//
// Copyright 2021 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
//

import Foundation
import zlib
import SignalServiceKit
import SignalUI

public struct DebugLogDumper {
    fileprivate var accountManager: (any TSAccountManager)?
    fileprivate var appVersion: any AppVersion
    fileprivate var db: (any DB)?

    static func preLaunch() -> Self {
        return Self(appVersion: AppVersionImpl.shared)
    }

    static func fromGlobals() -> Self {
        return Self(
            accountManager: DependenciesBridge.shared.tsAccountManager,
            appVersion: AppVersionImpl.shared,
            db: DependenciesBridge.shared.db,
        )
    }

    public func challengeReceivedRecently() -> Bool {
        guard let db else {
            return false
        }

        let challengeFloorDate = Date().addingTimeInterval(.day * -3)
        return db.read { tx in
            SupportKeyValueStore().lastChallengeWithinTimeframe(transaction: tx, lastChallengeFloor: challengeFloorDate)
        }
    }

    fileprivate func dump() {
        appVersion.dumpToLog()
        if let db {
            db.read { tx in
                if let accountManager {
                    if let localIdentifiers = accountManager.localIdentifiers(tx: tx) {
                        let deviceId = accountManager.storedDeviceId(tx: tx)
                        Logger.info("local ACI: \(localIdentifiers.aci), device ID: \(deviceId)")
                    } else {
                        let state = accountManager.registrationState(tx: tx)
                        Logger.info("no local ACI! registration state: \(state.logString)")
                    }
                }
                if DebugFlags.internalLogging {
                    NewKeyValueStore.logCollectionStatistics(tx: tx)
                }
            }
        }
    }
}

enum DebugLogs {

    @MainActor
    static func submitLogs(supportTag: String? = nil, dumper: DebugLogDumper, completion: (() -> Void)? = nil) {
        let submitLogsCompletion = {
            if let completion {
                // Wait a moment. If the user opens a URL, it needs a moment to complete.
                DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
                    completion()
                }
            }
        }

        var supportFilter = "Signal - iOS Debug Log"
        if let supportTag {
            supportFilter += " - \(supportTag)"
        }

        guard let frontmostViewController = UIApplication.shared.frontmostViewControllerIgnoringAlerts else {
            submitLogsCompletion()
            return
        }
        uploadLogsUsingViewController(frontmostViewController, dumper: dumper) { url in
            guard let presentingViewController = UIApplication.shared.frontmostViewControllerIgnoringAlerts else {
                submitLogsCompletion()
                return
            }

            let alert = ActionSheetController(
                title: NSLocalizedString("DEBUG_LOG_ALERT_TITLE", comment: "Title of the debug log alert."),
                message: NSLocalizedString("DEBUG_LOG_ALERT_MESSAGE", comment: "Message of the debug log alert.")
            )

            if ComposeSupportEmailOperation.canSendEmails {
                alert.addAction(ActionSheetAction(
                    title: NSLocalizedString(
                        "DEBUG_LOG_ALERT_OPTION_EMAIL",
                        comment: "Label for the 'email debug log' option of the debug log alert."
                    ),
                    style: .default,
                    handler: { _ in
                        Task {
                            await ComposeSupportEmailOperation.sendEmailWithDefaultErrorHandling(
                                supportFilter: supportFilter,
                                logUrl: url,
                                hasRecentChallenge: dumper.challengeReceivedRecently()
                            )
                        }
                        submitLogsCompletion()
                    }
                ))
            }
            alert.addAction(ActionSheetAction(
                title: NSLocalizedString(
                    "DEBUG_LOG_ALERT_OPTION_COPY_LINK",
                    comment: "Label for the 'copy link' option of the debug log alert."
                ),
                style: .default,
                handler: { _ in
                    UIPasteboard.general.string = url.absoluteString
                    submitLogsCompletion()
                }
            ))
            alert.addAction(ActionSheetAction(
                title: NSLocalizedString(
                    "DEBUG_LOG_ALERT_OPTION_SHARE",
                    comment: "Label for the 'Share' option of the debug log alert."
                ),
                style: .default,
                handler: { _ in
                    AttachmentSharing.showShareUI(
                        for: url.absoluteString,
                        sender: nil,
                        completion: submitLogsCompletion
                    )
                }
            ))
            alert.addAction(ActionSheetAction(
                title: CommonStrings.cancelButton,
                style: .cancel,
                handler: { _ in submitLogsCompletion() }
            ))
            presentingViewController.presentActionSheet(alert)
        }
    }

    @MainActor
    private static func uploadLogsUsingViewController(_ viewController: UIViewController, dumper: DebugLogDumper, completion: @escaping (URL) -> Void) {
        AssertIsOnMainThread()

        ModalActivityIndicatorViewController.present(
            fromViewController: viewController,
            canCancel: true,
            asyncBlock: { await _uploadLogs(dumper: dumper, modalActivityIndicator: $0, completion: completion) }
        )
    }

    @MainActor
    private static func _uploadLogs(dumper: DebugLogDumper, modalActivityIndicator: ModalActivityIndicatorViewController, completion: @escaping (URL) -> Void) async {
        do {
            let url = try await uploadLogs(dumper: dumper)
            guard !modalActivityIndicator.wasCancelled else { return }
            modalActivityIndicator.dismiss {
                completion(url)
            }
        } catch {
            guard !modalActivityIndicator.wasCancelled else {
                if let logArchiveOrDirectoryPath = error.logArchiveOrDirectoryPath {
                    OWSFileSystem.deleteFile(logArchiveOrDirectoryPath)
                }
                return
            }

            modalActivityIndicator.dismiss {
                DebugLogs.showFailureAlert(
                    with: error.localizedErrorMessage,
                    logArchiveOrDirectoryPath: error.logArchiveOrDirectoryPath
                )
            }
        }
    }

    // MARK: - Collecting & uploading

    private struct NoLogsError: Error {
        var errorString: String {
            OWSLocalizedString(
                "DEBUG_LOG_ALERT_NO_LOGS",
                comment: "Error indicating that no debug logs could be found."
            )
        }
    }

    private static func collectLogs() -> Result<String, NoLogsError> {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy.MM.dd hh.mm.ss"
        let dateString = dateFormatter.string(from: Date())
        let logsName = "\(dateString) \(UUID().uuidString)"

        let zipDirUrl = URL(fileURLWithPath: OWSTemporaryDirectory()).appendingPathComponent(logsName)
        let zipDirPath = zipDirUrl.path
        OWSFileSystem.ensureDirectoryExists(zipDirPath)

        let logFilePaths = DebugLogger.shared.allLogFilePaths
        if logFilePaths.isEmpty {
            return .failure(NoLogsError())
        }

        for logFilePath in logFilePaths {
            let lastLogFilePathComponent = URL(fileURLWithPath: logFilePath).lastPathComponent
            let copyFilePath = zipDirUrl.appendingPathComponent(lastLogFilePathComponent).path
            do {
                try FileManager.default.copyItem(atPath: logFilePath, toPath: copyFilePath)
            } catch {
                Logger.error("could not copy log file at \(logFilePath): \(error)")
                // Write the error to the file that would have been copied.
                try? error.localizedDescription.write(toFile: copyFilePath, atomically: true, encoding: .utf8)
            }
            OWSFileSystem.protectFileOrFolder(atPath: copyFilePath)
        }

        return .success(zipDirPath)
    }

    public static func exportLogs() {
        AssertIsOnMainThread()
        switch collectLogs() {
        case let .success(logsDirPath):
            AttachmentSharing.showShareUI(for: URL(fileURLWithPath: logsDirPath), sender: nil) {
                OWSFileSystem.deleteFile(logsDirPath)
            }
        case let .failure(error):
            Self.showFailureAlert(with: error.errorString, logArchiveOrDirectoryPath: nil)
            return
        }
    }

    struct UploadDebugLogError: Error {
        var localizedErrorMessage: String
        var logArchiveOrDirectoryPath: String?
    }

    /// - Note: Various dependencies might not be initialized yet when this
    /// method is called from the database recovery flow. Notably, the database
    /// isn't available in that flow.
    static func uploadLogs(dumper: DebugLogDumper) async throws(UploadDebugLogError) -> URL {
        // Phase 1: Dump any additional details that are relevant.
        dumper.dump()
        Logger.info("About to zip debug logs")

        // Phase 2: Flush pending logs to disk.
        Logger.flush()

        // Phase 3: Make a local copy of all of the log files.
        let zipDirPath: String
        switch collectLogs() {
        case let .success(logsDirPath):
            zipDirPath = logsDirPath
        case let .failure(error):
            throw UploadDebugLogError(localizedErrorMessage: error.errorString)
        }

        // Phase 4: Zip up the log files.
        let zipDirUrl = URL(fileURLWithPath: zipDirPath)
        let zipFileUrl = URL(fileURLWithPath: zipDirPath.appendingFileExtension("zip"))
        let fileCoordinator = NSFileCoordinator()
        var zipError: NSError?
        fileCoordinator.coordinate(readingItemAt: zipDirUrl, options: [.forUploading], error: &zipError) { temporaryFileUrl in
            do {
                try FileManager.default.copyItem(at: temporaryFileUrl, to: zipFileUrl)
            } catch {
                Logger.warn("Couldn't copy zipped file: \(error)")
            }
        }
        if zipError != nil || !OWSFileSystem.fileOrFolderExists(url: zipFileUrl) {
            let errorMessage = OWSLocalizedString(
                "DEBUG_LOG_ALERT_COULD_NOT_PACKAGE_LOGS",
                comment: "Error indicating that the debug logs could not be packaged."
            )
            throw UploadDebugLogError(localizedErrorMessage: errorMessage, logArchiveOrDirectoryPath: zipDirPath)
        }

        OWSFileSystem.protectFileOrFolder(atPath: zipFileUrl.path)
        OWSFileSystem.deleteFile(zipDirPath)

        // Phase 5: Upload the log files.
        do {
            let url = try await DebugLogUploader.uploadFile(fileUrl: zipFileUrl, mimeType: MimeType.applicationZip.rawValue)
            try OWSFileSystem.deleteFile(url: zipFileUrl)
            return url
        } catch {
            let errorMessage = OWSLocalizedString(
                "DEBUG_LOG_ALERT_ERROR_UPLOADING_LOG",
                comment: "Error indicating that a debug log could not be uploaded."
            )
            throw UploadDebugLogError(localizedErrorMessage: errorMessage, logArchiveOrDirectoryPath: zipFileUrl.path)
        }
    }

    private static func showFailureAlert(with message: String, logArchiveOrDirectoryPath: String?) {
        let deleteArchive: (String) -> Void = { filePath in
            OWSFileSystem.deleteFile(filePath)
        }

        let alert = ActionSheetController(title: nil, message: message)

        if let logArchiveOrDirectoryPath {
            alert.addAction(.init(
                title: OWSLocalizedString(
                    "DEBUG_LOG_ALERT_OPTION_EXPORT_LOG_ARCHIVE",
                    comment: "Label for the 'Export Logs' fallback option for the alert when debug log uploading fails."
                ),
            ) { _ in
                AttachmentSharing.showShareUI(
                    for: URL(fileURLWithPath: logArchiveOrDirectoryPath),
                    sender: nil,
                    completion: {
                        deleteArchive(logArchiveOrDirectoryPath)
                    }
                )
            })
        }

        alert.addAction(.init(title: CommonStrings.okButton) { _ in
            if let logArchiveOrDirectoryPath {
                deleteArchive(logArchiveOrDirectoryPath)
            }
        })

        let presentingViewController = UIApplication.shared.frontmostViewControllerIgnoringAlerts
        presentingViewController?.presentActionSheet(alert)
    }
}

private enum DebugLogUploader {

    static func uploadFile(fileUrl: URL, mimeType: String) async throws -> URL {
        do {
            let uploadParameters = try await getUploadParameters(fileUrl: fileUrl)
            return try await uploadFile(fileUrl: fileUrl, mimeType: mimeType, uploadParameters: uploadParameters)
        } catch {
            Logger.warn("\(error)")
            throw error
        }
    }

    private static func buildOWSURLSession() -> OWSURLSessionProtocol {
        OWSURLSession(
            securityPolicy: OWSURLSession.defaultSecurityPolicy,
            configuration: OWSURLSession.defaultConfigurationWithoutCaching
        )
    }

    private static func getUploadParameters(fileUrl: URL) async throws -> UploadParameters {
        let url = URL(string: "https://debuglogs.org/")!
        let response = try await buildOWSURLSession().performRequest(url.absoluteString, method: .get, ignoreAppExpiry: true)
        guard let params = response.responseBodyParamParser else {
            throw OWSAssertionError("Invalid response.")
        }
        let uploadUrl: String = try params.required(key: "url")
        let fieldMap: [String: String] = try params.required(key: "fields")
        guard !fieldMap.isEmpty else {
            throw OWSAssertionError("Empty fieldMap!")
        }
        for (key, value) in fieldMap {
            guard nil != key.nilIfEmpty,
                  nil != value.nilIfEmpty else {
                      throw OWSAssertionError("Empty key or value in fieldMap!")
                  }
        }
        guard let rawUploadKey = fieldMap["key"]?.nilIfEmpty else {
            throw OWSAssertionError("Missing rawUploadKey!")
        }
        guard let fileExtension = (fileUrl.lastPathComponent as NSString).pathExtension.nilIfEmpty else {
            throw OWSAssertionError("Invalid fileUrl: \(fileUrl)")
        }
        guard let uploadKey: String = (rawUploadKey as NSString).appendingPathExtension(fileExtension) else {
            throw OWSAssertionError("Could not modify uploadKey.")
        }
        var orderedFieldMap = OrderedDictionary<String, String>()
        for (key, value) in fieldMap {
            orderedFieldMap.append(key: key, value: value)
        }
        orderedFieldMap.replace(key: "key", value: uploadKey)
        return UploadParameters(uploadUrl: uploadUrl, fieldMap: orderedFieldMap, uploadKey: uploadKey)
    }

    private struct UploadParameters {
        let uploadUrl: String
        let fieldMap: OrderedDictionary<String, String>
        let uploadKey: String
    }

    private static func uploadFile(
        fileUrl: URL,
        mimeType: String,
        uploadParameters: UploadParameters
    ) async throws -> URL {
        let urlSession = buildOWSURLSession()

        guard let url = URL(string: uploadParameters.uploadUrl) else {
            throw OWSAssertionError("Invalid url: \(uploadParameters.uploadUrl)")
        }
        let request = URLRequest(url: url)

        var textParts = uploadParameters.fieldMap
        textParts.append(key: "Content-Type", value: mimeType)

        let response = try await urlSession.performMultiPartUpload(
            request: request,
            fileUrl: fileUrl,
            name: "file",
            fileName: fileUrl.lastPathComponent,
            mimeType: mimeType,
            textParts: textParts,
            ignoreAppExpiry: true,
            progress: nil
        )

        let statusCode = response.responseStatusCode
        // We'll accept any 2xx status code.
        guard statusCode/100 == 2 else {
            Logger.error("statusCode: \(statusCode)")
            Logger.error("headers: \(response.headers)")
            throw OWSAssertionError("Invalid status code: \(statusCode)")
        }

        let urlString = "https://debuglogs.org/\(uploadParameters.uploadKey)"
        guard let url = URL(string: urlString) else {
            throw OWSAssertionError("Invalid url: \(urlString)")
        }
        return url
    }
}