// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/base/load_log_util.h"

#include "base/string_util.h"

namespace net {
namespace {

class FormatHelper {
 public:
  std::string ToString(const LoadLog* log) {
    entries_.clear();

    // Pass 1: Match the start/end of indentation blocks. Fills |entries_|
    // with the results.
    PopulateEntries(log);

    // Pass 2: Figure out the maximum width of each column. This allows us
    // to right-justify text within each column.
    size_t max_time_width, max_indentation, max_type_width, max_dt_width;
    GetMaxExtent(
        &max_time_width, &max_indentation, &max_type_width, &max_dt_width);

    // Pass 3: Assemble the string.
    std::string result;

    const int kSpacesPerIndentation = 2;

    for (size_t i = 0; i < entries_.size(); ++i) {
      if (i > 0)
        result += "\n";

      int indentation_spaces = entries_[i].indentation * kSpacesPerIndentation;
      std::string event_str = GetEventString(i);

      result += StringPrintf("t=%s: %s%s",
          PadStringLeft(GetTimeString(i), max_time_width).c_str(),
          PadStringLeft("", indentation_spaces).c_str(),
          event_str.c_str());

      if (entries_[i].event->phase == LoadLog::PHASE_BEGIN) {
        // Summarize how long this block lasted.
        int padding = ((max_indentation - entries_[i].indentation) *
            kSpacesPerIndentation) + (max_type_width - event_str.size());
        result += StringPrintf("%s [dt=%s]",
            PadStringLeft("", padding).c_str(),
            PadStringLeft(GetBlockDtString(i), max_dt_width).c_str());
      }
    }

    return result;
  }

 private:
  struct Entry {
    explicit Entry(const LoadLog::Event* event)
        : event(event), indentation(0), block_index(-1) {}

    const LoadLog::Event* event;
    size_t indentation;
    int block_index;  // The index of the matching start / end of block.
  };

  void PopulateEntries(const LoadLog* log) {
    int current_indentation = 0;

    for (size_t i = 0; i < log->events().size(); ++i) {
      Entry entry(&log->events()[i]);

      entry.indentation = current_indentation;

      if (entry.event->phase == LoadLog::PHASE_BEGIN) {
        // Indent everything contained in this block.
        current_indentation++;
      }

      if (entry.event->phase == LoadLog::PHASE_END) {
        int start_index = FindStartOfBlockIndex(entry);
        if (start_index != -1) {
          // Point the start / end of block at each other.
          entry.block_index = start_index;
          entries_[start_index].block_index = i;

          // Restore the indentation prior to the block.
          // (Could be more than 1 level if close of blocks are missing).
          current_indentation = entries_[start_index].indentation;
          entry.indentation = current_indentation;
        }
      }

      entries_.push_back(entry);
    }
  }

  int FindStartOfBlockIndex(const Entry& entry) {
    DCHECK_EQ(LoadLog::PHASE_END, entry.event->phase);

    // Find the matching  start of block by scanning backwards.
    for (int i = entries_.size() - 1; i >= 0; --i) {
      if (entries_[i].event->phase == LoadLog::PHASE_BEGIN &&
          entries_[i].event->type == entry.event->type) {
        return i;
      }
    }
    return -1;  // Start not found.
  }

  void GetMaxExtent(size_t* max_time_width,
                    size_t* max_indentation,
                    size_t* max_type_width,
                    size_t* max_dt_width) {
    *max_time_width = *max_indentation = *max_type_width = *max_dt_width = 0;
    for (size_t i = 0; i < entries_.size(); ++i) {
      *max_time_width = std::max(*max_time_width, GetTimeString(i).size());
      *max_type_width = std::max(*max_type_width, GetEventString(i).size());
      *max_indentation = std::max(*max_indentation, entries_[i].indentation);

      if (entries_[i].event->phase == LoadLog::PHASE_BEGIN)
        *max_dt_width = std::max(*max_dt_width, GetBlockDtString(i).size());
    }
  }

  std::string GetBlockDtString(size_t start_index) {
    int end_index = entries_[start_index].block_index;
    if (end_index == -1) {
      // Block is not closed, implicitly close it at EOF.
      end_index = entries_.size() - 1;
    }
    int64 dt_ms = (entries_[end_index].event->time -
                   entries_[start_index].event->time).InMilliseconds();

    return Int64ToString(dt_ms);
  }

  std::string GetTimeString(size_t index) {
    int64 t_ms = (entries_[index].event->time -
                  base::TimeTicks()).InMilliseconds();
    return Int64ToString(t_ms);
  }

  std::string GetEventString(size_t index) {
    const LoadLog::Event* event = entries_[index].event;
    const char* type_str = LoadLog::EventTypeToString(event->type);

    switch (event->phase) {
      case LoadLog::PHASE_BEGIN:
        return std::string("+") + type_str;
      case LoadLog::PHASE_END:
        return std::string("-") + type_str;
      case LoadLog::PHASE_NONE:
        return std::string(" ") + type_str;
      default:
        NOTREACHED();
        return std::string();
    }
  }

  static std::string PadStringLeft(const std::string& str, size_t width) {
    DCHECK_LE(str.size(), width);
    std::string padding;
    padding.resize(width - str.size(), ' ');
    return padding + str;
  }

  std::vector<Entry> entries_;
};

}  // namespace

// static
std::string LoadLogUtil::PrettyPrintAsEventTree(const LoadLog* log) {
  FormatHelper helper;
  return helper.ToString(log);
}

}  // namespace net