Pagination, readable error messages to user, syntax highlighting started.

Pagination now works. Temporary hardcoded 10 pastes per page, will be put
in configuration later. Maybe.

From now user will receive readable error message if error occured.

Started to work on syntax highlighting, tried to make lexers detection
work but apparently to no avail.

pagination/exported.go

@@ -0,0 +1,84 @@
+package pagination
+
+import (
+	// stdlib
+	"strconv"
+	"strings"
+
+	// local
+	"github.com/pztrn/fastpastebin/api/http/static"
+)
+
+// CreateHTML creates pagination HTML based on passed parameters.
+func CreateHTML(currentPage int, pages int, linksBase string) string {
+	// Load templates.
+	paginationHTMLRaw, err := static.ReadFile("pagination.html")
+	if err != nil {
+		return "Missing pagination.html"
+	}
+
+	paginationLinkRaw, err1 := static.ReadFile("pagination_link.html")
+	if err1 != nil {
+		return "Missing pagination_link.html"
+	}
+
+	paginationLinkCurrentRaw, err2 := static.ReadFile("pagination_link_current.html")
+	if err2 != nil {
+		return "Missing pagination_link_current.html"
+	}
+
+	paginationEllipsisRaw, err3 := static.ReadFile("pagination_ellipsis.html")
+	if err3 != nil {
+		return "Missing pagination_ellipsis.html"
+	}
+
+	// First page should always be visible.
+	var paginationString = ""
+	if currentPage == 1 {
+		paginationString = strings.Replace(string(paginationLinkCurrentRaw), "{pageNum}", strconv.Itoa(currentPage), -1)
+	} else {
+		paginationString = strings.Replace(string(paginationLinkRaw), "{pageNum}", "1", -1)
+		paginationString = strings.Replace(string(paginationString), "{paginationLink}", linksBase+"1", -1)
+	}
+
+	var ellipsisStartAdded = false
+	var ellipsisEndAdded = false
+	i := 2
+	for i <= pages {
+		if pages > 5 {
+			if currentPage-3 < i && currentPage+3 > i || i == pages {
+				var paginationItemRaw = string(paginationLinkRaw)
+				if i == currentPage {
+					paginationItemRaw = string(paginationLinkCurrentRaw)
+				}
+				paginationItem := strings.Replace(paginationItemRaw, "{pageNum}", strconv.Itoa(i), -1)
+				paginationItem = strings.Replace(paginationItem, "{paginationLink}", linksBase+strconv.Itoa(i), 1)
+				paginationString += paginationItem
+			} else {
+				if currentPage-3 < i && !ellipsisStartAdded {
+					paginationString += string(paginationEllipsisRaw)
+					ellipsisStartAdded = true
+				} else if currentPage+3 > i && !ellipsisEndAdded {
+					paginationString += string(paginationEllipsisRaw)
+					ellipsisEndAdded = true
+				}
+			}
+		} else {
+			var paginationItemRaw = string(paginationLinkRaw)
+			if i == currentPage {
+				paginationItemRaw = string(paginationLinkCurrentRaw)
+			}
+			paginationItem := strings.Replace(paginationItemRaw, "{pageNum}", strconv.Itoa(i), -1)
+			paginationItem = strings.Replace(paginationItem, "{paginationLink}", linksBase+strconv.Itoa(i), 1)
+			paginationString += paginationItem
+		}
+
+		i += 1
+	}
+
+	pagination := strings.Replace(string(paginationHTMLRaw), "{paginationLinks}", paginationString, 1)
+	pagination = strings.Replace(pagination, "{nextPageLink}", linksBase+strconv.Itoa(currentPage+1), 1)
+	pagination = strings.Replace(pagination, "{previousPageLink}", linksBase+strconv.Itoa(currentPage-1), 1)
+
+	return pagination
+}