/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SRC_TRACE_PROCESSOR_IMPORTERS_COMMON_SLICE_TRACKER_H_
#define SRC_TRACE_PROCESSOR_IMPORTERS_COMMON_SLICE_TRACKER_H_

#include <stdint.h>

#include "src/trace_processor/importers/common/args_tracker.h"
#include "src/trace_processor/storage/trace_storage.h"

namespace perfetto {
namespace trace_processor {

class ArgsTracker;
class TraceProcessorContext;

class SliceTracker {
 public:
  using SetArgsCallback = std::function<void(ArgsTracker::BoundInserter*)>;
  using OnSliceBeginCallback = std::function<void(TrackId, SliceId)>;

  explicit SliceTracker(TraceProcessorContext*);
  virtual ~SliceTracker();

  // virtual for testing
  virtual base::Optional<SliceId> Begin(
      int64_t timestamp,
      TrackId track_id,
      StringId category,
      StringId name,
      SetArgsCallback args_callback = SetArgsCallback());

  // Unnestable slices are slices which do not have any concept of nesting so
  // starting a new slice when a slice already exists leads to no new slice
  // being added. The number of times a begin event is seen is tracked as well
  // as the latest time we saw a begin event. For legacy Android use only. See
  // the comment in SystraceParser::ParseSystracePoint for information on why
  // this method exists.
  void BeginLegacyUnnestable(tables::SliceTable::Row row,
                             SetArgsCallback args_callback);

  template <typename Table>
  base::Optional<SliceId> BeginTyped(
      Table* table,
      typename Table::Row row,
      SetArgsCallback args_callback = SetArgsCallback()) {
    // Ensure that the duration is pending for this row.
    row.dur = kPendingDuration;
    return StartSlice(row.ts, row.track_id, args_callback,
                      [table, &row]() { return table->Insert(row).id; });
  }

  // virtual for testing
  virtual base::Optional<SliceId> Scoped(
      int64_t timestamp,
      TrackId track_id,
      StringId category,
      StringId name,
      int64_t duration,
      SetArgsCallback args_callback = SetArgsCallback());

  template <typename Table>
  base::Optional<SliceId> ScopedTyped(
      Table* table,
      const typename Table::Row& row,
      SetArgsCallback args_callback = SetArgsCallback()) {
    PERFETTO_DCHECK(row.dur >= 0);
    return StartSlice(row.ts, row.track_id, args_callback,
                      [table, &row]() { return table->Insert(row).id; });
  }

  // virtual for testing
  virtual base::Optional<SliceId> End(
      int64_t timestamp,
      TrackId track_id,
      StringId opt_category = {},
      StringId opt_name = {},
      SetArgsCallback args_callback = SetArgsCallback());

  // Usually args should be added in the Begin or End args_callback but this
  // method is for the situation where new args need to be added to an
  // in-progress slice.
  base::Optional<uint32_t> AddArgs(TrackId track_id,
                                   StringId category,
                                   StringId name,
                                   SetArgsCallback args_callback);

  void FlushPendingSlices();

  void SetOnSliceBeginCallback(OnSliceBeginCallback callback);

  base::Optional<SliceId> GetTopmostSliceOnTrack(TrackId track_id) const;

 private:
  // Slices which have been opened but haven't been closed yet will be marked
  // with this duration placeholder.
  static constexpr int64_t kPendingDuration = -1;

  struct SliceInfo {
    uint32_t row;
    ArgsTracker args_tracker;
  };
  using SlicesStack = std::vector<SliceInfo>;

  struct TrackInfo {
    SlicesStack slice_stack;

    // These field is only valid for legacy unnestable slices.
    bool is_legacy_unnestable = false;
    uint32_t legacy_unnestable_begin_count = 0;
    int64_t legacy_unnestable_last_begin_ts = 0;
  };
  using StackMap = std::unordered_map<TrackId, TrackInfo>;

  // virtual for testing.
  virtual base::Optional<SliceId> StartSlice(int64_t timestamp,
                                             TrackId track_id,
                                             SetArgsCallback args_callback,
                                             std::function<SliceId()> inserter);

  base::Optional<SliceId> CompleteSlice(
      int64_t timestamp,
      TrackId track_id,
      SetArgsCallback args_callback,
      std::function<base::Optional<uint32_t>(const SlicesStack&)> finder);

  void MaybeCloseStack(int64_t end_ts, SlicesStack*, TrackId track_id);

  base::Optional<uint32_t> MatchingIncompleteSliceIndex(
      const SlicesStack& stack,
      StringId name,
      StringId category);

  int64_t GetStackHash(const SlicesStack&);

  void StackPop(TrackId track_id);
  void StackPush(TrackId track_id, uint32_t slice_idx);
  void FlowTrackerUpdate(TrackId track_id);

  OnSliceBeginCallback on_slice_begin_callback_;

  // Timestamp of the previous event. Used to discard events arriving out
  // of order.
  int64_t prev_timestamp_ = std::numeric_limits<int64_t>::min();

  const StringId legacy_unnestable_begin_count_string_id_;
  const StringId legacy_unnestable_last_begin_ts_string_id_;

  TraceProcessorContext* const context_;
  StackMap stacks_;
};

}  // namespace trace_processor
}  // namespace perfetto

#endif  // SRC_TRACE_PROCESSOR_IMPORTERS_COMMON_SLICE_TRACKER_H_