add paginator

paginator/paginator.go

@@ -0,0 +1,116 @@
+package paginator
+
+// Paginator
+type Paginator struct {
+	page  int
+	limit int
+}
+
+// New
+func New(page, limit int) *Paginator {
+	return &Paginator{page: page, limit: limit}
+}
+
+// Offset
+func (p *Paginator) Offset() int {
+	if p.page < 1 {
+		p.page = 1
+	}
+	offset := p.limit * (p.page - 1)
+	return int(offset)
+}
+
+// Limit
+func (p *Paginator) Limit() int {
+	return p.limit
+}
+
+// Pagination
+func (p *Paginator) Pagination(totalCount int) *Pagination {
+	pg := Pagination{}
+
+	total := (totalCount / p.limit)
+
+	// Calculator Total Page
+	remainder := totalCount % p.limit
+	if remainder == 0 {
+		pg.totalPage = total
+	} else {
+		pg.totalPage = total + 1
+	}
+
+	// Set current/record per page meta data
+	pg.currentPage = p.page
+	pg.recordPerPage = p.limit
+
+	// Calculator the Next/Previous Page
+	if p.page <= 0 {
+		pg.next = p.page + 1
+	} else if p.page < pg.totalPage {
+		pg.previous = p.page - 1
+		pg.next = p.page + 1
+	} else if p.page == pg.totalPage {
+		pg.previous = p.page - 1
+		pg.next = 0
+	}
+
+	return &pg
+}
+
+// Pagination Object
+type Pagination struct {
+	next          int
+	previous      int
+	recordPerPage int
+	currentPage   int
+	totalPage     int
+}
+
+// PageRange 迭代页码
+func (p *Pagination) PageRange() []int {
+	pages := []int{}
+	for i := 1; i <= p.totalPage; i++ {
+		pages = append(pages, i)
+	}
+	return pages
+}
+
+// NumPages 页码数量
+func (p *Pagination) NumPages() int {
+	return p.totalPage
+}
+
+// HasPrevious 是否有上一页
+func (p *Pagination) HasPrevious() bool {
+	return p.previous > 0
+}
+
+// PreviousPageNumber 上一页的页码
+func (p *Pagination) PreviousPageNumber() int {
+	return p.previous
+}
+
+// HasNext 是否有下一页
+func (p *Pagination) HasNext() bool {
+	return p.next > 0
+}
+
+// NextPageNumber 下一页的页码
+func (p *Pagination) NextPageNumber() int {
+	return p.next
+}
+
+// Number 当前页码
+func (p *Pagination) Number() int {
+	return p.currentPage
+}
+
+// Number 当前页码
+func (p *Pagination) IsFirstPage() bool {
+	return true
+}
+
+// Number 当前页码
+func (p *Pagination) IsLastPage() bool {
+	return false
+}