import Foundation
import UIKit
import UrlEscaping

let walletAddressLength: Int = 48
let walletTextLimit: Int = 512

func formatAddress(_ address: String) -> String {
    var address = address
    address.insert("\n", at: address.index(address.startIndex, offsetBy: address.count / 2))
    return address
}

func formatBalanceText(_ value: Int64, decimalSeparator: String) -> String {
    var balanceText = "\(abs(value))"
    while balanceText.count < 10 {
        balanceText.insert("0", at: balanceText.startIndex)
    }
    balanceText.insert(contentsOf: decimalSeparator, at: balanceText.index(balanceText.endIndex, offsetBy: -9))
    while true {
        if balanceText.hasSuffix("0") {
            if balanceText.hasSuffix("\(decimalSeparator)0") {
                balanceText.removeLast()
                balanceText.removeLast()
                break
            } else {
                balanceText.removeLast()
            }
        } else {
            break
        }
    }
    if value < 0 {
        balanceText.insert("-", at: balanceText.startIndex)
    }
    return balanceText
}

private enum ArabicNumeralStringType {
    case western
    case arabic
    case persian
}

private func normalizeArabicNumeralString(_ string: String, type: ArabicNumeralStringType) -> String {
    var string = string
    
    let numerals = [
        ("0", "٠", "۰"),
        ("1", "١", "۱"),
        ("2", "٢", "۲"),
        ("3", "٣", "۳"),
        ("4", "٤", "۴"),
        ("5", "٥", "۵"),
        ("6", "٦", "۶"),
        ("7", "٧", "۷"),
        ("8", "٨", "۸"),
        ("9", "٩", "۹"),
        (",", "٫", "٫")
    ]
    for (western, arabic, persian) in numerals {
        switch type {
        case .western:
            string = string.replacingOccurrences(of: arabic, with: western)
            string = string.replacingOccurrences(of: persian, with: western)
        case .arabic:
            string = string.replacingOccurrences(of: western, with: arabic)
            string = string.replacingOccurrences(of: persian, with: arabic)
        case .persian:
            string = string.replacingOccurrences(of: western, with: persian)
            string = string.replacingOccurrences(of: arabic, with: persian)
        }
        
    }
    return string
}

private let invalidAmountCharacters = CharacterSet(charactersIn: "01234567890.,").inverted
func isValidAmount(_ amount: String) -> Bool {
    let amount = normalizeArabicNumeralString(amount, type: .western)
    if amount.rangeOfCharacter(from: invalidAmountCharacters) != nil {
        return false
    }
    var hasDecimalSeparator = false
    var hasLeadingZero = false
    var index = 0
    for c in amount {
        if c == "." || c == "," {
            if !hasDecimalSeparator {
                hasDecimalSeparator = true
            } else {
                return false
            }
        }
        index += 1
    }
    
    var decimalIndex: String.Index?
    if let index = amount.firstIndex(of: ".") {
        decimalIndex = index
    } else if let index = amount.firstIndex(of: ",") {
        decimalIndex = index
    }
    
    if let decimalIndex = decimalIndex, amount.distance(from: decimalIndex, to: amount.endIndex) > 10 {
        return false
    }
    
    let string = amount.replacingOccurrences(of: ",", with: ".")
    if let range = string.range(of: ".") {
        let integralPart = String(string[..<range.lowerBound])
        let fractionalPart = String(string[range.upperBound...])
        let string = integralPart + fractionalPart + String(repeating: "0", count: max(0, 9 - fractionalPart.count))
        if let _ = Int64(string) {
        } else {
            return false
        }
    } else if !string.isEmpty {
        if let integral = Int64(string), integral <= maxIntegral {
        } else {
            return false
        }
    }
    
    return true
}

private let maxIntegral: Int64 = Int64.max / 1000000000

func amountValue(_ string: String) -> Int64 {
    let string = string.replacingOccurrences(of: ",", with: ".")
    if let range = string.range(of: ".") {
        let integralPart = String(string[..<range.lowerBound])
        let fractionalPart = String(string[range.upperBound...])
        let string = integralPart + fractionalPart + String(repeating: "0", count: max(0, 9 - fractionalPart.count))
        return Int64(string) ?? 0
    } else if let integral = Int64(string) {
        if integral > maxIntegral {
            return 0
        }
        return integral * 1000000000
    }
    return 0
}

func normalizedStringForGramsString(_ string: String, decimalSeparator: String = ".") -> String {
    return formatBalanceText(amountValue(string), decimalSeparator: decimalSeparator)
}

func formatAmountText(_ text: String, decimalSeparator: String) -> String {
    var text = normalizeArabicNumeralString(text, type: .western)
    if text == "." || text == "," {
        text = "0\(decimalSeparator)"
    } else if text == "0" {
        text = "0\(decimalSeparator)"
    } else if text.hasPrefix("0") && text.firstIndex(of: ".") == nil && text.firstIndex(of: ",") == nil {
        var trimmedText = text
        while trimmedText.first == "0" {
            trimmedText.removeFirst()
        }
        text = trimmedText
    }
    return text
}

private let invalidAddressCharacters = CharacterSet(charactersIn: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=").inverted

func isValidAddress(_ address: String, exactLength: Bool = false) -> Bool {
    if address.count > walletAddressLength || address.rangeOfCharacter(from: invalidAddressCharacters) != nil {
        return false
    }
    if exactLength && address.count != walletAddressLength {
        return false
    }
    return true
}

func walletInvoiceUrl(address: String, amount: String? = nil, comment: String? = nil) -> String {
    var arguments = ""
    if let amount = amount, !amount.isEmpty {
        arguments += arguments.isEmpty ? "?" : "&"
        arguments += "amount=\(amountValue(amount))"
    }
    if let comment = comment, !comment.isEmpty {
        arguments += arguments.isEmpty ? "?" : "&"
        arguments += "text=\(urlEncodedStringFromString(comment))"
    }
    return "ton://transfer/\(address)\(arguments)"
}

private let amountDelimeterCharacters = CharacterSet(charactersIn: "0123456789").inverted
func amountAttributedString(_ string: String, integralFont: UIFont, fractionalFont: UIFont, color: UIColor) -> NSAttributedString {
    let result = NSMutableAttributedString()
    if let range = string.rangeOfCharacter(from: amountDelimeterCharacters) {
        let integralPart = String(string[..<range.lowerBound])
        let fractionalPart = String(string[range.lowerBound...])
        result.append(NSAttributedString(string: integralPart, font: integralFont, textColor: color))
        result.append(NSAttributedString(string: fractionalPart, font: fractionalFont, textColor: color))
    } else {
        result.append(NSAttributedString(string: string, font: integralFont, textColor: color))
    }
    return result
}