//
//  ComposeHostingController.swift
//  Tusker
//
//  Created by Shadowfacts on 8/22/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import SwiftUI
import Combine
import Pachyderm
import PencilKit
import Duckable

protocol ComposeHostingControllerDelegate: AnyObject {
    func dismissCompose(mode: ComposeUIState.DismissMode) -> Bool
}

class ComposeHostingController: UIHostingController<ComposeHostingController.Wrapper>, DuckableViewController {
    
    weak var delegate: ComposeHostingControllerDelegate?
    weak var duckableDelegate: DuckableViewControllerDelegate?
    
    let mastodonController: MastodonController
    
    let uiState: ComposeUIState
    
    var draft: OldDraft { uiState.draft }
    
    private var cancellables = [AnyCancellable]()
    
    init(draft: OldDraft? = nil, mastodonController: MastodonController) {
        self.mastodonController = mastodonController
        let realDraft = draft ?? OldDraft(accountID: mastodonController.accountInfo!.id)
        OldDraftsManager.shared.add(realDraft)
        
        self.uiState = ComposeUIState(draft: realDraft)
        
        let wrapper = Wrapper(
            mastodonController: mastodonController,
            uiState: uiState
        )
        super.init(rootView: wrapper)
        
        self.uiState.delegate = self
        pasteConfiguration = UIPasteConfiguration(forAccepting: CompositionAttachment.self)
        userActivity = UserActivityManager.newPostActivity(accountID: mastodonController.accountInfo!.id)
        
        updateNavigationTitle(draft: uiState.draft)
        
        self.uiState.$draft
            .flatMap(\.objectWillChange)
            .debounce(for: .milliseconds(250), scheduler: DispatchQueue.global(qos: .utility))
            .sink {
                OldDraftsManager.save()
            }
            .store(in: &cancellables)
        
        self.uiState.$draft
            .sink { [unowned self] draft in
                self.updateNavigationTitle(draft: draft)
            }
            .store(in: &cancellables)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func updateNavigationTitle(draft: OldDraft) {
        if let id = draft.inReplyToID,
           let status = mastodonController.persistentContainer.status(for: id) {
            navigationItem.title = "Reply to @\(status.account.acct)"
        } else {
            navigationItem.title = "New Post"
        }
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        
        if !draft.hasContent {
            OldDraftsManager.shared.remove(draft)
        }
        OldDraftsManager.save()
    }
    
    override func canPaste(_ itemProviders: [NSItemProvider]) -> Bool {
        guard itemProviders.allSatisfy({ $0.canLoadObject(ofClass: CompositionAttachment.self) }) else { return false }
        if mastodonController.instanceFeatures.mastodonAttachmentRestrictions {
            guard draft.attachments.allSatisfy({ $0.data.type == .image }) else { return false }
            // todo: if providers are videos, this technically allows invalid video/image combinations
            return itemProviders.count + draft.attachments.count <= 4
        } else {
            return true
        }
    }
    
    override func paste(itemProviders: [NSItemProvider]) {
        for provider in itemProviders where provider.canLoadObject(ofClass: CompositionAttachment.self) {
            provider.loadObject(ofClass: CompositionAttachment.self) { (object, error) in
                guard let attachment = object as? CompositionAttachment else { return }
                DispatchQueue.main.async {
                    self.draft.attachments.append(attachment)
                }
            }
        }
    }
    
    override func accessibilityPerformEscape() -> Bool {
        dismissCompose(mode: .cancel)
        return true
    }
    
    // MARK: Duckable
    
    func duckableViewControllerWillAnimateDuck(withDuration duration: CGFloat, afterDelay delay: CGFloat) {
        withAnimation(.linear(duration: duration).delay(delay)) {
            uiState.isDucking = true
        }
    }
    
    func duckableViewControllerDidFinishAnimatingDuck() {
        uiState.isDucking = false
    }
    
    // MARK: Interaction
    
    @objc func cwButtonPressed() {
        draft.contentWarningEnabled = !draft.contentWarningEnabled
    }
    
    @objc func formatButtonPressed(_ sender: UIBarButtonItem) {
        let format = StatusFormat.allCases[sender.tag]
        uiState.currentInput?.applyFormat(format)
    }
    
    @objc func emojiPickerButtonPressed() {
        guard uiState.autocompleteState == nil else {
            return
        }
        uiState.shouldEmojiAutocompletionBeginExpanded = true
        uiState.currentInput?.beginAutocompletingEmoji()
    }
    
    @objc func draftsButtonPresed() {
        uiState.isShowingDraftsList = true
    }
    
}

extension ComposeHostingController {
    struct Wrapper: View {
        let mastodonController: MastodonController
        @ObservedObject var uiState: ComposeUIState
        var draft: OldDraft {
            uiState.draft
        }
        
        var body: some View {
            ComposeView()
                .environmentObject(mastodonController)
                .environmentObject(uiState)
                .environmentObject(draft)
        }
    }
}

extension ComposeHostingController: ComposeUIStateDelegate {
    var assetPickerDelegate: AssetPickerViewControllerDelegate? { self }
    
    func dismissCompose(mode: ComposeUIState.DismissMode) {
        let dismissed = delegate?.dismissCompose(mode: mode) ?? false
        if !dismissed {
            self.dismiss(animated: true)
            self.duckableDelegate?.duckableViewControllerWillDismiss(animated: true)
        }
    }
    
    func presentAssetPickerSheet() {
        let picker = AssetPickerViewController()
        picker.assetPickerDelegate = self
        picker.modalPresentationStyle = .pageSheet
        picker.overrideUserInterfaceStyle = .dark
        let sheet = picker.sheetPresentationController!
        sheet.detents = [.medium(), .large()]
        sheet.prefersEdgeAttachedInCompactHeight = true
        self.present(picker, animated: true)
    }
    
    func presentComposeDrawing() {
        let drawing: PKDrawing
        
        if case let .edit(id) = uiState.composeDrawingMode,
           let attachment = draft.attachments.first(where: { $0.id == id }),
           case let .drawing(existingDrawing) = attachment.data {
            drawing = existingDrawing
        } else {
            drawing = PKDrawing()
        }
        
        present(ComposeDrawingNavigationController(editing: drawing, delegate: self), animated: true)
    }
    
    func selectDraft(_ draft: OldDraft) {
        if self.draft.hasContent {
            OldDraftsManager.save()
        } else {
            OldDraftsManager.shared.remove(self.draft)
        }
        uiState.draft = draft
        uiState.isShowingDraftsList = false
    }
}

extension ComposeHostingController: AssetPickerViewControllerDelegate {
    func assetPicker(_ assetPicker: AssetPickerViewController, shouldAllowAssetOfType type: CompositionAttachmentData.AttachmentType) -> Bool {
        if mastodonController.instanceFeatures.mastodonAttachmentRestrictions {
            if (type == .video && draft.attachments.count > 0) ||
                draft.attachments.contains(where: { $0.data.type == .video }) ||
                assetPicker.currentCollectionSelectedAssets.contains(where: { $0.type == .video }) {
                return false
            }
            return draft.attachments.count + assetPicker.currentCollectionSelectedAssets.count < 4
        } else {
            return true
        }
    }
    
    func assetPicker(_ assetPicker: AssetPickerViewController, didSelectAttachments attachments: [CompositionAttachmentData]) {
        let attachments = attachments.map {
            CompositionAttachment(data: $0)
        }
        withAnimation {
            draft.attachments.append(contentsOf: attachments)
        }
    }
}

// superseded by duckable stuff
@available(iOS, obsoleted: 16.0)
extension ComposeHostingController: UIAdaptivePresentationControllerDelegate {
    func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {
        return Preferences.shared.automaticallySaveDrafts || !draft.hasContent
    }
    
    func presentationControllerWillDismiss(_ presentationController: UIPresentationController) {
        UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: self, for: nil)
    }

    func presentationControllerDidAttemptToDismiss(_ presentationController: UIPresentationController) {
        uiState.isShowingSaveDraftSheet = true
    }
    
    func presentationControllerDidDismiss(_ presentationController: UIPresentationController) {
        OldDraftsManager.save()
    }
}

extension ComposeHostingController: ComposeDrawingViewControllerDelegate {
    func composeDrawingViewControllerClose(_ drawingController: ComposeDrawingViewController) {
        dismiss(animated: true)
    }
    
    func composeDrawingViewController(_ drawingController: ComposeDrawingViewController, saveDrawing drawing: PKDrawing) {
        switch uiState.composeDrawingMode {
        case nil, .createNew:
            let attachment = CompositionAttachment(data: .drawing(drawing))
            draft.attachments.append(attachment)
            
        case let .edit(id):
            let existing = draft.attachments.first { $0.id == id }
            existing?.data = .drawing(drawing)
        }
        
        dismiss(animated: true)
    }
}