//
//  FormatNoteViewController.swift
//  Note
//
//  Created by fish on 2026/7/12.
//

import UIKit

class FormatNoteViewController: UIViewController {

    private var textView: UITextView!
    private var iCloudButton: UIButton!
    private var noteButton: UIButton!
    private var floatingDoneButton: UIButton!
    private var floatingDoneButtonBottomConstraint: NSLayoutConstraint!
    private var doneButton: UIBarButtonItem!
    private var pasteButton: UIBarButtonItem!
    private var resetButton: UIBarButtonItem!
    private var rightBarButtonMode: RightBarButtonMode = .paste
    private var isCloudFormatted = false
    private var isNoteFormatted = false
    var initialText: String?

    private enum RightBarButtonMode {
        case paste
        case reset
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        title = "格式化笔记"
        navigationItem.largeTitleDisplayMode = .never
        view.backgroundColor = .systemGroupedBackground
        setupUI()
        if let initialText = initialText {
            textView.text = initialText
        }
        setupKeyboardObservers()
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    private func setupUI() {
        textView = UITextView()
        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.backgroundColor = UIColor { traitCollection in
            traitCollection.userInterfaceStyle == .dark ? .secondarySystemBackground : .white
        }
        textView.layer.cornerRadius = 12
        textView.layer.borderWidth = 0.5
        textView.layer.borderColor = UIColor.separator.cgColor
        textView.layer.masksToBounds = true
        textView.font = UIFont.preferredFont(forTextStyle: .body)
        textView.textContainerInset = UIEdgeInsets(top: 12, left: 12, bottom: 12, right: 12)
        textView.isEditable = true
        textView.delegate = self
        view.addSubview(textView)

        doneButton = UIBarButtonItem(title: "完成", style: .plain, target: self, action: #selector(didTapDoneButton))
        pasteButton = UIBarButtonItem(title: "粘贴文案", style: .plain, target: self, action: #selector(didTapPasteButton))
        resetButton = UIBarButtonItem(title: "重置", style: .plain, target: self, action: #selector(didTapResetButton))
        updateRightBarButtonItem()

        iCloudButton = createBottomButton(title: "iCloud 格式化", color: .systemBlue)
        iCloudButton.addTarget(self, action: #selector(didTapiCloudButton), for: .touchUpInside)
        view.addSubview(iCloudButton)

        noteButton = createBottomButton(title: "Note 格式化", color: .systemGreen)
        noteButton.addTarget(self, action: #selector(didTapNoteButton), for: .touchUpInside)
        view.addSubview(noteButton)

        var doneConfig = UIButton.Configuration.glass()
        doneConfig.title = "完成"
        doneConfig.titleTextAttributesTransformer = UIConfigurationTextAttributesTransformer { incoming in
            var outgoing = incoming
            outgoing.font = UIFont.systemFont(ofSize: 17, weight: .semibold)
            return outgoing
        }
        doneConfig.baseForegroundColor = .label
        doneConfig.cornerStyle = .capsule
        doneConfig.contentInsets = NSDirectionalEdgeInsets(top: 15, leading: 22, bottom: 15, trailing: 22)
        floatingDoneButton = UIButton(configuration: doneConfig)
        floatingDoneButton.translatesAutoresizingMaskIntoConstraints = false
        floatingDoneButton.alpha = 0
        floatingDoneButton.addTarget(self, action: #selector(didTapFloatingDoneButton), for: .touchUpInside)
        view.addSubview(floatingDoneButton)

        let safeArea = view.safeAreaLayoutGuide
        let buttonHeight: CGFloat = 52
        let spacing: CGFloat = 16

        floatingDoneButtonBottomConstraint = floatingDoneButton.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -spacing)

        NSLayoutConstraint.activate([
            textView.topAnchor.constraint(equalTo: safeArea.topAnchor, constant: spacing),
            textView.leadingAnchor.constraint(equalTo: safeArea.leadingAnchor, constant: spacing),
            textView.trailingAnchor.constraint(equalTo: safeArea.trailingAnchor, constant: -spacing),

            iCloudButton.topAnchor.constraint(equalTo: textView.bottomAnchor, constant: spacing),
            iCloudButton.leadingAnchor.constraint(equalTo: safeArea.leadingAnchor, constant: spacing),
            iCloudButton.trailingAnchor.constraint(equalTo: safeArea.centerXAnchor, constant: -spacing / 2),
            iCloudButton.heightAnchor.constraint(equalToConstant: buttonHeight),
            iCloudButton.bottomAnchor.constraint(equalTo: safeArea.bottomAnchor, constant: -spacing),

            noteButton.topAnchor.constraint(equalTo: textView.bottomAnchor, constant: spacing),
            noteButton.leadingAnchor.constraint(equalTo: safeArea.centerXAnchor, constant: spacing / 2),
            noteButton.trailingAnchor.constraint(equalTo: safeArea.trailingAnchor, constant: -spacing),
            noteButton.heightAnchor.constraint(equalToConstant: buttonHeight),
            noteButton.bottomAnchor.constraint(equalTo: safeArea.bottomAnchor, constant: -spacing),

            floatingDoneButton.trailingAnchor.constraint(equalTo: safeArea.trailingAnchor, constant: -spacing),
            floatingDoneButtonBottomConstraint
        ])
    }

    private func createBottomButton(title: String, color: UIColor) -> UIButton {
        var config = UIButton.Configuration.filled()
        config.title = title
        config.baseBackgroundColor = color
        config.baseForegroundColor = .white
        config.cornerStyle = .medium
        config.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 16)

        let button = UIButton(configuration: config)
        button.translatesAutoresizingMaskIntoConstraints = false
        return button
    }

    @objc private func didTapDoneButton() {
        textView.resignFirstResponder()
    }

    @objc private func didTapFloatingDoneButton() {
        textView.resignFirstResponder()
    }

    private func setupKeyboardObservers() {
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)
    }

    @objc private func keyboardWillShow(_ notification: Notification) {
        guard let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else { return }
        let keyboardFrameInView = view.convert(keyboardFrame, from: nil)
        let intersection = keyboardFrameInView.intersection(view.bounds)
        let keyboardHeight = intersection.height

        let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? TimeInterval ?? 0.25

        UIView.animate(withDuration: duration, delay: 0, options: .beginFromCurrentState) {
            self.textView.contentInset.bottom = keyboardHeight
            self.textView.verticalScrollIndicatorInsets.bottom = keyboardHeight
            self.floatingDoneButtonBottomConstraint.constant = -(keyboardHeight + 8)
            self.floatingDoneButton.alpha = 1
            self.view.layoutIfNeeded()
        }
    }

    @objc private func keyboardWillHide(_ notification: Notification) {
        let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? TimeInterval ?? 0.25

        UIView.animate(withDuration: duration, delay: 0, options: .beginFromCurrentState) {
            self.textView.contentInset.bottom = 0
            self.textView.verticalScrollIndicatorInsets.bottom = 0
            self.floatingDoneButtonBottomConstraint.constant = -16
            self.floatingDoneButton.alpha = 0
            self.view.layoutIfNeeded()
        }
    }

    @objc private func didTapPasteButton() {
        if let string = UIPasteboard.general.string {
            textView.text = string
        }
    }

    private func trimmedText() -> String {
        return textView.text?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
    }

    private func showEmptyAlert() {
        let alert = UIAlertController(title: "提示", message: "请输入内容后再进行格式化", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "确定", style: .default))
        present(alert, animated: true)
    }

    @objc private func didTapResetButton() {
        let alert = UIAlertController(
            title: "确认重置",
            message: "确定要清空当前内容吗？",
            preferredStyle: .alert
        )
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "重置", style: .destructive) { [weak self] _ in
            self?.performReset()
        })
        present(alert, animated: true)
    }

    private func performReset() {
        textView.text = ""
        rightBarButtonMode = .paste
        isCloudFormatted = false
        isNoteFormatted = false
        iCloudButton.setTitle("iCloud 格式化", for: .normal)
        noteButton.setTitle("Note 格式化", for: .normal)
        updateRightBarButtonItem()
    }

    private func updateRightBarButtonItem() {
        if textView.isFirstResponder {
            navigationItem.rightBarButtonItem = doneButton
        } else {
            switch rightBarButtonMode {
            case .paste:
                navigationItem.rightBarButtonItem = pasteButton
            case .reset:
                navigationItem.rightBarButtonItem = resetButton
            }
        }
    }

    @objc private func didTapiCloudButton() {
        guard !trimmedText().isEmpty else {
            showEmptyAlert()
            return
        }
        if isCloudFormatted {
            saveToFiles()
        } else {
            textView.text = TextFormatter.formatForCloud(textView.text)
            isCloudFormatted = true
            iCloudButton.setTitle("保存到 iCloud", for: .normal)
            rightBarButtonMode = .reset
            updateRightBarButtonItem()
        }
    }

    @objc private func didTapNoteButton() {
        guard !trimmedText().isEmpty else {
            showEmptyAlert()
            return
        }
        if isNoteFormatted {
            copyAndOpenNotes()
        } else {
            textView.text = TextFormatter.formatForNote(textView.text)
            isNoteFormatted = true
            noteButton.setTitle("复制并打开备忘录", for: .normal)
            rightBarButtonMode = .reset
            updateRightBarButtonItem()
        }
    }

    private func copyAndOpenNotes() {
        UIPasteboard.general.string = textView.text
        guard let url = URL(string: "mobilenotes://") else { return }
        guard UIApplication.shared.canOpenURL(url) else { return }
        UIApplication.shared.open(url, options: [:], completionHandler: nil)
    }

    private func saveToFiles() {
        let fileName = generateFileName()
        let fileURL = FileManager.default.temporaryDirectory.appendingPathComponent(fileName)

        do {
            try textView.text.write(to: fileURL, atomically: true, encoding: .utf8)
            let documentPicker = UIDocumentPickerViewController(forExporting: [fileURL], asCopy: true)
            documentPicker.delegate = self
            present(documentPicker, animated: true)
        } catch {
            print("Failed to write file: \(error)")
        }
    }

    private func generateFileName() -> String {
        let text = textView.text ?? ""
        let firstLine = text.components(separatedBy: .newlines).first ?? ""
        let trimmed = firstLine.trimmingCharacters(in: .whitespaces)
        let withoutHash = trimmed.replacingOccurrences(of: "^#\\s*", with: "", options: .regularExpression)
        let cleanName = withoutHash.trimmingCharacters(in: .whitespaces)

        if cleanName.isEmpty {
            return "formatted_note_\(Int(Date().timeIntervalSince1970)).md"
        }
        return cleanName + ".md"
    }
}

extension FormatNoteViewController: UIDocumentPickerDelegate {

    func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
        // File saved to selected location
    }

    func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
        // User cancelled
    }
}

extension FormatNoteViewController: UITextViewDelegate {

    func textViewDidBeginEditing(_ textView: UITextView) {
        updateRightBarButtonItem()
    }

    func textViewDidEndEditing(_ textView: UITextView) {
        updateRightBarButtonItem()
    }
}