Absolutely minimal static site generator in Go
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350 lines
8.1 KiB

package main
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"path/filepath"
"strings"
"text/template"
"time"
"github.com/russross/blackfriday/v2"
"gopkg.in/yaml.v2"
)
const (
ZSDIR = ".zs"
PUBDIR = ".pub"
)
type Vars map[string]string
// renameExt renames extension (if any) from oldext to newext
// If oldext is an empty string - extension is extracted automatically.
// If path has no extension - new extension is appended
func renameExt(path, oldext, newext string) string {
if oldext == "" {
oldext = filepath.Ext(path)
}
if oldext == "" || strings.HasSuffix(path, oldext) {
return strings.TrimSuffix(path, oldext) + newext
} else {
return path
}
}
// globals returns list of global OS environment variables that start
// with ZS_ prefix as Vars, so the values can be used inside templates
func globals() Vars {
vars := Vars{}
for _, e := range os.Environ() {
pair := strings.Split(e, "=")
if strings.HasPrefix(pair[0], "ZS_") {
vars[strings.ToLower(pair[0][3:])] = pair[1]
}
}
return vars
}
// run executes a command or a script. Vars define the command environment,
// each zs var is converted into OS environemnt variable with ZS_ prefix
// prepended. Additional variable $ZS contains path to the zs binary. Command
// stderr is printed to zs stderr, command output is returned as a string.
func run(vars Vars, cmd string, args ...string) (string, error) {
// First check if partial exists (.html)
if b, err := ioutil.ReadFile(filepath.Join(ZSDIR, cmd+".html")); err == nil {
return string(b), nil
}
var errbuf, outbuf bytes.Buffer
c := exec.Command(cmd, args...)
env := []string{"ZS=" + os.Args[0], "ZS_OUTDIR=" + PUBDIR}
env = append(env, os.Environ()...)
for k, v := range vars {
env = append(env, "ZS_"+strings.ToUpper(k)+"="+v)
}
c.Env = env
c.Stdout = &outbuf
c.Stderr = &errbuf
err := c.Run()
if errbuf.Len() > 0 {
log.Println("ERROR:", errbuf.String())
}
if err != nil {
return "", err
}
return string(outbuf.Bytes()), nil
}
// getVars returns list of variables defined in a text file and actual file
// content following the variables declaration. Header is separated from
// content by an empty line. Header can be either YAML or JSON.
// If no empty newline is found - file is treated as content-only.
func getVars(path string, globals Vars) (Vars, string, error) {
b, err := ioutil.ReadFile(path)
if err != nil {
return nil, "", err
}
s := string(b)
// Pick some default values for content-dependent variables
v := Vars{}
title := strings.Replace(strings.Replace(path, "_", " ", -1), "-", " ", -1)
v["title"] = strings.ToTitle(title)
v["description"] = ""
v["file"] = path
v["url"] = path[:len(path)-len(filepath.Ext(path))] + ".html"
v["output"] = filepath.Join(PUBDIR, v["url"])
// Override default values with globals
for name, value := range globals {
v[name] = value
}
// Add layout if none is specified
if _, ok := v["layout"]; !ok {
v["layout"] = "layout.html"
}
delim := "\n---\n"
if sep := strings.Index(s, delim); sep == -1 {
return v, s, nil
} else {
header := s[:sep]
body := s[sep+len(delim):]
vars := Vars{}
if err := yaml.Unmarshal([]byte(header), &vars); err != nil {
fmt.Println("ERROR: failed to parse header", err)
return nil, "", err
} else {
// Override default values + globals with the ones defines in the file
for key, value := range vars {
v[key] = value
}
}
if strings.HasPrefix(v["url"], "./") {
v["url"] = v["url"][2:]
}
return v, body, nil
}
}
// Render expanding zs plugins and variables
func render(s string, vars Vars) (string, error) {
delim_open := "{{"
delim_close := "}}"
out := &bytes.Buffer{}
for {
if from := strings.Index(s, delim_open); from == -1 {
out.WriteString(s)
return out.String(), nil
} else {
if to := strings.Index(s, delim_close); to == -1 {
return "", fmt.Errorf("Close delim not found")
} else {
out.WriteString(s[:from])
cmd := s[from+len(delim_open) : to]
s = s[to+len(delim_close):]
m := strings.Fields(cmd)
if len(m) == 1 {
if v, ok := vars[m[0]]; ok {
out.WriteString(v)
continue
}
}
if res, err := run(vars, m[0], m[1:]...); err == nil {
out.WriteString(res)
} else {
fmt.Println(err)
}
}
}
}
return s, nil
}
// Renders markdown with the given layout into html expanding all the macros
func buildMarkdown(path string, w io.Writer, vars Vars) error {
v, body, err := getVars(path, vars)
if err != nil {
return err
}
content, err := render(body, v)
if err != nil {
return err
}
v["content"] = string(blackfriday.Run([]byte(content)))
if w == nil {
out, err := os.Create(filepath.Join(PUBDIR, renameExt(path, "", ".html")))
if err != nil {
return err
}
defer out.Close()
w = out
}
return buildHTML(filepath.Join(ZSDIR, v["layout"]), w, v)
}
// Renders text file expanding all variable macros inside it
func buildHTML(path string, w io.Writer, vars Vars) error {
v, body, err := getVars(path, vars)
if err != nil {
return err
}
if body, err = render(body, v); err != nil {
return err
}
tmpl, err := template.New("").Delims("<%", "%>").Parse(body)
if err != nil {
return err
}
if w == nil {
f, err := os.Create(filepath.Join(PUBDIR, path))
if err != nil {
return err
}
defer f.Close()
w = f
}
return tmpl.Execute(w, vars)
}
// Copies file as is from path to writer
func buildRaw(path string, w io.Writer) error {
in, err := os.Open(path)
if err != nil {
return err
}
defer in.Close()
if w == nil {
if out, err := os.Create(filepath.Join(PUBDIR, path)); err != nil {
return err
} else {
defer out.Close()
w = out
}
}
_, err = io.Copy(w, in)
return err
}
func build(path string, w io.Writer, vars Vars) error {
ext := filepath.Ext(path)
if ext == ".md" || ext == ".mkd" {
return buildMarkdown(path, w, vars)
} else if ext == ".html" || ext == ".xml" {
return buildHTML(path, w, vars)
} else {
return buildRaw(path, w)
}
}
func buildAll(watch bool) {
lastModified := time.Unix(0, 0)
modified := false
vars := globals()
for {
os.Mkdir(PUBDIR, 0755)
filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
// ignore hidden files and directories
if filepath.Base(path)[0] == '.' || strings.HasPrefix(path, ".") {
return nil
}
// inform user about fs walk errors, but continue iteration
if err != nil {
fmt.Println("error:", err)
return nil
}
if info.IsDir() {
os.Mkdir(filepath.Join(PUBDIR, path), 0755)
return nil
} else if info.ModTime().After(lastModified) {
if !modified {
// First file in this build cycle is about to be modified
run(vars, "prehook")
modified = true
}
log.Println("build:", path)
return build(path, nil, vars)
}
return nil
})
if modified {
// At least one file in this build cycle has been modified
run(vars, "posthook")
modified = false
}
if !watch {
break
}
lastModified = time.Now()
time.Sleep(1 * time.Second)
}
}
func init() {
// prepend .zs to $PATH, so plugins will be found before OS commands
p := os.Getenv("PATH")
p = ZSDIR + ":" + p
os.Setenv("PATH", p)
}
func main() {
if len(os.Args) == 1 {
fmt.Println(os.Args[0], "<command> [args]")
return
}
cmd := os.Args[1]
args := os.Args[2:]
switch cmd {
case "build":
if len(args) == 0 {
buildAll(false)
} else if len(args) == 1 {
if err := build(args[0], os.Stdout, globals()); err != nil {
fmt.Println("ERROR: " + err.Error())
}
} else {
fmt.Println("ERROR: too many arguments")
}
case "watch":
buildAll(true)
case "var":
if len(args) == 0 {
fmt.Println("var: filename expected")
} else {
s := ""
if vars, _, err := getVars(args[0], Vars{}); err != nil {
fmt.Println("var: " + err.Error())
} else {
if len(args) > 1 {
for _, a := range args[1:] {
s = s + vars[a] + "\n"
}
} else {
for k, v := range vars {
s = s + k + ":" + v + "\n"
}
}
}
fmt.Println(strings.TrimSpace(s))
}
default:
if s, err := run(globals(), cmd, args...); err != nil {
fmt.Println(err)
} else {
fmt.Println(s)
}
}
}