ds4/src/module/rolls/check.ts

import { RollResult, RollResultStatus } from "./roll-data";
import { ds4roll } from "./roll-executor";

interface TermData {
    number: number;
    faces: number;
    modifiers: Array<string>;
    options: Record<string, unknown>;
}

/**
 * Implements DS4 Checks as an emulated "dice throw".
 *
 * @notes
 * Be aware that, even though this behaves like one roll, it actually throws several ones internally
 *
 * @example
 * - Roll a check against a Check Target Number (CTV) of 18: `/r dsv18`
 * - Roll a check with multiple dice against a CTN of 34: `/r dsv34`
 * - Roll a check with a racial ability that makes `2` a coup and `19` a fumble: `/r dsv19c2,19`
 * - Roll a check with a racial ability that makes `5` a coup and default fumble: `/r dsv19c5`
 * - Roll a check with exploding dice: `/r dsv34x`
 */
export class DS4Check extends DiceTerm {
    constructor(termData: Partial<TermData>) {
        super({
            number: termData.number,
            faces: termData.faces, // should be null
            modifiers: termData.modifiers ?? [],
            options: termData.options ?? {},
        });

        // Store and parse target value.
        const targetValueModifier = this.modifiers.filter((m) => m[0] === "v")[0];
        const tvRgx = new RegExp("v([0-9]+)?");
        const tvMatch = targetValueModifier?.match(tvRgx);
        if (tvMatch) {
            const [parseTargetValue] = tvMatch.slice(1);
            this.targetValue = parseTargetValue ? parseInt(parseTargetValue) : DS4Check.DEFAULT_TARGET_VALUE;
        }

        // Store and parse min/max crit
        const critModifier = this.modifiers.filter((m) => m[0] === "c")[0];
        const cmRgx = new RegExp("c([0-9]+)?,([0-9]+)?");
        const cmMatch = critModifier?.match(cmRgx);
        if (cmMatch) {
            const [parseMaxCritSuccess, parseMinCritFailure] = cmMatch.slice(1);
            this.maxCritSuccess = parseMaxCritSuccess
                ? parseInt(parseMaxCritSuccess)
                : DS4Check.DEFAULT_MAX_CRIT_SUCCESS;
            this.minCritFailure = parseMinCritFailure
                ? parseInt(parseMinCritFailure)
                : DS4Check.DEFAULT_MIN_CRIT_FAILURE;
            if (this.minCritFailure <= this.maxCritSuccess)
                throw new SyntaxError(game.i18n.localize("DS4.ErrorDiceCritOverlap"));
        }
    }

    success = null;
    failure = null;
    targetValue = DS4Check.DEFAULT_TARGET_VALUE;
    minCritFailure = DS4Check.DEFAULT_MIN_CRIT_FAILURE;
    maxCritSuccess = DS4Check.DEFAULT_MAX_CRIT_SUCCESS;

    /**
     * @override
     */
    roll({ minimize = false, maximize = false } = {}): RollResult {
        const rollResult = this.rollWithDifferentBorders({ minimize, maximize });
        this.results.push(rollResult);
        if (rollResult.status == RollResultStatus.CRITICAL_SUCCESS) {
            this.success = true;
        } else if (rollResult.status == RollResultStatus.CRITICAL_FAILURE) {
            this.failure = true;
        }
        return rollResult;
    }

    rollWithDifferentBorders({ minimize = false, maximize = false } = {}, slayingDiceRepetition = false): RollResult {
        const targetValueToUse = this.targetValue;
        if (minimize) {
            return new RollResult(0, RollResultStatus.CRITICAL_FAILURE, [20], true);
        } else if (maximize) {
            const maximizedDice = Array(Math.ceil(targetValueToUse / 20)).fill(1);
            return new RollResult(targetValueToUse, RollResultStatus.CRITICAL_SUCCESS, maximizedDice, true);
        } else {
            return ds4roll(targetValueToUse, {
                maxCritSuccess: this.maxCritSuccess,
                minCritFailure: this.minCritFailure,
                slayingDiceRepetition: slayingDiceRepetition,
                useSlayingDice: slayingDiceRepetition,
            });
        }
    }

    /** Term Modifiers */
    noop(): this {
        return this;
    }

    // DS4 only allows recursive explosions
    explode(modifier: string): this {
        const rgx = /[xX]/;
        const match = modifier.match(rgx);
        if (!match) return this;

        this.results = (this.results as Array<RollResult>)
            .map((r) => {
                const intermediateResults = [r];

                let checked = 0;
                while (checked < intermediateResults.length) {
                    const r = intermediateResults[checked];
                    checked++;
                    if (!r.active) continue;

                    if (r.dice[0] <= this.maxCritSuccess) {
                        r.exploded = true;
                        const newRoll = this.rollWithDifferentBorders({}, true);
                        intermediateResults.push(newRoll);
                    }

                    if (checked > 1000) throw new Error(game.i18n.localize("DS4.ErrorExplodingRecursionLimitExceeded"));
                }
                return intermediateResults;
            })
            .reduce((acc, cur) => {
                return acc.concat(cur);
            }, []);
    }

    static readonly DEFAULT_TARGET_VALUE = 10;
    static readonly DEFAULT_MAX_CRIT_SUCCESS = 1;
    static readonly DEFAULT_MIN_CRIT_FAILURE = 20;
    static DENOMINATION = "s";
    static MODIFIERS = {
        x: "explode",
        c: "noop", // Modifier is consumed in constructor for target value
        v: "noop", // Modifier is consumed in constructor for target value
    };
}