package lagoon

// PageMeta is the pagination block of the house REST envelope (DATA-10).
type PageMeta struct {
	CurrentPage int   `json:"current_page"`
	LastPage    int   `json:"last_page"`
	PerPage     int   `json:"per_page"`
	Total       int64 `json:"total"`
}

// Page wraps already-built row DTOs. There is no links field.
type Page[T any] struct {
	Data []T      `json:"data"`
	Meta PageMeta `json:"meta"`
}

// Paginate builds {data, meta{current_page,last_page,per_page,total}} from
// a caller-sliced row set. LastPage is ceil(total/perPage); perPage<=0
// yields LastPage 1 instead of dividing by zero. Nil rows become [].
func Paginate[T any](rows []T, page, perPage int, total int64) Page[T] {
	last := 1
	if perPage > 0 {
		last = int((total + int64(perPage) - 1) / int64(perPage))
		if last < 1 {
			last = 1
		}
	}
	if rows == nil {
		rows = []T{}
	}
	return Page[T]{
		Data: rows,
		Meta: PageMeta{
			CurrentPage: page,
			LastPage:    last,
			PerPage:     perPage,
			Total:       total,
		},
	}
}