/*
Copyright 2019-2024 New Vector Ltd.

SPDX-License-Identifier: AGPL-3.0-only
Please see LICENSE in the repository root for full details.
 */

import Foundation

extension EmojiItem: Decodable {

    /// JSON keys associated to EmojiItem properties.
    /// See https://github.com/missive/emoji-mart/blob/master/src/utils/data.js for minified letters informations.
    ///
    /// - shortName: The commonly-agreed short name for the emoji, as supported in GitHub and others via the :short_name: syntax.
    /// - name: The offical Unicode name.
    /// - codepoint: The Unicode codepoint, as 4-5 hex digits. Where an emoji needs 2 or more codepoints, they are specified like 1F1EA-1F1F8.
    /// - shortNames: An array of all the other known short names.
    /// - keywords: Associated emoji keywords.
    enum CodingKeys: String, CodingKey {
        case shortName
        case name = "a"
        case codepoint = "b"
        case shortNames = "n"
        case keywords = "j"
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        
        guard let shortName = decoder.codingPath.last?.stringValue else {
            throw DecodingError.dataCorruptedError(forKey: .shortName, in: container, debugDescription: "Cannot initialize short name")
        }
        
        let emojiUnicodeStringValue = try container.decode(String.self, forKey: .codepoint)
        
        let unicodeStringComponents = emojiUnicodeStringValue.components(separatedBy: "-")
        
        var emoji = ""
        
        for unicodeStringComponent in unicodeStringComponents {
            if let unicodeCodePoint = Int(unicodeStringComponent, radix: 16),
                let emojiUnicodeScalar = UnicodeScalar(unicodeCodePoint) {
                emoji.append(String(emojiUnicodeScalar))
            } else {
                throw DecodingError.dataCorruptedError(forKey: .codepoint, in: container, debugDescription: "Cannot initialize emoji")
            }
        }
        
        let name = try container.decode(String.self, forKey: .name)
        
        let shortNames: [String]
        
        if let decodedShortNames = try container.decodeIfPresent([String].self, forKey: .shortNames) {
            shortNames = decodedShortNames
        } else {
            shortNames = []
        }
        
        let keywords: [String]
        
        if let decodedKeywords = try container.decodeIfPresent([String].self, forKey: .keywords) {
            keywords = decodedKeywords
        } else {
            keywords = []
        }
        
        self.init(shortName: shortName,
                  value: emoji,
                  name: name,
                  shortNames: shortNames,
                  keywords: keywords)
    }
}