/******************************************************************************
 * This program implements a spell checker.
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

#undef NDEBUG

#include "Utils.hpp"
#include <clocale>
#include <codecvt>
#include <fstream>
#include <iostream>
#include <regex>
#include <string>
#include <unordered_map>
#include <vector>

std::locale utf8loc(std::locale(), new std::codecvt_utf8<wchar_t>);
using namespace Utils;
using namespace std;

static unordered_map<wstring, bool> DICTIONARY = {};

void read_dictionary_file(wstring filespec) {
    wifstream ifh(filesystem::path(filespec).c_str());
    if (!ifh.good()) {
        throw ios_base::failure(Utils::wchar_to_UTF8(L"Problem opening dictionary file!"));
    }
    ifh.imbue(utf8loc);
    wstring line;
    while (getline(ifh, line)) {
        DICTIONARY[Utils::tolower(line)] = true;
    }
    ifh.close();
}

void spellcheck_file(wstring filespec) {
    wifstream ifh(filesystem::path(filespec).c_str());
    if (!ifh.good()) {
        throw ios_base::failure(Utils::wchar_to_UTF8(L"Problem opening input file!"));
    }
    ifh.imbue(utf8loc);
    wstring line;
    unordered_map<wstring, bool> misspelled_words = {};
    while (getline(ifh, line)) {
        vector<wstring> matches = Utils::regex_findall(wregex(L"\\w+"), line);
        if (Utils::defined(matches)) {
            for (wstring s : matches) {
                wstring const SLOWER = Utils::tolower(s);
                if (!DICTIONARY.count(SLOWER)) {
                    misspelled_words[SLOWER] = true;
                }
            }
        }
    }
    const vector<wstring> sortedkeys = Utils::sort(Utils::keys(misspelled_words));
    for (auto s : sortedkeys) {
        wcout << s << endl;
    }
    ifh.close();
}

int main(int argc, char **argv) {
    setlocale(LC_ALL, "en_US.UTF-8");
    wcout.imbue(utf8loc);
    wcin.imbue(utf8loc);

    if (argc != 3) {
        wcout << L"Syntax: " << Utils::UTF8_to_wstring(argv[0]) << L" {dictionary} {filename}" << endl;
        exit(1);
    }
    wstring dictionary_file = Utils::UTF8_to_wstring(argv[1]);
    wstring filename = Utils::UTF8_to_wstring(argv[2]);

    try {
        read_dictionary_file(dictionary_file);
        spellcheck_file(filename);
    } catch (ios_base::failure ex) {
        wcout << L"Error: " << Utils::exceptionMessage<wchar_t>(ex) << endl;
    }
    return 0;
}