = widget.slices = slices.filter(slice => slice.tops.length);
        if (!process.slaOpenTop && !process.xray) {
            // re-add last empty slice for closed top
            let cap = newSlice(bounds.max.z + height);
            cap.index = slices.last().index + 1;
            slices.push(cap);
        }
        // prepend raft layers to slices array
        if (process.slaSupportEnable && process.slaSupportLayers) {
            let layers = process.slaSupportLayers,
                zoff = height / 2,
                snew = [],
                polys = [],
                gap = process.slaSupportGap, // gap layers above raft
                grow = height, // union per layer expand
                off = 1 - (layers * grow); // starting union offset from part
            let outer = slices.forEach(slice => {
                // poly.clone prevents inner voids from forming
                polys.appendAll(slice.tops.map(t => t.poly.clone()));
            });
            // p.clone prevents inner voids from forming
            let union = POLY.union(polys, undefined, true).map(p => p.clone());
            let expand = POLY.expand(union, off, zoff, [], 1);
            let lastraft;
            for (let s=0; s<layers + gap; s++) {
                let slice = newSlice(zoff);
                slice.height = height;
                slice.index = snew.length;
                if (s < layers) {
                    slice.synth = true;
                    expand.forEach(u => {
                        slice.tops.push(newTop(u.clone(true).setZ(zoff)));
                    });
                    expand = POLY.expand(expand, grow, zoff, [], 1);
                    lastraft = slice;
                }
                snew.push(slice);
                zoff += height;
            }
            // compensate for midline start
            zoff -= height / 2;
            // replace slices with new appended array
            slices = widget.slices = snew.concat(slices.map(s => {
                s.tops.forEach(t => t.poly.setZ(s.z + zoff));
                s.index += snew.length;
                s.z += zoff;
                return s;
            }));
            // annotate widget for support generation
            widget.union = union;
            widget.lastraft = lastraft;
        }
        // re-connect slices into linked list for island/bridge projections
        for (let i=1; i<slices.length; i++) {
            slices[i-1].up = slices[i];
            slices[i].down = slices[i-1];
        }
        let solidLayers = Math.round(process.slaShell / process.slaSlice);
        // setup solid fill
        slices.forEach(function(slice) {
            slice.solids = [];
        });
        // compute total work for progress bar
        work_total = [
            5,  // shell
            10, // diff
            solidLayers ? 10 : 0, // shell project
            solidLayers ? 10 : 0, // shell fill
            !solidLayers ? 10 : 0, // solid
            process.slaFillDensity && process.slaShell ? 60 : 0, // infill
            process.slaSupportEnable && process.slaSupportLayers && process.slaSupportDensity ? 100 : 0
        ].reduce((t,v) => { return t+v });
        work_remain = work_total;
        forSlices(slices, 5, (slice,index) => {
            if (process.slaShell) {
                doShells(slice, 2, 0, process.slaShell);
            } else {
                doShells(slice, 1, 0);
            }
        }, "shells");
        forSlices(slices, 10, (slice) => {
            if (slice.synth) return;
            doDiff(slice, 0.000001, {
                sla: true,
                fakedown: !process.slaOpenBase
            });
        }, "delta");
        if (solidLayers) {
            forSlices(slices, 10, (slice) => {
                if (slice.synth) return;
                projectFlats(slice, solidLayers);
                projectBridges(slice, solidLayers);
            }, "project");
            async function doUnionSolid(slice) {
                if (slice.synth) return;
                let traces = POLY.nest(POLY.flatten(slice.topShells()));
                if (slice.solids) {
                    let trims = slice.solids || [];
                    traces.appendAll(trims);
                    // slice.unioned = POLY.setZ(POLY.union(traces, undefined, true), slice.z);
                    slice.unioned = POLY.setZ(await minions.union(traces), slice.z);
                } else {
                    slice.unioned = traces;
                }
            }
            let promises = slices.map(slice => doUnionSolid(slice));
            await tracker(promises, (i, t) => {
                doupdate(10 / promises.length, "solid");
            });
        } else {
            forSlices(slices, 10, (slice) => {
                if (slice.synth) return;
                slice.unioned = slice.topPolys();
            }, "solid");
        }
        if (process.slaFillDensity && process.slaShell) {
            fill_cache = [];
            forSlices(slices, 60, (slice) => {
                if (slice.synth) return;
                fillPolys(slice, settings);
            }, "infill");
        }
        if (process.slaSupportEnable && process.slaSupportLayers && process.slaSupportDensity) {
            computeSupports(widget, process, progress => {
                doupdate(100 * progress, "support");
            });
        }
        doRender(widget);
    }

    let bounds = widget.getBoundingBox();
    let points = widget.getPoints();

    slicer.slice(points, {
        indices: process.indices || process.xray,
        union: controller.healMesh,
        debug: process.xray,
        xray: process.xray,
        zMin: bounds.min.z + height / 2,
        zMax: bounds.max.z,
        zInc: height,
        // slicer function (worker local or minion distributed)
        slicer(z, points, opts) {
            return (isConcurrent ? minions.sliceZ : slicer.sliceZ)(z, points, opts);
        },
        onupdate(v) {
            return onupdate(0.0 + v * 0.25);
        }
    }).then(output => {
        let slices = widget.slices = output.slices.map(data => {
            let { z, lines, groups } = data;
            let tops = POLY.nest(groups);
            return newSlice(z).addTops(tops);
        });
        onSliceDone(slices).then(ondone);
    });
};

function doRender(widget) {
    widget.slices.forEach(slice => {
        const render = slice.output(), lopacity = 0.6, line = 0x010101;

        if (slice.unioned) {
            slice.unioned.forEach(poly => {
                poly = poly.clone(true);//.move(widget.track.pos);
                render
                    .setLayer("layers", { line, face: 0x0099cc, lopacity })
                    .addAreas([poly], { outline: true });
            });
        } else if (slice.tops) {
            slice.tops.forEach(top => {
                let poly = top.poly;//.clone(true).move(widget.track.pos);
                render
                    .setLayer("layers", { line, face: 0xfcba03, lopacity })
                    .addAreas([poly], { outline: true });
            });
        }

        if (slice.supports) {
            slice.supports.forEach(poly => {
                render
                    .setLayer("support", { line, face: 0xfcba03, lopacity })
                    .addAreas([poly], { outline: true });
            });
        }
    });
}

function computeSupports(widget, process, progress) {
    let area = widget.union.reduce((t,p) => { return t + p.areaDeep() }, 0),
        perim = widget.union.reduce((t,p) => { return t + p.perimeter() }, 0),
        slices = widget.slices,
        length = slices.length,
        tot_mass = 0, // total widget "mass"
        tot_bear = 0; // total "mass-bearing" area

    let ops = slices.filter(slice => !slice.synth);

    // compute total "mass" by slice
    ops.forEach(slice => {
        slice.mass = slice.unioned.reduce((t,p) => { return t + p.areaDeep() }, 0);
        if (slice.up && slice.up.bridges) {
            slice.bear = slice.up.bridges.reduce((t,p) => { return t + p.areaDeep() }, 0);
            slice.bear_up = slice.up.bridges;
            tot_bear += slice.bear;
        } else {
            slice.bear = 0;
        }
        tot_mass += slice.mass;
    });

    let mass_per_bear = (tot_mass / tot_bear) * (1 / process.slaSupportDensity);

    // console.log({tot_mass, tot_bear, ratio: tot_mass / tot_bear, mass_per_bear});

    let first;
    ops.slice().map((s,i) => {
        if (!first && s.bear) {
            s.ord_first = first = true;
        }
        // 30x lowest to 1x highest
        s.ord_weight = Math.pow(30,((ops.length - i) / ops.length));
        return s;
    }).sort((a,b) => {
        if (a.ord_first) return -1;
        if (b.ord_first) return 1;
        return (b.bear * b.ord_weight) - (a.bear * a.ord_weight);
    }).forEach((slice, index) => {
        slice.ord_bear = index;
    })

    let rem_mass = tot_mass,
        rem_bear = tot_bear;

    // compute remaining mass, bearing surface, for each slice
    let run, runLast, runCount = 0, runList = [];
    ops.forEach(slice => {
        slice.rem_mass = rem_mass;
        slice.rem_bear = rem_bear;
        // slice.can_bear = slice.mass * mass_per_bear;
        slice.can_bear = slice.bear * mass_per_bear;
        rem_mass -= slice.mass;
        rem_bear -= slice.bear;
    });

    let ord = ops.sort((a,b) => {
        return a.ord_bear - b.ord_bear;
    });

    rem_mass = tot_mass;
    rem_bear = tot_bear;

    // in order of load bearing capability, select layer
    // and recompute the requirements on the slices below
    for (let i=0; i<ord.length; i++) {
        let slice = ord[i],
            bearing = Math.min(slice.can_bear, slice.rem_mass);

        // remove from slices below the amount of mass they have to bear
        for (let j=slice.index - 1; j>ops[0].index; j--) {
            slices[j].rem_mass -= bearing;
        }

        // remove total mass left to bear
        rem_mass -= bearing;
        slice.can_emit = true;
        if (rem_mass <= 0) {
            // console.log({break: i, of: ord.length});
            break;
        }
    }

    let seq = 0,
        seqLast = 0,
        spacing = (1 - process.slaSupportDensity) * 10,
        size = Math.bound(process.slaSupportSize / 2, 0.25, 1);

    // compute and project support pillars
    slices.forEach((slice,index) => {
        if (slice.can_emit) {
            if (seq === 0 || slice.index - seqLast > 5) {
                slice.bear_up.map(p => {
                    return p.clone(true).setZ(slice.z);
                }).forEach(p => {
                    projectSupport(process, slice, p, size, spacing);
                });
                seq++;
            } else if (seq > 5) {
                seq = 0;
            } else {
                seq++;
            }
            seqLast = slice.index;
        }
        progress(1 / slices.length);
    });

    // union support pillars
    slices.forEach(slice => {
        if (slice.supports) {
            slice.supports = POLY.union(slice.supports, 0, true);
        }
    });
}

function projectSupport(process, slice, poly, size, spacing) {
    let flat = poly.circularityDeep() > 0.1,
        arr = [ poly ];

    // insetting polys produces arrays. consume til gone
    while (arr.length) {
        poly = arr.shift();
        let out = [],
            seg = [],
            per = poly.perimeter(),
            crit = 0,
            polys = poly.clone(true).flattenTo([]);

        polys.forEach(p => p.forEachSegment((p1, p2) => {
            let rec = {dist: p1.distTo2D(p2), p1, p2};
            if (rec.dist >= spacing || slice.ord_first) crit++;
            seg.push(rec);
        }));

        seg.sort((a,b) => {
            return b.dist - a.dist;
        });

        // emit all critical (long) segments. min 3
        while (seg.length && (crit > 0 || out.length < 3)) {
            let {dist, p1, p2} = seg.shift();
            if (dist >= spacing) {
                // spaced along line
                let num = Math.ceil(dist / spacing) + 1,
                    step = dist / num,
                    pt = p1;
                while (num-- >= 0) {
                    out.push(pt);
                    pt = pt.offsetPointTo(p2, step);
                }
                crit--;
            } else {
                // line midpoint
                out.push(p1.offsetPointTo(p2, dist / 2));
            }
        }

        // drop points too close to other pillars
        if (!slice.ord_first)
        drop: for (let i=0; i<out.length; i++) {
            for (let j=i+1; j<out.length; j++) {
                if (out[i].distTo2D(out[j]) <= size) {
                    out[i] = null;
                    continue drop;
                }
            }
            if (slice.pillars) slice.pillars.forEach(rec => {
                if (out[i] && out[i].distTo2D(rec.point) <= size) {
                    out[i] = null;
                }
            });
        }

        // mark support pillar for each point
        out.filter(p => p !== null)
            .forEach(p => {
                let track = projectPillar(process, slice, p, size, []);
                // find stunted pillars terminating on a face (not raft or merged)
                if (track.length && !(track.max || track.synth || track.merged)) {
                    // remove stunted pillar
                    track.forEach(rec => {
                        let sp = rec.slice.supports;
                        let rp = sp.indexOf(rec.pillar);
                        if (rp >= 0) sp.splice(rp,1);
                    });
                }
            });

        // inset polygon for flat area support
        if (flat) poly.offset(Math.max(0.2, 1 - process.slaSupportDensity), arr);
    }
}

function projectPillar(process, slice, point, size, track) {
    if (!slice.supports) slice.supports = [];
    if (!slice.pillars) slice.pillars = [];

    let points = process.slaSupportPoints,
        pillar = newPolygon()
            .centerCircle(point, size/2, points, true)
            .setZ(slice.z),
        max = process.slaSupportSize,
        inc = process.slaSlice/2,
        end = false, // center intersects
        over = [], // overlapping points
        safe = [], // non-overlapping points
        low = slice.index < process.slaSupportGap + process.slaSupportLayers;

    track.min = track.min ? Math.min(track.min, size) : size;
    track.max = (track.max ? true : false) || size >= max;
    track.synth = track.synth || slice.synth;

    slice.tops.forEach(t => {
        if (track.length > 3 && point.isInPolygon(t.poly)) {
            end = true;
        }
        pillar.points.forEach(p => {
            let isin = p.isInPolygon(t.poly);// || p.nearPolygon(t.poly, 0.001);
            if (isin) {
                over.push(p);
            } else {
                safe.push(p);
            }
        });
    });

    if (end) {
        // backtrack shrinking pillars to point if
        // not landing on the base and size is max'd
        if (!slice.synth && track.max) {
            let nusize = track.min;
            while (track.length) {
                let prec = track.pop(),
                    npil = newPolygon()
                            .centerCircle(prec.point, nusize/2, points, true)
                            .setZ(prec.slice.z),
                    spos = prec.slice.supports.indexOf(prec.pillar);
                // if we find our old pillar, replace
                if (spos >= 0) {
                    prec.slice.supports[spos] = npil;
                    nusize += inc;
                }
                if (nusize > prec.size) {
                    break;
                }
            }
        }
        return track;
    }

    let nextpoint = point;

    if (over.length) {
        // move toward average of safe (non-overlapping) points
        if (safe.length) {
            let x = 0, y = 0;
            safe.forEach(p => { x += p.x; y += p.y });
            x /= safe.length;
            y /= safe.length;
            nextpoint = point.offsetPointTo({x, y, z:slice.z}, inc);
        }
        // once max'ed out, can only shrink in size
        if (track.max) {
            size -= inc;
        }
    } else if (!track.max || low) {
        size += inc;
        if (low) max += (process.slaSupportGap * process.slaSlice * 2);
    }

    if (size < track.min) {
        return track;
    }

    // let close = [];
    // for (let i=0; i<slice.pillars.length; i++) {
    //     let p = slice.pillars[i].point;
    //     let d = point.distTo2D(p);
    //     // terminate if we're inside another pillar
    //     if (d < inc) {
    //         track.merged = true;
    //         return track;
    //     }
    //     if (d <= process.slaSupportSize * 1.5) {
    //         close.push(p);
    //     }
    // }
    // if (close.length) {
    //     let newp = point.clone();
    //     close.forEach(p => {
    //         newp.x += p.x;
    //         newp.y += p.y;
    //     });
    //     newp.x /= (close.length + 1);
    //     newp.y /= (close.length + 1);
    //     nextpoint = point.offsetPointTo(newp, inc);
    // }

    slice.supports.push(pillar);
    slice.pillars.push({point, pillar, size});
    track.push({slice, point, pillar, size});
    if (slice.down) {
        projectPillar(process, slice.down, nextpoint, Math.min(size, max), track);
    }
    return track;
}

function fillPolys(slice, settings) {
    let process = settings.process,
        device = settings.device,
        polys = slice.unioned,
        bounds = settings.bounds,
        width = bounds.max.x - bounds.min.x,
        depth = bounds.max.y - bounds.min.y,
        max = Math.max(width,depth),
        seq = Math.round(process.slaFillLine / process.slaSlice),
        linew = process.slaFillLine,
        units_w = (width / linew) * process.slaFillDensity,
        units_d = (depth / linew) * process.slaFillDensity,
        step_x = width / units_w,
        step_y = depth / units_d,
        start_x = -(width / 2),
        start_y = -(depth / 2),
        end_x = width / 2,
        end_y = depth / 2,
        fill = [];

    let seq_i = Math.floor(slice.index / seq),
        seq_c = seq_i % 4,
        cached = fill_cache[seq_c];

    if (!cached && seq_c !== 1)
    for (let x=start_x; x<end_x; x += step_x) {
        fill.push(
            newPolygon().centerRectangle({
                x: x + step_x/2,
                y: 0,
                z: slice.z
            }, linew, depth)
        );
    }

    if (!cached && seq_c !== 3)
    for (let y=start_y; y<end_y; y += step_y) {
        fill.push(
            newPolygon().centerRectangle({
                x: 0,
                y: y + step_y/2,
                z: slice.z
            }, width, linew)
        );
    }

    if (!cached) {
        fill = POLY.union(fill, 0, true);
        fill_cache[seq_c] = fill;
    } else {
        fill = cached.slice().map(p => p.clone(true).setZ(slice.z));
    }

    fill = POLY.trimTo(fill, slice.tops.map(t => t.poly));
    fill = POLY.union(slice.unioned.appendAll(fill), 0, true);

    slice.unioned = fill;
}

function pixAt(png,x,y) {
    let idx = (x + png.width * y) * 4;
    let dat = png.data;
    return [
        dat[idx++],
        dat[idx++],
        dat[idx++],
        dat[idx++]
    ];
}

function averageBlock(png,x1,y1,x2,y2) {
    let val = [0, 0, 0, 0], count = 0, x, y, z, v2;
    for (x=x1; x<x2; x++) {
        for (y=y1; y<y2; y++) {
            v2 = pixAt(png,x,y);
            for (z=0; z<4; z++) {
                val[z] += v2[z];
            }
            count++;
        }
    }
    for (z=0; z<4; z++) {
        val[z] = Math.abs(val[z] / count);
    }
    return val;
};

function samplePNG(png, width, height) {
    let th = width, tw = height,
        aspect = width / height, // was fixed at 4/3 for photon
        ratio = png.width / png.height,
        buf = new Uint8Array(th * tw * 4),
        div, xoff, yoff, dx, ex, dy, ey, bidx, pixval;

    if (ratio >= aspect) {
        div = png.height / tw;
        xoff = Math.round((png.width - (th * div)) / 2);
        yoff = 0;
    } else {
        div = png.width / th;
        xoff = 0;
        yoff = Math.round((png.height - (tw * div)) / 2);
    }

    for (let y=0; y<tw; y++) {
        dy = Math.round(y * div + yoff);
        if (dy < 0 || dy > png.height) continue;
        ey = Math.round((y+1) * div + yoff);
        for (let x=0; x<th; x++) {
            dx = Math.round(x * div + xoff);
            if (dx < 0 || dx > png.width) continue;
            ex = Math.round((x+1) * div + xoff);
            bidx = (y * th + x) * 4;
            pixval = averageBlock(png,dx,dy,ex,ey);
            buf[bidx+0] = pixval[0];
            buf[bidx+1] = pixval[1];
            buf[bidx+2] = pixval[2];
            buf[bidx+3] = pixval[3];
        }
    }

    return {width, height, data:buf, png};
}