import Foundation

public struct AirAcceptConfig: Codable, Equatable, Sendable {
    public static let defaultPollIntervalMilliseconds = 2_500

    public var pollIntervalMilliseconds: Int

    public init(
        pollIntervalMilliseconds: Int = Self.defaultPollIntervalMilliseconds
    ) {
        self.pollIntervalMilliseconds = pollIntervalMilliseconds
    }

    private enum CodingKeys: String, CodingKey {
        case pollIntervalMilliseconds = "poll_interval_ms"
    }

    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.pollIntervalMilliseconds = try container.decodeIfPresent(
            Int.self,
            forKey: .pollIntervalMilliseconds
        ) ?? Self.defaultPollIntervalMilliseconds
    }
}

public final class ConfigStore {
    public let configURL: URL
    private let fileManager: FileManager

    public init(
        configURL: URL = ConfigStore.defaultConfigURL(),
        fileManager: FileManager = .default
    ) {
        self.configURL = configURL
        self.fileManager = fileManager
    }

    public static func defaultConfigURL() -> URL {
        let baseURL = FileManager.default.homeDirectoryForCurrentUser
            .appendingPathComponent("Library/Application Support/AirAccept", isDirectory: true)
        return baseURL.appendingPathComponent("config.json", isDirectory: false)
    }

    public func loadOrCreate() throws -> AirAcceptConfig {
        if !fileManager.fileExists(atPath: configURL.path) {
            let config = AirAcceptConfig()
            try save(config)
            return config
        }

        let data = try Data(contentsOf: configURL)
        var config = try JSONDecoder().decode(AirAcceptConfig.self, from: data)
        var shouldSave = false
        if config.pollIntervalMilliseconds == 1_000 {
            config.pollIntervalMilliseconds = AirAcceptConfig.defaultPollIntervalMilliseconds
            shouldSave = true
        }
        if
            let rawConfig = String(data: data, encoding: .utf8),
            rawConfig.contains("dry_run") || rawConfig.contains("fallback_click_visible_airplay_banner")
        {
            shouldSave = true
        }
        if shouldSave {
            try save(config)
        }
        return config
    }

    public func save(_ config: AirAcceptConfig) throws {
        try fileManager.createDirectory(
            at: configURL.deletingLastPathComponent(),
            withIntermediateDirectories: true
        )
        let encoder = JSONEncoder()
        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
        let data = try encoder.encode(config)
        try data.write(to: configURL, options: [.atomic])
    }
}