// Codable mirror of gateway/src/contract.ts. docs/api.md describes the same JSON for humans.
// Change both sides together.
//
// String enums from the gateway (phase, host status, approval decision) are modeled as
// RawRepresentable structs rather than Swift enums, so a value the watch does not know yet still
// decodes instead of failing the whole feed.

import Foundation

struct Phase: RawRepresentable, Codable, Hashable, Sendable {
    let rawValue: String
    init(rawValue: String) { self.rawValue = rawValue }

    static let starting = Phase(rawValue: "starting")
    static let running = Phase(rawValue: "running")
    static let waitingForApproval = Phase(rawValue: "waiting_for_approval")
    static let waitingForInput = Phase(rawValue: "waiting_for_input")
    static let completed = Phase(rawValue: "completed")
    static let failed = Phase(rawValue: "failed")

    var needsYou: Bool { self == .waitingForApproval || self == .waitingForInput }
    var isWorking: Bool { self == .starting || self == .running }
}

struct HostStatus: RawRepresentable, Codable, Hashable, Sendable {
    let rawValue: String
    init(rawValue: String) { self.rawValue = rawValue }

    static let connecting = HostStatus(rawValue: "connecting")
    static let online = HostStatus(rawValue: "online")
    static let offline = HostStatus(rawValue: "offline")
    static let authInvalid = HostStatus(rawValue: "auth_invalid")
    static let incompatible = HostStatus(rawValue: "incompatible")

    /// A short label for a host that is not online, such as "offline" or "needs a new token".
    var problem: String? {
        switch self {
        case .online: nil
        case .connecting: "connecting"
        case .authInvalid: "needs a new token"
        case .incompatible: "incompatible"
        default: "offline"
        }
    }
}

struct ApprovalDecision: RawRepresentable, Codable, Hashable, Sendable {
    let rawValue: String
    init(rawValue: String) { self.rawValue = rawValue }

    static let accept = ApprovalDecision(rawValue: "accept")
    static let acceptForSession = ApprovalDecision(rawValue: "acceptForSession")
    static let acceptAlways = ApprovalDecision(rawValue: "acceptAlways")
    static let decline = ApprovalDecision(rawValue: "decline")
    static let cancel = ApprovalDecision(rawValue: "cancel")
}

struct HostSummary: Codable, Hashable, Sendable, Identifiable {
    var id: String
    var label: String
    var status: HostStatus
    var error: String?
}

/// Something a thread is waiting on: an approval, or questions for the user.
struct PendingRequest: Codable, Hashable, Sendable, Identifiable {
    struct Option: Codable, Hashable, Sendable {
        var decision: ApprovalDecision
        var label: String
    }

    struct Question: Codable, Hashable, Sendable, Identifiable {
        struct Choice: Codable, Hashable, Sendable {
            var label: String
            var value: String
        }

        var id: String
        var header: String
        var question: String
        var options: [Choice]
        var allowCustomAnswer: Bool
    }

    var id: String
    /// `command`, `file-change`, `permission`, `user_input`, ...
    var kind: String
    var prompt: String?
    var reason: String?
    var options: [Option]
    var questions: [Question]

    var isQuestion: Bool { !questions.isEmpty }

    /// The Allow and Deny pair shown on a feed card, when the server offers both.
    var quickOptions: (allow: Option, deny: Option)? {
        guard let allow = options.first(where: { $0.decision == .accept }),
              let deny = options.first(where: { $0.decision == .decline })
        else { return nil }
        return (allow, deny)
    }

    /// One line saying what the agent wants, for a feed card.
    var summary: String {
        if let question = questions.first { return question.question }
        if let prompt, !prompt.isEmpty { return prompt }
        if let reason, !reason.isEmpty { return reason }
        return switch kind {
        case "command": "Run a command"
        case "file-change", "file_change": "Change files"
        default: "Approve a request"
        }
    }
}

struct FeedItem: Codable, Hashable, Sendable, Identifiable {
    var hostId: String
    var hostLabel: String
    var threadId: String
    var projectId: String
    var projectTitle: String
    var title: String
    var phase: Phase
    var updatedAt: Date
    var lastMessage: String?
    var request: PendingRequest?

    var id: String { "\(hostId)/\(threadId)" }
    var route: Route { .thread(hostId: hostId, threadId: threadId) }
}

struct Feed: Codable, Hashable, Sendable {
    var needsYou: [FeedItem]
    var working: [FeedItem]
    var recent: [FeedItem]
    var hosts: [HostSummary]
}

struct Message: Codable, Hashable, Sendable, Identifiable {
    struct Role: RawRepresentable, Codable, Hashable, Sendable {
        let rawValue: String
        init(rawValue: String) { self.rawValue = rawValue }
        static let user = Role(rawValue: "user")
        static let assistant = Role(rawValue: "assistant")
        static let system = Role(rawValue: "system")
    }

    var id: String
    var role: Role
    var text: String
    var createdAt: Date
}

struct ThreadDetail: Codable, Hashable, Sendable {
    var item: FeedItem
    /// Oldest first, at most 20.
    var messages: [Message]
    var canStop: Bool
}

struct ProjectsResponse: Codable, Hashable, Sendable {
    struct Host: Codable, Hashable, Sendable, Identifiable {
        var id: String
        var label: String
        var status: HostStatus
        var error: String?
        var projects: [Project]

        /// Projects a new thread can start in. A project without a default model is not offered.
        var launchable: [Project] { projects.filter { $0.model != nil } }
    }

    struct Project: Codable, Hashable, Sendable, Identifiable {
        var id: String
        var title: String
        var model: String?
    }

    var hosts: [Host]
}

struct PairRequest: Codable, Sendable {
    var code: String
    var deviceName: String
}

struct PairResponse: Codable, Sendable {
    var deviceId: String
    var deviceToken: String
}

struct PushRegistration: Codable, Sendable {
    enum Environment: String, Codable, Sendable {
        case sandbox, production
    }

    var apnsToken: String
    var apnsEnvironment: Environment
}

struct SendMessageRequest: Codable, Sendable {
    var text: String
}

enum RespondRequest: Encodable, Sendable {
    case decision(requestId: String, decision: ApprovalDecision)
    case answers(requestId: String, answers: [String: String])

    private enum CodingKeys: String, CodingKey { case requestId, decision, answers }

    func encode(to encoder: any Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        switch self {
        case let .decision(requestId, decision):
            try container.encode(requestId, forKey: .requestId)
            try container.encode(decision, forKey: .decision)
        case let .answers(requestId, answers):
            try container.encode(requestId, forKey: .requestId)
            try container.encode(answers, forKey: .answers)
        }
    }
}

struct NewThreadRequest: Codable, Sendable {
    var hostId: String
    var projectId: String
    var text: String
}

struct NewThreadResponse: Codable, Sendable {
    var hostId: String
    var threadId: String
}

struct ErrorResponse: Codable, Sendable {
    var error: String
}

/// Notification categories the watch registers actions for.
enum PushCategory: String, CaseIterable, Sendable {
    case approval, finished, failed, input, host
}

enum JSON {
    static func decoder() -> JSONDecoder {
        let decoder = JSONDecoder()
        decoder.dateDecodingStrategy = .custom { decoder in
            let container = try decoder.singleValueContainer()
            let string = try container.decode(String.self)
            guard let date = parseDate(string) else {
                throw DecodingError.dataCorruptedError(
                    in: container, debugDescription: "Not an ISO 8601 date: \(string)")
            }
            return date
        }
        return decoder
    }

    static func encoder() -> JSONEncoder {
        let encoder = JSONEncoder()
        encoder.dateEncodingStrategy = .custom { date, encoder in
            var container = encoder.singleValueContainer()
            try container.encode(Date.ISO8601FormatStyle(includingFractionalSeconds: true).format(date))
        }
        return encoder
    }

    /// Parses ISO 8601 timestamps with or without fractional seconds.
    static func parseDate(_ string: String) -> Date? {
        let withFraction = Date.ISO8601FormatStyle(includingFractionalSeconds: true)
        if let date = try? withFraction.parse(string) { return date }
        return try? Date.ISO8601FormatStyle().parse(string)
    }
}