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/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file StringUtils.h
 * @author Balajiganapathi S <balajiganapathi.s@gmail.com>
 * @date 2017
 *
 * String routines
 */

#include "StringUtils.h"
#include <algorithm>
#include <string>
#include <vector>

using namespace std;
using namespace dev;

bool dev::stringWithinDistance(string const& _str1, string const& _str2, size_t _maxDistance)
{
    if (_str1 == _str2)
        return true;

    size_t n1 = _str1.size();
    size_t n2 = _str2.size();
    size_t distance = stringDistance(_str1, _str2);

    // if distance is not greater than _maxDistance, and distance is strictly less than length of both names, they can be considered similar
    // this is to avoid irrelevant suggestions
    return distance <= _maxDistance && distance < n1 && distance < n2;
}

size_t dev::stringDistance(string const& _str1, string const& _str2)
{
    size_t n1 = _str1.size();
    size_t n2 = _str2.size();
    // Optimize by storing only last 2 rows and current row. So first index is considered modulo 3
    // This is a two-dimensional array of size 3 x (n2 + 1).
    vector<size_t> dp(3 * (n2 + 1));

    // In this dp formulation of Damerau–Levenshtein distance we are assuming that the strings are 1-based to make base case storage easier.
    // So index accesser to _name1 and _name2 have to be adjusted accordingly
    for (size_t i1 = 0; i1 <= n1; ++i1)
        for (size_t i2 = 0; i2 <= n2; ++i2)
        {
            size_t x = 0;
            if (min(i1, i2) == 0) // base case
                x = max(i1, i2);
            else
            {
                size_t left = dp[(i1 - 1) % 3 + i2 * 3];
                size_t up = dp[(i1 % 3) + (i2 - 1) * 3];
                size_t upleft = dp[((i1 - 1) % 3) + (i2 - 1) * 3];
                // deletion and insertion
                x = min(left + 1, up + 1);
                if (_str1[i1-1] == _str2[i2-1])
                    // same chars, can skip
                    x = min(x, upleft);
                else
                    // different chars so try substitution
                    x = min(x, upleft + 1);

                // transposing
                if (i1 > 1 && i2 > 1 && _str1[i1 - 1] == _str2[i2 - 2] && _str1[i1 - 2] == _str2[i2 - 1])
                    x = min(x, dp[((i1 - 2) % 3) + (i2 - 2) * 3] + 1);
            }
            dp[(i1 % 3) + i2 * 3] = x;
        }

    return dp[(n1 % 3) + n2 * 3];
}

string dev::quotedAlternativesList(vector<string> const& suggestions)
{
    if (suggestions.empty())
        return "";
    if (suggestions.size() == 1)
        return "\"" + suggestions.front() + "\"";

    string choices = "\"" + suggestions.front() + "\"";
    for (size_t i = 1; i + 1 < suggestions.size(); ++i)
        choices += ", \"" + suggestions[i] + "\"";

    choices += " or \"" + suggestions.back() + "\"";

    return choices;
}