import * as lsys from "@thi.ng/lsys";
import * as g from "@thi.ng/geom";
import * as fs from "fs";

// example L-Systems shown above

const examples = [
    { rules: { s: "[f++f++f]", f: "f+f--f+f" }, delta: Math.PI / 3, iter: 5 },
    { rules: { s: "[f-f-f-f-f-f-f-f]", f: "f---f+f+f+f+f+f+f---f" }, delta: Math.PI / 4, iter: 6 },
    { rules: { s: "[x]", x: "-yf+xfx+fy-", y: "+xf-yfy-fx+" }, delta: Math.PI / 2, iter: 7 },
    { rules: { s: "[a]", a: "a-b--b+a++aa+b-", b: "+a-bb--b-a++a+b" }, delta: Math.PI / 3, iter: 5 }
];

const impl = lsys.TURTLE_IMPL_2D;

examples.forEach(({ rules, delta, iter }, i) =>
    fs.writeFileSync(
        `lsys-ex${i}.svg`,
        g.asSvg(
            g.svgDoc(
                { stroke: "#00f", "stroke-width": 0.25, width: 600, height: 600 },
                ...lsys.interpret(
                    // create turtle instance with customized delta (rot angle)
                    lsys.turtle2d({ delta }),
                    // customize implementation to process syms "a" & "b" as "f"
                    { ...impl, a: impl.f, b: impl.f },
                    // recursively expand start rule "s"
                    lsys.expand(rules, "s", iter)
                    //convert result paths to polylines for SVG export
                ).paths.map(g.polyline)
            )
        )
    )
);

import { XsAdd } from "@thi.ng/random";

lsys.interpret(
    // create turtle instance with customized delta (rot angle)
    lsys.turtle2d({
        // initial movement step distance
        step: 20,
        // initial direction
        theta: -PI / 2,
        // rotation offset
        delta: PI / 10,
        // direction jitter (percentage of delta, i.e. here 50%)
        jitter: 0.5,
        // initial survival chance
        aliveProb: 0.999,
        // decay factors for rotation, step, branch survival chance
        decayDelta: 0.98,
        decayStep: 0.85,
        decayAlive: 0.975,
        // use seedable PRNG for deterministic outcome
        rnd: new XsAdd(0x7337c0de)
    }),
    // process syms "a" & "g" as "f"
    { ...impl, a: impl.f, g: impl.f },
    // recursively expand start rule "s" by ping-ponging between f & g
    // (only difference between f & g is swapped branch orientations)
    // see description of all symbols further below
    lsys.expand(
        {
            s: "[f]",
            f: "a[kp!>/-g]/a[kp!>/+g]",
            g: "a[kp!>/+f]/a[kp!>/-f]"
        },
        "s",
        13
    )
)

/**
 * Current position
 */
pos: Vec;
/**
 * Current direction (in radians)
 */
theta: number;
/**
 * Rotation angle for "+" / "-" symbols
 */
delta: number;
/**
 * Max. random direction change when processing "/" symbol.
 * Normalized percentage of `delta`. Default: 0.25 (25%)
 */
jitter: number;
/**
 * Step distance. Default: 1
 */
step: number;
/**
 * Probability to keep current branch alive when processing "k"
 * symbol. Default: 0.99
 */
aliveProb: number;
/**
 * Decay factor for `delta`. Should be in (0,1) interval.
 * Default: 0.9
 */
decayDelta: number;
/**
 * Decay factor for `step`. Should be in (0,1) interval.
 * Default: 0.9
 */
decayStep: number;
/**
 * Decay factor for `aliveProp`.
 * Default: 0.95
 */
decayAlive: number;
/**
 * PRNG to use for probability checks. Default: SYSTEM
 */
rnd: IRandom;