import Foundation

/// A failure from either API surface, already mapped off the exit code so
/// callers switch on meaning rather than on numbers.
///
///     exit  http  case
///        2   400  usage         a bug in the app
///        3   404  notFound      an empty state, not an error banner
///        4   403  denied        the message explains the rule; show it verbatim
///     1, 5   500  failure       retried once by the client, then surfaced
///        —   401  unauthorized  the token is invalid, expired or revoked
///        —   429  rateLimited   Retry-After was longer than the client will wait
nonisolated enum GitbayError: LocalizedError, Sendable {
    case usage(String)
    case notFound(String)
    case denied(String)
    case failure(String)
    case unauthorized(String)
    case rateLimited(retryAfter: TimeInterval)
    /// The command exists but is not read-only, so it cannot be reached
    /// with GET. Also an app bug: it means we routed a write through `read`.
    case notReadable(String)
    case transport(any Error)
    case decoding(any Error)
    /// A major protocol version the app does not understand.
    case protocolMismatch(Int)
    /// The client refused to send the token somewhere other than the instance.
    case unexpectedHost(URL)

    /// Text for a person. `denied` and `notFound` come from the server
    /// verbatim — those messages exist to explain a rule, and rewording
    /// them loses the explanation.
    var userFacingMessage: String {
        switch self {
        case .denied(let message), .notFound(let message):
            message
        case .unauthorized:
            "Your token is no longer valid. Sign in again."
        case .rateLimited(let seconds):
            "Too many requests. Try again in \(Int(seconds.rounded()))s."
        case .failure(let message):
            message.isEmpty ? "The server could not complete that." : message
        case .transport:
            "Check your connection and try again."
        // A usage or protocol failure is ours, not the user's. argv never
        // reaches the screen.
        case .usage, .notReadable, .decoding, .protocolMismatch, .unexpectedHost:
            "Something went wrong. Please try again."
        }
    }

    var errorDescription: String? { userFacingMessage }

    /// True when the right response is an empty screen rather than a banner.
    var isEmptyState: Bool {
        if case .notFound = self { return true }
        return false
    }

    /// True when the token needs replacing and the app should sign out.
    var requiresReauthentication: Bool {
        if case .unauthorized = self { return true }
        return false
    }
}