//
//  ComposeInput.swift
//  ComposeUI
//
//  Created by Shadowfacts on 3/5/23.
//

import Foundation
import Combine
import UIKit
import SwiftUI

protocol ComposeInput: AnyObject, ObservableObject {
    var toolbarElements: [ToolbarElement] { get }
    var textInputMode: UITextInputMode? { get }
    
    var autocompleteState: AutocompleteState? { get }
    var autocompleteStatePublisher: Published<AutocompleteState?>.Publisher { get }
    
    func autocomplete(with string: String)
    
    func applyFormat(_ format: StatusFormat)
    
    func beginAutocompletingEmoji()
}

enum ToolbarElement {
    case emojiPicker
    case formattingButtons
}

private struct FocusedComposeInput: FocusedValueKey {
    typealias Value = (any ComposeInput)?
}

extension FocusedValues {
    // double optional is necessary pre-iOS 16
    var composeInput: (any ComposeInput)?? {
        get { self[FocusedComposeInput.self] }
        set { self[FocusedComposeInput.self] = newValue }
    }
}

@propertyWrapper
final class MutableObservableBox<Value>: ObservableObject {
    @Published var wrappedValue: Value
    
    init(wrappedValue: Value) {
        self.wrappedValue = wrappedValue
    }
}

private struct FocusedComposeInputBox: EnvironmentKey {
    static let defaultValue: MutableObservableBox<(any ComposeInput)?> = .init(wrappedValue: nil)
}

extension EnvironmentValues {
    var composeInputBox: MutableObservableBox<(any ComposeInput)?> {
        get { self[FocusedComposeInputBox.self] }
        set { self[FocusedComposeInputBox.self] = newValue }
    }
}

struct FocusedInputModifier: ViewModifier {
    @StateObject var box: MutableObservableBox<(any ComposeInput)?> = .init(wrappedValue: nil)
    
    func body(content: Content) -> some View {
        content
            .environment(\.composeInputBox, box)
            .focusedValue(\.composeInput, box.wrappedValue)
    }
}