import Foundation

/// One evaluated flag, as returned inside `EvaluateResponse.result.flags[key]`.
public struct FeatureControlFlag: Decodable, Sendable, Equatable {
    public let enabled: Bool
    public let variant: String?
    public let payload: FeatureControlJSON?
    public let reason: String?

    public init(enabled: Bool, variant: String?, payload: FeatureControlJSON?, reason: String?) {
        self.enabled = enabled
        self.variant = variant
        self.payload = payload
        self.reason = reason
    }
}

/// `EvaluateResponse.result` — the batch evaluation result for a set of keys.
public struct FeatureControlSnapshot: Sendable, Equatable {
    public let evaluatedAt: Date
    public let configVersion: Int
    public let flags: [String: FeatureControlFlag]

    public init(evaluatedAt: Date, configVersion: Int, flags: [String: FeatureControlFlag]) {
        self.evaluatedAt = evaluatedAt
        self.configVersion = configVersion
        self.flags = flags
    }
}

extension FeatureControlSnapshot: Decodable {
    private enum CodingKeys: String, CodingKey {
        case evaluatedAt, configVersion, flags
    }

    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let rawDate = try container.decode(String.self, forKey: .evaluatedAt)
        guard let date = FeatureControlDateParsing.parse(rawDate) else {
            throw DecodingError.dataCorruptedError(forKey: .evaluatedAt, in: container,
                                                    debugDescription: "Unrecognized date format: \(rawDate)")
        }
        self.evaluatedAt = date
        self.configVersion = try container.decode(Int.self, forKey: .configVersion)
        self.flags = try container.decode([String: FeatureControlFlag].self, forKey: .flags)
    }
}

/// Wire envelope for `POST /api/feature-control/evaluate` — `{error, code, result}`.
struct FeatureControlEvaluateEnvelope: Decodable, Sendable {
    let error: Bool
    let code: String?
    let result: FeatureControlSnapshot
}

/// Request body for `POST /api/feature-control/evaluate`.
struct FeatureControlEvaluateRequestBody: Encodable, Sendable {
    let environment: String
    let keys: [String]
    let context: FeatureControlContext
}