import argparse
import logging

from toolchain.common.language_detector import LanguageDetector

logger = logging.getLogger(__name__)

class PostAlignmentCleaner:

    DEFAULT_LANGUAGE_DETECTION_THRESHOLD = 40
    DEFAULT_REJECTED_LINE_DELIMITER = "@@@"
    REJECTION_EMPTY = "empty_segment"
    REJECTION_NONALPHA = "nonalpha"
    REJECTION_UNEXPECTED_LANGUAGE = "unexpected_language_[{0}:{1}]"

    def __init__(self, lang_src, lang_tgt, config={}, language_detector=LanguageDetector()):
        self.lang_src = lang_src
        self.lang_tgt = lang_tgt
        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}", "{2}"])


    def clean(self, input_path_src, input_path_tgt, output_path_src, output_path_tgt, output_path_rejected):
        logger.info("Cleaning {0} and {1} to {2} and {3} with rejections to {4}.".format(input_path_src, input_path_tgt, output_path_src, output_path_tgt, output_path_rejected))
        with open(input_path_src) as input_src, open(input_path_tgt) as input_tgt,\
                open(output_path_src, "w") as output_src, open(output_path_tgt, "w") as output_tgt, open(output_path_rejected, "w") as output_rejected:
            self.clean_text(input_src, input_tgt, output_src, output_tgt, output_rejected)


    def clean_text(self, input_src, input_tgt, output_src, output_tgt, output_rejected):
        for input_pair in zip(input_src, input_tgt):
            term_src, term_tgt = input_pair[0].rstrip("\n"), input_pair[1].rstrip("\n")
            should_include, message = self.should_include(term_src.strip(), term_tgt.strip())
            if should_include:
                self.write_file_line(output_src, term_src)
                self.write_file_line(output_tgt, term_tgt)
            else:
                self.write_file_line(output_rejected, message)


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

        if not self.contains_alpha(term_src) and not self.contains_alpha(term_tgt):
            message = self.rejected_line_template.format(self.REJECTION_NONALPHA, term_src, term_tgt)
            return False, message

        if len(term_src) >= self.language_detection_threshold or len(term_tgt) >= self.language_detection_threshold or term_src == term_tgt:
            detected_lang_src = self.language_detector.detect(term_src)
            detected_lang_tgt = self.language_detector.detect(term_tgt)
            if detected_lang_src != self.lang_src or detected_lang_tgt != self.lang_tgt:
                reason = self.REJECTION_UNEXPECTED_LANGUAGE.format(detected_lang_src, detected_lang_tgt)
                message = self.rejected_line_template.format(reason, term_src, term_tgt)
                return False, message

        return True, ""


    def contains_alpha(self, token):
        return any(c.isalpha() for c in token)


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


if __name__ == "__main__":
    argparser = argparse.ArgumentParser()
    argparser.add_argument("lang_src", help="source language code")
    argparser.add_argument("lang_tgt", help="target language code")
    argparser.add_argument("input_path_src", help="path to input file of source language")
    argparser.add_argument("input_path_tgt", help="path to input file of target language")
    argparser.add_argument("output_path_src", help="path to output file of source language")
    argparser.add_argument("output_path_tgt", help="path to output file of target language")
    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,
    }

    PostAlignmentCleaner(args.lang_src, args.lang_tgt, config=config).clean(args.input_path_src, args.input_path_tgt,
            args.output_path_src, args.output_path_tgt, args.output_path_rejected)