// Copyright 2011 the V8 project authors. 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.
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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
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

/**
 * @fileoverview Log Reader is used to process log file produced by V8.
 */
 import { CsvParser } from "./csvparser.mjs";


// Parses dummy variable for readability;
export const parseString = 'parse-string';
export const parseVarArgs = 'parse-var-args';

/**
 * Base class for processing log files.
 *
 * @param {Array.<Object>} dispatchTable A table used for parsing and processing
 *     log records.
 * @param {boolean} timedRange Ignore ticks outside timed range.
 * @param {boolean} pairwiseTimedRange Ignore ticks outside pairs of timer
 *     markers.
 * @constructor
 */
export class LogReader {
  constructor (dispatchTable, timedRange, pairwiseTimedRange) {
    /**
     * @type {Array.<Object>}
     */
    this.dispatchTable_ = dispatchTable;

    /**
     * @type {boolean}
     */
    this.timedRange_ = timedRange;

    /**
     * @type {boolean}
     */
    this.pairwiseTimedRange_ = pairwiseTimedRange;
    if (pairwiseTimedRange) {
      this.timedRange_ = true;
    }

    /**
     * Current line.
     * @type {number}
     */
    this.lineNum_ = 0;

    /**
     * CSV lines parser.
     * @type {CsvParser}
     */
    this.csvParser_ = new CsvParser();

    /**
     * Keeps track of whether we've seen a "current-time" tick yet.
     * @type {boolean}
     */
    this.hasSeenTimerMarker_ = false;

    /**
     * List of log lines seen since last "current-time" tick.
     * @type {Array.<String>}
     */
    this.logLinesSinceLastTimerMarker_ = [];
  }


  /**
   * A thin wrapper around shell's 'read' function showing a file name on error.
   */
  readFile(fileName) {
    try {
      return read(fileName);
    } catch (e) {
      printErr(`file="${fileName}": ${e.message || e}`);
      throw e;
    }
  }

  /**
   * Used for printing error messages.
   *
   * @param {string} str Error message.
   */
  printError(str) {
    // Do nothing.
  }

  /**
   * Processes a portion of V8 profiler event log.
   *
   * @param {string} chunk A portion of log.
   */
  async processLogChunk(chunk) {
    await this.processLog_(chunk.split('\n'));
  }

  /**
   * Processes a line of V8 profiler event log.
   *
   * @param {string} line A line of log.
   */
  async processLogLine(line) {
    if (!this.timedRange_) {
      await this.processLogLine_(line);
      return;
    }
    if (line.startsWith("current-time")) {
      if (this.hasSeenTimerMarker_) {
        await this.processLog_(this.logLinesSinceLastTimerMarker_);
        this.logLinesSinceLastTimerMarker_ = [];
        // In pairwise mode, a "current-time" line ends the timed range.
        if (this.pairwiseTimedRange_) {
          this.hasSeenTimerMarker_ = false;
        }
      } else {
        this.hasSeenTimerMarker_ = true;
      }
    } else {
      if (this.hasSeenTimerMarker_) {
        this.logLinesSinceLastTimerMarker_.push(line);
      } else if (!line.startsWith("tick")) {
        await this.processLogLine_(line);
      }
    }
  }

  /**
   * Processes stack record.
   *
   * @param {number} pc Program counter.
   * @param {number} func JS Function.
   * @param {Array.<string>} stack String representation of a stack.
   * @return {Array.<number>} Processed stack.
   */
  processStack(pc, func, stack) {
    const fullStack = func ? [pc, func] : [pc];
    let prevFrame = pc;
    for (let i = 0, n = stack.length; i < n; ++i) {
      const frame = stack[i];
      const firstChar = frame.charAt(0);
      if (firstChar == '+' || firstChar == '-') {
        // An offset from the previous frame.
        prevFrame += parseInt(frame, 16);
        fullStack.push(prevFrame);
      // Filter out possible 'overflow' string.
      } else if (firstChar != 'o') {
        fullStack.push(parseInt(frame, 16));
      } else {
        console.error(`dropping: ${frame}`);
      }
    }
    return fullStack;
  }

  /**
   * Returns whether a particular dispatch must be skipped.
   *
   * @param {!Object} dispatch Dispatch record.
   * @return {boolean} True if dispatch must be skipped.
   */
  skipDispatch(dispatch) {
    return false;
  }

  /**
   * Does a dispatch of a log record.
   *
   * @param {Array.<string>} fields Log record.
   * @private
   */
  async dispatchLogRow_(fields) {
    // Obtain the dispatch.
    const command = fields[0];
    const dispatch = this.dispatchTable_[command];
    if (dispatch === undefined) return;
    if (dispatch === null || this.skipDispatch(dispatch)) {
      return;
    }

    // Parse fields.
    const parsedFields = [];
    for (let i = 0; i < dispatch.parsers.length; ++i) {
      const parser = dispatch.parsers[i];
      if (parser === parseString) {
        parsedFields.push(fields[1 + i]);
      } else if (typeof parser == 'function') {
        parsedFields.push(parser(fields[1 + i]));
      } else if (parser === parseVarArgs) {
        // var-args
        parsedFields.push(fields.slice(1 + i));
        break;
      } else {
        throw new Error(`Invalid log field parser: ${parser}`);
      }
    }

    // Run the processor.
    await dispatch.processor.apply(this, parsedFields);
  }

  /**
   * Processes log lines.
   *
   * @param {Array.<string>} lines Log lines.
   * @private
   */
  async processLog_(lines) {
    for (let i = 0, n = lines.length; i < n; ++i) {
      await this.processLogLine_(lines[i]);
    }
  }

  /**
   * Processes a single log line.
   *
   * @param {String} a log line
   * @private
   */
  async processLogLine_(line) {
    if (line.length > 0) {
      try {
        const fields = this.csvParser_.parseLine(line);
        await this.dispatchLogRow_(fields);
      } catch (e) {
        this.printError(`line ${this.lineNum_ + 1}: ${e.message || e}\n${e.stack}`);
      }
    }
    this.lineNum_++;
  }
}