@randsum/root-rpg/src/rollRootRpg/index.ts

A flexible, type-safe dice roller for the Root RPG system

import type { RollResult } from '@randsum/roller'
import { roll } from '@randsum/roller'
import type { RootRpgRollResult } from '../types'
import { interpretResult } from './interpretResult'

export function rollRootRpg(bonus: number): RollResult<RootRpgRollResult> {
  if (!Number.isFinite(bonus)) {
    throw new Error(`Root RPG bonus must be a finite number, received: ${bonus}`)
  }

  if (bonus < -20 || bonus > 20) {
    throw new Error(`Root RPG bonus is outside reasonable range (-20 to +20), received: ${bonus}`)
  }

  const rollResult = roll({
    quantity: 2,
    sides: 6,
    modifiers: { plus: bonus }
  })

  return {
    ...rollResult,
    result: {
      hit: interpretResult(rollResult.total),
      total: rollResult.total
    }
  }
}