/*
 * Copyright (C) 2020 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_PERFETTO_SQL_INTRINSICS_TABLE_FUNCTIONS_CONNECTED_FLOW_H_
#define SRC_TRACE_PROCESSOR_PERFETTO_SQL_INTRINSICS_TABLE_FUNCTIONS_CONNECTED_FLOW_H_

#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "perfetto/base/logging.h"
#include "perfetto/ext/base/flat_hash_map.h"
#include "perfetto/trace_processor/basic_types.h"
#include "src/trace_processor/core/dataframe/specs.h"
#include "src/trace_processor/perfetto_sql/intrinsics/table_functions/static_table_function.h"
#include "src/trace_processor/perfetto_sql/intrinsics/table_functions/tables_py.h"
#include "src/trace_processor/storage/trace_storage.h"
#include "src/trace_processor/tables/flow_tables_py.h"
#include "src/trace_processor/tables/slice_tables_py.h"

namespace perfetto::trace_processor {

class TraceProcessorContext;

// Represents the flow graph with pre-computed adjacency lists.
struct FlowGraph {
  base::FlatHashMap<SliceId, std::vector<tables::FlowTable::RowNumber>>
      outgoing_flows;
  base::FlatHashMap<SliceId, std::vector<tables::FlowTable::RowNumber>>
      incoming_flows;

  static FlowGraph Build(const tables::FlowTable& flow_table) {
    FlowGraph graph;
    for (uint32_t i = 0; i < flow_table.row_count(); ++i) {
      tables::FlowTable::RowNumber row(i);
      auto ref = row.ToRowReference(flow_table);
      graph.outgoing_flows[ref.slice_out()].push_back(row);
      graph.incoming_flows[ref.slice_in()].push_back(row);
    }
    return graph;
  }
};

// Implementation of tables:
// - DIRECTLY_CONNECTED_FLOW
// - PRECEDING_FLOW
// - FOLLOWING_FLOW
class ConnectedFlow : public StaticTableFunction {
 public:
  enum class Mode : uint8_t {
    // Directly connected slices through the same flow ID given by the trace
    // writer.
    kDirectlyConnectedFlow,
    // Flow events which can be reached from the given slice by going over
    // incoming flow events or to parent slices.
    kPrecedingFlow,
    // Flow events which can be reached from the given slice by going over
    // outgoing flow events or to child slices.
    kFollowingFlow,
  };

  class Cursor : public StaticTableFunction::Cursor {
   public:
    Cursor(Mode mode, TraceStorage* storage);
    bool Run(const std::vector<SqlValue>& arguments) override;

   private:
    Mode mode_;
    TraceStorage* storage_ = nullptr;
    tables::ConnectedFlowTable table_;
    tables::SliceTable::ConstCursor descendant_cursor_;
    std::optional<FlowGraph> cached_flow_graph_;
  };

  ConnectedFlow(Mode mode, TraceStorage*);
  ~ConnectedFlow() override;

  std::unique_ptr<StaticTableFunction::Cursor> MakeCursor() override;
  dataframe::DataframeSpec CreateSpec() override;
  std::string TableName() override;
  uint32_t GetArgumentCount() const override;

 private:
  Mode mode_;
  TraceStorage* storage_ = nullptr;
};

}  // namespace perfetto::trace_processor

#endif  // SRC_TRACE_PROCESSOR_PERFETTO_SQL_INTRINSICS_TABLE_FUNCTIONS_CONNECTED_FLOW_H_
