"""
LegacyLibraryContent: The XBlock used to randomly select a subset of blocks from a "v1" (modulestore-backed) library.

In Studio, it's called the "Randomized Content Module".

In the long-term, this block is deprecated in favor of "v2" (learning core-backed) library references:
https://github.com/openedx/edx-platform/issues/32457

We need to retain backwards-compatibility, but please do not build any new features into this.
"""
from __future__ import annotations

import json
import logging
from gettext import ngettext, gettext

import nh3
from django.core.exceptions import ObjectDoesNotExist, PermissionDenied
from opaque_keys.edx.locator import LibraryLocator
from web_fragments.fragment import Fragment
from webob import Response
from xblock.core import XBlock
from xblock.fields import Integer, Scope, String

from xmodule.capa.responsetypes import registry
from xmodule.modulestore.exceptions import ItemNotFoundError
from xmodule.item_bank_block import ItemBankMixin
from xmodule.validation import StudioValidation, StudioValidationMessage
from xmodule.x_module import XModuleToXBlockMixin

_ = lambda text: text

logger = logging.getLogger(__name__)

ANY_CAPA_TYPE_VALUE = 'any'


def _get_human_name(problem_class):
    """
    Get the human-friendly name for a problem type.
    """
    return getattr(problem_class, 'human_name', problem_class.__name__)


def _get_capa_types():
    """
    Gets capa types tags and labels
    """
    capa_types = {tag: _get_human_name(registry.get_class_for_tag(tag)) for tag in registry.registered_tags()}

    return [{'value': ANY_CAPA_TYPE_VALUE, 'display_name': _('Any Type')}] + sorted([
        {'value': capa_type, 'display_name': caption}
        for capa_type, caption in capa_types.items()
    ], key=lambda item: item.get('display_name'))


class LibraryToolsUnavailable(ValueError):
    """
    Raised when the library_tools service is requested in a runtime that doesn't provide it.
    """
    def __init__(self):
        super().__init__("Needed 'library_tools' features which were not available in the current runtime")


@XBlock.wants('library_tools')
@XBlock.wants('studio_user_permissions')  # Only available in CMS.
class LegacyLibraryContentBlock(ItemBankMixin, XModuleToXBlockMixin, XBlock):
    """
    An XBlock whose children are chosen dynamically from a legacy (v1) content library.
    Can be used to create randomized assessments among other things.

    Note: technically, all matching blocks from the content library are added
    as children of this block, but only a subset of those children are shown to
    any particular student.
    """
    display_name = String(
        display_name=_("Display Name"),
        help=_("The display name for this component."),
        default="Randomized Content Block",
        scope=Scope.settings,
    )
    source_library_id = String(
        display_name=_("Library"),
        help=_("Select the library from which you want to draw content."),
        scope=Scope.settings,
        values_provider=lambda instance: instance.source_library_values(),
    )
    source_library_version = String(
        # This is a hidden field that stores the version of source_library when we last pulled content from it
        display_name=_("Library Version"),
        scope=Scope.settings,
    )
    max_count = Integer(
        display_name=_("Count"),
        help=_("Enter the number of components to display to each student. Set it to -1 to display all components."),
        default=1,
        scope=Scope.settings,
    )
    capa_type = String(
        display_name=_("Problem Type"),
        help=_('Choose a problem type to fetch from the library. If "Any Type" is selected no filtering is applied.'),
        default=ANY_CAPA_TYPE_VALUE,
        values=_get_capa_types(),
        scope=Scope.settings,
    )

    @property
    def source_library_key(self):
        """
        Convenience method to get the library ID as a LibraryLocator and not just a string.
        """
        return LibraryLocator.from_string(self.source_library_id)

    def author_view(self, context):
        """
        Renders the Studio views.
        Normal studio view: If block is properly configured, displays library status summary
        Studio container view: displays a preview of all possible children.
        """
        fragment = Fragment()
        root_xblock = context.get('root_xblock')
        is_root = root_xblock and root_xblock.location == self.location
        try:
            is_updating = self.get_tools().are_children_syncing(self)
        except LibraryToolsUnavailable:
            is_updating = False
        if is_root and not is_updating:
            # User has clicked the "View" link. Show a preview of all possible children:
            if self.children:  # pylint: disable=no-member
                max_count = self.max_count
                if max_count < 0:
                    max_count = len(self.children)

                fragment.add_content(self.runtime.service(self, 'mako').render_cms_template(
                    "library-block-author-preview-header.html", {
                        'max_count': max_count,
                        'display_name': self.display_name or self.url_name,
                    }))
                context['can_edit_visibility'] = False
                context['can_move'] = False
                context['can_collapse'] = True
                self.render_children(context, fragment, can_reorder=False, can_add=False)
        # else: When shown on a unit page, don't show any sort of preview -
        # just the status of this block in the validation area.
        context['is_loading'] = is_updating

        # The following JS is used to make the "Update now" button work on the unit page and the container view:
        if root_xblock and 'library' in root_xblock.category:
            if root_xblock.source_library_id and len(root_xblock.children) > 0:
                fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/library_content_edit.js'))
        else:
            fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/library_content_edit.js'))

        fragment.initialize_js('LibraryContentAuthorView')
        return fragment

    @property
    def non_editable_metadata_fields(self):
        non_editable_fields = super().non_editable_metadata_fields
        non_editable_fields.extend([
            LegacyLibraryContentBlock.source_library_version,
        ])
        return non_editable_fields

    def get_tools(self, to_read_library_content: bool = False) -> 'LegacyLibraryToolsService':
        """
        Grab the library tools service and confirm that it'll work for us. Else, raise LibraryToolsUnavailable.
        """
        if tools := self.runtime.service(self, 'library_tools'):
            if (not to_read_library_content) or tools.can_use_library_content(self):
                return tools
        raise LibraryToolsUnavailable()

    def _validate_sync_permissions(self):
        """
        Raises PermissionDenied() if we can't confirm that user has write on this block and read on source library.

        If source library isn't set, then that's OK.
        """
        if not (user_perms := self.runtime.service(self, 'studio_user_permissions')):
            raise PermissionDenied("Access cannot be validated in the current runtime.")
        if not user_perms.can_write(self.scope_ids.usage_id.context_key):
            raise PermissionDenied(f"Cannot write to block at {self.scope_ids.usage_id}")
        if self.source_library_key:
            if not user_perms.can_read(self.source_library_key):
                raise PermissionDenied(f"Cannot read library at {self.source_library_key}")

    @XBlock.handler
    def upgrade_and_sync(self, request=None, suffix=None):  # pylint: disable=unused-argument
        """
        HTTP handler allowing Studio users to update to latest version of source library and synchronize children.

        This is a thin wrapper around `sync_from_library(upgrade_to_latest=True)`, plus permission checks.

        Returns 400 if libraray tools or user permission services are not available.
        Returns 403/404 if user lacks read access on source library or write access on this block.
        """
        self._validate_sync_permissions()
        if not self.source_library_id:
            return Response(_("Source content library has not been specified."), status=400)
        try:
            self.sync_from_library(upgrade_to_latest=True)
        except LibraryToolsUnavailable:
            return Response(_("Content libraries are not available in the current runtime."), status=400)
        except ObjectDoesNotExist:
            return Response(
                _("Source content library does not exist: {source_library_id}").format(
                    source_library_id=self.source_library_id
                ),
                status=400,
            )
        return Response()

    def sync_from_library(self, upgrade_to_latest: bool = False) -> None:
        """
        Synchronize children with source library.

        If `upgrade_to_latest==True` or if source library version is unset, update library version to latest.
        Otherwise, use current source library version.

        Raises ObjectDoesNotExist if library or version is missing.
        """
        self.get_tools(to_read_library_content=True).trigger_library_sync(
            dest_block=self,
            library_version=(None if upgrade_to_latest else self.source_library_version),
        )

    @XBlock.handler
    def children_are_syncing(self, request, suffix=''):  # pylint: disable=unused-argument
        """
        Returns whether this block is currently having its children updated from the source library.
        """
        try:
            is_updating = self.get_tools().are_children_syncing(self)
        except LibraryToolsUnavailable:
            is_updating = False
        return Response(json.dumps(is_updating))

    def studio_post_duplicate(self, store, source_block):
        """
        Used by the studio after basic duplication of a source block. We handle the children
        ourselves, because we have to properly reference the library upstream and set the overrides.

        Otherwise we'll end up losing data on the next refresh.
        """
        if hasattr(super(), 'studio_post_duplicate'):
            super().studio_post_duplicate(store, source_block)

        self._validate_sync_permissions()
        self.get_tools(to_read_library_content=True).trigger_duplication(source_block=source_block, dest_block=self)
        return True  # Children have been handled.

    def studio_post_paste(self, store, source_node) -> bool:
        """
        Pull the children from the library and let library_tools assign their IDs.
        """
        if hasattr(super(), 'studio_post_paste'):
            super().studio_post_paste(store, source_node)

        self.sync_from_library(upgrade_to_latest=False)
        return True  # Children have been handled

    def _validate_library_version(self, validation, lib_tools, version, library_key):
        """
        Validates library version
        """
        latest_version = lib_tools.get_latest_library_version(library_key)
        if latest_version is not None:
            if version is None or version != latest_version:
                validation.set_summary(
                    StudioValidationMessage(
                        StudioValidationMessage.WARNING,
                        _('This component is out of date. The library has new content.'),
                        # TODO: change this to action_runtime_event='...' once the unit page supports that feature.
                        # See https://openedx.atlassian.net/browse/TNL-993
                        action_class='library-update-btn',
                        # Translators: {refresh_icon} placeholder is substituted to "↻" (without double quotes)
                        action_label=_("{refresh_icon} Update now.").format(refresh_icon="↻")
                    )
                )
                return False
        else:
            validation.set_summary(
                StudioValidationMessage(
                    StudioValidationMessage.ERROR,
                    _('Library is invalid, corrupt, or has been deleted.'),
                    action_class='edit-button',
                    action_label=_("Edit Library List.")
                )
            )
            return False
        return True

    def _set_validation_error_if_empty(self, validation, summary):
        """  Helper method to only set validation summary if it's empty """
        if validation.empty:
            validation.set_summary(summary)

    def validate(self):
        """
        Validates the state of this Library Content Block Instance. This
        is the override of the general XBlock method, and it will also ask
        its superclass to validate.
        """
        validation = super().validate()
        if not isinstance(validation, StudioValidation):
            validation = StudioValidation.copy(validation)
        try:
            lib_tools = self.get_tools(to_read_library_content=True)
        except LibraryToolsUnavailable:
            validation.set_summary(
                StudioValidationMessage(
                    StudioValidationMessage.ERROR,
                    _(
                        "This course does not support content libraries. "
                        "Contact your system administrator for more information."
                    )
                )
            )
            return validation
        if not self.source_library_id:
            validation.set_summary(
                StudioValidationMessage(
                    StudioValidationMessage.NOT_CONFIGURED,
                    _("A library has not yet been selected."),
                    action_class='edit-button',
                    action_label=_("Select a Library.")
                )
            )
            return validation
        self._validate_library_version(validation, lib_tools, self.source_library_version, self.source_library_key)

        # Note: we assume children have been synced
        # since the last time fields like source_library_id or capa_types were changed.
        matching_children_count = len(self.children)  # pylint: disable=no-member
        if matching_children_count == 0:
            self._set_validation_error_if_empty(
                validation,
                StudioValidationMessage(
                    StudioValidationMessage.WARNING,
                    (gettext('There are no problems in the specified library of type {capa_type}.'))
                    .format(capa_type=self.capa_type),
                    action_class='edit-button',
                    action_label=_("Select another problem type.")
                )
            )

        if matching_children_count < self.max_count:
            self._set_validation_error_if_empty(
                validation,
                StudioValidationMessage(
                    StudioValidationMessage.WARNING,
                    (
                        ngettext(
                            'The specified library is configured to fetch {count} problem, ',
                            'The specified library is configured to fetch {count} problems, ',
                            self.max_count
                        ) +
                        ngettext(
                            'but there is only {actual} matching problem.',
                            'but there are only {actual} matching problems.',
                            matching_children_count
                        )
                    ).format(count=self.max_count, actual=matching_children_count),
                    action_class='edit-button',
                    action_label=_("Edit the library configuration.")
                )
            )

        return validation

    def source_library_values(self):
        """
        Return a list of possible values for self.source_library_id
        """
        lib_tools = self.get_tools()
        user_perms = self.runtime.service(self, 'studio_user_permissions')
        all_libraries = [
            (key, nh3.clean(name)) for key, name in lib_tools.list_available_libraries()
            if user_perms.can_read(key) or self.source_library_id == str(key)
        ]
        all_libraries.sort(key=lambda entry: entry[1])  # Sort by name
        if self.source_library_id and self.source_library_key not in [entry[0] for entry in all_libraries]:
            all_libraries.append((self.source_library_id, _("Invalid Library")))
        all_libraries = [("", _("No Library Selected"))] + all_libraries
        values = [{"display_name": name, "value": str(key)} for key, name in all_libraries]
        return values

    def post_editor_saved(self, user, old_metadata, old_content):  # pylint: disable=unused-argument
        """
        If source library or capa_type have been edited, upgrade library & sync automatically.
        """
        source_lib_changed = (self.source_library_id != old_metadata.get("source_library_id", ""))
        capa_filter_changed = (self.capa_type != old_metadata.get("capa_type", ANY_CAPA_TYPE_VALUE))
        if source_lib_changed or capa_filter_changed:
            try:
                self.sync_from_library(upgrade_to_latest=True)
            except (ObjectDoesNotExist, LibraryToolsUnavailable):
                # The validation area will display an error message, no need to do anything now.
                pass

    def format_block_keys_for_analytics(self, block_keys: list[tuple[str, str]]) -> list[dict]:
        """
        Implement format_block_keys_for_analytics using the modulestore-specific legacy library original-usage system.
        """
        def summarize_block(usage_key):
            """ Basic information about the given block """
            orig_key, orig_version = self.runtime.modulestore.get_block_original_usage(usage_key)
            return {
                "usage_key": str(usage_key),
                "original_usage_key": str(orig_key.replace(version=None, branch=None)) if orig_key else None,
                "original_usage_version": str(orig_version) if orig_version else None,
            }

        result_json = []
        for block_key in block_keys:
            key = self.context_key.make_usage_key(*block_key)
            info = summarize_block(key)
            info['descendants'] = []
            try:
                block = self.runtime.modulestore.get_item(key, depth=None)  # Load the item and all descendants
                children = list(getattr(block, "children", []))
                while children:
                    child_key = children.pop().replace(version=None, branch=None)
                    child = self.runtime.modulestore.get_item(child_key)
                    info['descendants'].append(summarize_block(child_key))
                    children.extend(getattr(child, "children", []))
            except ItemNotFoundError:
                pass  # The block has been deleted
            result_json.append(info)
        return result_json

    @classmethod
    def get_selected_event_prefix(cls) -> str:
        """
        Prefix for events on `self.selected`.

        We use librarycontent rather than legacylibrarycontent for backwards compatibility (this wasn't always the
        "legacy" library content block :)
        """
        return "edx.librarycontentblock.content"


class LegacyLibrarySummary:
    """
    A library summary object which contains the fields required for library listing on studio.
    """

    def __init__(self, library_locator, display_name):
        """
        Initialize LegacyLibrarySummary

        Arguments:
        library_locator (LibraryLocator):  LibraryLocator object of the library.

        display_name (unicode): display name of the library.
        """
        self.display_name = display_name if display_name else _("Empty")

        self.id = library_locator  # pylint: disable=invalid-name
        self.location = library_locator.make_usage_key('library', 'library')

    @property
    def display_org_with_default(self):
        """
        Org display names are not implemented. This just provides API compatibility with CourseBlock.
        Always returns the raw 'org' field from the key.
        """
        return self.location.library_key.org

    @property
    def display_number_with_default(self):
        """
        Display numbers are not implemented. This just provides API compatibility with CourseBlock.
        Always returns the raw 'library' field from the key.
        """
        return self.location.library_key.library