/*
 * Copyright 2012, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 */

package org.jf.dexlib2.dexbacked.instruction;

import org.jf.dexlib2.Opcode;
import org.jf.dexlib2.dexbacked.DexBackedDexFile;
import org.jf.dexlib2.dexbacked.util.FixedSizeList;
import org.jf.dexlib2.iface.instruction.SwitchElement;
import org.jf.dexlib2.iface.instruction.formats.SparseSwitchPayload;

import javax.annotation.Nonnull;
import java.util.List;

public class DexBackedSparseSwitchPayload extends DexBackedInstruction implements SparseSwitchPayload {
    public final int elementCount;

    private static final int ELEMENT_COUNT_OFFSET = 2;
    private static final int KEYS_OFFSET = 4;

    public DexBackedSparseSwitchPayload(@Nonnull DexBackedDexFile dexFile,
                                        int instructionStart) {
        super(dexFile, Opcode.SPARSE_SWITCH_PAYLOAD, instructionStart);

        elementCount = dexFile.readUshort(instructionStart + ELEMENT_COUNT_OFFSET);
    }

    @Nonnull
    @Override
    public List<? extends SwitchElement> getSwitchElements() {
        return new FixedSizeList<SwitchElement>() {
            @Nonnull
            @Override
            public SwitchElement readItem(final int index) {
                return new SwitchElement() {
                    @Override
                    public int getKey() {
                        return dexFile.readInt(instructionStart + KEYS_OFFSET + index*4);
                    }

                    @Override
                    public int getOffset() {
                        return dexFile.readInt(instructionStart + KEYS_OFFSET + elementCount*4 + index*4);
                    }
                };
            }

            @Override public int size() { return elementCount; }
        };
    }

    @Override public int getCodeUnits() { return 2 + elementCount*4; }
}