import copy
from collections import defaultdict

from django.conf import settings
from django.template.backends.django import get_template_tag_modules

from . import Error, Tags, register

E001 = Error(
    "You have 'APP_DIRS': True in your TEMPLATES but also specify 'loaders' "
    "in OPTIONS. Either remove APP_DIRS or remove the 'loaders' option.",
    id='templates.E001',
)
E002 = Error(
    "'string_if_invalid' in TEMPLATES OPTIONS must be a string but got: {} ({}).",
    id="templates.E002",
)
E003 = Error(
    '{} is used for multiple template tag modules: {}',
    id='templates.E003',
)


@register(Tags.templates)
def check_setting_app_dirs_loaders(app_configs, **kwargs):
    return [E001] if any(
        conf.get('APP_DIRS') and 'loaders' in conf.get('OPTIONS', {})
        for conf in settings.TEMPLATES
    ) else []


@register(Tags.templates)
def check_string_if_invalid_is_string(app_configs, **kwargs):
    errors = []
    for conf in settings.TEMPLATES:
        string_if_invalid = conf.get('OPTIONS', {}).get('string_if_invalid', '')
        if not isinstance(string_if_invalid, str):
            error = copy.copy(E002)
            error.msg = error.msg.format(string_if_invalid, type(string_if_invalid).__name__)
            errors.append(error)
    return errors


@register(Tags.templates)
def check_for_template_tags_with_the_same_name(app_configs, **kwargs):
    errors = []
    libraries = defaultdict(list)

    for conf in settings.TEMPLATES:
        custom_libraries = conf.get('OPTIONS', {}).get('libraries', {})
        for module_name, module_path in custom_libraries.items():
            libraries[module_name].append(module_path)

    for module_name, module_path in get_template_tag_modules():
        libraries[module_name].append(module_path)

    for library_name, items in libraries.items():
        if len(items) > 1:
            errors.append(Error(
                E003.msg.format(
                    repr(library_name),
                    ', '.join(repr(item) for item in items),
                ),
                id=E003.id,
            ))

    return errors