daggerheart/module/data/adversaryRoll.mjs

export default class DhpAdversaryRoll extends foundry.abstract.TypeDataModel {
    static defineSchema() {
        const fields = foundry.data.fields;

        return {
            title: new fields.StringField(),
            origin: new fields.StringField({ required: true }),
            roll: new fields.StringField({}),
            total: new fields.NumberField({ integer: true }),
            modifiers: new fields.ArrayField(
                new fields.SchemaField({
                    value: new fields.NumberField({ integer: true }),
                    label: new fields.StringField({}),
                    title: new fields.StringField({})
                })
            ),
            advantageState: new fields.NumberField({ required: true, choices: [0, 1, 2], initial: 0 }),
            dice: new fields.EmbeddedDataField(DhpAdversaryRollDice),
            targets: new fields.ArrayField(
                new fields.SchemaField({
                    id: new fields.StringField({}),
                    name: new fields.StringField({}),
                    img: new fields.StringField({}),
                    difficulty: new fields.NumberField({ integer: true, nullable: true }),
                    evasion: new fields.NumberField({ integer: true }),
                    hit: new fields.BooleanField({ initial: false })
                })
            ),
            damage: new fields.SchemaField(
                {
                    value: new fields.StringField({}),
                    type: new fields.StringField({ choices: Object.keys(SYSTEM.GENERAL.damageTypes), integer: false })
                },
                { nullable: true, initial: null }
            )
        };
    }

    prepareDerivedData() {
        const diceKeys = Object.keys(this.dice.rolls);
        const highestDiceIndex =
            diceKeys.length < 2
                ? null
                : this.dice.rolls[diceKeys[0]].value > this.dice.rolls[diceKeys[1]].value
                  ? 0
                  : 1;
        if (highestDiceIndex !== null) {
            this.dice.rolls = this.dice.rolls.map((roll, index) => ({
                ...roll,
                discarded: this.advantageState === 1 ? index !== highestDiceIndex : index === highestDiceIndex
            }));
        }

        this.targets.forEach(target => {
            target.hit = target.difficulty ? this.total >= target.difficulty : this.total >= target.evasion;
        });
    }
}

class DhpAdversaryRollDice extends foundry.abstract.DataModel {
    static defineSchema() {
        const fields = foundry.data.fields;

        return {
            type: new fields.StringField({ required: true }),
            rolls: new fields.ArrayField(
                new fields.SchemaField({
                    value: new fields.NumberField({ required: true, integer: true }),
                    discarded: new fields.BooleanField({ initial: false })
                })
            )
        };
    }

    get rollTotal() {
        return this.rolls.reduce((acc, roll) => acc + (!roll.discarded ? roll.value : 0), 0);
    }
}