//
//  FileManager+ZIP.swift
//  ZIPFoundation
//
//  Copyright © 2017-2020 Thomas Zoechling, https://www.peakstep.com and the ZIP Foundation project authors.
//  Released under the MIT License.
//
//  See https://github.com/weichsel/ZIPFoundation/blob/master/LICENSE for license information.
//

import Foundation

extension FileManager {
    typealias CentralDirectoryStructure = Entry.CentralDirectoryStructure

    /// Zips the file or direcory contents at the specified source URL to the destination URL.
    ///
    /// If the item at the source URL is a directory, the directory itself will be
    /// represented within the ZIP `Archive`. Calling this method with a directory URL
    /// `file:///path/directory/` will create an archive with a `directory/` entry at the root level.
    /// You can override this behavior by passing `false` for `shouldKeepParent`. In that case, the contents
    /// of the source directory will be placed at the root of the archive.
    /// - Parameters:
    ///   - sourceURL: The file URL pointing to an existing file or directory.
    ///   - destinationURL: The file URL that identifies the destination of the zip operation.
    ///   - shouldKeepParent: Indicates that the directory name of a source item should be used as root element
    ///                       within the archive. Default is `true`.
    ///   - compressionMethod: Indicates the `CompressionMethod` that should be applied.
    ///                        By default, `zipItem` will create uncompressed archives.
    ///   - progress: A progress object that can be used to track or cancel the zip operation.
    /// - Throws: Throws an error if the source item does not exist or the destination URL is not writable.
    public func zipItem(at sourceURL: URL, to destinationURL: URL,
                        shouldKeepParent: Bool = true, compressionMethod: CompressionMethod = .none,
                        progress: Progress? = nil) throws {
        let fileManager = FileManager()
        guard fileManager.itemExists(at: sourceURL) else {
            throw CocoaError(.fileReadNoSuchFile, userInfo: [NSFilePathErrorKey: sourceURL.path])
        }
        guard !fileManager.itemExists(at: destinationURL) else {
            throw CocoaError(.fileWriteFileExists, userInfo: [NSFilePathErrorKey: destinationURL.path])
        }
        guard let archive = Archive(url: destinationURL, accessMode: .create) else {
            throw Archive.ArchiveError.unwritableArchive
        }
        let isDirectory = try FileManager.typeForItem(at: sourceURL) == .directory
        if isDirectory {
            let subPaths = try self.subpathsOfDirectory(atPath: sourceURL.path)
            var totalUnitCount = Int64(0)
            if let progress = progress {
                totalUnitCount = subPaths.reduce(Int64(0), {
                    let itemURL = sourceURL.appendingPathComponent($1)
                    let itemSize = archive.totalUnitCountForAddingItem(at: itemURL)
                    return $0 + itemSize
                })
                progress.totalUnitCount = totalUnitCount
            }

            // If the caller wants to keep the parent directory, we use the lastPathComponent of the source URL
            // as common base for all entries (similar to macOS' Archive Utility.app)
            let directoryPrefix = sourceURL.lastPathComponent
            for entryPath in subPaths {
                let finalEntryPath = shouldKeepParent ? directoryPrefix + "/" + entryPath : entryPath
                let finalBaseURL = shouldKeepParent ? sourceURL.deletingLastPathComponent() : sourceURL
                if let progress = progress {
                    let itemURL = sourceURL.appendingPathComponent(entryPath)
                    let entryProgress = archive.makeProgressForAddingItem(at: itemURL)
                    progress.addChild(entryProgress, withPendingUnitCount: entryProgress.totalUnitCount)
                    try archive.addEntry(with: finalEntryPath, relativeTo: finalBaseURL,
                                         compressionMethod: compressionMethod, progress: entryProgress)
                } else {
                    try archive.addEntry(with: finalEntryPath, relativeTo: finalBaseURL,
                                         compressionMethod: compressionMethod)
                }
            }
        } else {
            progress?.totalUnitCount = archive.totalUnitCountForAddingItem(at: sourceURL)
            let baseURL = sourceURL.deletingLastPathComponent()
            try archive.addEntry(with: sourceURL.lastPathComponent, relativeTo: baseURL,
                                 compressionMethod: compressionMethod, progress: progress)
        }
    }

    /// Unzips the contents at the specified source URL to the destination URL.
    ///
    /// - Parameters:
    ///   - sourceURL: The file URL pointing to an existing ZIP file.
    ///   - destinationURL: The file URL that identifies the destination directory of the unzip operation.
    ///   - skipCRC32: Optional flag to skip calculation of the CRC32 checksum to improve performance.
    ///   - progress: A progress object that can be used to track or cancel the unzip operation.
    ///   - preferredEncoding: Encoding for entry paths. Overrides the encoding specified in the archive.
    /// - Throws: Throws an error if the source item does not exist or the destination URL is not writable.
    public func unzipItem(at sourceURL: URL, to destinationURL: URL, skipCRC32: Bool = false,
                          progress: Progress? = nil, preferredEncoding: String.Encoding? = nil) throws {
        let fileManager = FileManager()
        guard fileManager.itemExists(at: sourceURL) else {
            throw CocoaError(.fileReadNoSuchFile, userInfo: [NSFilePathErrorKey: sourceURL.path])
        }
        guard let archive = Archive(url: sourceURL, accessMode: .read, preferredEncoding: preferredEncoding) else {
            throw Archive.ArchiveError.unreadableArchive
        }
        // Defer extraction of symlinks until all files & directories have been created.
        // This is necessary because we can't create links to files that haven't been created yet.
        let sortedEntries = archive.sorted { (left, right) -> Bool in
            switch (left.type, right.type) {
            case (.directory, .file): return true
            case (.directory, .symlink): return true
            case (.file, .symlink): return true
            default: return false
            }
        }
        var totalUnitCount = Int64(0)
        if let progress = progress {
            totalUnitCount = sortedEntries.reduce(0, { $0 + archive.totalUnitCountForReading($1) })
            progress.totalUnitCount = totalUnitCount
        }

        for entry in sortedEntries {
            let path = preferredEncoding == nil ? entry.path : entry.path(using: preferredEncoding!)
            let destinationEntryURL = destinationURL.appendingPathComponent(path)
            guard destinationEntryURL.isContained(in: destinationURL) else {
                throw CocoaError(.fileReadInvalidFileName,
                                 userInfo: [NSFilePathErrorKey: destinationEntryURL.path])
            }
            if let progress = progress {
                let entryProgress = archive.makeProgressForReading(entry)
                progress.addChild(entryProgress, withPendingUnitCount: entryProgress.totalUnitCount)
                _ = try archive.extract(entry, to: destinationEntryURL, skipCRC32: skipCRC32, progress: entryProgress)
            } else {
                _ = try archive.extract(entry, to: destinationEntryURL, skipCRC32: skipCRC32)
            }
        }
    }

    // MARK: - Helpers

    func itemExists(at url: URL) -> Bool {
        // Use `URL.checkResourceIsReachable()` instead of `FileManager.fileExists()` here
        // because we don't want implicit symlink resolution.
        // As per documentation, `FileManager.fileExists()` traverses symlinks and therefore a broken symlink
        // would throw a `.fileReadNoSuchFile` false positive error.
        // For ZIP files it may be intended to archive "broken" symlinks because they might be
        // resolvable again when extracting the archive to a different destination.
        return (try? url.checkResourceIsReachable()) == true
    }

    func createParentDirectoryStructure(for url: URL) throws {
        let parentDirectoryURL = url.deletingLastPathComponent()
        try self.createDirectory(at: parentDirectoryURL, withIntermediateDirectories: true, attributes: nil)
    }

    class func attributes(from entry: Entry) -> [FileAttributeKey: Any] {
        let centralDirectoryStructure = entry.centralDirectoryStructure
        let entryType = entry.type
        let fileTime = centralDirectoryStructure.lastModFileTime
        let fileDate = centralDirectoryStructure.lastModFileDate
        let defaultPermissions = entryType == .directory ? defaultDirectoryPermissions : defaultFilePermissions
        var attributes = [.posixPermissions: defaultPermissions] as [FileAttributeKey: Any]
        // Certain keys are not yet supported in swift-corelibs
        #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
        attributes[.modificationDate] = Date(dateTime: (fileDate, fileTime))
        #endif
        let versionMadeBy = centralDirectoryStructure.versionMadeBy
        guard let osType = Entry.OSType(rawValue: UInt(versionMadeBy >> 8)) else { return attributes }

        let externalFileAttributes = centralDirectoryStructure.externalFileAttributes
        let permissions = self.permissions(for: externalFileAttributes, osType: osType, entryType: entryType)
        attributes[.posixPermissions] = NSNumber(value: permissions)
        return attributes
    }

    class func permissions(for externalFileAttributes: UInt32, osType: Entry.OSType,
                           entryType: Entry.EntryType) -> UInt16 {
        switch osType {
        case .unix, .osx:
            let permissions = mode_t(externalFileAttributes >> 16) & (~S_IFMT)
            let defaultPermissions = entryType == .directory ? defaultDirectoryPermissions : defaultFilePermissions
            return permissions == 0 ? defaultPermissions : UInt16(permissions)
        default:
            return entryType == .directory ? defaultDirectoryPermissions : defaultFilePermissions
        }
    }

    class func externalFileAttributesForEntry(of type: Entry.EntryType, permissions: UInt16) -> UInt32 {
        var typeInt: UInt16
        switch type {
        case .file:
            typeInt = UInt16(S_IFREG)
        case .directory:
            typeInt = UInt16(S_IFDIR)
        case .symlink:
            typeInt = UInt16(S_IFLNK)
        }
        var externalFileAttributes = UInt32(typeInt|UInt16(permissions))
        externalFileAttributes = (externalFileAttributes << 16)
        return externalFileAttributes
    }

    class func permissionsForItem(at URL: URL) throws -> UInt16 {
        let fileManager = FileManager()
        let entryFileSystemRepresentation = fileManager.fileSystemRepresentation(withPath: URL.path)
        var fileStat = stat()
        lstat(entryFileSystemRepresentation, &fileStat)
        let permissions = fileStat.st_mode
        return UInt16(permissions)
    }

    class func fileModificationDateTimeForItem(at url: URL) throws -> Date {
        let fileManager = FileManager()
        guard fileManager.itemExists(at: url) else {
            throw CocoaError(.fileReadNoSuchFile, userInfo: [NSFilePathErrorKey: url.path])
        }
        let entryFileSystemRepresentation = fileManager.fileSystemRepresentation(withPath: url.path)
        var fileStat = stat()
        lstat(entryFileSystemRepresentation, &fileStat)
        #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
        let modTimeSpec = fileStat.st_mtimespec
        #else
        let modTimeSpec = fileStat.st_mtim
        #endif

        let timeStamp = TimeInterval(modTimeSpec.tv_sec) + TimeInterval(modTimeSpec.tv_nsec)/1000000000.0
        let modDate = Date(timeIntervalSince1970: timeStamp)
        return modDate
    }

    class func fileSizeForItem(at url: URL) throws -> UInt32 {
        let fileManager = FileManager()
        guard fileManager.itemExists(at: url) else {
            throw CocoaError(.fileReadNoSuchFile, userInfo: [NSFilePathErrorKey: url.path])
        }
        let entryFileSystemRepresentation = fileManager.fileSystemRepresentation(withPath: url.path)
        var fileStat = stat()
        lstat(entryFileSystemRepresentation, &fileStat)
        return UInt32(fileStat.st_size)
    }

    class func typeForItem(at url: URL) throws -> Entry.EntryType {
        let fileManager = FileManager()
        guard url.isFileURL, fileManager.itemExists(at: url) else {
            throw CocoaError(.fileReadNoSuchFile, userInfo: [NSFilePathErrorKey: url.path])
        }
        let entryFileSystemRepresentation = fileManager.fileSystemRepresentation(withPath: url.path)
        var fileStat = stat()
        lstat(entryFileSystemRepresentation, &fileStat)
        return Entry.EntryType(mode: fileStat.st_mode)
    }
}

extension Date {
    init(dateTime: (UInt16, UInt16)) {
        var msdosDateTime = Int(dateTime.0)
        msdosDateTime <<= 16
        msdosDateTime |= Int(dateTime.1)
        var unixTime = tm()
        unixTime.tm_sec = Int32((msdosDateTime&31)*2)
        unixTime.tm_min = Int32((msdosDateTime>>5)&63)
        unixTime.tm_hour = Int32((Int(dateTime.1)>>11)&31)
        unixTime.tm_mday = Int32((msdosDateTime>>16)&31)
        unixTime.tm_mon = Int32((msdosDateTime>>21)&15)
        unixTime.tm_mon -= 1 // UNIX time struct month entries are zero based.
        unixTime.tm_year = Int32(1980+(msdosDateTime>>25))
        unixTime.tm_year -= 1900 // UNIX time structs count in "years since 1900".
        let time = timegm(&unixTime)
        self = Date(timeIntervalSince1970: TimeInterval(time))
    }

    var fileModificationDateTime: (UInt16, UInt16) {
        return (self.fileModificationDate, self.fileModificationTime)
    }

    var fileModificationDate: UInt16 {
        var time = time_t(self.timeIntervalSince1970)
        guard let unixTime = gmtime(&time) else {
            return 0
        }
        var year = unixTime.pointee.tm_year + 1900 // UNIX time structs count in "years since 1900".
        // ZIP uses the MSDOS date format which has a valid range of 1980 - 2099.
        year = year >= 1980 ? year : 1980
        year = year <= 2099 ? year : 2099
        let month = unixTime.pointee.tm_mon + 1 // UNIX time struct month entries are zero based.
        let day = unixTime.pointee.tm_mday
        return (UInt16)(day + ((month) * 32) +  ((year - 1980) * 512))
    }

    var fileModificationTime: UInt16 {
        var time = time_t(self.timeIntervalSince1970)
        guard let unixTime = gmtime(&time) else {
            return 0
        }
        let hour = unixTime.pointee.tm_hour
        let minute = unixTime.pointee.tm_min
        let second = unixTime.pointee.tm_sec
        return (UInt16)((second/2) + (minute * 32) + (hour * 2048))
    }
}

#if swift(>=4.2)
#else

#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
#else

// The swift-corelibs-foundation version of NSError.swift was missing a convenience method to create
// error objects from error codes. (https://github.com/apple/swift-corelibs-foundation/pull/1420)
// We have to provide an implementation for non-Darwin platforms using Swift versions < 4.2.

public extension CocoaError {
    public static func error(_ code: CocoaError.Code, userInfo: [AnyHashable: Any]? = nil, url: URL? = nil) -> Error {
        var info: [String: Any] = userInfo as? [String: Any] ?? [:]
        if let url = url {
            info[NSURLErrorKey] = url
        }
        return NSError(domain: NSCocoaErrorDomain, code: code.rawValue, userInfo: info)
    }
}

#endif
#endif

public extension URL {
    func isContained(in parentDirectoryURL: URL) -> Bool {
        // Ensure this URL is contained in the passed in URL
        let parentDirectoryURL = URL(fileURLWithPath: parentDirectoryURL.path, isDirectory: true).standardized
        return self.standardized.absoluteString.hasPrefix(parentDirectoryURL.absoluteString)
    }
}