import { DispatchHandler, DispatchOptions } from './types'
import findMatch from './match'
import * as Errors from './error'

export default function addOverride<TReturn, TDispatch>(
  types: TDispatch[],
  handler: (...types: TDispatch[]) => TReturn,
  dispatchers: DispatchHandler<TReturn, TDispatch>[],
  options: DispatchOptions<TDispatch>
) {
  if (!options.ignoreArity && options.params.length !== types.length) {
    if (options.throw) {
      throw new Errors.InvalidOverride(
        `Insufficient type parameters provided. Expected ${options.params.length}, received ${types.length}`
      )
    }
    return false
  }
  if (typeof handler !== 'function') {
    if (options.throw) {
      throw new Errors.InvalidOverride('Dispatch handler provided is not a function')
    }
    return false
  }

  if (dispatchers.length === 0) {
    dispatchers.push({ types, handler })
    return true
  }

  const existingMatch = findMatch(types, dispatchers, options, false)
  if (existingMatch) {
    if (options.throw) {
      throw new Errors.InvalidOverride(`A match already exists for the provided types. [${types.toString()}]`)
    }
    return false
  }

  dispatchers.push({ types, handler })
  return true
}