import Foundation
import CoreText
import AVFoundation

public extension UnicodeScalar {
    var isEmoji: Bool {
        switch self.value {
            case 0x1F600...0x1F64F, // Emoticons
            0x1F300...0x1F5FF, // Misc Symbols and Pictographs
            0x1F680...0x1F6FF, // Transport and Map
            0x1F1E6...0x1F1FF, // Regional country flags
            0xE0020...0xE007F, // Tags
            0xFE00...0xFE0F, // Variation Selectors
            0x1F900...0x1F9FF, // Supplemental Symbols and Pictographs
            0x1F018...0x1F0F5,
            0x1F200...0x1F270, // Various asian characters
            65024...65039, // Variation selector
            9100...9300, // Misc items
            8400...8447: // Combining Diacritical Marks for Symbols
                return true
            case 0x1f004:
                return true
            case 0x270b, 0x2728:
                return true
            default:
                return false
        }
    }
    
    var maybeEmoji: Bool {
        switch self.value {
            case 0x2600...0x26FF, // Misc symbols
            0x2700...0x27BF, // Dingbats
            0x1F100...0x1F1FF: //Enclosed Alphanumeric
                return true
            default:
                return false
        }
    }
    
    var isZeroWidthJoiner: Bool {
        return self.value == 8205
    }
}

private final class FrameworkClass: NSObject {
}

public extension String {
    func trimmingTrailingSpaces() -> String {
        var t = self
        while t.hasSuffix(" ") {
            t = "" + t.dropLast()
        }
        return t
    }
    
    var isSingleEmoji: Bool {
        print(Bundle(for: FrameworkClass.self).bundlePath)
        return self.emojis.count == 1 && self.containsEmoji
    }
    
    var containsEmoji: Bool {
        return self.unicodeScalars.contains { $0.isEmoji }
    }
    
    var containsOnlyEmoji: Bool {
        guard !self.isEmpty else {
            return false
        }
        var nextShouldBeFE0F = false
        for scalar in self.unicodeScalars {
            if nextShouldBeFE0F {
                if scalar.value == 0xfe0f {
                    nextShouldBeFE0F = false
                    continue
                } else {
                    return false
                }
            }
            if !scalar.isEmoji && scalar.maybeEmoji {
                nextShouldBeFE0F = true
            }
            else if !scalar.isEmoji && !scalar.isZeroWidthJoiner {
                return false
            }
        }
        return !nextShouldBeFE0F
    }
    
    var emojis: [String] {
        var emojis: [String] = []
        self.enumerateSubstrings(in: self.startIndex ..< self.endIndex, options: .byComposedCharacterSequences) { substring, _, _, _ in
            if let substring = substring {
                emojis.append(substring)
            }
        }
        return emojis
    }
    
    var trimmingEmojis: String {
        var string: String = ""
        self.enumerateSubstrings(in: self.startIndex ..< self.endIndex, options: .byComposedCharacterSequences) { substring, _, _, _ in
            if let substring = substring, !substring.containsEmoji {
                string.append(substring)
            }
        }
        return string
    }
    
    var normalizedEmoji: String {
        var string = ""
        
        var nextShouldBeFE0F = false
        for scalar in self.unicodeScalars {
            if nextShouldBeFE0F {
                if scalar.value != 0xfe0f {
                    string.unicodeScalars.append("\u{fe0f}")
                }
                nextShouldBeFE0F = false
            }
            string.unicodeScalars.append(scalar)
            if !scalar.isEmoji && scalar.maybeEmoji {
                nextShouldBeFE0F = true
            }
        }
        
        if nextShouldBeFE0F {
            string.unicodeScalars.append("\u{fe0f}")
        }
        
        return string
    }
    
    var basicEmoji: (String, String?) {
        let fitzCodes: [UInt32] = [
            0x1f3fb,
            0x1f3fc,
            0x1f3fd,
            0x1f3fe,
            0x1f3ff
        ]
        
        var string = ""
        var fitzModifier: String?
        for scalar in self.unicodeScalars {
            if fitzCodes.contains(scalar.value) {
                fitzModifier = String(scalar)
                continue
            }
            string.unicodeScalars.append(scalar)
            if scalar.value == 0x2764, self.unicodeScalars.count > 1, self.emojis.count == 1 {
                break
            }
        }
        return (string, fitzModifier)
    }
}