Added a basic homepage

internal/pager/pager.go

@@ -0,0 +1,81 @@
+package pager
+
+import (
+	"math"
+	"strconv"
+
+	"github.com/labstack/echo/v4"
+)
+
+// QueryKey stores the query key used to indicate the current page.
+const QueryKey = "page"
+
+// Pager provides a mechanism to allow a user to page results via a query parameter.
+type Pager struct {
+	// Items stores the total amount of items in the result set.
+	Items int
+
+	// Page stores the current page number.
+	Page int
+
+	// ItemsPerPage stores the amount of items to display per page.
+	ItemsPerPage int
+
+	// Pages stores the total amount of pages in the result set.
+	Pages int
+}
+
+// NewPager creates a new Pager.
+func NewPager(ctx echo.Context, itemsPerPage int) Pager {
+	p := Pager{
+		ItemsPerPage: itemsPerPage,
+		Pages:        1,
+		Page:         1,
+	}
+
+	if page := ctx.QueryParam(QueryKey); page != "" {
+		if pageInt, err := strconv.Atoi(page); err == nil {
+			if pageInt > 0 {
+				p.Page = pageInt
+			}
+		}
+	}
+
+	return p
+}
+
+// SetItems sets the amount of items in total for the pager and calculate the amount
+// of total pages based off on the item per page.
+// This should be used rather than setting either items or pages directly.
+func (p *Pager) SetItems(items int) {
+	p.Items = items
+
+	if items > 0 {
+		p.Pages = int(math.Ceil(float64(items) / float64(p.ItemsPerPage)))
+	} else {
+		p.Pages = 1
+	}
+
+	if p.Page > p.Pages {
+		p.Page = p.Pages
+	}
+}
+
+// IsBeginning determines if the pager is at the beginning of the pages
+func (p *Pager) IsBeginning() bool {
+	return p.Page == 1
+}
+
+// IsEnd determines if the pager is at the end of the pages
+func (p *Pager) IsEnd() bool {
+	return p.Page >= p.Pages
+}
+
+// GetOffset determines the offset of the results in order to get the items for
+// the current page
+func (p *Pager) GetOffset() int {
+	if p.Page == 0 {
+		p.Page = 1
+	}
+	return (p.Page - 1) * p.ItemsPerPage
+}