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package com.zoomlion.cloud.common.crypto;



import java.io.File;
import java.io.InputStream;
import java.util.Arrays;

import com.zoomlion.cloud.common.codec.Base64;
import com.zoomlion.cloud.common.codec.CodecSupport;
import com.zoomlion.cloud.common.codec.Hex;

/**
 * Very simple {@link ByteSource ByteSource} implementation that maintains an internal {@code byte[]} array and uses the
 * {@link Hex Hex} and {@link Base64 Base64} codec classes to support the
 * {@link #toHex() toHex()} and {@link #toBase64() toBase64()} implementations.
 * 
 * The constructors on this class accept the following implicit byte-backed data types and will convert them to
 * a byte-array automatically:
 * 
 * byte[]
 * char[]
 * String
 * {@link ByteSource ByteSource}
 * {@link File File}
 * {@link InputStream InputStream}
 * 
 *
 * @since 1.0
 */
public class SimpleByteSource implements ByteSource {

    private final byte[] bytes;
    private String cachedHex;
    private String cachedBase64;

    public SimpleByteSource(byte[] bytes) {
        this.bytes = bytes;
    }

    /**
     * Creates an instance by converting the characters to a byte array (assumes UTF-8 encoding).
     *
     * @param chars the source characters to use to create the underlying byte array.
     * @since 1.1
     */
    public SimpleByteSource(char[] chars) {
        this.bytes = CodecSupport.toBytes(chars);
    }

    /**
     * Creates an instance by converting the String to a byte array (assumes UTF-8 encoding).
     *
     * @param string the source string to convert to a byte array (assumes UTF-8 encoding).
     * @since 1.1
     */
    public SimpleByteSource(String string) {
        this.bytes = CodecSupport.toBytes(string);
    }

    /**
     * Creates an instance using the sources bytes directly - it does not create a copy of the
     * argument's byte array.
     *
     * @param source the source to use to populate the underlying byte array.
     * @since 1.1
     */
    public SimpleByteSource(ByteSource source) {
        this.bytes = source.getBytes();
    }

    /**
     * Creates an instance by converting the file to a byte array.
     *
     * @param file the file from which to acquire bytes.
     * @since 1.1
     */
    public SimpleByteSource(File file) {
        this.bytes = new BytesHelper().getBytes(file);
    }

    /**
     * Creates an instance by converting the stream to a byte array.
     *
     * @param stream the stream from which to acquire bytes.
     * @since 1.1
     */
    public SimpleByteSource(InputStream stream) {
        this.bytes = new BytesHelper().getBytes(stream);
    }

    /**
     * Returns {@code true} if the specified object is a recognized data type that can be easily converted to
     * bytes by instances of this class, {@code false} otherwise.
     * 
     * This implementation returns {@code true} IFF the specified object is an instance of one of the following
     * types:
     * 
     * {@code byte[]}
     * {@code char[]}
     * {@link ByteSource}
     * {@link String}
     * {@link File}
     * {@link InputStream}
     * 
     *
     * @param o the object to test to see if it can be easily converted to bytes by instances of this class.
     * @return {@code true} if the specified object can be easily converted to bytes by instances of this class,
     *         {@code false} otherwise.
     * @since 1.2
     */
    public static boolean isCompatible(Object o) {
        return o instanceof byte[] || o instanceof char[] || o instanceof String ||
                o instanceof ByteSource || o instanceof File || o instanceof InputStream;
    }

    public byte[] getBytes() {
        return this.bytes;
    }

    public boolean isEmpty() {
        return this.bytes == null || this.bytes.length == 0;
    }

    public String toHex() {
        if ( this.cachedHex == null ) {
            this.cachedHex = Hex.encodeToString(getBytes());
        }
        return this.cachedHex;
    }

    public String toBase64() {
        if ( this.cachedBase64 == null ) {
            this.cachedBase64 = Base64.encodeToString(getBytes());
        }
        return this.cachedBase64;
    }

    public String toString() {
        return toBase64();
    }

    public int hashCode() {
        if (this.bytes == null || this.bytes.length == 0) {
            return 0;
        }
        return Arrays.hashCode(this.bytes);
    }

    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }
        if (o instanceof ByteSource) {
            ByteSource bs = (ByteSource) o;
            return Arrays.equals(getBytes(), bs.getBytes());
        }
        return false;
    }

    //will probably be removed in Shiro 2.0.  See SHIRO-203:
    //https://issues.apache.org/jira/browse/SHIRO-203
    private static final class BytesHelper extends CodecSupport {
        public byte[] getBytes(File file) {
            return toBytes(file);
        }

        public byte[] getBytes(InputStream stream) {
            return toBytes(stream);
        }
    }
}