//
//  Copyright (c) 2022 Touch Instinct
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the Software), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

import TISwiftUtils
import UIKit
import OSLog

public protocol LogsListViewOutput: AnyObject {
    func reloadTableView()
    func setLoadingState()
    func setNormalState()
    func startSearch()
    func stopSearch()
}

@available(iOS 15, *)
open class LogsStorageViewModel {

    public enum LevelType: String, CaseIterable {
        case all
        case `default`
        case info
        case debug
        case error
        case fault
    }

    private var allLogs: [OSLogEntryLog] = [] {
        didSet {
            filterLogs()
        }
    }

    public var filteredLogs: [OSLogEntryLog] = [] {
        didSet {
            logsListView?.reloadTableView()
        }
    }

    public var fileCreator: FileCreator?
    weak public var logsListView: LogsListViewOutput?

    public init() { }

    open func loadLogs(preCompletion: VoidClosure? = nil, postCompletion: VoidClosure? = nil) {
        allLogs = []
        logsListView?.setLoadingState()

        preCompletion?()

        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            let logStore = try? OSLogStore(scope: .currentProcessIdentifier)
            let entries = try? logStore?.getEntries()

            let logs = entries?
                .reversed()
                .compactMap { $0 as? OSLogEntryLog }

            DispatchQueue.main.async {
                self?.allLogs = logs ?? []
                self?.logsListView?.setNormalState()
                postCompletion?()
            }
        }
    }

    open func filterLogs(filter: Closure<OSLogEntryLog, Bool>? = nil) {
        filteredLogs = allLogs.filter { filter?($0) ?? true }
    }

    open func filterLogs(byText text: String) {
        guard !text.isEmpty else {
            filteredLogs = allLogs
            return
        }

        logsListView?.startSearch()

        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            let localFilteredLogs = self?.allLogs.filter { log in
                let isDate = log.date.formatted().contains(text)
                let isMessage = log.composedMessage.contains(text)
                let isCategory = log.category.contains(text)
                let isSubsystem = log.subsystem.contains(text)
                let isProcess = log.process.contains(text)

                return isDate || isMessage || isCategory || isSubsystem || isProcess
            }

            DispatchQueue.main.async {
                self?.filteredLogs = localFilteredLogs ?? []
                self?.logsListView?.stopSearch()
            }
        }
    }

    open func getFileWithLogs() -> URL? {
        guard let data = encodeLogs() else {
            return nil
        }

        return fileCreator?.createFile(withData: data)
    }

    func encodeLogs() -> Data? {
        filteredLogs
            .map { $0.getDescription() }
            .joined(separator: "\n\n")
            .data(using: .utf8)
    }

    open func actionHandler(for action: UIAction) {
        guard let level = LevelType(rawValue: action.title) else { return }

        switch level {
        case .all:
            filterLogs()

        case .info:
            filterLogs(filter: { $0.level == .info })

        case .default:
            filterLogs(filter: { $0.level == .notice })

        case .debug:
            filterLogs(filter: { $0.level == .debug })

        case .error:
            filterLogs(filter: { $0.level == .error })

        case .fault:
            filterLogs(filter: { $0.level == .fault })
        }
    }
}

@available(iOS 15, *)
private extension OSLogEntryLog {
    func getDescription() -> String {
        return "[\(date)] - [\(category)]: \(composedMessage)"
    }
}