/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

#include "atn/PredictionContext.h"
#include "atn/ATNConfig.h"
#include "atn/ATNSimulator.h"
#include "Exceptions.h"
#include "atn/SemanticContext.h"
#include "support/Arrays.h"

#include "atn/ATNConfigSet.h"

using namespace antlr4::atn;
using namespace antlrcpp;

ATNConfigSet::ATNConfigSet(bool fullCtx) : fullCtx(fullCtx) {
  InitializeInstanceFields();
}

ATNConfigSet::ATNConfigSet(const Ref<ATNConfigSet> &old) : ATNConfigSet(old->fullCtx) {
  addAll(old);
  uniqueAlt = old->uniqueAlt;
  conflictingAlts = old->conflictingAlts;
  hasSemanticContext = old->hasSemanticContext;
  dipsIntoOuterContext = old->dipsIntoOuterContext;
}

ATNConfigSet::~ATNConfigSet() {
}

bool ATNConfigSet::add(const Ref<ATNConfig> &config) {
  return add(config, nullptr);
}

bool ATNConfigSet::add(const Ref<ATNConfig> &config, PredictionContextMergeCache *mergeCache) {
  if (_readonly) {
    throw IllegalStateException("This set is readonly");
  }
  if (config->semanticContext != SemanticContext::NONE) {
    hasSemanticContext = true;
  }
  if (config->getOuterContextDepth() > 0) {
    dipsIntoOuterContext = true;
  }

  size_t hash = getHash(config.get());
  ATNConfig *existing = _configLookup[hash];
  if (existing == nullptr) {
    _configLookup[hash] = config.get();
    _cachedHashCode = 0;
    configs.push_back(config); // track order here

    return true;
  }

  // a previous (s,i,pi,_), merge with it and save result
  bool rootIsWildcard = !fullCtx;
  Ref<PredictionContext> merged = PredictionContext::merge(existing->context, config->context, rootIsWildcard, mergeCache);
  // no need to check for existing.context, config.context in cache
  // since only way to create new graphs is "call rule" and here. We
  // cache at both places.
  existing->reachesIntoOuterContext = std::max(existing->reachesIntoOuterContext, config->reachesIntoOuterContext);

  // make sure to preserve the precedence filter suppression during the merge
  if (config->isPrecedenceFilterSuppressed()) {
    existing->setPrecedenceFilterSuppressed(true);
  }

  existing->context = merged; // replace context; no need to alt mapping

  return true;
}

bool ATNConfigSet::addAll(const Ref<ATNConfigSet> &other) {
  for (auto &c : other->configs) {
    add(c);
  }
  return false;
}

std::vector<ATNState*> ATNConfigSet::getStates() {
  std::vector<ATNState*> states;
  for (auto c : configs) {
    states.push_back(c->state);
  }
  return states;
}

/**
 * Gets the complete set of represented alternatives for the configuration
 * set.
 *
 * @return the set of represented alternatives in this configuration set
 *
 * @since 4.3
 */

BitSet ATNConfigSet::getAlts() {
  BitSet alts;
  for (ATNConfig config : configs) {
    alts.set(config.alt);
  }
  return alts;
}

std::vector<Ref<SemanticContext>> ATNConfigSet::getPredicates() {
  std::vector<Ref<SemanticContext>> preds;
  for (auto c : configs) {
    if (c->semanticContext != SemanticContext::NONE) {
      preds.push_back(c->semanticContext);
    }
  }
  return preds;
}

Ref<ATNConfig> ATNConfigSet::get(size_t i) const {
  return configs[i];
}

void ATNConfigSet::optimizeConfigs(ATNSimulator *interpreter) {
  if (_readonly) {
    throw IllegalStateException("This set is readonly");
  }
  if (_configLookup.empty())
    return;

  for (auto &config : configs) {
    config->context = interpreter->getCachedContext(config->context);
  }
}

bool ATNConfigSet::operator == (const ATNConfigSet &other) {
  if (&other == this) {
    return true;
  }

  if (configs.size() != other.configs.size())
    return false;

  if (fullCtx != other.fullCtx || uniqueAlt != other.uniqueAlt ||
      conflictingAlts != other.conflictingAlts || hasSemanticContext != other.hasSemanticContext ||
      dipsIntoOuterContext != other.dipsIntoOuterContext) // includes stack context
    return false;

  return Arrays::equals(configs, other.configs);
}

size_t ATNConfigSet::hashCode() {
  if (!isReadonly() || _cachedHashCode == 0) {
    _cachedHashCode = 1;
    for (auto &i : configs) {
      _cachedHashCode = 31 * _cachedHashCode + i->hashCode(); // Same as Java's list hashCode impl.
    }
  }

  return _cachedHashCode;
}

size_t ATNConfigSet::size() {
  return configs.size();
}

bool ATNConfigSet::isEmpty() {
  return configs.empty();
}

void ATNConfigSet::clear() {
  if (_readonly) {
    throw IllegalStateException("This set is readonly");
  }
  configs.clear();
  _cachedHashCode = 0;
  _configLookup.clear();
}

bool ATNConfigSet::isReadonly() {
  return _readonly;
}

void ATNConfigSet::setReadonly(bool readonly) {
  _readonly = readonly;
  _configLookup.clear();
}

std::string ATNConfigSet::toString() {
  std::stringstream ss;
  ss << "[";
  for (size_t i = 0; i < configs.size(); i++) {
    ss << configs[i]->toString();
  }
  ss << "]";

  if (hasSemanticContext) {
    ss << ",hasSemanticContext = " <<  hasSemanticContext;
  }
  if (uniqueAlt != ATN::INVALID_ALT_NUMBER) {
    ss << ",uniqueAlt = " << uniqueAlt;
  }

  if (conflictingAlts.size() > 0) {
    ss << ",conflictingAlts = ";
    ss << conflictingAlts.toString();
  }

  if (dipsIntoOuterContext) {
    ss << ", dipsIntoOuterContext";
  }
  return ss.str();
}

size_t ATNConfigSet::getHash(ATNConfig *c) {
  size_t hashCode = 7;
  hashCode = 31 * hashCode + c->state->stateNumber;
  hashCode = 31 * hashCode + c->alt;
  hashCode = 31 * hashCode + c->semanticContext->hashCode();
  return hashCode;
}

void ATNConfigSet::InitializeInstanceFields() {
  uniqueAlt = 0;
  hasSemanticContext = false;
  dipsIntoOuterContext = false;

  _readonly = false;
  _cachedHashCode = 0;
}
