// Copyright 2017-2020 The Verible Authors.
//
// 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.

#include "verilog/CST/data.h"

#include <vector>

#include "common/analysis/matcher/matcher.h"
#include "common/analysis/matcher/matcher_builders.h"
#include "common/analysis/syntax_tree_search.h"
#include "common/text/concrete_syntax_leaf.h"
#include "common/text/concrete_syntax_tree.h"
#include "common/text/symbol.h"
#include "common/text/tree_utils.h"
#include "verilog/CST/identifier.h"
#include "verilog/CST/verilog_matchers.h"  // IWYU pragma: keep

namespace verilog {

using verible::Symbol;
using verible::TokenInfo;

// Helper predicate to match all types of applicable variables
static bool ExpectedTagPredicate(const Symbol& symbol) {
  verible::SymbolTag reg_symbol = {
      verible::SymbolKind::kNode,
      static_cast<int>(NodeEnum::kRegisterVariable)};
  verible::SymbolTag gate_symbol = {verible::SymbolKind::kNode,
                                    static_cast<int>(NodeEnum::kGateInstance)};

  // This exploits the fact that data identifiers can be found in:
  // - kRegisterVariable, e.g.:
  //     module top; logic x; endmodule;
  //
  // - as well as kGateInstance, e.g.:
  //     module top; foo bar(0); endmodule;

  return symbol.Tag() == reg_symbol || symbol.Tag() == gate_symbol;
}

std::vector<const TokenInfo*> GetIdentifiersFromDataDeclaration(
    const Symbol& symbol) {
  // TODO(fangism): leverage GetInstanceListFromDataDeclaration().
  // Instead of searching, use direct access.  See CST/declaration.h.
  std::vector<const TokenInfo*> identifiers;

  auto matcher = verible::matcher::Matcher(ExpectedTagPredicate,
                                           verible::matcher::InnerMatchAll);

  std::vector<verible::TreeSearchMatch> identifier_nodes =
      SearchSyntaxTree(symbol, matcher);

  for (auto& id : identifier_nodes) {
    const auto* identifier = SymbolCastToNode(*id.match)[0].get();

    const auto* identifier_leaf =
        AutoUnwrapIdentifier(*ABSL_DIE_IF_NULL(identifier));

    identifiers.push_back(&identifier_leaf->get());
  }

  return identifiers;
}

}  // namespace verilog