import argparse
import logging

from toolchain.common.language_detector import LanguageDetector

logger = logging.getLogger(__name__)

class MonolingualCleaner:

    DEFAULT_LANGUAGE_DETECTION_THRESHOLD = 40
    DEFAULT_REJECTED_LINE_DELIMITER = "@@@"
    REJECTION_EMPTY = "empty_segment"
    REJECTION_UNEXPECTED_LANGUAGE = "unexpected_language_[{0}]"

    def __init__(self, lang, config={}, language_detector=LanguageDetector()):
        self.lang = lang
        self.language_detector = language_detector
        self.language_detection_threshold = int(config.get("language_detection_threshold", self.DEFAULT_LANGUAGE_DETECTION_THRESHOLD))
        rejected_line_delimiter = config.get("rejected_line_delimiter", self.DEFAULT_REJECTED_LINE_DELIMITER)
        self.rejected_line_template = rejected_line_delimiter.join(["{0}", "{1}"])


    def clean(self, input_path, output_path_retained, output_path_rejected):
        logger.info("Cleaning {0} to {1} with rejections to {2}.".format(input_path, output_path_retained, output_path_rejected))
        with open(input_path) as input, open(output_path_retained, "w") as output_retained, open(output_path_rejected, "w") as output_rejected:
            self.clean_text(input, output_retained, output_rejected)


    def clean_text(self, input, output_retained, output_rejected):
        for line in input:
            term = line.rstrip("\n")
            should_include, message = self.should_include(term.strip())
            if should_include:
                self.write_file_line(output_retained, term)
            else:
                self.write_file_line(output_rejected, message)


    def should_include(self, term):
        if not term:
            message = self.rejected_line_template.format(self.REJECTION_EMPTY, term)
            return False, message

        if len(term) >= self.language_detection_threshold:
            detected_lang = self.language_detector.detect(term)
            if detected_lang != self.lang:
                reason = self.REJECTION_UNEXPECTED_LANGUAGE.format(detected_lang)
                message = self.rejected_line_template.format(reason, term)
                return False, message

        return True, ""


    def write_file_line(self, file, text):
        file.write(text + "\n")


if __name__ == "__main__":
    argparser = argparse.ArgumentParser()
    argparser.add_argument("lang", help="language code")
    argparser.add_argument("input_path", help="path to input file")
    argparser.add_argument("output_path_retained", help="path to output file")
    argparser.add_argument("output_path_rejected", help="path to output rejection file")
    argparser.add_argument("--langdetect_threshold", type=int, default=40, help="check language of only lines of this number of characters or more")
    argparser.add_argument("--rejected_line_delimiter", type=str, default="@@@", help="string to use to delimit fields of rejection lines")
    args = argparser.parse_args()

    config = {
        "language_detection_threshold" : args.langdetect_threshold,
        "rejected_line_delimiter" : args.rejected_line_delimiter,
    }

    MonolingualCleaner(args.lang, config=config).clean(args.input_path, args.output_path_retained, args.output_path_rejected)