Files
oddmu/changes.go
2025-12-06 14:10:20 +01:00

241 lines
7.4 KiB
Go

package main
import (
"log"
"path"
"regexp"
"strings"
"time"
)
// notify adds a link to the "changes" page, the "index" page, as well as to all the existing hashtag pages. The link to
// the "index" page is only added if the page being edited is a blog page for the current year. The link to existing
// hashtag pages is only added for blog pages. If the "changes" page does not exist, it is created. If the hashtag page
// does not exist, it is not. Hashtag pages are considered optional. If the page that's being edited is in a
// subdirectory, then the "changes", "index" and hashtag pages of that particular subdirectory are affected. Every
// subdirectory is treated like a potentially independent wiki. Errors are logged before being returned because the
// error messages are confusing from the point of view of the saveHandler.
func (p *Page) notify() error {
p.handleTitle(false)
if p.Title == "" {
p.Title = p.Name
}
esc := nameEscape(p.Base())
link := "* [" + p.Title + "](" + esc + ")\n"
re := regexp.MustCompile(`(?m)^\* \[[^\]]+\]\(` + esc + `\)\n`)
dir := p.Dir()
err := addLinkWithDate(path.Join(dir, "changes"), link, re)
if err != nil {
log.Printf("Updating changes in %s failed: %s", dir, err)
return err
}
if p.IsBlog() {
// Add to the index only if the blog post is for the current year
if strings.HasPrefix(p.Base(), time.Now().Format("2006")) {
err := addLink(path.Join(dir, "index"), true, link, re)
if err != nil {
log.Printf("Updating index in %s failed: %s", dir, err)
return err
}
}
p.renderHTML() // to set hashtags
for _, hashtag := range p.Hashtags {
err := addLink(path.Join(dir, hashtag), false, link, re)
if err != nil {
log.Printf("Updating hashtag %s in %s failed: %s", hashtag, dir, err)
return err
}
}
}
return nil
}
// addLinkWithDate adds the link to a page, with date header for today. If a match already exists, it is removed. If
// this leaves a date header without any links, it is removed as well. If a list is found, the link is added at the top
// of the list. Lists must use the asterisk, not the minus character.
func addLinkWithDate(name, link string, re *regexp.Regexp) error {
date := time.Now().Format(time.DateOnly)
org := ""
p, err := loadPage(name)
if err != nil {
// create a new page
p = &Page{Name: name, Body: []byte("# Changes\n\n## " + date + "\n" + link)}
} else {
org = string(p.Body)
// remove the old match, if one exists
loc := re.FindIndex(p.Body)
if loc != nil {
r := p.Body[:loc[0]]
if loc[1] < len(p.Body) {
r = append(r, p.Body[loc[1]:]...)
}
p.Body = r
if loc[0] >= 14 && len(p.Body) >= loc[0]+15 {
// remove the preceding date if there are now two dates following each other
re := regexp.MustCompile(`(?m)^## (\d\d\d\d-\d\d-\d\d)\n\n## (\d\d\d\d-\d\d-\d\d)\n`)
if re.Match(p.Body[loc[0]-14 : loc[0]+15]) {
p.Body = append(p.Body[0:loc[0]-14], p.Body[loc[0]+1:]...)
}
} else if len(p.Body) == loc[0] {
// remove a trailing date
re := regexp.MustCompile(`## (\d\d\d\d-\d\d-\d\d)\n`)
if re.Match(p.Body[loc[0]-14 : loc[0]]) {
p.Body = p.Body[0 : loc[0]-14]
}
}
}
// locate the beginning of the list to insert the line
re := regexp.MustCompile(`(?m)^\* \[[^\]]+\]\([^\)]+\)\n`)
loc = re.FindIndex(p.Body)
if loc == nil {
// if no list was found, use the end of the page
loc = []int{len(p.Body)}
}
// start with new page content
r := []byte("")
// check if there is a date right before the insertion point
addDate := true
if loc[0] >= 14 {
re := regexp.MustCompile(`(?m)^## (\d\d\d\d-\d\d-\d\d)\n`)
m := re.Find(p.Body[loc[0]-14 : loc[0]])
switch {
case m == nil:
// not a date: insert date, don't move insertion point
case string(p.Body[loc[0]-11:loc[0]-1]) == date:
// if the date is our date, don't add it, don't move insertion point
addDate = false
default:
// if the date is not out date, move the insertion point
loc[0] -= 14
}
}
// append up to the insertion point
r = append(r, p.Body[:loc[0]]...)
// append date, if necessary
if addDate {
// ensure paragraph break
if len(r) > 0 && r[len(r)-1] != '\n' {
r = append(r, '\n')
}
if len(r) > 1 && r[len(r)-2] != '\n' {
r = append(r, '\n')
}
r = append(r, []byte("## ")...)
r = append(r, []byte(date)...)
r = append(r, '\n')
}
// append link
r = append(r, []byte(link)...)
// if we just added a date, add an empty line after the single-element list
if len(p.Body) > loc[0] && p.Body[loc[0]] != '*' {
r = append(r, '\n')
}
// append the rest
r = append(r, p.Body[loc[0]:]...)
p.Body = r
}
// only save if something changed
if string(p.Body) != org {
return p.save()
}
return nil
}
// addLink adds a link to a named page, if the page exists and doesn't contain the link. If the link exists but with a
// different title, the title is fixed.
func addLink(name string, mandatory bool, link string, re *regexp.Regexp) error {
p, err := loadPage(name)
if err != nil {
if mandatory {
p = &Page{Name: name, Body: []byte(link)}
return p.save()
}
// Skip non-existing files: no error
return nil
}
org := string(p.Body)
addLinkToPage(p, link, re)
// only save if something changed
if string(p.Body) != org {
return p.save()
}
return nil
}
func addLinkToPage(p *Page, link string, re *regexp.Regexp) {
// if a link exists, that's the place to insert the new link (in which case loc[0] and loc[1] differ)
loc := re.FindIndex(p.Body)
// if no link exists, find a good place to insert it
if loc == nil {
// locate the list items
re = regexp.MustCompile(`(?m)^\* \[[^\]]+\]\([^\)]+\)\n?`)
items := re.FindAllIndex(p.Body, -1)
first := false
pos := -1
// skip newer items
for i, it := range items {
// break if the current line is older (earlier in sort order)
stop := string(p.Body[it[0]:it[1]]) < link
// before the first match is always a good insert point
if i == 0 {
pos = it[0]
first = true
}
// if we're not stopping, then after the current item is a good insert point
if !stop {
pos = it[1]
first = false
} else {
break
}
}
// otherwise it's at the end of the list, after the last item
if pos == -1 && len(items) > 0 {
pos = items[len(items)-1][1]
first = false
}
// if no list was found, use the end of the page
if pos == -1 {
pos = len(p.Body)
first = true
}
if first {
p.Body, pos = ensureTwoNewlines(p.Body, pos)
}
// mimic a zero-width match at the insert point
loc = []int{pos, pos}
}
// start with new page content
r := []byte("")
// append up to the insertion point
r = append(r, p.Body[:loc[0]]...)
// append link
r = append(r, []byte(link)...)
// append the rest
r = append(r, p.Body[loc[1]:]...)
p.Body = r
}
// ensureTwoNewlines makes sure that the two bytes before pos in buf are newlines. If the are not, newlines are inserted
// and pos is increased. The new buf and pos is returned.
func ensureTwoNewlines(buf []byte, pos int) ([]byte, int) {
var insert []byte
if pos >= 1 && buf[pos-1] != '\n' {
// add two newlines if buf doesn't end with a newline
insert = []byte("\n\n")
} else if pos >= 2 && buf[pos-2] != '\n' {
// add one newline if Body ends with just one newline
insert = []byte("\n")
}
if insert != nil {
r := []byte("")
r = append(r, buf[:pos]...)
r = append(r, insert...)
r = append(r, buf[pos:]...)
buf = r
pos += len(insert)
}
return buf, pos
}