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// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package blog implements a web server for articles written in present format.
package blog // import "golang.org/x/tools/blog"
import (
"bytes"
"encoding/json"
"encoding/xml"
"fmt"
"html/template"
"log"
"net/http"
"os"
"path/filepath"
"regexp"
"sort"
"strings"
"time"
"golang.org/x/tools/blog/atom"
"golang.org/x/tools/present"
)
var (
validJSONPFunc = regexp.MustCompile(`(?i)^[a-z_][a-z0-9_.]*$`)
// used to serve relative paths when ServeLocalLinks is enabled.
golangOrgAbsLinkReplacer = strings.NewReplacer(
`href="https://golang.org/pkg`, `href="/pkg`,
`href="https://golang.org/cmd`, `href="/cmd`,
)
)
// Config specifies Server configuration values.
type Config struct {
ContentPath string // Relative or absolute location of article files and related content.
TemplatePath string // Relative or absolute location of template files.
BaseURL string // Absolute base URL (for permalinks; no trailing slash).
BasePath string // Base URL path relative to server root (no trailing slash).
GodocURL string // The base URL of godoc (for menu bar; no trailing slash).
Hostname string // Server host name, used for rendering ATOM feeds.
HomeArticles int // Articles to display on the home page.
FeedArticles int // Articles to include in Atom and JSON feeds.
FeedTitle string // The title of the Atom XML feed
PlayEnabled bool
ServeLocalLinks bool // rewrite golang.org/{pkg,cmd} links to host-less, relative paths.
}
// Doc represents an article adorned with presentation data.
type Doc struct {
*present.Doc
Permalink string // Canonical URL for this document.
Path string // Path relative to server root (including base).
HTML template.HTML // rendered article
Related []*Doc
Newer, Older *Doc
}
// Server implements an http.Handler that serves blog articles.
type Server struct {
cfg Config
docs []*Doc
tags []string
docPaths map[string]*Doc // key is path without BasePath.
docTags map[string][]*Doc
template struct {
home, index, article, doc *template.Template
}
atomFeed []byte // pre-rendered Atom feed
jsonFeed []byte // pre-rendered JSON feed
content http.Handler
}
// NewServer constructs a new Server using the specified config.
func NewServer(cfg Config) (*Server, error) {
present.PlayEnabled = cfg.PlayEnabled
if notExist(cfg.TemplatePath) {
return nil, fmt.Errorf("template directory not found: %s", cfg.TemplatePath)
}
root := filepath.Join(cfg.TemplatePath, "root.tmpl")
parse := func(name string) (*template.Template, error) {
path := filepath.Join(cfg.TemplatePath, name)
if notExist(path) {
return nil, fmt.Errorf("template %s was not found in %s", name, cfg.TemplatePath)
}
t := template.New("").Funcs(funcMap)
return t.ParseFiles(root, path)
}
s := &Server{cfg: cfg}
// Parse templates.
var err error
s.template.home, err = parse("home.tmpl")
if err != nil {
return nil, err
}
s.template.index, err = parse("index.tmpl")
if err != nil {
return nil, err
}
s.template.article, err = parse("article.tmpl")
if err != nil {
return nil, err
}
p := present.Template().Funcs(funcMap)
s.template.doc, err = p.ParseFiles(filepath.Join(cfg.TemplatePath, "doc.tmpl"))
if err != nil {
return nil, err
}
// Load content.
err = s.loadDocs(filepath.Clean(cfg.ContentPath))
if err != nil {
return nil, err
}
err = s.renderAtomFeed()
if err != nil {
return nil, err
}
err = s.renderJSONFeed()
if err != nil {
return nil, err
}
// Set up content file server.
s.content = http.StripPrefix(s.cfg.BasePath, http.FileServer(http.Dir(cfg.ContentPath)))
return s, nil
}
var funcMap = template.FuncMap{
"sectioned": sectioned,
"authors": authors,
}
// sectioned returns true if the provided Doc contains more than one section.
// This is used to control whether to display the table of contents and headings.
func sectioned(d *present.Doc) bool {
return len(d.Sections) > 1
}
// authors returns a comma-separated list of author names.
func authors(authors []present.Author) string {
var b bytes.Buffer
last := len(authors) - 1
for i, a := range authors {
if i > 0 {
if i == last {
b.WriteString(" and ")
} else {
b.WriteString(", ")
}
}
b.WriteString(authorName(a))
}
return b.String()
}
// authorName returns the first line of the Author text: the author's name.
func authorName(a present.Author) string {
el := a.TextElem()
if len(el) == 0 {
return ""
}
text, ok := el[0].(present.Text)
if !ok || len(text.Lines) == 0 {
return ""
}
return text.Lines[0]
}
// loadDocs reads all content from the provided file system root, renders all
// the articles it finds, adds them to the Server's docs field, computes the
// denormalized docPaths, docTags, and tags fields, and populates the various
// helper fields (Next, Previous, Related) for each Doc.
func (s *Server) loadDocs(root string) error {
// Read content into docs field.
const ext = ".article"
fn := func(p string, info os.FileInfo, err error) error {
if filepath.Ext(p) != ext {
return nil
}
f, err := os.Open(p)
if err != nil {
return err
}
defer f.Close()
d, err := present.Parse(f, p, 0)
if err != nil {
return err
}
var html bytes.Buffer
err = d.Render(&html, s.template.doc)
if err != nil {
return err
}
p = p[len(root) : len(p)-len(ext)] // trim root and extension
p = filepath.ToSlash(p)
s.docs = append(s.docs, &Doc{
Doc: d,
Path: s.cfg.BasePath + p,
Permalink: s.cfg.BaseURL + p,
HTML: template.HTML(html.String()),
})
return nil
}
err := filepath.Walk(root, fn)
if err != nil {
return err
}
sort.Sort(docsByTime(s.docs))
// Pull out doc paths and tags and put in reverse-associating maps.
s.docPaths = make(map[string]*Doc)
s.docTags = make(map[string][]*Doc)
for _, d := range s.docs {
s.docPaths[strings.TrimPrefix(d.Path, s.cfg.BasePath)] = d
for _, t := range d.Tags {
s.docTags[t] = append(s.docTags[t], d)
}
}
// Pull out unique sorted list of tags.
for t := range s.docTags {
s.tags = append(s.tags, t)
}
sort.Strings(s.tags)
// Set up presentation-related fields, Newer, Older, and Related.
for _, doc := range s.docs {
// Newer, Older: docs adjacent to doc
for i := range s.docs {
if s.docs[i] != doc {
continue
}
if i > 0 {
doc.Newer = s.docs[i-1]
}
if i+1 < len(s.docs) {
doc.Older = s.docs[i+1]
}
break
}
// Related: all docs that share tags with doc.
related := make(map[*Doc]bool)
for _, t := range doc.Tags {
for _, d := range s.docTags[t] {
if d != doc {
related[d] = true
}
}
}
for d := range related {
doc.Related = append(doc.Related, d)
}
sort.Sort(docsByTime(doc.Related))
}
return nil
}
// renderAtomFeed generates an XML Atom feed and stores it in the Server's
// atomFeed field.
func (s *Server) renderAtomFeed() error {
var updated time.Time
if len(s.docs) > 0 {
updated = s.docs[0].Time
}
feed := atom.Feed{
Title: s.cfg.FeedTitle,
ID: "tag:" + s.cfg.Hostname + ",2013:" + s.cfg.Hostname,
Updated: atom.Time(updated),
Link: []atom.Link{{
Rel: "self",
Href: s.cfg.BaseURL + "/feed.atom",
}},
}
for i, doc := range s.docs {
if i >= s.cfg.FeedArticles {
break
}
e := &atom.Entry{
Title: doc.Title,
ID: feed.ID + doc.Path,
Link: []atom.Link{{
Rel: "alternate",
Href: doc.Permalink,
}},
Published: atom.Time(doc.Time),
Updated: atom.Time(doc.Time),
Summary: &atom.Text{
Type: "html",
Body: summary(doc),
},
Content: &atom.Text{
Type: "html",
Body: string(doc.HTML),
},
Author: &atom.Person{
Name: authors(doc.Authors),
},
}
feed.Entry = append(feed.Entry, e)
}
data, err := xml.Marshal(&feed)
if err != nil {
return err
}
s.atomFeed = data
return nil
}
type jsonItem struct {
Title string
Link string
Time time.Time
Summary string
Content string
Author string
}
// renderJSONFeed generates a JSON feed and stores it in the Server's jsonFeed
// field.
func (s *Server) renderJSONFeed() error {
var feed []jsonItem
for i, doc := range s.docs {
if i >= s.cfg.FeedArticles {
break
}
item := jsonItem{
Title: doc.Title,
Link: doc.Permalink,
Time: doc.Time,
Summary: summary(doc),
Content: string(doc.HTML),
Author: authors(doc.Authors),
}
feed = append(feed, item)
}
data, err := json.Marshal(feed)
if err != nil {
return err
}
s.jsonFeed = data
return nil
}
// summary returns the first paragraph of text from the provided Doc.
func summary(d *Doc) string {
if len(d.Sections) == 0 {
return ""
}
for _, elem := range d.Sections[0].Elem {
text, ok := elem.(present.Text)
if !ok || text.Pre {
// skip everything but non-text elements
continue
}
var buf bytes.Buffer
for _, s := range text.Lines {
buf.WriteString(string(present.Style(s)))
buf.WriteByte('\n')
}
return buf.String()
}
return ""
}
// rootData encapsulates data destined for the root template.
type rootData struct {
Doc *Doc
BasePath string
GodocURL string
Data interface{}
}
// ServeHTTP serves the front, index, and article pages
// as well as the ATOM and JSON feeds.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
var (
d = rootData{BasePath: s.cfg.BasePath, GodocURL: s.cfg.GodocURL}
t *template.Template
)
switch p := strings.TrimPrefix(r.URL.Path, s.cfg.BasePath); p {
case "/":
d.Data = s.docs
if len(s.docs) > s.cfg.HomeArticles {
d.Data = s.docs[:s.cfg.HomeArticles]
}
t = s.template.home
case "/index":
d.Data = s.docs
t = s.template.index
case "/feed.atom", "/feeds/posts/default":
w.Header().Set("Content-type", "application/atom+xml; charset=utf-8")
w.Write(s.atomFeed)
return
case "/.json":
if p := r.FormValue("jsonp"); validJSONPFunc.MatchString(p) {
w.Header().Set("Content-type", "application/javascript; charset=utf-8")
fmt.Fprintf(w, "%v(%s)", p, s.jsonFeed)
return
}
w.Header().Set("Content-type", "application/json; charset=utf-8")
w.Write(s.jsonFeed)
return
default:
doc, ok := s.docPaths[p]
if !ok {
// Not a doc; try to just serve static content.
s.content.ServeHTTP(w, r)
return
}
d.Doc = doc
t = s.template.article
}
var err error
if s.cfg.ServeLocalLinks {
var buf bytes.Buffer
err = t.ExecuteTemplate(&buf, "root", d)
if err != nil {
log.Println(err)
return
}
_, err = golangOrgAbsLinkReplacer.WriteString(w, buf.String())
} else {
err = t.ExecuteTemplate(w, "root", d)
}
if err != nil {
log.Println(err)
}
}
// docsByTime implements sort.Interface, sorting Docs by their Time field.
type docsByTime []*Doc
func (s docsByTime) Len() int { return len(s) }
func (s docsByTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s docsByTime) Less(i, j int) bool { return s[i].Time.After(s[j].Time) }
// notExist reports whether the path exists or not.
func notExist(path string) bool {
_, err := os.Stat(path)
return os.IsNotExist(err)
}