// Copyright 2011 Google Inc. All Rights Reserved.
//
// 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 "eval_env.h"

string BindingEnv::LookupVariable(const string& var) {
  map<string, string>::iterator i = bindings_.find(var);
  if (i != bindings_.end())
    return i->second;
  if (parent_)
    return parent_->LookupVariable(var);
  return "";
}

void BindingEnv::AddBinding(const string& key, const string& val) {
  bindings_[key] = val;
}

bool EvalString::Parse(const string& input, string* err, size_t* err_index) {
  unparsed_ = input;

  string::size_type start, end;
  start = 0;
  do {
    end = input.find('$', start);
    if (end == string::npos) {
      end = input.size();
      break;
    }
    if (end > start)
      parsed_.push_back(make_pair(input.substr(start, end - start), RAW));
    start = end + 1;
    if (start < input.size() && input[start] == '{') {
      ++start;
      for (end = start + 1; end < input.size(); ++end) {
        if (input[end] == '}')
          break;
      }
      if (end >= input.size()) {
        *err = "expected closing curly after ${";
        if (err_index)
          *err_index = end;
        return false;
      }
      parsed_.push_back(make_pair(input.substr(start, end - start), SPECIAL));
      ++end;
    } else if (start < input.size() && input[start] == '$') {
      parsed_.push_back(make_pair("$", RAW));
      end = start + 1;
    } else {
      for (end = start; end < input.size(); ++end) {
        char c = input[end];
        if (!(('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') ||
              ('0' <= c && c <= '9') || c == '_')) {
          break;
        }
      }
      if (end == start) {
        *err = "expected variable after $";
        if (err_index)
          *err_index = start;
        return false;
      }
      parsed_.push_back(make_pair(input.substr(start, end - start), SPECIAL));
    }
    start = end;
  } while (end < input.size());
  if (end > start)
    parsed_.push_back(make_pair(input.substr(start, end - start), RAW));

  return true;
}

string EvalString::Evaluate(Env* env) const {
  string result;
  for (TokenList::const_iterator i = parsed_.begin(); i != parsed_.end(); ++i) {
    if (i->second == RAW)
      result.append(i->first);
    else
      result.append(env->LookupVariable(i->first));
  }
  return result;
}