package slangc.streams;

import slang.vm.SystemCall;
import slang.vm.DeviceHandle;

public class SimpleVFS extends VFS {
    public String separator() {
        return "/";
    }

    public File[] list(String path) throws Error {
        String[] names = new String[0];
        int n = SystemCall.fileList(path, names);
        if (n < 0) {
            return null;
        }
        names = new String[n];
        SystemCall.fileList(path, names);
        File[] files = new File[n];
        for (int i = 0; i < n; i++) {
            files[i] = file(path + separator() + names[i]);
        }
        return files;
    }

    public long size(String path) throws Error {
        duck[] stats = new duck[2];
        SystemCall.fileStat(path, stats);
        if (stats[0] == 1) {
            return (long) stats[1];
        } else {
            return -1;
        }
    }

    public static class SimpleInput extends FileInput {
        DeviceHandle dev;
        public SimpleInput(VFS vfs, String path, DeviceHandle dev) {
            super(vfs, path);
            this.dev = dev;
        }
        

        public int readBuffer(byte[] buffer, int beginAt, int maxLength) {
            uint8[] internal = new uint8[buffer.length];
            int total = SystemCall.readBytes(dev, internal, beginAt, maxLength);
            for (int i = 0; i < total; i++) {
                buffer[beginAt + i] = (byte) internal[beginAt + i];
            }
            return total;
        }

        public void close() {
            dev.close();
        }
    }

    public FileInput openInput(String path) throws Error {
        DeviceHandle dev = SystemCall.fileOpen(path, "rb");
        if (dev == null) {
            throw new Error("Unable to open file '" + path + "' for reading");
        }
        return new SimpleInput(this, path, dev);
    }

    public static class SimpleOutput extends FileOutput {
        DeviceHandle dev;
        public SimpleOutput(VFS vfs, String path, DeviceHandle dev) {
            super(vfs, path);
            this.dev = dev;
        }

        public int writeBuffer(byte[] buffer, int beginAt, int maxLength) {
            uint8[] internal = new uint8[buffer.length];
            for (int i = 0; i < maxLength; i++) {
                internal[beginAt + i] = (uint8) buffer[beginAt + i];
            }
            int total = SystemCall.writeBytes(dev, internal, beginAt, maxLength);
            return total;
        }
        
        public void close() {
            dev.close();
            //SystemCall.devicePoll(dev, true);
        }
    }

    public FileOutput openOutput(String path) throws Error {
        DeviceHandle dev = SystemCall.fileOpen(path, "wb");
        if (dev == null) {
            throw new Error("Unable to open file '" + path + "' for writing");
        }
        return new SimpleOutput(this, path, dev);
    }
}