sjansen/messageformat

package main

import (
    "bytes"
    "fmt"
    "go/format"
    "html/template"
    "io/ioutil"
    "os"
    "path/filepath"
    "strings"
)

func main() {
    for _, src := range os.Args[1:] {
        if src != filepath.Base(src) || !strings.HasSuffix(src, ".go.tmpl") {
            fmt.Fprintf(os.Stderr, "invalid template filename: %q\n", src)
            os.Exit(1)
        }

        fi, err := os.Stat(src)
        if os.IsNotExist(err) {
            fmt.Fprintf(os.Stderr, "file not found: %q\n", src)
            os.Exit(1)
        } else if err != nil {
            fmt.Fprintln(os.Stderr, err)
            os.Exit(1)
        }

        dst := strings.TrimSuffix(src, ".tmpl")
        fmt.Println("generating:", dst)

        tmpl := template.New(src).Funcs(template.FuncMap{
            "split": func(s string) []string { return strings.Split(s, ",") },
        })
        if _, err = tmpl.ParseFiles(src); err != nil {
            fmt.Fprintln(os.Stderr, err)
            os.Exit(1)
        }

        var buf bytes.Buffer
        buf.Write([]byte(
            "// Code generated by scripts/tmpl-to-go. DO NOT EDIT.\n",
        ))

        if err = tmpl.Execute(&buf, nil); err != nil {
            fmt.Fprintln(os.Stderr, err)
            os.Exit(1)
        }

        code := buf.Bytes()
        if formatted, err := format.Source(code); err == nil {
            code = formatted
        } else {
            _ = ioutil.WriteFile(dst, code, fi.Mode())
            fmt.Fprintln(os.Stderr, err)
            os.Exit(1)
        }

        if err = ioutil.WriteFile(dst, code, fi.Mode()); err != nil {
            fmt.Fprintln(os.Stderr, err)
            os.Exit(1)
        }
    }
}