import {configDependency} from '../core/Config.js'
import {Signature, ImpType, Dependency} from '../core/Dispatcher.js'

const DBL_EPSILON = Number.EPSILON || 2.2204460492503130808472633361816E-16

declare module "./type" {
   interface NumbersReturn<Params> {
      equal: Signature<Params, [number, number], boolean>
      unequal: Signature<Params, [number, number], boolean>
   }
}

export const equal =
   (dep: configDependency): ImpType<'equal', [number, number]> =>
      (x, y) => {
         const eps = dep.config.epsilon
         if (eps === null || eps === undefined) return x === y
         if (x === y) return true
         if (isNaN(x) || isNaN(y)) return false

         if (isFinite(x) && isFinite(y)) {
            const diff = Math.abs(x - y)
            if (diff < DBL_EPSILON) return true
            return diff <= Math.max(Math.abs(x), Math.abs(y)) * eps
         }

         return false
      }

export const unequal = (dep: Dependency<'equal', [number, number]>):
   ImpType<'unequal', [number, number]> =>
   (x, y) => {
      return !dep.equal(x, y)
   }