HaishinKit.swift/RTMPHaishinKit/Sources/AMF/AMF0Serializer.swift

import Foundation
import HaishinKit

enum AMFSerializerError: Error {
    case deserialize
    case outOfIndex
}

// MARK: -
protocol AMFSerializer: ByteArrayConvertible {
    var reference: AMFReference { get set }

    @discardableResult
    func serialize(_ value: Bool) -> Self
    func deserialize() throws -> Bool

    @discardableResult
    func serialize(_ value: String) -> Self
    func deserialize() throws -> String

    @discardableResult
    func serialize(_ value: Int) -> Self
    func deserialize() throws -> Int

    @discardableResult
    func serialize(_ value: Double) -> Self
    func deserialize() throws -> Double

    @discardableResult
    func serialize(_ value: Date) -> Self
    func deserialize() throws -> Date

    @discardableResult
    func serialize(_ value: [(any Sendable)?]) -> Self
    func deserialize() throws -> [(any Sendable)?]

    @discardableResult
    func serialize(_ value: AMFArray) -> Self
    func deserialize() throws -> AMFArray

    @discardableResult
    func serialize(_ value: AMFObject) -> Self
    func deserialize() throws -> AMFObject

    @discardableResult
    func serialize(_ value: AMFXMLDocument) -> Self
    func deserialize() throws -> AMFXMLDocument

    @discardableResult
    func serialize(_ value: (any Sendable)?) -> Self
    func deserialize() throws -> (any Sendable)?
}

enum AMF0Type: UInt8 {
    case number = 0x00
    case bool = 0x01
    case string = 0x02
    case object = 0x03
    // case MovieClip   = 0x04
    case null = 0x05
    case undefined = 0x06
    case reference = 0x07
    case ecmaArray = 0x08
    case objectEnd = 0x09
    case strictArray = 0x0a
    case date = 0x0b
    case longString = 0x0c
    case unsupported = 0x0d
    // case RecordSet   = 0x0e
    case xmlDocument = 0x0f
    case typedObject = 0x10
    case avmplush = 0x11
}

// MARK: - AMF0Serializer
final class AMF0Serializer: ByteArray {
    var reference = AMFReference()
}

extension AMF0Serializer: AMFSerializer {
    // MARK: AMFSerializer
    @discardableResult
    func serialize(_ value: (any Sendable)?) -> Self {
        if value == nil {
            return writeUInt8(AMF0Type.null.rawValue)
        }
        switch value {
        case let value as Int:
            return serialize(Double(value))
        case let value as UInt:
            return serialize(Double(value))
        case let value as Int8:
            return serialize(Double(value))
        case let value as UInt8:
            return serialize(Double(value))
        case let value as Int16:
            return serialize(Double(value))
        case let value as UInt16:
            return serialize(Double(value))
        case let value as Int32:
            return serialize(Double(value))
        case let value as UInt32:
            return serialize(Double(value))
        case let value as Float:
            return serialize(Double(value))
        case let value as CGFloat:
            return serialize(Double(value))
        case let value as Double:
            return serialize(Double(value))
        case let value as Date:
            return serialize(value)
        case let value as String:
            return serialize(value)
        case let value as Bool:
            return serialize(value)
        case let value as [(any Sendable)?]:
            return serialize(value)
        case let value as AMFArray:
            return serialize(value)
        case let value as AMFObject:
            return serialize(value)
        default:
            return writeUInt8(AMF0Type.undefined.rawValue)
        }
    }

    func deserialize() throws -> (any Sendable)? {
        guard let type = AMF0Type(rawValue: try readUInt8()) else {
            return nil
        }
        position -= 1
        switch type {
        case .number:
            return try deserialize() as Double
        case .bool:
            return try deserialize() as Bool
        case .string:
            return try deserialize() as String
        case .object:
            return try deserialize() as AMFObject
        case .null:
            position += 1
            return nil
        case .undefined:
            position += 1
            return kAMFUndefined
        case .reference:
            assertionFailure("TODO")
            return nil
        case .ecmaArray:
            return try deserialize() as AMFArray
        case .objectEnd:
            assertionFailure()
            return nil
        case .strictArray:
            return try deserialize() as [(any Sendable)?]
        case .date:
            return try deserialize() as Date
        case .longString:
            return try deserialize() as String
        case .unsupported:
            assertionFailure("Unsupported")
            return nil
        case .xmlDocument:
            return try deserialize() as AMFXMLDocument
        case .typedObject:
            return nil
        case .avmplush:
            assertionFailure("TODO")
            return nil
        }
    }

    /**
     * - seealso: 2.2 Number Type
     */
    func serialize(_ value: Double) -> Self {
        writeUInt8(AMF0Type.number.rawValue).writeDouble(value)
    }

    func deserialize() throws -> Double {
        guard try readUInt8() == AMF0Type.number.rawValue else {
            throw AMFSerializerError.deserialize
        }
        return try readDouble()
    }

    func serialize(_ value: Int) -> Self {
        serialize(Double(value))
    }

    func deserialize() throws -> Int {
        Int(try deserialize() as Double)
    }

    /**
     * - seealso: 2.3 Boolean Type
     */
    func serialize(_ value: Bool) -> Self {
        writeBytes(Data([AMF0Type.bool.rawValue, value ? 0x01 : 0x00]))
    }

    func deserialize() throws -> Bool {
        guard try readUInt8() == AMF0Type.bool.rawValue else {
            throw AMFSerializerError.deserialize
        }
        return try readUInt8() == 0x01 ? true : false
    }

    /**
     * - seealso: 2.4 String Type
     */
    func serialize(_ value: String) -> Self {
        let isLong = UInt32(UInt16.max) < UInt32(value.count)
        writeUInt8(isLong ? AMF0Type.longString.rawValue : AMF0Type.string.rawValue)
        return serializeUTF8(value, isLong)
    }

    func deserialize() throws -> String {
        switch try readUInt8() {
        case AMF0Type.string.rawValue:
            return try deserializeUTF8(false)
        case AMF0Type.longString.rawValue:
            return try deserializeUTF8(true)
        default:
            assertionFailure()
            return ""
        }
    }

    /**
     * 2.5 Object Type
     * typealias ECMAObject = [String, Any?]
     */
    func serialize(_ value: AMFObject) -> Self {
        writeUInt8(AMF0Type.object.rawValue)
        for (key, data) in value {
            serializeUTF8(key, false).serialize(data)
        }
        return serializeUTF8("", false).writeUInt8(AMF0Type.objectEnd.rawValue)
    }

    func deserialize() throws -> AMFObject {
        var result = AMFObject()

        switch try readUInt8() {
        case AMF0Type.null.rawValue:
            return result
        case AMF0Type.object.rawValue:
            break
        default:
            throw AMFSerializerError.deserialize
        }

        while true {
            let key: String = try deserializeUTF8(false)
            guard !key.isEmpty else {
                position += 1
                break
            }
            result[key] = try deserialize()
        }

        return result
    }

    /**
     * - seealso: 2.10 ECMA Array Type
     */
    func serialize(_ value: AMFArray) -> Self {
        writeUInt8(AMF0Type.ecmaArray.rawValue)
        writeUInt32(UInt32(value.data.count))
        value.data.enumerated().forEach { index, value in
            serializeUTF8(index.description, false).serialize(value)
        }
        value.dict.forEach { key, value in
            serializeUTF8(key, false).serialize(value)
        }
        serializeUTF8("", false)
        writeUInt8(AMF0Type.objectEnd.rawValue)
        return self
    }

    func deserialize() throws -> AMFArray {
        switch try readUInt8() {
        case AMF0Type.null.rawValue:
            return AMFArray()
        case AMF0Type.ecmaArray.rawValue:
            break
        default:
            throw AMFSerializerError.deserialize
        }

        var result = AMFArray(count: Int(try readUInt32()))
        while true {
            let key = try deserializeUTF8(false)
            guard !key.isEmpty else {
                position += 1
                break
            }
            result[key] = try deserialize()
        }

        return result
    }

    /**
     * - seealso: 2.12 Strict Array Type
     */
    func serialize(_ value: [(any Sendable)?]) -> Self {
        writeUInt8(AMF0Type.strictArray.rawValue)
        if value.isEmpty {
            writeBytes(Data([0x00, 0x00, 0x00, 0x00]))
            return self
        }
        writeUInt32(UInt32(value.count))
        for v in value {
            serialize(v)
        }
        return self
    }

    func deserialize() throws -> [(any Sendable)?] {
        guard try readUInt8() == AMF0Type.strictArray.rawValue else {
            throw AMFSerializerError.deserialize
        }
        var result: [(any Sendable)?] = []
        let count = Int(try readUInt32())
        for _ in 0..<count {
            result.append(try deserialize())
        }
        return result
    }

    /**
     * - seealso: 2.13 Date Type
     */
    func serialize(_ value: Date) -> Self {
        writeUInt8(AMF0Type.date.rawValue).writeDouble(value.timeIntervalSince1970 * 1000).writeBytes(Data([0x00, 0x00]))
    }

    func deserialize() throws -> Date {
        guard try readUInt8() == AMF0Type.date.rawValue else {
            throw AMFSerializerError.deserialize
        }
        let date = Date(timeIntervalSince1970: try readDouble() / 1000)
        position += 2 // timezone offset
        return date
    }

    /**
     * - seealso: 2.17 XML Document Type
     */
    func serialize(_ value: AMFXMLDocument) -> Self {
        writeUInt8(AMF0Type.xmlDocument.rawValue).serializeUTF8(value.description, true)
    }

    func deserialize() throws -> AMFXMLDocument {
        guard try readUInt8() == AMF0Type.xmlDocument.rawValue else {
            throw AMFSerializerError.deserialize
        }
        return AMFXMLDocument(data: try deserializeUTF8(true))
    }

    func deserialize() throws -> AMFTypedObject {
        guard try readUInt8() == AMF0Type.typedObject.rawValue else {
            throw AMFSerializerError.deserialize
        }

        let typeName = try deserializeUTF8(false)
        var result = AMFObject()
        while true {
            let key = try deserializeUTF8(false)
            guard !key.isEmpty else {
                position += 1
                break
            }
            result[key] = try deserialize()
        }

        return AMFTypedObject(typeName: typeName, data: result)
    }

    @discardableResult
    private func serializeUTF8(_ value: String, _ isLong: Bool) -> Self {
        let utf8 = Data(value.utf8)
        if isLong {
            writeUInt32(UInt32(utf8.count))
        } else {
            writeUInt16(UInt16(utf8.count))
        }
        return writeBytes(utf8)
    }

    private func deserializeUTF8(_ isLong: Bool) throws -> String {
        let length: Int = isLong ? Int(try readUInt32()) : Int(try readUInt16())
        return try readUTF8Bytes(length)
    }
}