"""
Utility functions to create MongoDB processes.

Handles all the nitty-gritty parameter conversion.
"""

from __future__ import absolute_import

import json
import os
import os.path
import stat

from . import process as _process
from .. import utils
from .. import config


def mongod_program(logger, executable=None, process_kwargs=None, **kwargs):
    """
    Returns a Process instance that starts a mongod executable with
    arguments constructed from 'kwargs'.
    """

    executable = utils.default_if_none(executable, config.DEFAULT_MONGOD_EXECUTABLE)
    args = [executable]

    # Apply the --setParameter command line argument.
    set_parameter = kwargs.pop("set_parameters", {})
    _apply_set_parameters(args, set_parameter)

    shortcut_opts = {
        "nojournal": config.NO_JOURNAL,
        "nopreallocj": config.NO_PREALLOC_JOURNAL,
        "storageEngine": config.STORAGE_ENGINE,
        "wiredTigerCollectionConfigString": config.WT_COLL_CONFIG,
        "wiredTigerEngineConfigString": config.WT_ENGINE_CONFIG,
        "wiredTigerIndexConfigString": config.WT_INDEX_CONFIG,
    }

    # These options are just flags, so they should not take a value.
    opts_without_vals = ("nojournal", "nopreallocj")

    # Have the --nojournal command line argument to resmoke.py unset the journal option.
    if shortcut_opts["nojournal"] is not None and "journal" in kwargs:
        del kwargs["journal"]

    for opt_name in shortcut_opts:
        if shortcut_opts[opt_name] is not None:
            # Command line options override the YAML configuration.
            if opt_name in opts_without_vals:
                kwargs[opt_name] = ""
            else:
                kwargs[opt_name] = shortcut_opts[opt_name]

    # Apply the rest of the command line arguments.
    _apply_kwargs(args, kwargs)

    if "keyFile" in kwargs:
        _set_keyfile_permissions(kwargs["keyFile"])

    process_kwargs = utils.default_if_none(process_kwargs, {})
    return _process.Process(logger, args, **process_kwargs)


def mongos_program(logger, executable=None, process_kwargs=None, **kwargs):
    """
    Returns a Process instance that starts a mongos executable with
    arguments constructed from 'kwargs'.
    """

    executable = utils.default_if_none(executable, config.DEFAULT_MONGOS_EXECUTABLE)
    args = [executable]

    # Apply the --setParameter command line argument.
    set_parameter = kwargs.pop("set_parameters", {})
    _apply_set_parameters(args, set_parameter)

    # Apply the rest of the command line arguments.
    _apply_kwargs(args, kwargs)

    if "keyFile" in kwargs:
        _set_keyfile_permissions(kwargs["keyFile"])

    process_kwargs = utils.default_if_none(process_kwargs, {})
    return _process.Process(logger, args, **process_kwargs)


def mongo_shell_program(logger, executable=None, filename=None, process_kwargs=None, **kwargs):
    """
    Returns a Process instance that starts a mongo shell with arguments
    constructed from 'kwargs'.
    """

    executable = utils.default_if_none(executable, config.DEFAULT_MONGO_EXECUTABLE)
    args = [executable]

    eval_sb = []  # String builder.
    global_vars = kwargs.pop("global_vars", {})

    shortcut_opts = {
        "noJournal": (config.NO_JOURNAL, False),
        "noJournalPrealloc": (config.NO_PREALLOC_JOURNAL, False),
        "storageEngine": (config.STORAGE_ENGINE, ""),
        "testName": (os.path.splitext(os.path.basename(filename))[0], ""),
        "wiredTigerCollectionConfigString": (config.WT_COLL_CONFIG, ""),
        "wiredTigerEngineConfigString": (config.WT_ENGINE_CONFIG, ""),
        "wiredTigerIndexConfigString": (config.WT_INDEX_CONFIG, ""),
    }

    test_data = global_vars.get("TestData", {}).copy()
    for opt_name in shortcut_opts:
        (opt_value, opt_default) = shortcut_opts[opt_name]
        if opt_value is not None:
            test_data[opt_name] = opt_value
        elif opt_name not in test_data:
            # Only use 'opt_default' if the property wasn't set in the YAML configuration.
            test_data[opt_name] = opt_default
    global_vars["TestData"] = test_data

    for var_name in global_vars:
        _format_shell_vars(eval_sb, var_name, global_vars[var_name])

    if "eval" in kwargs:
        eval_sb.append(kwargs.pop("eval"))

    eval_str = "; ".join(eval_sb)
    args.append("--eval")
    args.append(eval_str)

    if config.SHELL_WRITE_MODE is not None:
        kwargs["writeMode"] = config.SHELL_WRITE_MODE

    # Apply the rest of the command line arguments.
    _apply_kwargs(args, kwargs)

    # Have the mongos shell run the specified file.
    args.append(filename)

    if "keyFile" in global_vars["TestData"]:
        _set_keyfile_permissions(global_vars["TestData"]["keyFile"])

    process_kwargs = utils.default_if_none(process_kwargs, {})
    return _process.Process(logger, args, **process_kwargs)


def _format_shell_vars(sb, path, value):
    """
    Formats 'value' in a way that can be passed to --eval.

    If 'value' is a dictionary, then it is unrolled into the creation of
    a new JSON object with properties assigned for each key of the
    dictionary.
    """

    # Only need to do special handling for JSON objects.
    if not isinstance(value, dict):
        sb.append("%s = %s" % (path, json.dumps(value)))
        return

    # Avoid including curly braces and colons in output so that the command invocation can be
    # copied and run through bash.
    sb.append("%s = new Object()" % (path))
    for subkey in value:
        _format_shell_vars(sb, ".".join((path, subkey)), value[subkey])


def dbtest_program(logger, executable=None, suites=None, process_kwargs=None, **kwargs):
    """
    Returns a Process instance that starts a dbtest executable with
    arguments constructed from 'kwargs'.
    """

    executable = utils.default_if_none(executable, config.DEFAULT_DBTEST_EXECUTABLE)
    args = [executable]

    if suites is not None:
        args.extend(suites)

    if config.STORAGE_ENGINE is not None:
        kwargs["storageEngine"] = config.STORAGE_ENGINE

    for arg_name in kwargs:
        arg_value = str(kwargs[arg_name])
        args.append("--%s" % (arg_name))
        if arg_value:
            args.append(arg_value)

    process_kwargs = utils.default_if_none(process_kwargs, {})
    return _process.Process(logger, args, **process_kwargs)


def _apply_set_parameters(args, set_parameter):
    """
    Converts key-value pairs from 'kwargs' into --setParameter key=value
    arguments to an executable and appends them to 'args'.
    """

    for param_name in set_parameter:
        param_value = set_parameter[param_name]
        # --setParameter takes boolean values as lowercase strings.
        if isinstance(param_value, bool):
            param_value = "true" if param_value else "false"
        args.append("--setParameter")
        args.append("%s=%s" % (param_name, param_value))


def _apply_kwargs(args, kwargs):
    """
    Converts key-value pairs from 'kwargs' into --key value arguments
    to an executable and appends them to 'args'.

    A --flag without a value is represented with the empty string.
    """

    for arg_name in kwargs:
        arg_value = str(kwargs[arg_name])
        args.append("--%s" % (arg_name))
        if arg_value:
            args.append(arg_value)


def _set_keyfile_permissions(keyfile_path):
    """
    Change the permissions on 'keyfile_path' to 600, i.e. only the user
    can read and write the file.

    This necessary to avoid having the mongod/mongos fail to start up
    because "permissions on 'keyfile_path' are too open".
    """
    os.chmod(keyfile_path, stat.S_IRUSR | stat.S_IWUSR)