#pragma once
#include "date.h"
#include <map>
#include <set>
#include <vector>
#include <string>
#include <utility>
#include <algorithm>
#include <sstream>
#include <iostream>

class Database
{
public:
    void
    Add(const Date &date, const string &event);

    void
    Print(ostream &out) const;

    template<typename Func>
    int
    RemoveIf(const Func &func);

    template<typename Func>
    vector<string>
    FindIf(const Func &func) const;

    string
    Last(const Date &date) const;

private:
    map<Date, pair<set<string>, vector<string>>> database;
};

template<typename Func>
int
Database::RemoveIf(const Func &func)
{
    int counter = 0;
    map<Date, vector<string>> database_copy(begin(database), end(database));

    auto date_it = begin(database_copy);
    for (; date_it!=end(database_copy); ++date_it)
    {
        pair<set<string>, vector<string>> &events_pair = database[date_it->first];
        set<string> &events_set = events_pair.first;
        vector<string> &events_vector = events_pair.second;

        auto border = stable_partition(begin(events_vector), end(events_vector), [&](const string &event)
        {
            return func(date_it->first, event);
        });

        counter += border - begin(events_vector);
        events_vector.erase(begin(events_vector), border);

        set<string> new_events_set(begin(events_vector), end(events_vector));
        events_set = new_events_set;

        if (events_vector.empty())
        {
            database.erase(date_it->first);
        }
    }

    return counter;
}

template<typename Func>
vector<string>
Database::FindIf(const Func &func) const
{
    vector<string> result;

    auto date_it = begin(database);
    for (; date_it!=end(database); ++date_it)
    {
        const pair<set<string>, vector<string>> &events_pair = date_it->second;
        const vector<string> &events = events_pair.second;
        for (const auto &event: events)
        {
            if (func(date_it->first, event))
            {
                ostringstream out;
                out << date_it->first << ' ' << event;
                result.push_back(out.str());
            }
        }
    }
    return result;
}