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package org.jruby.util;

import java.nio.channels.SeekableByteChannel;
import jnr.constants.platform.Errno;
import jnr.constants.platform.Fcntl;
import jnr.enxio.channels.NativeDeviceChannel;
import jnr.posix.FileStat;
import jnr.posix.POSIX;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.Channel;
import java.nio.channels.FileChannel;

import org.jruby.ext.fcntl.FcntlLibrary;
import org.jruby.RubyFile;
import org.jruby.platform.Platform;
import org.jruby.util.io.ModeFlags;
import org.jruby.util.io.PosixShim;

/**
 * Represents a "regular" file, backed by regular file system.
 */
class RegularFileResource extends AbstractFileResource {
    private final JRubyFile file;
    private final POSIX posix;

    RegularFileResource(POSIX posix, File file) {
        this(posix, file.getAbsolutePath());
    }

    protected RegularFileResource(POSIX posix, String filename) {
        this.file = new JRubyFile(filename);
        this.posix = posix;
    }

    @Override
    public String absolutePath() {
        return RubyFile.canonicalize(file.getAbsolutePath());
    }

    @Override
    public String canonicalPath() {
        // Seems like for Ruby absolute path implies resolving system links,
        // so canonicalization is in order.
        try {
            return file.getCanonicalPath();
        } catch (IOException ioError) {
            // I guess absolute path is next best thing?
            return file.getAbsolutePath();
        }
    }

    @Override
    public long length() {
        return file.length();
    }

    @Override
    public long lastModified() {
        return file.lastModified();
    }

    @Override
    public boolean exists() {
        // MRI behavior: Even broken symlinks should return true.
        // FIXME: Where is the above statement true?  For RubyFile{,Test} it does not seem to be.
        return file.exists(); // || isSymLink();
    }

    @Override
    public boolean canExecute() {
        return file.canExecute();
    }

    public int errno() {
        return posix.errno();
    }

    @Override
    public boolean isFile() {
        return file.isFile();
    }

    @Override
    public boolean isDirectory() {
        return file.isDirectory();
    }

    @Override
    public boolean isSymLink() {
        FileStat stat = posix.allocateStat();

        return posix.lstat(file.getAbsolutePath(), stat) < 0 ?
                false : stat.isSymlink();
    }

    @Override
    public boolean canRead() {
        return file.canRead();
    }

    @Override
    public boolean canWrite() {
        return file.canWrite();
    }

    @Override
    public String[] list() {
        String[] fileList = file.list();

        if (fileList == null) return null;

        // If we got some entries, then it's probably a directory and in Ruby all file
        // directories should have '.' and '..' entries
        String[] list = new String[fileList.length + 2];
        list[0] = ".";
        list[1] = "..";
        System.arraycopy(fileList, 0, list, 2, fileList.length);

        return list;
    }

    @Override
    public FileStat stat() {
        FileStat stat = posix.allocateStat();

        return posix.stat(file.getAbsolutePath(), stat) < 0 ? null : stat;
    }

    @Override
    public FileStat lstat() {
        FileStat stat = posix.allocateStat();

        return posix.lstat(file.getAbsolutePath(), stat) < 0 ? null : stat;
    }

    @Override
    public String toString() {
        return file.toString();
    }

    @Override
    public JRubyFile hackyGetJRubyFile() {
        return file;
    }

    @Override
    InputStream openInputStream() throws IOException {
        return new FileInputStream(file);
    }

    @Override
    public Channel openChannel(ModeFlags flags, int perm) throws ResourceException {
        if (posix.isNative() && !Platform.IS_WINDOWS) {
            int fd = posix.open(absolutePath(), flags.getFlags(), perm);
            if (fd < 0) {
                Errno errno = Errno.valueOf(posix.errno());
                switch (errno) {
                    case EACCES:
                        throw new ResourceException.PermissionDenied(absolutePath());
                    case EEXIST:
                        throw new ResourceException.FileExists(absolutePath());
                    case EINVAL:
                        throw new ResourceException.InvalidArguments(absolutePath());
                    case ENOENT:
                        throw new ResourceException.NotFound(absolutePath());
                    case ELOOP:
                        throw new ResourceException.TooManySymlinks(absolutePath());
                    case EISDIR:
                        throw new ResourceException.FileIsDirectory(absolutePath());
                    default:
                        throw new ResourceException.IOError(new IOException("unhandled errno: " + errno));

                }
            }
            posix.fcntlInt(fd, Fcntl.F_SETFD, posix.fcntl(fd, Fcntl.F_GETFD) | FcntlLibrary.FD_CLOEXEC);
            return new NativeDeviceChannel(fd);
        }

        if (flags.isCreate()) {
            boolean fileCreated;
            try {
                fileCreated = file.createNewFile();
            } catch (IOException ioe) {
                // See JRUBY-4380.
                // when the directory for the file doesn't exist.
                // Java in such cases just throws IOException.
                File parent = file.getParentFile();
                if (parent != null && parent != file && !parent.exists()) {
                    throw new ResourceException.NotFound(absolutePath());
                } else if (!file.canWrite()) {
                    throw new ResourceException.PermissionDenied(absolutePath());
                } else {
                    // for all other IO errors, we report it as general IO error
                    throw new ResourceException.IOError(ioe);
                }
            }

            if (!fileCreated && flags.isExclusive()) {
                throw new ResourceException.FileExists(absolutePath());
            }

            Channel channel = createChannel(flags);

            // attempt to set the permissions, if we have been passed a POSIX instance,
            // perm is > 0, and only if the file was created in this call.
            if (fileCreated && posix != null) {
                perm = perm & ~PosixShim.umask(posix);

                if (perm > 0) posix.chmod(file.getPath(), perm);
            }

            return channel;
        }

        if (file.isDirectory() && flags.isWritable()) {
            throw new ResourceException.FileIsDirectory(absolutePath());
        }

        if (!file.exists()) {
            throw new ResourceException.NotFound(absolutePath());
        }

        return createChannel(flags);
    }

    private Channel createChannel(ModeFlags flags) throws ResourceException {
        SeekableByteChannel fileChannel;

        try{
            if (flags.isWritable() && !flags.isReadable()) {
                FileOutputStream fos = new FileOutputStream(file, flags.isAppendable());
                fileChannel = fos.getChannel();
            } else {
                RandomAccessFile raf = new RandomAccessFile(file, flags.toJavaModeString());
                fileChannel = raf.getChannel();

                // O_APPEND specifies that all writes will always be at the end of the open file
                // (even if we happened to have seek'd away from the end of the file o_O). RAF
                // does not have these semantics so we wrap it to support this unusual case.
                if (flags.isAppendable()) fileChannel = new AppendModeChannel((FileChannel) fileChannel);
            }
        } catch (FileNotFoundException fnfe) {
            // Jave throws FileNotFoundException both if the file doesn't exist or there were
            // permission issues, but Ruby needs to disambiguate those two cases
            throw file.exists() ?
                    new ResourceException.PermissionDenied(absolutePath()) :
                    new ResourceException.NotFound(absolutePath());
        }

        try {
            if (flags.isTruncate()) fileChannel.truncate(0);
        } catch (IOException ioe) {
            // ignore; it's a pipe or fifo that can't be truncated (we only care about illegal seek).
            if (!ioe.getMessage().equals("Illegal seek")) throw new ResourceException.IOError(ioe);
        }

        return fileChannel;
    }
}