Implement pagination support

booklist/authorlist.go

@@ -28,3 +28,17 @@ func (al AuthorList) Sorted(less func(a, b struct{ Name, ID string }) bool) Auth
 	})
 	return nal
 }
+
+func (al AuthorList) Skip(n int) AuthorList {
+	if n >= len(al) {
+		return AuthorList{}
+	}
+	return al[n:]
+}
+
+func (al AuthorList) Take(n int) AuthorList {
+	if n > len(al) {
+		return al
+	}
+	return al[:n]
+}

booklist/serieslist.go

@@ -28,3 +28,17 @@ func (sl SeriesList) Sorted(less func(a, b struct{ Name, ID string }) bool) Seri
 	})
 	return nsl
 }
+
+func (sl SeriesList) Skip(n int) SeriesList {
+	if n >= len(sl) {
+		return SeriesList{}
+	}
+	return sl[n:]
+}
+
+func (sl SeriesList) Take(n int) SeriesList {
+	if n > len(sl) {
+		return sl
+	}
+	return sl[:n]
+}

public/static/style.css

@@ -626,4 +626,37 @@ a:visited {
 
 a:hover {
     color: #004479;
+}
+
+.pagination,
+.pagination a {
+    display: flex;
+    flex-direction: row;
+    flex-wrap: wrap;
+    justify-content: center;
+    align-items: center;
+    margin-bottom: 10px;
+}
+
+.pagination a,
+.pagination a:link,
+.pagination a:visited,
+.pagination a:active,
+.pagination a:hover {
+    text-decoration: none;
+    padding: 4px 12px;
+    border: none;
+    background: #ddd;
+    color: #000;
+    margin-right: 2px;
+}
+
+.pagination a.current {
+    font-weight: bold;
+}
+.pagination a.next:before {
+    content: "\00bb";
+}
+.pagination a.prev:before {
+    content: "\00ab";
 }

public/templates/authors.tmpl

@@ -2,4 +2,8 @@
 {{range .Authors}}
 <a href="/authors/{{.ID}}" class="item">{{.Name}}</a>
 {{end}}
-</div>
+</div>
+
+{{if .Authors}}
+{{template "pagination" .Pagination}}
+{{end}}

public/templates/books.tmpl

@@ -24,4 +24,8 @@
     {{end}}
 </div>
 
-{{if not .Books}} Not found (or still indexing){{end}}
+{{if .Books}}
+{{template "pagination" .Pagination}}
+{{else}}
+Not found (or still indexing)
+{{end}}

public/templates/pagination.tmpl

@@ -0,0 +1,3 @@
+	<div class="pagination">
+    {{range .Pages}}<a href="?{{.QueryString}}"{{if .Current}} class="current"{{end}}{{if .Next}} class="next"{{end}}{{if .Prev}} class="prev"{{end}}>{{if .Index}}{{.Index}}{{end}}</a>{{end}}
+    </div>

public/templates/search.tmpl

@@ -1,7 +1,7 @@
 <br>
 {{if .Query}}
 {{if .Books}}
-<center>{{len .Books}} books found</center>
+<center>{{.Pagination.ItemTotal}} books found</center>
 {{else}}
 <center>No books were found matching your query "{{.Query}}"</center>
 {{end}}

public/templates/seriess.tmpl

@@ -2,4 +2,8 @@
 {{range .Series}}
 <a href="/series/{{.ID}}" class="item">{{.Name}}</a>
 {{end}}
-</div>
+</div>
+
+{{if .Series}}
+{{template "pagination" .Pagination}}
+{{end}}

server/pagination.go

@@ -0,0 +1,126 @@
+package server
+
+import (
+	"net/url"
+	"strconv"
+	"strings"
+	"fmt"
+	"html/template"
+)
+
+type Pagination struct {
+	ItemOffset int
+	ItemLimit int
+	ItemTotal int
+	CurrentPage int
+	TotalPages int
+
+	queryStringFormat string
+}
+
+type Page struct {
+	Index int
+	Current bool
+	Offset int
+	Limit int
+	QueryString template.URL
+
+	Prev bool
+	Next bool
+}
+
+const defaultQueryLimit = 24		// default number of items to return, if no limit is specified; 24 is evenly divisible by the default of 4 items displayed per row
+const maxQueryLimit = 1000			// maximum number of items to return, to prevent users from doing dumb things
+
+func queryStringFormat(o url.Values) string {
+	n := url.Values{}
+	for k, v := range o {
+		if k != "offset" && k != "limit" {
+			for _, vv := range v {
+				n.Set(k, vv)
+			}
+		}
+	}
+	f := strings.Replace(n.Encode(),"%","%%", -1)
+	if len(f) != 0 {
+		f += "&"
+	}
+	f += "offset=%d&limit=%d"
+	return f
+}
+
+func NewPagination(v url.Values, totalItems int) *Pagination {
+
+	p := &Pagination{
+		queryStringFormat: queryStringFormat(v),
+		ItemTotal: totalItems,
+	}
+
+	p.ItemOffset, _ = strconv.Atoi(v.Get("offset"))
+	if p.ItemOffset < 0 {
+		p.ItemOffset = 0
+	}
+
+	p.ItemLimit, _ = strconv.Atoi(v.Get("limit"))
+	if p.ItemLimit < 1 {
+		p.ItemLimit = defaultQueryLimit
+	}
+	if p.ItemLimit > maxQueryLimit {
+		p.ItemLimit = maxQueryLimit
+	}
+
+	p.TotalPages = totalItems / p.ItemLimit
+	if totalItems % p.ItemLimit != 0 {
+		p.TotalPages++
+	}
+
+	p.CurrentPage = (p.ItemOffset+1) / p.ItemLimit
+	if (p.ItemOffset+1) % p.ItemLimit != 0 {
+		p.CurrentPage++
+	}
+
+	return p
+}
+
+func (p *Pagination) Pages() []Page {
+	pages := make([]Page,0,p.TotalPages)
+
+	if p.CurrentPage != 1 {
+		offset := p.ItemOffset - p.ItemLimit
+		if offset < 0 {
+			offset = 0
+		}
+		pages = append(pages,Page{
+			Prev: true,
+			Current: false,
+			Offset: offset,
+			Limit: p.ItemLimit,
+			QueryString: template.URL(fmt.Sprintf(p.queryStringFormat,offset,p.ItemLimit)),
+		})
+	}
+
+	for idx := 0; idx<p.TotalPages; idx++ {
+		pages = append(pages,Page{
+			Index: idx+1,
+			Current: idx+1 == p.CurrentPage,
+			Offset: idx*p.ItemLimit,
+			Limit: p.ItemLimit,
+			QueryString: template.URL(fmt.Sprintf(p.queryStringFormat,idx*p.ItemLimit,p.ItemLimit)),
+		})
+	}
+
+	if p.CurrentPage != p.TotalPages {
+		offset := p.ItemOffset + p.ItemLimit
+		pages = append(pages,Page{
+			Next: true,
+			Current: false,
+			Offset: offset,
+			Limit: p.ItemLimit,
+			QueryString: template.URL(fmt.Sprintf(p.queryStringFormat,offset,p.ItemLimit)),
+		})
+	}
+
+
+
+	return pages
+}

server/server.go

@@ -298,16 +298,23 @@ func (s *Server) handleDownload(w http.ResponseWriter, r *http.Request, p httpro
 }
 
 func (s *Server) handleAuthors(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+
+	al := s.Indexer.BookList().Authors().Sorted(func(a, b struct{ Name, ID string }) bool {
+		return a.Name < b.Name
+	})
+
+	pagination := NewPagination(r.URL.Query(),len(al))
+	al = al.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
+
 	s.render.HTML(w, http.StatusOK, "authors", map[string]interface{}{
 		"CurVersion":       s.version,
 		"PageTitle":        "Authors",
 		"ShowBar":          true,
 		"ShowSearch":       false,
 		"ShowViewSelector": true,
 		"Title":            "Authors",
-		"Authors": s.Indexer.BookList().Authors().Sorted(func(a, b struct{ Name, ID string }) bool {
-			return a.Name < b.Name
-		}),
+		"Authors":			al,
+		"Pagination":		pagination,
 	})
 }
 
@@ -326,6 +333,9 @@ func (s *Server) handleAuthor(w http.ResponseWriter, r *http.Request, p httprout
 		bl, _ = bl.SortBy("title-asc")
 		bl, _ = bl.SortBy(r.URL.Query().Get("sort"))
 
+		pagination := NewPagination(r.URL.Query(),len(bl))
+		bl = bl.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
+
 		s.render.HTML(w, http.StatusOK, "author", map[string]interface{}{
 			"CurVersion":       s.version,
 			"PageTitle":        aname,
@@ -334,6 +344,7 @@ func (s *Server) handleAuthor(w http.ResponseWriter, r *http.Request, p httprout
 			"ShowViewSelector": true,
 			"Title":            aname,
 			"Books":            bl,
+			"Pagination":		pagination,
 		})
 		return
 	}
@@ -350,16 +361,23 @@ func (s *Server) handleAuthor(w http.ResponseWriter, r *http.Request, p httprout
 }
 
 func (s *Server) handleSeriess(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+
+	seriess := s.Indexer.BookList().Series().Sorted(func(a, b struct{ Name, ID string }) bool {
+		return a.Name < b.Name
+	})
+
+	pagination := NewPagination(r.URL.Query(),len(seriess))
+	seriess = seriess.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
+
 	s.render.HTML(w, http.StatusOK, "seriess", map[string]interface{}{
 		"CurVersion":       s.version,
 		"PageTitle":        "Series",
 		"ShowBar":          true,
 		"ShowSearch":       false,
 		"ShowViewSelector": true,
 		"Title":            "Series",
-		"Series": s.Indexer.BookList().Series().Sorted(func(a, b struct{ Name, ID string }) bool {
-			return a.Name < b.Name
-		}),
+		"Series":			seriess,
+		"Pagination":		pagination,
 	})
 }
 
@@ -372,11 +390,25 @@ func (s *Server) handleSeries(w http.ResponseWriter, r *http.Request, p httprout
 	}
 
 	if sname != "" {
+		/* the bl variable created here was unused by the original s.render.HTML() call below and seems to be
+			dead code... @geek1011, safe to remove this?
+
 		bl := s.Indexer.BookList().Filtered(func(book *booklist.Book) bool {
 			return book.Series != "" && book.SeriesID() == p.ByName("id")
 		})
 		bl, _ = bl.SortBy("seriesindex-asc")
 		bl, _ = bl.SortBy(r.URL.Query().Get("sort"))
+		*/
+
+
+		bl := s.Indexer.BookList().Filtered(func(book *booklist.Book) bool {
+			return book.Series != "" && book.SeriesID() == p.ByName("id")
+		}).Sorted(func(a, b *booklist.Book) bool {
+			return a.SeriesIndex < b.SeriesIndex
+		})
+
+		pagination := NewPagination(r.URL.Query(),len(bl))
+		bl = bl.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
 
 		s.render.HTML(w, http.StatusOK, "series", map[string]interface{}{
 			"CurVersion":       s.version,
@@ -385,11 +417,8 @@ func (s *Server) handleSeries(w http.ResponseWriter, r *http.Request, p httprout
 			"ShowSearch":       false,
 			"ShowViewSelector": true,
 			"Title":            sname,
-			"Books": s.Indexer.BookList().Filtered(func(book *booklist.Book) bool {
-				return book.Series != "" && book.SeriesID() == p.ByName("id")
-			}).Sorted(func(a, b *booklist.Book) bool {
-				return a.SeriesIndex < b.SeriesIndex
-			}),
+			"Books":			bl,
+			"Pagination":		pagination,
 		})
 		return
 	}
@@ -409,6 +438,9 @@ func (s *Server) handleBooks(w http.ResponseWriter, r *http.Request, _ httproute
 	bl, _ := s.Indexer.BookList().SortBy("modified-desc")
 	bl, _ = bl.SortBy(r.URL.Query().Get("sort"))
 
+	pagination := NewPagination(r.URL.Query(),len(bl))
+	bl = bl.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
+
 	s.render.HTML(w, http.StatusOK, "books", map[string]interface{}{
 		"CurVersion":       s.version,
 		"PageTitle":        "Books",
@@ -417,6 +449,7 @@ func (s *Server) handleBooks(w http.ResponseWriter, r *http.Request, _ httproute
 		"ShowViewSelector": true,
 		"Title":            "",
 		"Books":            bl,
+		"Pagination":		pagination,
 	})
 }
 
@@ -462,6 +495,9 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request, _ httprout
 		bl, _ = bl.SortBy("title-asc")
 		bl, _ = bl.SortBy(r.URL.Query().Get("sort"))
 
+		pagination := NewPagination(r.URL.Query(),len(bl))
+		bl = bl.Skip(pagination.ItemOffset).Take(pagination.ItemLimit)
+
 		s.render.HTML(w, http.StatusOK, "search", map[string]interface{}{
 			"CurVersion":       s.version,
 			"PageTitle":        "Search Results",
@@ -471,6 +507,7 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request, _ httprout
 			"Title":            "Search Results",
 			"Query":            q,
 			"Books":            bl,
+			"Pagination":		pagination,
 		})
 		return
 	}