#    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 __future__ import print_function

import sys

import prettytable


def pretty_choice_list(l):
    return ', '.join("'%s'" % i for i in l)


def print_list(objs, fields, formatters={}, custom_labels={}, sortby=0,
               outfile=sys.stdout):
    '''Prints a list of objects.

    :param objs: list of objects to print
    :param fields: list of attributes of the objects to print;
        attributes beginning with '!' have a special meaning - they
        should be used with custom field labels and formatters only,
        and the formatter receives the whole object
    :param formatters: dict of functions that perform pre-print
        formatting of attributes (keys are strings from `fields`
        parameter, values are functions that take one parameter - the
        attribute)
    :param custom_labels: dict of label overrides for fields (keys are
        strings from `fields` parameter, values are custom labels -
        headers of the table)
    '''
    field_labels = [custom_labels.get(f, f) for f in fields]
    pt = prettytable.PrettyTable([f for f in field_labels],
                                 caching=False, print_empty=False)
    pt.align = 'l'

    for o in objs:
        row = []
        for field in fields:
            if field[0] == '!':  # custom field
                if field in formatters:
                    row.append(formatters[field](o))
                else:
                    raise KeyError(
                        'Custom field "%s" needs a formatter.' % field)
            else:  # attribute-based field
                if hasattr(o, field) and field in formatters:
                    row.append(formatters[field](getattr(o, field)))
                else:
                    row.append(getattr(o, field, ''))
        pt.add_row(row)
    print(pt.get_string(sortby=field_labels[sortby]), file=outfile)


def print_dict(d, formatters={}, custom_labels={}, outfile=sys.stdout):
    '''Prints a dict.

    :param d: dict to print
    :param formatters: dict of functions that perform pre-print
        formatting of dict values (keys are keys from `d` parameter,
        values are functions that take one parameter - the dict value
        to format)
    :param custom_labels: dict of label overrides for keys (keys are
        keys from `d` parameter, values are custom labels)
    '''
    pt = prettytable.PrettyTable(['Property', 'Value'],
                                 caching=False, print_empty=False)
    pt.align = 'l'

    for field in d.keys():
        label = custom_labels.get(field, field)
        if field in formatters:
            pt.add_row([label, formatters[field](d[field])])
        else:
            pt.add_row([label, d[field]])
    print(pt.get_string(sortby='Property'), file=outfile)


def attr_proxy(attr, formatter=lambda a: a, allow_undefined=True):
    '''Creates a new formatter function. It will format an object for
    output by printing it's attribute or running another formatter on
    that attribute.

    :param attr: name of the attribute to look for on an object
    :param formatter: formatter to run on that attribute (if not given,
        the attribute is returned as-is)
    :param allow_undefined: if true, the created function will return
        None if `attr` is not defined on the formatted object
    '''
    def formatter_proxy(obj):
        try:
            attr_value = getattr(obj, attr)
        except AttributeError as e:
            if allow_undefined:
                return None
            else:
                raise e
        return formatter(attr_value)

    return formatter_proxy


def capacities_formatter(capacities):
    '''Formats a list of capacities for output. Capacity is a dict
    containing 'name', 'value' and 'unit' keys.
    '''
    sorted_capacities = sorted(capacities,
                               key=lambda c: c['name'])
    return '\n'.join(['{0}: {1} {2}'.format(c['name'], c['value'], c['unit'])
                      for c in sorted_capacities])


def links_formatter(links):
    '''Formats a list of links. Link is a dict that has 'href' and
    'rel' keys.
    '''
    sorted_links = sorted(links, key=lambda l: l['rel'])
    return '\n'.join(['{0}: {1}'.format(l['rel'], l['href'])
                      for l in sorted_links])


def resource_links_formatter(links):
    '''Formats an array of resource links. Resource link is a dict
    with keys 'id' and 'links'. Under 'links' key there is an array of
    links. Link is a dict with 'href' and 'rel' keys. Currently we
    expect only one link to be in the array, so we print the first
    one. (We cannot fetch by 'rel', values in 'rel' are not used
    consistently.)
    '''
    sorted_links = sorted(links, key=lambda l: l['id'])
    return '\n'.join(['{0}: {1}'.format(l['id'], l['links'][0]['href'])
                      for l in sorted_links])


def resource_link_formatter(link):
    '''Formats one resource link. See docs of
    `resource_links_formatter` for more details.
    '''
    return resource_links_formatter([link])