//
//  CalculatorHistoryViewController.swift
//  Swift iOS Calculator
//
//  Created by RSK World on 23/01/2026.
//  Copyright © 2026 RSK World. All rights reserved.
//
//  Developer: Molla Samser (Founder, RSK World)
//  Designer & Tester: Rima Khatun
//  Contact: info@rskworld.com, +91 93305 39277
//  Website: https://rskworld.in
//  Address: Nutanhat, Mongolkote, Purba Burdwan, West Bengal, India - 713147
//

import UIKit

class CalculatorHistoryViewController: UIViewController {
    
    // MARK: - Outlets
    @IBOutlet weak var tableView: UITableView!
    @IBOutlet weak var clearHistoryButton: UIBarButtonItem!
    
    // MARK: - Properties
    private var history: [String] = []
    private var calculator = CalculatorLogic()
    
    // MARK: - Lifecycle
    override func viewDidLoad() {
        super.viewDidLoad()
        setupUI()
        loadHistory()
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        loadHistory()
    }
    
    // MARK: - UI Setup
    private func setupUI() {
        title = "History"
        
        navigationItem.rightBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .trash,
            target: self,
            action: #selector(clearHistoryTapped)
        )
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .done,
            target: self,
            action: #selector(doneTapped)
        )
        
        tableView.delegate = self
        tableView.dataSource = self
        
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "HistoryCell")
    }
    
    private func loadHistory() {
        history = calculator.getHistory()
        tableView.reloadData()
        updateClearButtonState()
    }
    
    private func updateClearButtonState() {
        clearHistoryButton.isEnabled = !history.isEmpty
    }
    
    // MARK: - Actions
    @objc private func clearHistoryTapped() {
        let alert = UIAlertController(
            title: "Clear History",
            message: "Are you sure you want to clear all calculation history?",
            preferredStyle: .alert
        )
        
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
        alert.addAction(UIAlertAction(title: "Clear", style: .destructive) { _ in
            self.calculator.clearHistory()
            self.loadHistory()
        })
        
        present(alert, animated: true)
    }
    
    @objc private func doneTapped() {
        dismiss(animated: true)
    }
    
    @IBAction func shareHistoryTapped(_ sender: UIBarButtonItem) {
        guard !history.isEmpty else {
            let alert = UIAlertController(
                title: "No History",
                message: "There is no history to share.",
                preferredStyle: .alert
            )
            alert.addAction(UIAlertAction(title: "OK", style: .default))
            present(alert, animated: true)
            return
        }
        
        let historyText = history.enumerated().map { index, calculation in
            "\(index + 1). \(calculation)"
        }.joined(separator: "\n")
        
        let activityViewController = UIActivityViewController(
            activityItems: [historyText],
            applicationActivities: nil
        )
        
        if let popover = activityViewController.popoverPresentationController {
            popover.barButtonItem = sender
        }
        
        present(activityViewController, animated: true)
    }
}

// MARK: - UITableViewDataSource
extension CalculatorHistoryViewController: UITableViewDataSource {
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return history.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "HistoryCell", for: indexPath)
        
        let calculation = history[indexPath.row]
        cell.textLabel?.text = calculation
        cell.textLabel?.font = UIFont.systemFont(ofSize: 16)
        cell.textLabel?.numberOfLines = 0
        cell.selectionStyle = .none
        
        return cell
    }
}

// MARK: - UITableViewDelegate
extension CalculatorHistoryViewController: UITableViewDelegate {
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        
        let calculation = history[indexPath.row]
        
        let alert = UIAlertController(
            title: "Calculation",
            message: calculation,
            preferredStyle: .alert
        )
        
        alert.addAction(UIAlertAction(title: "Copy", style: .default) { _ in
            UIPasteboard.general.string = calculation
        })
        
        alert.addAction(UIAlertAction(title: "Use in Calculator", style: .default) { _ in
            // Extract the result from the calculation and use it
            if let result = self.extractResult(from: calculation) {
                NotificationCenter.default.post(
                    name: NSNotification.Name("UseHistoryResult"),
                    object: result
                )
                self.dismiss(animated: true)
            }
        })
        
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
        
        present(alert, animated: true)
    }
    
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return UITableView.automaticDimension
    }
    
    func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
        return 60
    }
    
    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        if editingStyle == .delete {
            history.remove(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: .fade)
            updateClearButtonState()
        }
    }
    
    // MARK: - Helper Methods
    private func extractResult(from calculation: String) -> String? {
        // Extract the result from a calculation string like "5 + 3 = 8"
        let components = calculation.components(separatedBy: "=")
        return components.last?.trimmingCharacters(in: .whitespaces)
    }
}