import Foundation
import Meta

extension State where Value: Codable {

    /// Initialize a property remembered between launches using a JSON file.
    /// - Parameters:
    ///   - wrappedValue: The default value if no stored value exists.
    ///   - stateID: Unique key for the value.
    ///   - forceUpdates: Whether to force update all available views when modified.
    public init(
        wrappedValue: @autoclosure @escaping () -> Value,
        _ stateID: String,
        forceUpdates: Bool = false
    ) {
        self.init(
            wrappedValue: {
                guard let data = try? Data(contentsOf: URL(fileURLWithPath: JSONDatabase.path)),
                    let storage = try? JSONDecoder().decode([String: Data].self, from: data),
                    let storedValueData = storage[stateID],
                    let value = try? JSONDecoder().decode(Value.self, from: storedValueData)
                else {
                    return wrappedValue()
                }
                return value
            },
            writeValue: { value in
                var storage: [String: Data] = [:]
                let url = URL(fileURLWithPath: JSONDatabase.path)

                if let data = try? Data(contentsOf: url),
                    let decoded = try? JSONDecoder().decode([String: Data].self, from: data)
                {
                    storage = decoded
                }

                if let encodedValue = try? JSONEncoder().encode(value) {
                    storage[stateID] = encodedValue

                    let encoder = JSONEncoder()
                    encoder.outputFormatting = .prettyPrinted

                    if let newData = try? encoder.encode(storage) {
                        try? FileManager.default.createDirectory(
                            at: url.deletingLastPathComponent(),
                            withIntermediateDirectories: true
                        )
                        try? newData.write(to: url, options: .atomic)
                    }
                }
            },

            forceUpdates: forceUpdates
        )
    }

}

public enum JSONDatabase {

    /// The path to the JSON file.
    static var path = "./database.json"

    /// Optionally allow customization of the path.
    public static func setPath(_ newPath: String) {
        self.path = newPath
    }
}