util.go

package sdp

import "math"

// CalculatePaginationOffsetLimit Calculates the offset and limit for pagination
// in SQL queries, along with the current page and total pages that should be
// included in the response
//
// This also sets sane defaults for the page size if pagination is not provided.
// These defaults are page 1 with a page size of 10
//
// NOTE: If there are no items, then this will return 0 for all values
func CalculatePaginationOffsetLimit(pagination *PaginationRequest, totalItems int32) (offset, limit, page, totalPages int32) {
	if totalItems == 0 {
		// If there are no items, there are no pages
		return 0, 0, 0, 0
	}

	var requestedPageSize int32
	var requestedPage int32

	if pagination == nil {
		// Set sane defaults
		requestedPageSize = 10
		requestedPage = 1
	} else {
		requestedPageSize = pagination.GetPageSize()
		requestedPage = pagination.GetPage()
	}

	// pagesize is at least 10, at most 100
	limit = min(100, max(10, requestedPageSize))
	// calculate the total number of pages
	totalPages = int32(math.Ceil(float64(totalItems) / float64(limit)))

	// page has to be at least 1, and at most totalPages
	page = min(totalPages, requestedPage)
	page = max(1, page)

	// calculate the offset
	if totalPages == 0 {
		offset = 0
	} else {
		offset = (page * limit) - limit
	}
	return offset, limit, page, totalPages
}

// An object that returns all of the adapter metadata for a given source
type AdapterMetadataProvider interface {
	AllAdapterMetadata() []*AdapterMetadata
}

// A list of adapter metadata, this is used to store all the adapter metadata
// for a given source so that it can be retrieved later for the purposes of
// generating documentation and Terraform mappings
type AdapterMetadataList struct {
	// The list of adapter metadata
	list []*AdapterMetadata
}

// AllAdapterMetadata returns all the adapter metadata
func (a *AdapterMetadataList) AllAdapterMetadata() []*AdapterMetadata {
	return a.list
}

// RegisterAdapterMetadata registers a new adapter metadata with the list and
// returns a pointer to that same metadata to be used elsewhere
func (a *AdapterMetadataList) Register(metadata *AdapterMetadata) *AdapterMetadata {
	if a == nil {
		return metadata
	}

	a.list = append(a.list, metadata)

	return metadata
}