//
//  TimelineMarkers.swift
//  Pachyderm
//
//  Created by Shadowfacts on 2/14/23.
//

import Foundation

public struct TimelineMarkers {
    private init() {}
    
    public static func request<T: TimelineMarkerType>(timeline: T) -> Request<TimelineMarker<T.Payload>> {
        Request(method: .get, path: "/api/v1/markers", queryParameters: ["timeline[]" => T.name])
    }
    
    public static func update<T: TimelineMarkerType>(timeline: T, lastReadID: String) -> Request<Empty> {
        Request(method: .post, path: "/api/v1/markers", body: ParametersBody([
            "\(T.name)[last_read_id]" => lastReadID
        ]))
    }
}

public struct TimelineMarker<Payload: TimelineMarkerTypePayload>: Decodable, Sendable {
    let payload: Payload
    
    public var lastReadID: String {
        payload.payload.lastReadID
    }
    public var version: Int {
        payload.payload.version
    }
    public var updatedAt: Date {
        payload.payload.updatedAt
    }

    public init(from decoder: any Decoder) throws {
        self.payload = try Payload(from: decoder)
    }
}

public protocol TimelineMarkerTypePayload: Decodable, Sendable {
    var payload: MarkerPayload { get }
}

public struct HomeMarkerPayload: TimelineMarkerTypePayload {
    public var home: MarkerPayload
    public var payload: MarkerPayload { home }
}

public struct NotificationsMarkerPayload: TimelineMarkerTypePayload {
    public var notifications: MarkerPayload
    public var payload: MarkerPayload { notifications }
}

public struct MarkerPayload: Decodable, Sendable {
    public let lastReadID: String
    public let version: Int
    public let updatedAt: Date
    
    enum CodingKeys: String, CodingKey {
        case lastReadID = "last_read_id"
        case version
        case updatedAt = "updated_at"
    }
}

public protocol TimelineMarkerType {
    static var name: String { get }
    associatedtype Payload: TimelineMarkerTypePayload
}

extension TimelineMarkerType where Self == HomeMarker {
    public static var home: Self { .init() }
}

extension TimelineMarkerType where Self == NotificationsMarker {
    public static var notifications: Self { .init() }
}

public struct HomeMarker: TimelineMarkerType {
    public typealias Payload = HomeMarkerPayload
    public static var name: String { "home" }
}

public struct NotificationsMarker: TimelineMarkerType {
    public typealias Payload = NotificationsMarkerPayload
    public static var name: String { "notifications" }
}