#include "search_server.h"
#include "iterator_range.h"

#include <algorithm>
#include <iterator>
#include <sstream>
#include <iostream>

#define sz(v) (int)v.size()

vector<string> SplitIntoWords(const string& line) {
  istringstream words_input(line);
  return {istream_iterator<string>(words_input), istream_iterator<string>()};
}

SearchServer::SearchServer(istream& document_input) {
  UpdateDocumentBase(document_input);
}

void SearchServer::UpdateDocumentBase(istream& document_input) {
  InvertedIndex new_index;

  for (string current_document; getline(document_input, current_document); ) {
    new_index.Add(move(current_document));
  }

  index = move(new_index);
}

void SearchServer::AddQueriesStream(
  istream& query_input, ostream& search_results_output
) {
    vector<int> cnt (index.get_sz ());
    for (string current_query; getline(query_input, current_query); ) {
    const auto words = SplitIntoWords(current_query);
    for (auto& x: cnt) x = 0;
    for (const auto& word : words) {
      for (const int docid : index.Lookup(word)) {
        ++cnt[docid];
      }
    }
    set <pair <int, int>> kek;
    for (int i = 0; i < sz (cnt); ++i) {
        if (!cnt[i]) continue;
        if (sz (kek) < 5) kek.insert ({cnt[i], -i});
        else {
            auto it = kek.begin ();
            if (*it < make_pair (cnt[i], -i)) {
                kek.erase (it);
                kek.insert ({cnt[i], -i});
            }
        }
    }
    vector<pair<int, int>> res (kek.begin (), kek.end ());
    reverse (res.begin (), res.end ());
    search_results_output << current_query << ':';
    for (auto [hitcount, docid] : res) {
      search_results_output << " {"
        << "docid: " << -docid << ", "
        << "hitcount: " << hitcount << '}';
    }
    search_results_output << endl;
  }
}

void InvertedIndex::Add(const string& document) {
  docs.push_back(document);

  const size_t docid = docs.size() - 1;
  for (const auto& word : SplitIntoWords(document)) {
    index[word].push_back(docid);
  }
}

const vector<int>& InvertedIndex::Lookup(const string& word) const {
  if (auto it = index.find(word); it != index.end()) {
    return it->second;
  } else {
    return empty_vector;
  }
}