# Copyright 2015 Oliver Cope
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from getpass import getpass
import argparse
import configparser
import logging
import os
import sys
import typing as t

from yoyo import connections
from yoyo import default_migration_table
from yoyo import logger
from yoyo import utils
from yoyo.config import CONFIG_FILENAME
from yoyo.config import find_config
from yoyo.config import read_config
from yoyo.config import save_config
from yoyo.config import config_changed
from yoyo.config import update_argparser_defaults

verbosity_levels = {
    0: logging.ERROR,
    1: logging.WARN,
    2: logging.INFO,
    3: logging.DEBUG,
}

min_verbosity = min(verbosity_levels)
max_verbosity = max(verbosity_levels)

LEGACY_CONFIG_FILENAME = ".yoyo-migrate"


class InvalidArgument(Exception):
    pass


def parse_args(
    argv=None,
) -> t.Tuple[configparser.ConfigParser, argparse.ArgumentParser, argparse.Namespace]:
    """
    Parse the config file and command line args.

    :return: tuple of ``(parsed config file, argument parser, parsed arguments)``
    """
    #: List of arguments whose defaults should be read from the config file
    config_args = {
        "batch_mode": "getboolean",
        "sources": "get",
        "database": "get",
        "verbosity": "getint",
        "migration_table": "get",
    }

    globalparser, argparser, subparsers = make_argparser()

    # Initial parse to extract --config and any global arguments
    global_args, _ = globalparser.parse_known_args(argv)

    # Read the config file and create a dictionary of defaults for argparser
    configfile = global_args.config or find_config()
    config = read_config(configfile if global_args.use_config_file else None)

    defaults = {}
    for argname, getter in config_args.items():
        try:
            defaults[argname] = getattr(config, getter)("DEFAULT", argname)
        except configparser.NoOptionError:
            pass

    if "sources" in defaults:
        defaults["sources"] = defaults["sources"].split()

    # Set the argparser defaults to values read from the config file
    update_argparser_defaults(globalparser, defaults)
    update_argparser_defaults(argparser, defaults)
    for subp in subparsers.choices.values():
        update_argparser_defaults(subp, defaults)

    # Now parse for real, starting from the top
    args = argparser.parse_args(argv)

    # Update the args namespace with the global args.
    # This ensures that global args (eg '-v) are recognized regardless
    # of whether they were placed before or after the subparser command.
    # If we do not do this then the sub_parser copy of the argument takes
    # precedence, and overwrites any global args set before the command name.
    args.__dict__.update(globalparser.parse_known_args(argv)[0].__dict__)

    return config, argparser, args


def make_argparser():
    """
    Return a top-level ArgumentParser parser object,
    plus a list of sub_parsers
    """
    global_parser = argparse.ArgumentParser(add_help=False)
    global_parser.add_argument(
        "--config", "-c", default=None, help="Path to config file"
    )
    global_parser.add_argument(
        "-v",
        dest="verbosity",
        action="count",
        default=min_verbosity,
        help="Verbose output. Use multiple times to increase level of verbosity",
    )
    global_parser.add_argument(
        "-b",
        "--batch",
        dest="batch_mode",
        action="store_true",
        default=(not sys.stdout.isatty()),
        help="Run in batch mode" ". Turns off all user prompts",
    )

    global_parser.add_argument(
        "--no-config-file",
        "--no-cache",
        dest="use_config_file",
        action="store_false",
        default=True,
        help="Don't look for a yoyo.ini config file",
    )
    argparser = argparse.ArgumentParser(prog="yoyo", parents=[global_parser])

    subparsers = argparser.add_subparsers(help="Commands help")

    from . import migrate
    from . import newmigration
    from . import init

    init.install_argparsers(global_parser, subparsers)
    migrate.install_argparsers(global_parser, subparsers)
    newmigration.install_argparsers(global_parser, subparsers)

    return global_parser, argparser, subparsers


def configure_logging(level):
    """
    Configure the python logging module with the requested loglevel
    """
    logging.basicConfig(level=verbosity_levels[level])


def prompt_save_config(config, path):
    # Offer to save the current configuration for future runs
    # Don't cache anything in batch mode (because we can't prompt to find the
    # user's preference).

    if utils.confirm(
        "Save migration configuration to {}?\n"
        "This is saved in plain text and "
        "contains your database password.\n\n"
        "Answering 'y' means you do not have to specify "
        "the migration source or database connection "
        "for future runs".format(path)
    ):
        save_config(config, path)


def upgrade_legacy_config(args, config, sources):
    for dir in reversed(sources):
        path = os.path.join(dir, LEGACY_CONFIG_FILENAME)
        if not os.path.isfile(path):
            continue

        legacy_config = read_config(path)

        def transfer_setting(oldname, newname, transform=None, section="DEFAULT"):
            try:
                config.get(section, newname)
            except configparser.NoOptionError:
                try:
                    value = legacy_config.get(section, oldname)
                except configparser.NoOptionError:
                    pass
                else:
                    if transform:
                        value = transform(value)
                    config.set(section, newname, value)

        transfer_setting("dburi", "database")
        transfer_setting(
            "migration_table",
            "migration_table",
            lambda v: (default_migration_table if v == "None" else v),
        )

        config_path = args.config or CONFIG_FILENAME
        if not args.batch_mode:
            if utils.confirm(
                "Move legacy configuration in {!r} to {!r}?".format(path, config_path)
            ):
                save_config(config, config_path)
                try:
                    if utils.confirm(
                        "Delete legacy configuration file {!r}".format(path)
                    ):
                        os.unlink(path)
                except OSError:
                    logger.warn(
                        "Could not remove %r. Manually remove this file "
                        "to avoid future warnings",
                        path,
                    )
                return True
        else:
            logger.warn(
                "Found legacy configuration in %r. Run "
                "yoyo in interactive mode to update your "
                "configuration files",
                path,
            )

            try:
                args.database = args.database or legacy_config.get("DEFAULT", "dburi")
            except configparser.NoOptionError:
                pass
            try:
                if not vars(args).get("migration_table"):
                    args.migration_table = legacy_config.get(
                        "DEFAULT", "migration_table"
                    )
            except configparser.NoOptionError:
                pass

        return False


def get_backend(args, config):
    try:
        dburi = args.database
    except AttributeError:
        dburi = config.get("DEFAULT", "database")

    try:
        migration_table = args.migration_table
    except AttributeError:
        try:
            migration_table = config.get("DEFAULT", "migration_table")
        except configparser.NoOptionError:
            migration_table = default_migration_table

    if dburi is None:
        raise InvalidArgument("Please specify a database uri")

    try:
        if args.prompt_password:
            password = getpass("Password for %s: " % dburi)
            parsed = connections.parse_uri(dburi)
            dburi = parsed._replace(password=password).uri
    except AttributeError:
        pass

    return connections.get_backend(dburi, migration_table)


def main(argv=None):
    config, argparser, args = parse_args(argv)

    if getattr(args, "func", None) is None:
        argparser.print_usage(sys.stderr)
        argparser.exit(1)

    config_is_empty = config.sections() == [] and config.items("DEFAULT") == []

    sources = getattr(args, "sources", None)

    verbosity = args.verbosity
    verbosity = min(max_verbosity, max(min_verbosity, verbosity))
    configure_logging(verbosity)

    if vars(args).get("sources"):
        config.set("DEFAULT", "sources", " ".join(args.sources))
    if vars(args).get("database"):
        # ConfigParser requires that any percent signs in the db uri be escaped.
        config.set("DEFAULT", "database", args.database.replace("%", "%%"))
    if vars(args).get("migration_table"):
        config.set("DEFAULT", "migration_table", args.migration_table)
    config.set(
        "DEFAULT",
        "batch_mode",
        "on" if vars(args).get("batch_mode") else "off",
    )
    config.set("DEFAULT", "verbosity", str(vars(args).get("verbosity")))

    if sources:
        if upgrade_legacy_config(args, config, sources):
            return main(argv)

    try:
        if vars(args).get("func"):
            exitcode = args.func(args, config)
    except InvalidArgument as e:
        argparser.error(e.args[0])

    if config_is_empty and args.use_config_file and not args.batch_mode:
        config_file = args.config or CONFIG_FILENAME
        if config_changed(config, config_file):
            prompt_save_config(config, config_file)

    return exitcode


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))