//
//  SyncController.swift
//  MastoSearchCore
//
//  Created by Shadowfacts on 7/3/22.
//

import Foundation
import Combine
import OSLog

public class SyncController {
    private init() {}
    
    public static let shared = SyncController()
    
    public let onSync = PassthroughSubject<Void, Never>()
    
    private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "Sync")
    private var syncTotal = 0
    
    public func syncStatuses(errorHandler: @escaping (APIController.Error) -> Void) {
        DatabaseController.shared.getNewestStatus { status in
            guard let status else {
                return
            }
            
            self.logger.log("Starting sync...")
            self.syncTotal = 0
            self.syncStatuses(range: .after(status.id), errorHandler: errorHandler)
        }
    }
    
    private func syncStatuses(range: APIController.RequestRange, errorHandler: @escaping (APIController.Error) -> Void) {
        APIController.shared.getStatuses(range: range) { response in
            switch response {
            case .failure(let error):
                self.logger.error("Erorr syncing statuses: \(String(describing: error), privacy: .public)")
                DispatchQueue.main.async {
                    errorHandler(error)
                }
                
            case .success(let statuses):
                guard statuses.count > 0 else {
                    DispatchQueue.main.async {
                        self.logger.log("Finished sync of \(self.syncTotal, privacy: .public) statuses")
                        self.onSync.send()
                    }
                    return
                }
                
                DatabaseController.shared.addStatuses(statuses.compactMap {
                    if $0.hasReblog {
                        return nil
                    } else {
                        return Status(id: $0.id, url: $0.url, summary: $0.spoiler_text, content: $0.content, published: $0.created_at)
                    }
                })
                DispatchQueue.main.async {
                    self.onSync.send()
                }
                
                self.syncTotal += statuses.count
                
                self.syncStatuses(range: .after(statuses.first!.id), errorHandler: errorHandler)
            }
        }
    }

}