scriptshifter/scriptshifter/rest_api.py

import logging

from base64 import b64encode
from copy import deepcopy
from email.message import EmailMessage
from json import dumps
from os import environ, urandom
from smtplib import SMTP

from flask import Flask, jsonify, render_template, request
from flask_cors import CORS

from scriptshifter import EMAIL_FROM, EMAIL_TO, SMTP_HOST, SMTP_PORT
from scriptshifter.exceptions import ApiError
from scriptshifter.tables import list_tables, load_table
from scriptshifter.trans import transliterate


logger = logging.getLogger(__name__)
logging.basicConfig(level=environ.get("TXL_LOGLEVEL", logging.INFO))


def create_app():
    flask_env = environ.get("TXL_APP_MODE", "production")
    app = Flask(__name__)
    app.config.update({
        "ENV": flask_env,
        "SECRET_KEY": environ.get("TXL_FLASK_SECRET", b64encode(urandom(64))),
        "JSON_AS_ASCII": False,
        "JSONIFY_PRETTYPRINT_REGULAR": True,
    })
    CORS(app)

    return app


app = create_app()


@app.errorhandler(ApiError)
def handle_exception(e: ApiError):
    if e.status_code >= 500:
        warnings = [
            "An internal error occurred.",
            "If the error persists, contact the technical support team."
        ]
    else:
        warnings = [
            "ScriptShifter API replied with status code "
            f"{e.status_code}: {e.msg}"
        ]
        if e.status_code >= 400:
            warnings.append(
                    "Please review your input before repeating this request.")

    body = {
        "warnings": warnings,
        "output": "",
    }
    if logging.DEBUG >= logging.root.level:
        body["debug"] = {
            "form_data": request.json or request.form,
        }
    return (body, e.status_code)


@app.route("/", methods=["GET"])
def index():
    return render_template(
            "index.html",
            languages=list_tables(),
            feedback_form=SMTP_HOST is not None)


@app.route("/health", methods=["GET"])
def health_check():
    return "I'm alive!\n"


@app.route("/languages", methods=["GET"])
def list_languages():
    return jsonify(list_tables())


@app.route("/table/<lang>")
def dump_table(lang):
    """
    Dump parsed transliteration table for a language.
    """
    tbl = deepcopy(load_table(lang))
    for sec_name in ("roman_to_script", "script_to_roman"):
        if sec_name in tbl:
            for hname, fn_defs in tbl[sec_name].get("hooks", {}).items():
                tbl[sec_name]["hooks"][hname] = [
                        (fn.__name__, kw) for (fn, kw) in fn_defs]

    return jsonify(tbl)


@app.route("/options/<lang>", methods=["GET"])
def get_options(lang):
    """
    Get extra options for a table.
    """
    tbl = load_table(lang)

    return jsonify(tbl.get("options", []))


@app.route("/trans", methods=["POST"])
def transliterate_req():
    lang = request.json["lang"]
    in_txt = request.json["text"]
    capitalize = request.json.get("capitalize", False)
    t_dir = request.json.get("t_dir", "s2r")
    if t_dir not in ("s2r", "r2s"):
        return f"Invalid direction: {t_dir}", 400

    if not len(in_txt):
        return ("No input text provided! ", 400)
    options = request.json.get("options", {})
    logger.debug(f"Extra options: {options}")

    try:
        out, warnings = transliterate(in_txt, lang, t_dir, capitalize, options)
    except (NotImplementedError, ValueError) as e:
        raise ApiError(str(e), 400)
    except Exception as e:
        raise ApiError(str(e), 500)

    return {"output": out, "warnings": warnings}


@app.route("/feedback", methods=["POST"])
def feedback():
    """
    Allows users to provide feedback to improve a specific result.
    """
    t_dir = request.json.get("t_dir", "s2r")
    options = request.json.get("options", {})
    contact = request.json.get("contact")

    msg = EmailMessage()
    msg["subject"] = "Scriptshifter feedback report"
    msg["from"] = EMAIL_FROM
    msg["to"] = EMAIL_TO
    if contact:
        msg["cc"] = contact
    msg.set_content(f"""
        *Scriptshifter feedback report from {contact or 'anonymous'}*\n\n
        *Language:* {request.json['lang']}\n
        *Direction:* {
                    'Roman to Script' if t_dir == 'r2s'
                    else 'Script to Roman'}\n
        *Source:* {request.json['src']}\n
        *Result:* {request.json['result']}\n
        *Expected result:* {request.json['expected']}\n
        *Applied options:* {dumps(options)}\n
        *Notes:*\n
        {request.json['notes']}""")

    # TODO This uses a test SMTP server:
    # python -m smtpd -n -c DebuggingServer localhost:1025
    smtp = SMTP(SMTP_HOST, SMTP_PORT)
    smtp.send_message(msg)
    smtp.quit()

    return {"message": "Feedback message sent."}