BasiciOSCalculator.swift

//
//  BasiciOSCalculator.swift

import SwiftUI

struct BasiciOSCalculator: View {
    @State private var displayValue: String = "0"
    @State private var currentOperation: Operation? = nil
    @State private var previousValue: Double? = nil
    @State private var shouldResetDisplay: Bool = false
    
    enum Operation {
        case add, subtract, multiply, divide, percentage
    }
    
    var body: some View {
        Button {
            // Main button action (if needed)
        } label: {
            VStack(spacing: 0) {
                TextField("0", text: $displayValue)
                    .font(.system(size: 64))
                    .foregroundColor(.white)
                    .frame(maxWidth: .infinity, alignment: .trailing)
                    .padding()
                    .disabled(true)
                
                VStack(spacing: 1) {
                    HStack(spacing: 1) {
                        Button(action: { /* Show menu */ }) {
                            Image(systemName: "list.bullet")
                                .foregroundColor(.white)
                                .frame(maxWidth: .infinity, maxHeight: .infinity)
                                .background(Color.secondary.opacity(0.5))
                        }
                        .contextMenu {
                            Button("Basic") { }
                            Button("Scientific") { }
                            Button("Math Notes") { }
                            Toggle("Convert", isOn: .constant(false))
                        }
                        Button("AC") { clear() }
                            .foregroundStyle(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.secondary.opacity(0.5))
                        Button("%") { performOperation(.percentage) }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.secondary.opacity(0.5))
                        Button("÷") { performOperation(.divide) }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.orange)
                    }
                    HStack(spacing: 1) {
                        ForEach(["7", "8", "9"], id: \.self) { number in
                            Button(number) { appendNumber(number) }
                                .foregroundColor(.white)
                                .frame(maxWidth: .infinity, maxHeight: .infinity)
                                .background(Color.secondary)
                        }
                        Button("×") { performOperation(.multiply) }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.orange)
                    }
                    HStack(spacing: 1) {
                        ForEach(["4", "5", "6"], id: \.self) { number in
                            Button(number) { appendNumber(number) }
                                .foregroundColor(.white)
                                .frame(maxWidth: .infinity, maxHeight: .infinity)
                                .background(Color.secondary)
                        }
                        Button("-") { performOperation(.subtract) }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.orange)
                    }
                    HStack(spacing: 1) {
                        ForEach(["1", "2", "3"], id: \.self) { number in
                            Button(number) { appendNumber(number) }
                                .foregroundColor(.white)
                                .frame(maxWidth: .infinity, maxHeight: .infinity)
                                .background(Color.secondary)
                        }
                        Button("+") { performOperation(.add) }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.orange)
                    }
                    HStack(spacing: 1) {
                        Button("0") { appendNumber("0") }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.secondary)
                        Button(".") { appendDecimal() }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.secondary)
                        Button("=") { calculateResult() }
                            .foregroundColor(.white)
                            .frame(maxWidth: .infinity, maxHeight: .infinity)
                            .background(Color.orange)
                    }
                }
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .background(Color.black)
        }
        .buttonStyle(.plain)
    }
    
    private func appendNumber(_ number: String) {
        if shouldResetDisplay {
            displayValue = number
            shouldResetDisplay = false
        } else {
            displayValue = displayValue == "0" ? number : displayValue + number
        }
    }
    
    private func appendDecimal() {
        if !displayValue.contains(".") {
            displayValue += "."
        }
    }
    
    private func clear() {
        displayValue = "0"
        currentOperation = nil
        previousValue = nil
        shouldResetDisplay = false
    }
    
    private func performOperation(_ operation: Operation) {
        if let value = Double(displayValue) {
            if let previous = previousValue, let current = currentOperation {
                let result = calculate(previous, current, value)
                displayValue = formatResult(result)
                previousValue = result
            } else {
                previousValue = value
            }
        }
        currentOperation = operation
        shouldResetDisplay = true
    }
    
    private func calculateResult() {
        if let value = Double(displayValue), let previous = previousValue, let operation = currentOperation {
            let result = calculate(previous, operation, value)
            displayValue = formatResult(result)
            previousValue = nil
            currentOperation = nil
        }
    }
    
    private func calculate(_ a: Double, _ operation: Operation, _ b: Double) -> Double {
        switch operation {
        case .add: return a + b
        case .subtract: return a - b
        case .multiply: return a * b
        case .divide: return b != 0 ? a / b : Double.nan
        case .percentage: return a * (b / 100)
        }
    }
    
    private func formatResult(_ result: Double) -> String {
        return result.truncatingRemainder(dividingBy: 1) == 0 ? String(format: "%.0f", result) : String(result)
    }
}

#Preview {
    BasiciOSCalculator()
        .preferredColorScheme(.dark)
}