package api;

import java.io.BufferedWriter;

import java.io.IOException;

/** Fixing the problem caused by mixing subclassing and delegation in 

 * the <code>java.io.BufferedWriter</code>

 *

 * @author Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 */

public final class Writer {

    private final Impl impl;

    private final ImplSeq seq;

    private Writer(Impl impl, ImplSeq seq) {

        this.impl = impl;

        this.seq = seq;

    }

    public final void write(int c) throws IOException {

        if (impl != null) {

            char[] arr = {(char) c};

            impl.write(arr, 0, 1);

        } else {

            seq.write(new CharSeq(c));

        }

    }

    public final void write(char cbuf[]) throws IOException {

        if (impl != null) {

            impl.write(cbuf, 0, cbuf.length);

        } else {

            seq.write(new CharSeq(cbuf, 0, cbuf.length));

        }

    }

    public final void write(char cbuf[], int off, int len) throws IOException {

        if (impl != null) {

            impl.write(cbuf, off, len);

        } else {

            seq.write(new CharSeq(cbuf, off, len));

        }

    }

    public final void write(String str) throws IOException {

        if (impl != null) {

            impl.write(str, 0, str.length());

        } else {

            seq.write(str);

        }

    }

    public final void write(String str, int off, int len) throws IOException {

        if (impl != null) {

            impl.write(str, off, len);

        } else {

            seq.write(str.subSequence(off, off + len));

        }

    }

    public final void flush() throws IOException {

        if (impl != null) {

            impl.flush();

        } else {

            seq.flush();

        }

    }

    public final void close() throws IOException {

        if (impl != null) {

            impl.close();

        } else {

            seq.flush();

        }

    }

    public static Writer create(Impl impl) {

        return new Writer(impl, null);

    }

    public static Writer create(ImplSeq impl) {

        return new Writer(null, impl);

    }

    public static Writer create(final java.io.Writer w) {

        return new Writer(new Impl() {

            public void write(String str, int off, int len) throws IOException {

                w.write(str, off, len);

            }

            public void write(char[] arr, int off, int len) throws IOException {

                w.write(arr, off, len);

            }

            public void close() throws IOException {

                w.close();

            }

            public void flush() throws IOException {

                w.flush();

            }

        }, null);

    }

    public static Writer createBuffered(final Writer out) {

        class Delegate extends java.io.Writer {

            @Override

            public void write(char[] cbuf, int off, int len) throws IOException {

                out.write(cbuf, off, len);

            }

            @Override

            public void flush() throws IOException {

                out.flush();

            }

            @Override

            public void close() throws IOException {

                out.close();

            }

        }

        return create(new BufferedWriter(new Delegate()));

    }

    public static interface Impl {

        public void close() throws IOException;

        public void flush() throws IOException;

        public void write(String str, int off, int len) throws IOException;

        public void write(char[] arr, int off, int len) throws IOException;

    }

    public static interface ImplSeq {

        public void close() throws IOException;

        public void flush() throws IOException;

        public void write(CharSequence seq) throws IOException;

    }

}