import CommonCrypto
import Foundation
import ZIPFoundation

@objc(FileAccessImpl)
public class FileAccess : NSObject {
    private let fetchCalls = NSMapTable<NSNumber, URLSessionDownloadTask>.init(keyOptions: .copyIn, valueOptions: .weakMemory)

    @objc(appendFile:withData:withEncoding:withResolver:withRejecter:)
    public func appendFile(path: String, data: String, encoding: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            guard let encodedData = encoding == "base64" ? Data(base64Encoded: data) : data.data(using: .utf8),
                  let handle = FileHandle(forWritingAtPath: path.path()) else {
                reject("ERR", "Failed to append to '\(path)'.", nil)
                return
            }

            handle.seekToEndOfFile()
            handle.write(encodedData)
            handle.closeFile()
            resolve(nil)
        }
    }

    @objc(cancelFetch:withResolver:withRejecter:)
    public func cancelFetch(requestId: Int, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
        if let call = fetchCalls.object(forKey: requestId as NSNumber) {
            fetchCalls.removeObject(forKey: requestId as NSNumber)
            call.cancel()
        }
        resolve(nil)
    }

    @objc(concatFiles:withTarget:withResolver:withRejecter:)
    public func concatFiles(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            guard let input = InputStream(fileAtPath: source.path()), let output = OutputStream(toFileAtPath: target.path(), append: true) else {
                reject("ERR", "Failed to concat '\(source)' to '\(target)'.", nil)
                return
            }

            input.open()
            output.open()
            var bytesCopied = 0
            let bufferSize = 8 * 1024
            var buffer = [UInt8](repeating: 0, count: bufferSize);
            var bytes = input.read(&buffer, maxLength: bufferSize)
            while bytes > 0 {
                output.write(buffer, maxLength: bytes)
                bytesCopied += bytes
                bytes = input.read(&buffer, maxLength: bufferSize)
            }
            output.close()
            input.close()

            resolve(bytesCopied)
        }
    }

    @objc(cp:withTarget:withResolver:withRejecter:)
    public func cp(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try FileManager.default.copyItem(atPath: source.path(), toPath: target.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to copy '\(source)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(cpAsset:withTarget:withResolver:withRejecter:)
    public func cpAsset(asset: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            guard let assetPath = Bundle.main.path(forResource: asset, ofType: nil) else {
                reject("ENOENT", "Asset \(asset) not found", nil)
                return
            }

            do {
                try FileManager.default.copyItem(atPath: assetPath, toPath: target.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to copy '\(asset)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(cpExternal:withTargetName:withDir:withResolver:withRejecter:)
    public func cpExternal(source: String, targetName: String, dir: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        let targetFolder: String
        switch dir {
        case "audio":
            targetFolder = NSSearchPathForDirectoriesInDomains(.musicDirectory, .userDomainMask, true).first!
        case "downloads":
            targetFolder = NSSearchPathForDirectoriesInDomains(.downloadsDirectory, .userDomainMask, true).first!
        case "images":
            targetFolder = NSSearchPathForDirectoriesInDomains(.picturesDirectory, .userDomainMask, true).first!
        case "video":
            targetFolder = NSSearchPathForDirectoriesInDomains(.moviesDirectory, .userDomainMask, true).first!
        default:
            reject("ERR", "Unknown destination '\(dir)'.", nil)
            return
        }

        try? FileManager.default.createDirectory(atPath: targetFolder, withIntermediateDirectories: true, attributes: nil)

        let targetUrl = URL(fileURLWithPath: targetFolder, isDirectory: true)
            .appendingPathComponent(targetName, isDirectory: false)
        cp(source: source.path(), target: targetUrl.path, resolve: resolve, reject: reject)
    }

    @objc(df:withRejecter:)
    public func df(resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
#if NO_PRIVACY_API
            reject("ERR", "Filesystem stat API disabled via compile time flag.", nil)
#else
            do {
                let stat = try FileManager.default.attributesOfFileSystem(
                    forPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
                )

                resolve([
                    "internal_free": stat[.systemFreeSize],
                    "internal_total": stat[.systemSize]
                ])
            } catch {
                reject("ERR", "Failed to stat filesystem. \(error.localizedDescription)", error)
            }
#endif
        }
    }

    @objc(exists:withResolver:withRejecter:)
    public func exists(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            resolve(FileManager.default.fileExists(atPath: path.path()))
        }
    }

    @objc
    public func fetch(requestId: Int, resource: String, body: String?, headers: NSDictionary?, method: String?, network: String?, path: String?, emitOnProgress: @escaping EventEmitter, emitOnError: @escaping EventEmitter, emitOnComplete: @escaping EventEmitter) -> Void {
        let handler = NetworkHandler(requestId: requestId, emitOnProgress: emitOnProgress, emitOnError: emitOnError, emitOnComplete: emitOnComplete) {
            self.fetchCalls.removeObject(forKey: requestId as NSNumber)
        }
        if let call = handler.fetch(resource: resource, body: body, headers: headers, method: method, network: network, path: path) {
            fetchCalls.setObject(call, forKey: requestId as NSNumber)
        }
    }

    @objc(getAppGroupDir:withResolver:withRejecter:)
    public func getAppGroupDir(groupName: String, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
        guard let groupURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: groupName) else {
            reject("ERR", "Could not resolve app group directory. The group name '\(groupName)' is invalid.", nil)
            return
        }

        resolve(groupURL.path)
    }

    @objc(hardlink:withTarget:withResolver:withRejecter:)
    public func hardlink(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try FileManager.default.linkItem(atPath: source.path(), toPath: target.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to create hard link from '\(source)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(hash:withAlgorithm:withResolver:withRejecter:)
    public func hash(path: String, algorithm: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            guard let data = NSData(contentsOfFile: path.path()) else {
                reject("ERR", "Failed to read '\(path)'.", nil)
                return
            }

            let hashAlgo: (UnsafeRawPointer?, CC_LONG, UnsafeMutablePointer<UInt8>?) -> UnsafeMutablePointer<UInt8>?
            let digestLength: Int32
            switch algorithm {
            case "MD5":
                hashAlgo = CC_MD5
                digestLength = CC_MD5_DIGEST_LENGTH
            case "SHA-1":
                hashAlgo = CC_SHA1
                digestLength = CC_SHA1_DIGEST_LENGTH
            case "SHA-224":
                hashAlgo = CC_SHA224
                digestLength = CC_SHA224_DIGEST_LENGTH
            case "SHA-256":
                hashAlgo = CC_SHA256
                digestLength = CC_SHA256_DIGEST_LENGTH
            case "SHA-384":
                hashAlgo = CC_SHA384
                digestLength = CC_SHA384_DIGEST_LENGTH
            case "SHA-512":
                hashAlgo = CC_SHA512
                digestLength = CC_SHA512_DIGEST_LENGTH
            default:
                reject("ERR", "Unknown algorithm '\(algorithm)'.", nil)
                return
            }

            var digest = [UInt8](repeating: 0, count: Int(digestLength));
            _ = hashAlgo(data.bytes, CC_LONG(data.length), &digest)
            resolve(digest.map { String(format: "%02x", $0) }.joined())
        }
    }

    @objc(isDir:withResolver:withRejecter:)
    public func isDir(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            let status = self.checkIfIsDirectory(path: path.path())
            resolve(status.exists && status.isDirectory)
        }
    }

    @objc(ls:withResolver:withRejecter:)
    public func ls(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try resolve(FileManager.default.contentsOfDirectory(atPath: path.path()))
            } catch {
                reject("ERR", "Failed to list '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(mkdir:withResolver:withRejecter:)
    public func mkdir(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try FileManager.default.createDirectory(atPath: path.path(), withIntermediateDirectories: true, attributes: nil)
                resolve(path)
            } catch {
                reject("ERR", "Failed to create directory '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(mv:withTarget:withResolver:withRejecter:)
    public func mv(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try? FileManager.default.removeItem(atPath: target.path())
                try FileManager.default.moveItem(atPath: source.path(), toPath: target.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to rename '\(source)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(readFile:withEncoding:withResolver:withRejecter:)
    public func readFile(path: String, encoding: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                if encoding == "base64" {
                    let binaryData = try Data(contentsOf: URL(fileURLWithPath: path.path()))
                    resolve(binaryData.base64EncodedString())
                } else {
                    try resolve(String(contentsOfFile: path.path()))
                }
            } catch {
                reject("ERR", "Failed to read '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(readFileChunk:withOffset:withLength:withEncoding:withResolver:withRejecter:)
    public func readFileChunk(path: String, offset: Int, length: Int, encoding: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                let fileHandle = try FileHandle(forReadingFrom: URL(fileURLWithPath: path.path()))
                defer {
                    fileHandle.closeFile()
                }

                fileHandle.seek(toFileOffset: UInt64(offset))
                let binaryData = fileHandle.readData(ofLength: length)

                if encoding == "base64" {
                    resolve(binaryData.base64EncodedString())
                } else {
                    if let content = String(data: binaryData, encoding: .utf8) {
                        resolve(content)
                    } else {
                        reject("ERR", "Failed to decode content from file '\(path)' with specified encoding.", nil)
                    }
                }
            } catch {
                reject("ERR", "Failed to read '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(stat:withResolver:withRejecter:)
    public func stat(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                resolve(try self.statFile(path: path))
            } catch {
                reject("ERR", "Failed to stat '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(statDir:withResolver:withRejecter:)
    public func statDir(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            let base = URL(fileURLWithPath: path.path())
            do {
                try resolve(FileManager.default.contentsOfDirectory(atPath: path.path())
                    .compactMap { try? self.statFile(path: base.appendingPathComponent($0).path) }
                )
            } catch {
                reject("ERR", "Failed to list '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(symlink:withTarget:withResolver:withRejecter:)
    public func symlink(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try FileManager.default.createSymbolicLink(atPath: target.path(), withDestinationPath: source.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to create symbolic link from '\(source)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(unlink:withResolver:withRejecter:)
    public func unlink(path: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                try FileManager.default.removeItem(atPath: path.path())
                resolve(nil)
            } catch {
                reject("ERR", "Failed to unlink '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(unzip:withTarget:withResolver:withRejecter:)
    public func unzip(source: String, target: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            let sourceUrl = URL(fileURLWithPath: source.path())
            let targetUrl = URL(fileURLWithPath: target.path())
            do {
                try FileManager.default.unzipItem(at: sourceUrl, to: targetUrl)
                resolve(nil)
            } catch {
                reject("ERR", "Failed to unzip '\(source)' to '\(target)'. \(error.localizedDescription)", error)
            }
        }
    }

    @objc(writeFile:withData:withEncoding:withResolver:withRejecter:)
    public func writeFile(path: String, data: String, encoding: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) -> Void {
        DispatchQueue.global().async {
            do {
                if encoding == "base64" {
                    let pathUrl = URL(fileURLWithPath: path.path())
                    guard let decoded = Data(base64Encoded: data, options: .ignoreUnknownCharacters) else {
                        reject("ERR", "Failed to write to '\(path)', invalid base64.", nil)
                        return
                    }
                    try decoded.write(to: pathUrl)
                } else {
                    try data.write(toFile: path.path(), atomically: false, encoding: .utf8)
                }
                resolve(nil)
            } catch {
                reject("ERR", "Failed to write to '\(path)'. \(error.localizedDescription)", error)
            }
        }
    }

    private func checkIfIsDirectory(path: String) -> (exists: Bool, isDirectory: Bool) {
        var isDir: ObjCBool = false
        let exists = FileManager.default.fileExists(atPath: path.path(), isDirectory: &isDir)
        let isDirectory = isDir.boolValue
        return (exists, isDirectory)
    }

    private func statFile(path: String) throws -> [String : Any?] {
        let pathUrl = URL(fileURLWithPath: path.path())
        let attrs = try FileManager.default.attributesOfItem(atPath: path.path())
#if NO_PRIVACY_API
        let lastModified = 0
#else
        let lastModified = 1000 * (attrs[.modificationDate] as! NSDate).timeIntervalSince1970
#endif
        return [
            "filename": pathUrl.lastPathComponent,
            "lastModified": lastModified,
            "path": pathUrl.path,
            "size": attrs[.size],
            "type": self.checkIfIsDirectory(path: path).isDirectory ? "directory" : "file"
        ]
    }
}