Swiftgram/submodules/TelegramUI/Sources/ChatTextFormat.swift

import Foundation
import TextFormat
import AccountContext

func chatTextInputAddFormattingAttribute(_ state: ChatTextInputState, attribute: NSAttributedString.Key) -> ChatTextInputState {
    if !state.selectionRange.isEmpty {
        let nsRange = NSRange(location: state.selectionRange.lowerBound, length: state.selectionRange.count)
        var addAttribute = true
        var attributesToRemove: [NSAttributedString.Key] = []
        state.inputText.enumerateAttributes(in: nsRange, options: .longestEffectiveRangeNotRequired) { attributes, range, stop in
            for (key, _) in attributes {
                if key == attribute && range == nsRange {
                    addAttribute = false
                    attributesToRemove.append(key)
                }
            }
        }
        
        let result = NSMutableAttributedString(attributedString: state.inputText)
        for attribute in attributesToRemove {
            result.removeAttribute(attribute, range: nsRange)
        }
        if addAttribute {
            result.addAttribute(attribute, value: true as Bool, range: nsRange)
        }
        return ChatTextInputState(inputText: result, selectionRange: state.selectionRange)
    } else {
        return state
    }
}

func chatTextInputClearFormattingAttributes(_ state: ChatTextInputState) -> ChatTextInputState {
    if !state.selectionRange.isEmpty {
        let nsRange = NSRange(location: state.selectionRange.lowerBound, length: state.selectionRange.count)
        var attributesToRemove: [NSAttributedString.Key] = []
        state.inputText.enumerateAttributes(in: nsRange, options: .longestEffectiveRangeNotRequired) { attributes, range, stop in
            for (key, _) in attributes {
                attributesToRemove.append(key)
            }
        }
        
        let result = NSMutableAttributedString(attributedString: state.inputText)
        for attribute in attributesToRemove {
            result.removeAttribute(attribute, range: nsRange)
        }
        return ChatTextInputState(inputText: result, selectionRange: state.selectionRange)
    } else {
        return state
    }
}

func chatTextInputAddLinkAttribute(_ state: ChatTextInputState, url: String) -> ChatTextInputState {
    if !state.selectionRange.isEmpty {
        let nsRange = NSRange(location: state.selectionRange.lowerBound, length: state.selectionRange.count)
        var linkRange = nsRange
        var attributesToRemove: [(NSAttributedString.Key, NSRange)] = []
        state.inputText.enumerateAttributes(in: nsRange, options: .longestEffectiveRangeNotRequired) { attributes, range, stop in
            for (key, _) in attributes {
                if key == ChatTextInputAttributes.textUrl {
                    attributesToRemove.append((key, range))
                    linkRange = linkRange.union(range)
                } else {
                    attributesToRemove.append((key, nsRange))
                }
            }
        }
        
        let result = NSMutableAttributedString(attributedString: state.inputText)
        for (attribute, range) in attributesToRemove {
            result.removeAttribute(attribute, range: range)
        }
        result.addAttribute(ChatTextInputAttributes.textUrl, value: ChatTextInputTextUrlAttribute(url: url), range: nsRange)
        return ChatTextInputState(inputText: result, selectionRange: state.selectionRange)
    } else {
        return state
    }
}