google-translate

#!/usr/bin/env python3

import sys
import os

from argparse import ArgumentParser
from google.cloud import translate

def format_usage():
    p = os.path.basename(sys.argv[0])
    return """
{p} - Translate with Google
Usage: {p} [target-language] [source-language] < input > output
Example:
  $ echo This is a pen. | {p} ja
  $ echo This is a pen. | {p} zh en | {p} ja zh
Note:
  - Either set GOOGLE_APPLICATION_CREDENTIALS envvar or save credential
    key in JSON at ~/.google-translate/key.json

""".strip().format(**locals()) + "\n"

def usage():
    sys.stderr.write(format_usage())
    sys.exit(0)

def main():
    ap = ArgumentParser()
    ap.format_usage = ap.format_help = format_usage
    ap.add_argument('args', nargs='*')
    opt = ap.parse_args()

    if len(opt.args) == 0:
        usage()

    GACK = "GOOGLE_APPLICATION_CREDENTIALS"
    if not os.environ.get(GACK):
        home = os.environ["HOME"]
        os.environ[GACK] = os.path.join(home, ".google-translate/credential.json")

    kw = {
        "target_language": "ja"
    }

    if len(opt.args) > 0:
        kw["target_language"] = opt.args[0]
    if len(opt.args) > 1:
        kw["source_language"] = opt.args[1]

    ua = translate.Client()
    text = sys.stdin.read()
    ret = ua.translate(text, **kw)
    print(ret['translatedText'])

if __name__ == '__main__':
    main()