Implement provider calculation for each providers (repository layer)

[aldy505]

It should be put on a sub-package under the repository package. The logic on how the pricing works is totally up to you. If possible, please include unit tests.

https://github.com/TokoBapak/mock-shipping-provider/blob/68058d64cc9b8f7db73478fd0a1392055c5c8d45/repository/provider_calculation.go#L5-L10

Providers are defined here:

https://github.com/TokoBapak/mock-shipping-provider/blob/413bb3e6abb6362ced4b4bdc42173c1c82f6065d/primitive/provider.go#L6-L12

Example:

type JNE struct{}

func (JNE) CalculatePrice(distance float64, dimension primitive.Dimension, weight float64) int64 {
  var basePrice = 9000
  // Multiply basePrice by volume
  var volume = dimension.Width * dimension.Height * dimension.Depth

  // 1 hop every 200 km
  var hops float64
  if distance < 1 {
    hops = 1
  } else {
    hops = distance / 200 // division by 0 causes panic, avoid that!
  }

  return basePrice * int64(volume) * hops
}

func (JNE) CalculateTimeOfArrival(distance float64) int64 {
  return 0 // do it yourself
}

That's just an example, you don't have to follow it. Be creative.