# Copyright (c) 2022, Frappe Technologies Pvt. Ltd. and Contributors
# License: GNU General Public License v3. See license.txt

import json

import frappe
from frappe import _
from frappe.utils.redis_wrapper import RedisWrapper
from redis import ResponseError
from redis.commands.search.field import TagField, TextField
from redis.commands.search.indexDefinition import IndexDefinition
from redis.commands.search.suggestion import Suggestion

WEBSITE_ITEM_INDEX = "website_items_index"
WEBSITE_ITEM_KEY_PREFIX = "website_item:"
WEBSITE_ITEM_NAME_AUTOCOMPLETE = "website_items_name_dict"
WEBSITE_ITEM_CATEGORY_AUTOCOMPLETE = "website_items_category_dict"


def get_indexable_web_fields():
	"Return valid fields from Website Item that can be searched for."
	web_item_meta = frappe.get_meta("Website Item", cached=True)
	valid_fields = filter(
		lambda df: df.fieldtype in ("Link", "Table MultiSelect", "Data", "Small Text", "Text Editor"),
		web_item_meta.fields,
	)

	return [df.fieldname for df in valid_fields]


def is_redisearch_enabled():
	"Return True only if redisearch is loaded and enabled."
	is_redisearch_enabled = frappe.db.get_single_value("E Commerce Settings", "is_redisearch_enabled")
	return is_search_module_loaded() and is_redisearch_enabled


def is_search_module_loaded():
	try:
		cache = frappe.cache()
		for module in cache.module_list():
			if module.get(b"name") == b"search":
				return True
	except Exception:
		return False  # handling older redis versions


def if_redisearch_enabled(function):
	"Decorator to check if Redisearch is enabled."

	def wrapper(*args, **kwargs):
		if is_redisearch_enabled():
			func = function(*args, **kwargs)
			return func
		return

	return wrapper


def make_key(key):
	return frappe.cache().make_key(key)


@if_redisearch_enabled
def create_website_items_index():
	"Creates Index Definition."

	redis = frappe.cache()
	index = redis.ft(WEBSITE_ITEM_INDEX)

	try:
		index.dropindex()  # drop if already exists
	except ResponseError:
		# will most likely raise a ResponseError if index does not exist
		# ignore and create index
		pass
	except Exception:
		raise_redisearch_error()

	idx_def = IndexDefinition([make_key(WEBSITE_ITEM_KEY_PREFIX)])

	# Index fields mentioned in e-commerce settings
	idx_fields = frappe.db.get_single_value("E Commerce Settings", "search_index_fields")
	idx_fields = idx_fields.split(",") if idx_fields else []

	if "web_item_name" in idx_fields:
		idx_fields.remove("web_item_name")

	idx_fields = [to_search_field(f) for f in idx_fields]

	# TODO: sortable?
	index.create_index(
		[TextField("web_item_name", sortable=True)] + idx_fields,
		definition=idx_def,
	)

	reindex_all_web_items()
	define_autocomplete_dictionary()


def to_search_field(field):
	if field == "tags":
		return TagField("tags", separator=",")

	return TextField(field)


@if_redisearch_enabled
def insert_item_to_index(website_item_doc):
	# Insert item to index
	key = get_cache_key(website_item_doc.name)
	cache = frappe.cache()
	web_item = create_web_item_map(website_item_doc)

	for field, value in web_item.items():
		super(RedisWrapper, cache).hset(make_key(key), field, value)

	insert_to_name_ac(website_item_doc.web_item_name, website_item_doc.name)


@if_redisearch_enabled
def insert_to_name_ac(web_name, doc_name):
	ac = frappe.cache().ft()
	ac.sugadd(WEBSITE_ITEM_NAME_AUTOCOMPLETE, Suggestion(web_name, payload=doc_name))


def create_web_item_map(website_item_doc):
	fields_to_index = get_fields_indexed()
	web_item = {}

	for field in fields_to_index:
		web_item[field] = website_item_doc.get(field) or ""

	return web_item


@if_redisearch_enabled
def update_index_for_item(website_item_doc):
	# Reinsert to Cache
	insert_item_to_index(website_item_doc)
	define_autocomplete_dictionary()


@if_redisearch_enabled
def delete_item_from_index(website_item_doc):
	cache = frappe.cache()
	key = get_cache_key(website_item_doc.name)

	try:
		cache.delete(key)
	except Exception:
		raise_redisearch_error()

	delete_from_ac_dict(website_item_doc)
	return True


@if_redisearch_enabled
def delete_from_ac_dict(website_item_doc):
	"""Removes this items's name from autocomplete dictionary"""
	ac = frappe.cache().ft()
	ac.sugdel(website_item_doc.web_item_name)


@if_redisearch_enabled
def define_autocomplete_dictionary():
	"""
	Defines/Redefines an autocomplete search dictionary for Website Item Name.
	Also creats autocomplete dictionary for Published Item Groups.
	"""

	cache = frappe.cache()

	# Delete both autocomplete dicts
	try:
		cache.delete(make_key(WEBSITE_ITEM_NAME_AUTOCOMPLETE))
		cache.delete(make_key(WEBSITE_ITEM_CATEGORY_AUTOCOMPLETE))
	except Exception:
		raise_redisearch_error()

	create_items_autocomplete_dict()
	create_item_groups_autocomplete_dict()


@if_redisearch_enabled
def create_items_autocomplete_dict():
	"Add items as suggestions in Autocompleter."

	ac = frappe.cache().ft()
	items = frappe.get_all(
		"Website Item", fields=["web_item_name", "item_group"], filters={"published": 1}
	)
	for item in items:
		ac.sugadd(WEBSITE_ITEM_NAME_AUTOCOMPLETE, Suggestion(item.web_item_name))


@if_redisearch_enabled
def create_item_groups_autocomplete_dict():
	"Add item groups with weightage as suggestions in Autocompleter."

	published_item_groups = frappe.get_all(
		"Item Group", fields=["name", "route", "weightage"], filters={"show_in_website": 1}
	)
	if not published_item_groups:
		return

	ac = frappe.cache().ft()

	for item_group in published_item_groups:
		payload = json.dumps({"name": item_group.name, "route": item_group.route})
		ac.sugadd(
			WEBSITE_ITEM_CATEGORY_AUTOCOMPLETE,
			Suggestion(
				string=item_group.name,
				score=frappe.utils.flt(item_group.weightage) or 1.0,
				payload=payload,  # additional info that can be retrieved later
			),
		)


@if_redisearch_enabled
def reindex_all_web_items():
	items = frappe.get_all("Website Item", fields=get_fields_indexed(), filters={"published": True})

	cache = frappe.cache()
	for item in items:
		web_item = create_web_item_map(item)
		key = make_key(get_cache_key(item.name))

		for field, value in web_item.items():
			super(RedisWrapper, cache).hset(key, field, value)


def get_cache_key(name):
	name = frappe.scrub(name)
	return f"{WEBSITE_ITEM_KEY_PREFIX}{name}"


def get_fields_indexed():
	fields_to_index = frappe.db.get_single_value("E Commerce Settings", "search_index_fields")
	fields_to_index = fields_to_index.split(",") if fields_to_index else []

	mandatory_fields = ["name", "web_item_name", "route", "thumbnail", "ranking"]
	fields_to_index = fields_to_index + mandatory_fields

	return fields_to_index


def raise_redisearch_error():
	"Create an Error Log and raise error."
	log = frappe.log_error("Redisearch Error")
	log_link = frappe.utils.get_link_to_form("Error Log", log.name)

	frappe.throw(
		msg=_("Something went wrong. Check {0}").format(log_link), title=_("Redisearch Error")
	)