daggerheart/module/applications/sheets/rollTables/rollTable.mjs

export default class DhRollTableSheet extends foundry.applications.sheets.RollTableSheet {
    static DEFAULT_OPTIONS = {
        ...super.DEFAULT_OPTIONS,
        classes:['daggerheart', 'sheet', 'dh-style'],
        actions: {
            addAltFormula: DhRollTableSheet.#onAddAltFormula,
            removeAltFormula: DhRollTableSheet.#onRemoveAltFormula
        }
    };

    static buildParts() {
        const { footer, ...parts } = super.PARTS;
        const test = {
            ...parts,
            summary: { template: 'systems/daggerheart/templates/sheets/rollTable/summary.hbs' },
            footer
        };
        return test;
    }

    static PARTS = DhRollTableSheet.buildParts();

    async _preparePartContext(partId, context, options) {
        context = await super._preparePartContext(partId, context, options);

        switch (partId) {
            case 'summary':
                context.flagFields = this.daggerheartFlag.schema.fields;
                context.flagData = this.daggerheartFlag;
                const formulas =[];
                formulas.push({
                    index: 0,
                    key: this.daggerheartFlag.formulaName, //Stored in flags as discussed
                    formula: context.source.formula, //Settinng default formula as part of first element
                    formulaInputName: "formula",
                    keyInputName: "flags.daggerheart.formulaName"
                });
                this.daggerheartFlag.altFormula.forEach((alt,i) =>{
                    formulas.push({
                        index: i+1,
                        key: alt.key,
                        formula: alt.formula,
                        formulaInputName:`flags.daggerheart.altFormula.${i}.formula`,
                        keyInputName: `flags.daggerheart.altFormula.${i}.key`
                    });
                });
                context.formulaList=formulas;
                context.isListView=formulas.length>1; //Condition to show list view only if more than one entry
                break;
        }

        return context;
    }

    async _preRender(context, options) {
        await super._preRender(context, options);

        if (!options.internalReferesh)
            this.daggerheartFlag = new game.system.api.data.DhRollTable(this.document.flags.daggerheart);
    }

    /** @override */
    async _processSubmitData(event, form, submitData, options) {
        //submitData.flags.daggerheart = this.daggerheartFlag.toObject(); caused render headaches 

        super._processSubmitData(event, form, submitData, options);
    }

    static async #onAddAltFormula(_event, target) {
        const currentAltFormula=this.daggerheartFlag.altFormula;
        await this.daggerheartFlag.updateSource({
            altFormula:[...currentAltFormula,{key:"",formula:""}]
        });
        this.render({ internalRefresh: true });
    }

    static async #onRemoveAltFormula(_event, target) {
        const visualIndex = parseInt(target.dataset.index);
        const currentAltFormula=this.daggerheartFlag.altFormula;
        if(visualIndex===0) {//If deleting formula at [0] index
            if(currentAltFormula.length>0) {
                const newCore = currentAltFormula[0];
                const newAlt = currentAltFormula.slice(1);
                await this.document.update({formula: newCore.formula});
                await this.daggerheartFlag.updateSource({
                    formulaName:newCore.key,
                    altFormula:newAlt
                });
            } else {
                await this.document.update({ formula: "" });
                await this.daggerheartFlag.updateSource({ formulaName: "" });
            }
        } else {
            const arrayIndex = visualIndex - 1;           
            await this.daggerheartFlag.updateSource({
                altFormula: currentAltFormula.filter((_, i) => i !== arrayIndex)
            });
        }
        this.render({ internalRefresh: true });
    }
}