"""Insert samples into the database."""
import sys
import logging
import pathlib
import argparse

import MySQLdb as mdb
from redis import Redis

from qc_app.db_utils import database_connection
from qc_app.check_connections import check_db, check_redis
from qc_app.db import species_by_id, population_by_id
from qc_app.samples import (
    save_samples_data,
    read_samples_file,
    cross_reference_samples)

stderr_handler = logging.StreamHandler(stream=sys.stderr)
root_logger = logging.getLogger()
root_logger.addHandler(stderr_handler)
root_logger.setLevel("INFO")

class SeparatorAction(argparse.Action):
    """Action to handle the separator values."""
    def __init__(self, option_strings, dest, nargs=None, **kwargs):
        """Init the action"""
        if nargs is not None:
            raise ValueError("nargs not allowed.")
        super().__init__(option_strings, dest, nargs, **kwargs)

    def __call__(self, parser, namespace, values, option_string=None):
        """Process the value passed in."""
        setattr(namespace, self.dest, (chr(9) if values == "\\t" else values))

def insert_samples(conn: mdb.Connection,# pylint: disable=[too-many-arguments]
                   rconn: Redis,# pylint: disable=[unused-argument]
                   speciesid: int,
                   populationid: int,
                   samplesfile: pathlib.Path,
                   separator: str,
                   firstlineheading: bool,
                   quotechar: str):
    """Insert the samples into the database."""
    print("Checking for errors:")
    species = species_by_id(conn, speciesid)
    if not bool(species):
        logging.error("Species with id '%s' does not exist.", str(speciesid))
        return 1
    print(f"\tSpecies with ID '{speciesid}' found")
    population = population_by_id(conn, populationid)
    if not bool(population):
        logging.error("Population with id '%s' does not exist.",
                      str(populationid))
        return 1
    print(f"\tPopulations with ID '{populationid}' found")
    print("No errors found. Continuing...")
    print("\nInserting samples ...")
    save_samples_data(
        conn,
        speciesid,
        read_samples_file(samplesfile, separator, firstlineheading))
    print("Cross-referencing samples with their populations.")
    cross_reference_samples(
        conn,
        speciesid,
        populationid,
        (row["Name"] for row in
         read_samples_file(samplesfile,
                           separator,
                           firstlineheading,
                           quotechar=quotechar)))
    print("Samples upload successfully completed.")
    return 0

if __name__ == "__main__":

    def cli_args():
        """Process the command-line arguments."""
        #
        parser = argparse.ArgumentParser(
            prog="insert_samples",
            description = (
                "Script to parse and insert sample data from a file into the "
                "database."))

        # == Mandatory Arguments ==
        parser.add_argument(
            "databaseuri",
            help="URL to be used to initialise the connection to the database")
        parser.add_argument("speciesid",
                            type=int,
                            help="The species identifier in the database.")
        parser.add_argument(
            "populationid",
            type=int,
            help="The grouping/population identifier in the database.")
        parser.add_argument(
            "samplesfile",
            type=pathlib.Path,
            help="Path to the CSV file containing the samples data.")
        parser.add_argument(
            "separator",
            action=SeparatorAction,
            help="The 'character' in the CSV file that separates the fields.",
            default=chr(9))

        # == Optional Arguments ==
        parser.add_argument(
            "--firstlineheading",
            action="store_true",
            help=("If the first line of the file is a header row, invoke the "
                  "program with this flag."))
        parser.add_argument(
            "--quotechar",
            default='"',
            help=("The character used to delimit (surround?) the value in "
                  "each column."))

        # == Script-specific extras ==
        parser.add_argument("--redisuri",
                            help="URL to initialise connection to redis",
                            default="redis:///")

        args = parser.parse_args()
        return args

    def main():
        """Run script to insert samples into the database."""

        args = cli_args()
        check_db(args.databaseuri)
        check_redis(args.redisuri)
        if not args.samplesfile.exists():
            logging.error("File not found: '%s'.", args.samplesfile)
            return 2

        with (Redis.from_url(args.redisuri, decode_responses=True) as rconn,
              database_connection(args.databaseuri) as dbconn):
            return insert_samples(dbconn,
                                  rconn,
                                  args.speciesid,
                                  args.populationid,
                                  args.samplesfile,
                                  args.separator,
                                  args.firstlineheading,
                                  args.quotechar)

    sys.exit(main())