/*
 * Copyright (C) 2020 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.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * 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,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import * as Common from '../../core/common/common.js';
import * as WasmParser from '../../third_party/wasmparser/wasmparser.js';

export function dissambleWASM(
    params: {
      content: string,
    },
    postMessage: (arg0: unknown) => void): void {
  try {
    const dataBuffer = Common.Base64.decode(params.content);

    let parser: WasmParser.WasmParser.BinaryReader = new WasmParser.WasmParser.BinaryReader();
    parser.setData(dataBuffer, 0, dataBuffer.byteLength);
    const nameGenerator = new WasmParser.WasmDis.DevToolsNameGenerator();
    nameGenerator.read(parser);

    const data = new Uint8Array(dataBuffer);
    parser = new WasmParser.WasmParser.BinaryReader();
    const dis = new WasmParser.WasmDis.WasmDisassembler();
    dis.addOffsets = true;
    dis.exportMetadata = nameGenerator.getExportMetadata();
    dis.nameResolver = nameGenerator.getNameResolver();
    const lines = [];
    const offsets = [];
    const functionBodyOffsets = [];
    let chunkSize: number = 128 * 1024;
    let buffer = new Uint8Array(chunkSize);
    let pendingSize = 0;
    let offsetInModule = 0;
    for (let i = 0; i < data.length;) {
      if (chunkSize > data.length - i) {
        chunkSize = data.length - i;
      }
      const bufferSize = pendingSize + chunkSize;
      if (buffer.byteLength < bufferSize) {
        const newBuffer = new Uint8Array(bufferSize);
        newBuffer.set(buffer);
        buffer = newBuffer;
      }
      while (pendingSize < bufferSize) {
        buffer[pendingSize++] = data[i++];
      }
      parser.setData(buffer.buffer, 0, bufferSize, i === data.length);

      // The disassemble will attemp to fetch the data as much as possible.
      const finished = dis.disassembleChunk(parser, offsetInModule);

      const result = (dis.getResult() as {
        lines: Array<string>,
        offsets: Array<number>,
        functionBodyOffsets: Array<{
          start: number,
          end: number,
        }>,
      });

      for (const line of result.lines) {
        lines.push(line);
      }
      for (const offset of result.offsets) {
        offsets.push(offset);
      }
      for (const functionBodyOffset of result.functionBodyOffsets) {
        functionBodyOffsets.push(functionBodyOffset);
      }

      if (finished) {
        break;
      }

      if (parser.position === 0) {
        // Parser did not consume anything, needs more data.
        pendingSize = bufferSize;
        continue;
      }

      // Shift the data to the beginning of the buffer.
      const pending = parser.data.subarray(parser.position, parser.length);
      pendingSize = pending.length;
      buffer.set(pending);
      offsetInModule += parser.position;

      const percentage = Math.floor((offsetInModule / data.length) * 100);
      postMessage({event: 'progress', params: {percentage}});
    }

    postMessage({event: 'progress', params: {percentage: 100}});

    postMessage({method: 'disassemble', result: {lines, offsets, functionBodyOffsets}});
  } catch (error) {
    postMessage({method: 'disassemble', error});
  }
}