import Foundation
import Testing

@Suite("File System Operation Tests", .tags(.fileSystem))
struct FileSystemTests {
    // MARK: - Path Operations

    @Test("Path normalization and resolution")
    func pathNormalization() {
        // Test path normalization
        func normalizePath(_ path: String) -> String {
            (path as NSString).standardizingPath
        }

        #expect(normalizePath("/Users/test/./Documents") == "/Users/test/Documents")
        #expect(normalizePath("/Users/test/../test/Documents") == "/Users/test/Documents")
        #expect(normalizePath("~/Documents") != "~/Documents") // Should expand tilde
        #expect(normalizePath("/Users//test///Documents") == "/Users/test/Documents")
    }

    @Test("File extension handling")
    func fileExtensions() {
        struct FileInfo {
            let path: String

            var filename: String {
                (path as NSString).lastPathComponent
            }

            var `extension`: String {
                (path as NSString).pathExtension
            }

            var nameWithoutExtension: String {
                (filename as NSString).deletingPathExtension
            }

            func appendingExtension(_ ext: String) -> String {
                (path as NSString).appendingPathExtension(ext) ?? path
            }
        }

        let file = FileInfo(path: "/Users/test/document.txt")
        #expect(file.filename == "document.txt")
        #expect(file.extension == "txt")
        #expect(file.nameWithoutExtension == "document")

        let noExtFile = FileInfo(path: "/Users/test/README")
        #expect(noExtFile.extension == "")
        #expect(noExtFile.nameWithoutExtension == "README")
    }

    // MARK: - File Permissions

    @Test("File permission checks")
    func filePermissions() {
        struct FilePermissions {
            let isReadable: Bool
            let isWritable: Bool
            let isExecutable: Bool
            let isDeletable: Bool

            var octalRepresentation: String {
                var value = 0
                if isReadable { value += 4 }
                if isWritable { value += 2 }
                if isExecutable { value += 1 }
                return String(value)
            }
        }

        let readOnly = FilePermissions(
            isReadable: true,
            isWritable: false,
            isExecutable: false,
            isDeletable: false
        )
        #expect(readOnly.octalRepresentation == "4")

        let readWrite = FilePermissions(
            isReadable: true,
            isWritable: true,
            isExecutable: false,
            isDeletable: true
        )
        #expect(readWrite.octalRepresentation == "6")

        let executable = FilePermissions(
            isReadable: true,
            isWritable: false,
            isExecutable: true,
            isDeletable: false
        )
        #expect(executable.octalRepresentation == "5")
    }

    // MARK: - Directory Operations

    @Test("Directory traversal and listing")
    func directoryTraversal() {
        struct DirectoryEntry {
            let name: String
            let isDirectory: Bool
            let size: Int64?
            let modificationDate: Date?

            var type: String {
                isDirectory ? "directory" : "file"
            }
        }

        // Test directory entry creation
        let fileEntry = DirectoryEntry(
            name: "test.txt",
            isDirectory: false,
            size: 1_024,
            modificationDate: Date()
        )
        #expect(fileEntry.type == "file")
        #expect(fileEntry.size == 1_024)

        let dirEntry = DirectoryEntry(
            name: "Documents",
            isDirectory: true,
            size: nil,
            modificationDate: Date()
        )
        #expect(dirEntry.type == "directory")
        #expect(dirEntry.size == nil)
    }

    @Test("Recursive directory size calculation")
    func directorySizeCalculation() {
        // Simulate directory size calculation
        func calculateDirectorySize(files: [(name: String, size: Int64)]) -> Int64 {
            files.reduce(0) { $0 + $1.size }
        }

        let files = [
            ("file1.txt", Int64(1_024)),
            ("file2.doc", Int64(2_048)),
            ("image.jpg", Int64(4_096))
        ]

        let totalSize = calculateDirectorySize(files: files)
        #expect(totalSize == 7_168)

        // Test size formatting
        func formatFileSize(_ bytes: Int64) -> String {
            let formatter = ByteCountFormatter()
            formatter.countStyle = .file
            return formatter.string(fromByteCount: bytes)
        }

        #expect(!formatFileSize(1_024).isEmpty)
        #expect(!formatFileSize(1_048_576).isEmpty) // 1 MB
    }

    // MARK: - File Operations

    @Test("Safe file operations")
    func safeFileOperations() {
        enum FileOperation {
            case read
            case write
            case delete
            case move(to: String)
            case copy(to: String)

            var requiresWritePermission: Bool {
                switch self {
                case .read:
                    false
                case .write, .delete, .move, .copy:
                    true
                }
            }
        }

        #expect(FileOperation.read.requiresWritePermission == false)
        #expect(FileOperation.write.requiresWritePermission == true)
        #expect(FileOperation.delete.requiresWritePermission == true)
        #expect(FileOperation.move(to: "/tmp/file").requiresWritePermission == true)
    }

    @Test("Atomic file writing")
    func atomicFileWriting() {
        struct AtomicFileWriter {
            let destinationPath: String

            var temporaryPath: String {
                destinationPath + ".tmp"
            }

            func writeSteps() -> [String] {
                [
                    "Write to temporary file: \(temporaryPath)",
                    "Verify temporary file integrity",
                    "Atomically rename to: \(destinationPath)",
                    "Clean up any failed attempts"
                ]
            }
        }

        let writer = AtomicFileWriter(destinationPath: "/Users/test/important.dat")
        let steps = writer.writeSteps()

        #expect(steps.count == 4)
        #expect(writer.temporaryPath == "/Users/test/important.dat.tmp")
    }

    // MARK: - File Watching

    @Test("File change detection")
    func fileChangeDetection() {
        struct FileSnapshot {
            let path: String
            let size: Int64
            let modificationDate: Date
            let contentHash: String

            func hasChanged(comparedTo other: FileSnapshot) -> Bool {
                size != other.size ||
                    modificationDate != other.modificationDate ||
                    contentHash != other.contentHash
            }
        }

        let snapshot1 = FileSnapshot(
            path: "/test/file.txt",
            size: 1_024,
            modificationDate: Date(),
            contentHash: "abc123"
        )

        let snapshot2 = FileSnapshot(
            path: "/test/file.txt",
            size: 1_024,
            modificationDate: Date().addingTimeInterval(10),
            contentHash: "abc123"
        )

        let snapshot3 = FileSnapshot(
            path: "/test/file.txt",
            size: 2_048,
            modificationDate: Date().addingTimeInterval(20),
            contentHash: "def456"
        )

        #expect(!snapshot1.hasChanged(comparedTo: snapshot1))
        #expect(snapshot1.hasChanged(comparedTo: snapshot2)) // Different date
        #expect(snapshot1.hasChanged(comparedTo: snapshot3)) // Different size and hash
    }

    // MARK: - Sandbox and Security

    @Test("Sandbox path validation")
    func sandboxPaths() {
        struct SandboxValidator {
            let appGroupIdentifier = "group.com.vibetunnel"

            var documentsDirectory: String {
                "~/Documents"
            }

            var temporaryDirectory: String {
                NSTemporaryDirectory()
            }

            var appGroupDirectory: String {
                "~/Library/Group Containers/\(appGroupIdentifier)"
            }

            func isWithinSandbox(_ path: String) -> Bool {
                let normalizedPath = (path as NSString).standardizingPath
                let expandedDocs = (documentsDirectory as NSString).expandingTildeInPath
                let expandedAppGroup = (appGroupDirectory as NSString).expandingTildeInPath

                return normalizedPath.hasPrefix(expandedDocs) ||
                    normalizedPath.hasPrefix(temporaryDirectory) ||
                    normalizedPath.hasPrefix(expandedAppGroup)
            }
        }

        let validator = SandboxValidator()
        #expect(validator.isWithinSandbox("~/Documents/file.txt"))
        #expect(validator.isWithinSandbox(NSTemporaryDirectory() + "temp.dat"))
        #expect(!validator.isWithinSandbox("/System/Library/file.txt"))
    }

    // MARK: - File Type Detection

    @Test("MIME type detection")
    func mIMETypeDetection() {
        func mimeType(for fileExtension: String) -> String {
            let mimeTypes: [String: String] = [
                "txt": "text/plain",
                "html": "text/html",
                "json": "application/json",
                "pdf": "application/pdf",
                "jpg": "image/jpeg",
                "png": "image/png",
                "mp4": "video/mp4",
                "zip": "application/zip"
            ]

            return mimeTypes[fileExtension.lowercased()] ?? "application/octet-stream"
        }

        #expect(mimeType(for: "txt") == "text/plain")
        #expect(mimeType(for: "JSON") == "application/json")
        #expect(mimeType(for: "unknown") == "application/octet-stream")
    }

    @Test("Text encoding detection")
    func textEncodingDetection() {
        // Test BOM (Byte Order Mark) detection
        func detectEncoding(from bom: [UInt8]) -> String.Encoding? {
            if bom.starts(with: [0xEF, 0xBB, 0xBF]) {
                return .utf8
            } else if bom.starts(with: [0xFF, 0xFE]) {
                return .utf16LittleEndian
            } else if bom.starts(with: [0xFE, 0xFF]) {
                return .utf16BigEndian
            } else if bom.starts(with: [0xFF, 0xFE, 0x00, 0x00]) {
                return .utf32LittleEndian
            } else if bom.starts(with: [0x00, 0x00, 0xFE, 0xFF]) {
                return .utf32BigEndian
            }
            return nil
        }

        #expect(detectEncoding(from: [0xEF, 0xBB, 0xBF]) == .utf8)
        #expect(detectEncoding(from: [0xFF, 0xFE]) == .utf16LittleEndian)
        #expect(detectEncoding(from: [0x41, 0x42]) == nil) // No BOM
    }

    // MARK: - URL and Path Conversion

    @Test("URL to path conversion")
    func uRLPathConversion() {
        func filePathFromURL(_ urlString: String) -> String? {
            guard let url = URL(string: urlString),
                  url.isFileURL else { return nil }
            return url.path
        }

        #expect(filePathFromURL("file:///Users/test/file.txt") == "/Users/test/file.txt")
        #expect(filePathFromURL("file://localhost/Users/test/file.txt") == "/Users/test/file.txt")
        #expect(filePathFromURL("https://example.com/file.txt") == nil)

        // Test path to URL conversion
        func fileURLFromPath(_ path: String) -> URL? {
            URL(fileURLWithPath: path)
        }

        let url = fileURLFromPath("/Users/test/file.txt")
        #expect(url?.isFileURL == true)
        #expect(url?.path == "/Users/test/file.txt")
    }
}
