[Feature request] search CJK characters

[swifterslb]

Official Telegram doesn't support searching for CJK (Chinese, Japanese and Korean) characters. This is very inconvenient. Swiftgram has realized this function. Is it possible to implement it in Forkgram? Thanks!

[Crystal-RainSlide]

I took a look within the changes made to offical iOS version in version 11.5.3 of Swiftgram. It's not a specifc CJK character searching support, but a local message searching fallback, which only happens when there is a "no result found" from Telegram server.

Instead of doesn't support CJK, offical Telegram kind of like only support searching the words of Latin-like languages, it don't work for partial matching for any language that are written without words and spaces.

On the other side, a program language's "local search", like text.contains(query), is mostly just plain text matching, which almost always works to some extent (as long as there isn't any nasty Unicode stuff):

https://github.com/Swiftgram/Telegram-iOS/blob/7d4b4eaf6cf4cffaf328a8edf2e161e0de180795/submodules/TelegramCore/Sources/TelegramEngine/Messages/SearchMessages.swift#L330-L347

                    // MARK: Swiftgram
                    var result: [Message] = []
                    if forceLocal {
                        transaction.withAllMessages(peerId: peerId, reversed: true, { message in
                            if result.count >= limit {
                                return false
                            }
                            if let tags = tags, message.tags != tags {
                                return true
                            }
                            if message.text.contains(query) {
                                result.append(message)
                            }
                            return true
                        })
                    } else {
                        result = transaction.searchMessages(peerId: peerId, query: query, tags: tags)
                    }

This is a good addition even if it only support local messages.

However, since full-text matching still works, when the Telegram server actually returns some message(s) from the full-text matching (when result.0.totalCount > 0 is true), then Swiftgram won't trigger the local searching:

https://github.com/Swiftgram/Telegram-iOS/blob/7d4b4eaf6cf4cffaf328a8edf2e161e0de180795/submodules/TelegramCore/Sources/TelegramEngine/Messages/TelegramEngineMessages.swift#L79-L85

            // TODO(swiftgram): Try to fallback on error when searching. RX is hard...
            |> mapToSignal { result -> Signal<(SearchMessagesResult, SearchMessagesState), NoError> in
                if (result.0.totalCount > 0) {
                    return .single(result)
                }
                return _internal_searchMessages(account: self.account, location: location, query: query, state: state, centerId: centerId, limit: limit, forceLocal: true)
            }

So, other than the local search feature itself, a "Local Search" toggle (or anything like that) is also needed to make it accessible, to make it a finished feature. Instead of only do local search when Telegram server search returns no result.

(Open Swiftgram/Telegram-iOS@7d4b4ea on PC, then search forceLocal: in the top right commit search box to locate those changes yourself.)