source: code/trunk/zs.go@ 15

package main

import (
        "bytes"
        "fmt"
        "io"
        "io/ioutil"
        "log"
        "os"
        "os/exec"
        "path"
        "path/filepath"
        "strings"
        "time"

        "github.com/russross/blackfriday"
)

const (
        ZSDIR  = ".zs"
        PUBDIR = ".pub"
)

type EvalFn func(args []string, vars map[string]string) (string, error)

func split2(s, delim string) (string, string) {
        parts := strings.SplitN(s, delim, 2)
        if len(parts) == 2 {
                return parts[0], parts[1]
        } else {
                return parts[0], ""
        }
}

func md(path, s string) (map[string]string, string) {
        url := path[:len(path)-len(filepath.Ext(path))] + ".html"
        v := map[string]string{
                "file":   path,
                "url":    url,
                "output": filepath.Join(PUBDIR, url),
                "layout": "index.html",
        }
        if strings.Index(s, "\n\n") == -1 {
                return map[string]string{}, s
        }
        header, body := split2(s, "\n\n")
        for _, line := range strings.Split(header, "\n") {
                key, value := split2(line, ":")
                v[strings.ToLower(strings.TrimSpace(key))] = strings.TrimSpace(value)
        }
        if strings.HasPrefix(v["url"], "./") {
                v["url"] = v["url"][2:]
        }
        return v, body
}

func render(s string, vars map[string]string, eval EvalFn) (string, error) {
        delim_open := "{{"
        delim_close := "}}"

        out := bytes.NewBuffer(nil)
        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 := eval(m, vars); err == nil {
                                        out.WriteString(res)
                                } else {
                                        log.Println(err) // silent
                                }
                        }
                }
        }
}

func env(vars map[string]string) []string {
        env := []string{"ZS=" + os.Args[0], "ZS_OUTDIR=" + PUBDIR}
        env = append(env, os.Environ()...)
        if vars != nil {
                for k, v := range vars {
                        env = append(env, "ZS_"+strings.ToUpper(k)+"="+v)
                }
        }
        return env
}

func run(cmd string, args []string, vars map[string]string, output io.Writer) error {
        var errbuf bytes.Buffer
        c := exec.Command(cmd, args...)
        c.Env = env(vars)
        c.Stdout = output
        c.Stderr = &errbuf

        err := c.Run()

        if errbuf.Len() > 0 {
                log.Println(errbuf.String())
        }

        if err != nil {
                return err
        }
        return nil
}

func eval(cmd []string, vars map[string]string) (string, error) {
        outbuf := bytes.NewBuffer(nil)
        err := run(path.Join(ZSDIR, cmd[0]), cmd[1:], vars, outbuf)
        if err != nil {
                if _, ok := err.(*exec.ExitError); ok {
                        return "", err
                }
                outbuf = bytes.NewBuffer(nil)
                err := run(cmd[0], cmd[1:], vars, outbuf)
                // Return exit errors, but ignore if the command was not found
                if _, ok := err.(*exec.ExitError); ok {
                        return "", err
                }
        }
        return outbuf.String(), nil
}

func buildMarkdown(path string) error {
        b, err := ioutil.ReadFile(path)
        if err != nil {
                return err
        }
        v, body := md(path, string(b))
        content, err := render(body, v, eval)
        if err != nil {
                return err
        }
        v["content"] = string(blackfriday.MarkdownBasic([]byte(content)))
        return buildPlain(filepath.Join(ZSDIR, v["layout"]), v)
}

func buildPlain(path string, vars map[string]string) error {
        b, err := ioutil.ReadFile(path)
        if err != nil {
                return err
        }
        content, err := render(string(b), vars, eval)
        if err != nil {
                return err
        }
        output := filepath.Join(PUBDIR, path)
        if s, ok := vars["output"]; ok {
                output = s
        }
        err = ioutil.WriteFile(output, []byte(content), 0666)
        if err != nil {
                return err
        }
        return nil
}

func copyFile(path string) (err error) {
        var in, out *os.File
        if in, err = os.Open(path); err == nil {
                defer in.Close()
                if out, err = os.Create(filepath.Join(PUBDIR, path)); err == nil {
                        defer out.Close()
                        _, err = io.Copy(out, in)
                }
        }
        return err
}

func buildAll(once bool) {
        lastModified := time.Unix(0, 0)
        modified := false
        for {
                os.Mkdir(PUBDIR, 0755)
                err := 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
                        }

                        if info.IsDir() {
                                os.Mkdir(filepath.Join(PUBDIR, path), 0755)
                                return nil
                        } else if info.ModTime().After(lastModified) {
                                if !modified {
                                        // About to be modified, so run pre-build hook
                                        run(filepath.Join(ZSDIR, "pre"), []string{}, nil, nil)
                                        modified = true
                                }
                                ext := filepath.Ext(path)
                                if ext == ".md" || ext == ".mkd" {
                                        log.Println("mkd: ", path)
                                        return buildMarkdown(path)
                                } else {
                                        log.Println("raw: ", path)
                                        return copyFile(path)
                                }
                        }
                        return nil
                })
                if err != nil {
                        log.Println("ERROR:", err)
                }
                if modified {
                        // Something was modified, so post-build hook
                        run(filepath.Join(ZSDIR, "post"), []string{}, nil, nil)
                        modified = false
                }
                lastModified = time.Now()
                if once {
                        break
                }
                time.Sleep(1 * time.Second)
        }
}

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":
                buildAll(true)
        case "watch":
                buildAll(false) // pass duration
        case "var":
                if len(args) == 0 {
                        log.Println("ERROR: filename expected")
                        return
                }
                if b, err := ioutil.ReadFile(args[0]); err == nil {
                        vars, _ := md(args[0], string(b))
                        if len(args) > 1 {
                                for _, a := range args[1:] {
                                        fmt.Println(vars[a])
                                }
                        } else {
                                for k, v := range vars {
                                        fmt.Println(k + ":" + v)
                                }
                        }
                } else {
                        log.Println(err)
                }
        default:
                err := run(path.Join(ZSDIR, cmd), args, map[string]string{}, os.Stdout)
                if err != nil {
                        log.Println(err)
                }
        }
}