import logging

from base64 import b64encode
from copy import deepcopy
from json import dumps, loads
from os import environ, urandom

from flask import Flask, jsonify, render_template, request

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,
    })

    return app


app = create_app()


@app.errorhandler(ApiError)
def handle_exception(e: ApiError):
    return ({
        "warnings": [
            "ScriptShifter HTTP request failed with status code "
            f"{e.status_code}: {e.msg}"
        ],
        "output": "",
    }, e.status_code)


@app.route("/", methods=["GET"])
def index():
    return render_template("index.html", languages=list_tables())


@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.form["lang"]
    in_txt = request.form["text"]
    capitalize = request.form.get("capitalize", False)
    t_dir = request.form.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 = loads(request.form.get("options", "{}"))
    logger.debug(f"Extra options: {options}")

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

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