/
render.go
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/
render.go
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//
// Blackblog
// Copyright 2012 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package main
import (
"bytes"
"fmt"
"path"
"sort"
"text/template"
"time"
"github.com/gorilla/feeds"
"github.com/russross/blackfriday/v2"
)
const xmlFeedNumPosts = 15
// RenderPost runs the input source through the blackfriday library.
func RenderPost(post *Post, page PageParams) ([]byte, error) {
content, err := renderPostMarkdown(page.Blog, post)
if err != nil {
return nil, err
}
tpl, err := page.getTemplate("post")
if err != nil {
return nil, err
}
page.Title = post.Title
params := PostPageParams{
Post: post,
Content: content,
PageParams: page,
}
buf := new(bytes.Buffer)
if err := tpl.Execute(buf, params); err != nil {
return nil, err
}
return wrapPage(buf.Bytes(), params.PageParams)
}
func renderPostMarkdown(blog *Blog, post *Post) (string, error) {
data, err := post.GetContents()
if err != nil {
return "", err
}
renderer := blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
Flags: blog.GetMarkdownHTMLOptions(),
})
content := blackfriday.Run(
data,
blackfriday.WithRenderer(renderer),
blackfriday.WithExtensions(blog.GetMarkdownExtensions()))
return string(content), nil
}
// CreateIndex takes the sorted list of posts and generates HTML output listing
// each one.
func CreateIndex(posts PostList, blog *Blog) ([]byte, error) {
page := CreatePageParams(blog, nil)
tpl, err := page.getTemplate("index")
if err != nil {
return nil, err
}
sort.Sort(posts)
page.Title = "Posts"
params := IndexPageParams{
Posts: posts,
PageParams: page,
}
buf := new(bytes.Buffer)
err = tpl.Execute(buf, params)
if err != nil {
return nil, err
}
return wrapPage(buf.Bytes(), params.PageParams)
}
// CreateXMLFeed takes a list of posts and generates an XML
// document for an Atom feed.
func CreateXMLFeed(posts PostList, blog *Blog) ([]byte, error) {
sort.Sort(sort.Reverse(posts))
numPosts := len(posts)
if numPosts > xmlFeedNumPosts {
numPosts = xmlFeedNumPosts
}
latestPost := time.Now()
generated := latestPost
items := make([]*feeds.Item, 0)
for i, post := range posts[:numPosts] {
content, err := renderPostMarkdown(blog, post)
if err != nil {
return nil, err
}
date := post.GetDate()
if date == nil {
continue
}
if i == 0 {
latestPost = *date
}
items = append(items, &feeds.Item{
Title: post.Title,
Link: &feeds.Link{Href: post.CreatePermalink(blog)},
Created: *date,
Content: content,
})
}
feed := &feeds.Feed{
Title: blog.Title(),
Description: fmt.Sprintf("Recent posts on %s", blog.Title()),
Link: &feeds.Link{Href: blog.URL()},
Created: latestPost,
Updated: generated,
Items: items,
}
xml, err := feed.ToAtom()
return []byte(xml), err
}
// PageParams contains the varaibles passed to the basic header/footer
// page templates.
type PageParams struct {
// The blog configuration object.
Blog *Blog
// The title of the blog post.
Title string
// Relative path linking up to the root of the blog.
RootPath string
// Relative path to the page being rendered.
URL string
}
// CreatePageParams sets up the parameters for PageParams.
func CreatePageParams(blog *Blog, render *render) PageParams {
var url, rootPath string
if render == nil {
url = "index.html"
rootPath = ""
} else {
post := render.object.(*Post)
url = post.CreateURL()
rootPath = depthPath(render)
}
return PageParams{
Blog: blog,
RootPath: rootPath,
URL: url,
}
}
// The directory in which static files live.
const StaticFilesDir = "/static/"
// StaticFileLink returns a link for a static file.
// BUG: This cannot be on type *PageParams for some reason. File a bug?
func (p PageParams) StaticFileLink(file string) string {
// Strip of the prefix / for StaticFilesDir so that if rendering to files, it
// does not create an absolute path.
return path.Join(p.RootPath, StaticFilesDir[1:], file)
}
// IndexPageParams is used to render out the blog post list page.
type IndexPageParams struct {
PageParams
Posts PostList
}
func (p IndexPageParams) PostsDescending() PostList {
return p.PostsDescendingLimit(-1)
}
func (p IndexPageParams) PostsAscending() PostList {
return p.PostsAscendingLimit(-1)
}
func (p IndexPageParams) PostsDescendingLimit(limit int) PostList {
sort.Sort(sort.Reverse(p.Posts))
if limit < len(p.Posts) && limit > 0 {
return p.Posts[:limit]
}
return p.Posts
}
func (p IndexPageParams) PostsAscendingLimit(limit int) PostList {
sort.Sort(p.Posts)
if limit < len(p.Posts) && limit > 0 {
return p.Posts[:limit]
}
return p.Posts
}
// PostPageParams is used for displaying a rendered post.
type PostPageParams struct {
PageParams
Post *Post
Content string // The HTML content rendered from (*Post).GetContents() markdown original.
}
func wrapPage(content []byte, vars PageParams) ([]byte, error) {
buf := new(bytes.Buffer)
header, err := vars.getTemplate("header")
if err != nil {
return nil, err
}
footer, err := vars.getTemplate("footer")
if err != nil {
return nil, err
}
if err := header.Execute(buf, vars); err != nil {
return nil, err
}
buf.Write(content)
if err := footer.Execute(buf, vars); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (p *PageParams) getTemplate(name string) (*template.Template, error) {
name = path.Join(p.Blog.TemplatesDir(), name+".html")
return template.ParseFiles(name)
}
func generateRedirect(url string) string {
return fmt.Sprintf(`<html><head><meta http-equiv="refresh" content="0;url=%s"></head></html>`, url)
}