//
//  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 doneButton: UIBarButtonItem!
    private var pasteButton: UIBarButtonItem!
    private var resetButton: UIBarButtonItem!
    private var rightBarButtonMode: RightBarButtonMode = .paste
    private var isCloudFormatted = false

    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()
    }

    private func setupUI() {
        textView = UITextView()
        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.backgroundColor = .systemBackground
        textView.layer.cornerRadius = 12
        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)

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

        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)
        ])
    }

    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 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() {
        textView.text = ""
        rightBarButtonMode = .paste
        isCloudFormatted = false
        iCloudButton.setTitle("iCloud 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 = 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
        }
        textView.text = formatForNote(textView.text)
        rightBarButtonMode = .reset
        updateRightBarButtonItem()
    }

    private func formatForCloud(_ text: String) -> String {
        var content = text
        content = content.replacingOccurrences(of: " ", with: "")
        content = content.replacingOccurrences(of: "　", with: "")
        content = content.replacingOccurrences(of: "\u{00A0}", with: "")
        content = content.replacingOccurrences(of: "# ", with: "")
        content = content.replacingOccurrences(of: "#", with: "")
        content = content.replacingOccurrences(of: "！", with: "。")
        content = content.replacingOccurrences(of: "!", with: "。")
        content = content.replacingOccurrences(of: ";", with: "。")
        content = content.replacingOccurrences(of: "；", with: "。")
        content = content.replacingOccurrences(of: ".", with: "。")
        content = content.replacingOccurrences(of: "（", with: "(")
        content = content.replacingOccurrences(of: "）", with: ")")
        content = content.replacingOccurrences(of: "?", with: "？")
        content = content.replacingOccurrences(of: ",", with: "，")
        content = content.replacingOccurrences(of: ":", with: "：")

        let numberReplacements: [(String, String)] = [
            ("20、", "二十、"), ("19、", "十九、"), ("18、", "十八、"), ("17、", "十七、"),
            ("16、", "十六、"), ("15、", "十五、"), ("14、", "十四、"), ("13、", "十三、"),
            ("12、", "十二、"), ("11、", "十一、"), ("10、", "十、"),
            ("9、", "九、"), ("8、", "八、"), ("7、", "七、"), ("6、", "六、"),
            ("5、", "五、"), ("4、", "四、"), ("3、", "三、"), ("2、", "二、"), ("1、", "一、")
        ]
        for (old, new) in numberReplacements {
            content = content.replacingOccurrences(of: old, with: new)
        }

        content = content.replacingOccurrences(of: "。", with: "。\n")
        content = content.replacingOccurrences(of: "？", with: "？\n")
        content = removeEmptyLines(content)
        content = content.replacingOccurrences(of: "：\\s*", with: "：\n\n", options: .regularExpression)
        content = content.replacingOccurrences(of: "。", with: "。\n")
        content = content.replacingOccurrences(of: "？", with: "？\n")
        content = content.replacingOccurrences(of: "：\n\n", with: "：")
        content = content.replacingOccurrences(of: "：一、", with: "：\n\n一、")
        content = content.replacingOccurrences(of: " ", with: "")
        content = content.replacingOccurrences(of: "---", with: "---\n")
        content = content.replacingOccurrences(of: "日星期", with: "日 星期")
        content = "# " + content
        content = insertEmptyLineAfterFirstLine(content)
        return content
    }

    private func formatForNote(_ text: String) -> String {
        var content = text
        content = content.replacingOccurrences(of: " ", with: "")
        content = content.replacingOccurrences(of: "# ", with: "")
        content = content.replacingOccurrences(of: "#", with: "")
        content = content.replacingOccurrences(of: "！", with: "。")
        content = content.replacingOccurrences(of: "!", with: "。")
        content = content.replacingOccurrences(of: ";", with: "。")
        content = content.replacingOccurrences(of: "；", with: "。")
        content = content.replacingOccurrences(of: ".", with: "。")
        content = content.replacingOccurrences(of: "（", with: "(")
        content = content.replacingOccurrences(of: "）", with: ")")
        content = content.replacingOccurrences(of: "?", with: "？")
        content = content.replacingOccurrences(of: ",", with: "，")
        content = content.replacingOccurrences(of: ":", with: "：")
        content = content.replacingOccurrences(of: "。", with: "。\n")
        content = content.replacingOccurrences(of: "？", with: "？\n")
        content = removeEmptyLines(content)
        content = content.replacingOccurrences(of: "---", with: "")
        content = content.replacingOccurrences(of: "日星期", with: "日 星期")
        content = insertEmptyLineAfterFirstLine(content)
        return content
    }

    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"
    }

    private func removeEmptyLines(_ text: String) -> String {
        let lines = text.components(separatedBy: .newlines)
        let nonEmptyLines = lines.filter { !$0.trimmingCharacters(in: .whitespaces).isEmpty }
        return nonEmptyLines.joined(separator: "\n")
    }

    private func insertEmptyLineAfterFirstLine(_ text: String) -> String {
        var lines = text.components(separatedBy: .newlines)
        if !lines.isEmpty {
            lines.insert("", at: 1)
        }
        return lines.joined(separator: "\n")
    }
}

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()
    }
}