#include <iostream>
#include <cstdlib>
#include <string>
#include <stdexcept>
#include <climits>
#include <regex>
#include <algorithm>
#include <getopt.h>
#include <libscnumerics.hpp>
#include "version.hpp"

// globals
std::string upper {"ABCDEFGHIJKLMNOPQRSTUVWXYZ"};
std::string lower {"abcdefghijklmnopqrstuvwxyz"};
std::string digits {"0123456789"};
std::string symbols {"_-=+<>,.!@#$%^&*"};
std::string special;
std::string valid;
int len {24};
int min_upper {0};
int min_lower {0};
int min_digits {0};
int min_symbols {0};
int min_special {0};

void validate_range(const std::string& arg, int& min_val, int& max_val) {
    std::regex pat {R"((\d+)(?:-(\d+))?)"};
    std::smatch match;
    if (std::regex_match(arg, match, pat)) {
        min_val = std::atoi(match[1].str().c_str());
        if (match.size() > 2) {
            max_val = std::atoi(match[2].str().c_str());
        }
    }
    throw std::runtime_error("invalid range");
}

int main(int argc, char* argv[]) {
    try {
        bool noflags {true};
        int opt_char, opt_val;
        struct option long_options[] = {
            {"version", no_argument, &opt_val, 1},
            {"count", required_argument, nullptr, 'c'},
            {"digit", required_argument, nullptr, 'd'},
            {"lower", required_argument, nullptr, 'l'},
            {"symbol", required_argument, nullptr, 's'},
            {"special", required_argument, nullptr, 'S'},
            {"upper", required_argument, nullptr, 'u'},
            {nullptr, 0, nullptr, 0}
        };
        while ((opt_char = getopt_long(argc, argv, "c:u:l:d:s:S:", long_options, nullptr)) != -1) {
            std::string arg {optarg ? optarg : ""};
            switch (opt_char) {
                case 0: {
                    // handle long-only options here
                    switch (opt_val) {
                        case 1:
                            std::cout << pw_version() << '\n';
                            return EXIT_SUCCESS;
                    }
                    break;
                }
                case 'u':
                    valid += upper;
                    min_upper = std::atoi(optarg);
                    if (min_upper < 0) throw std::runtime_error("minimum amout of upper case must be zero or more");
                    noflags = false;
                    break;
                case 'l':
                    valid += lower;
                    min_lower = std::atoi(optarg);
                    if (min_upper < 0) throw std::runtime_error("minimum amout of lower case must be zero or more");
                    noflags = false;
                    break;
                case 'd':
                    valid += digits;
                    min_digits = std::atoi(optarg);
                    if (min_upper < 0) throw std::runtime_error("minimum amout of digits must be zero or more");
                    noflags = false;
                    break;
                case 's':
                    valid += symbols;
                    min_symbols = std::atoi(optarg);
                    if (min_upper < 0) throw std::runtime_error("minimum amout of symbols must be zero or more");
                    noflags = false;
                    break;
                case 'S':
                    special = arg;
                    valid += arg;
                    min_special = 1;
                    noflags = false;
                    break;
                case 'c':
                    len = std::stoi(optarg);
                    break;
                case '?':
                    throw std::runtime_error("unrecognized option");
            }
        }
        if (noflags) {
            valid = upper + lower + digits + symbols;
        }
        int num_free_choice = len - min_digits - min_lower - min_upper - min_symbols;
        if (num_free_choice < 0) {
            throw std::runtime_error("total minimum required exceeds password length");
        }
        std::string password;
        for (int i = 0; i < min_digits; ++i) {
            password += sc::random::choice<char>(digits.begin(), digits.end());
        }
        for (int i = 0; i < min_lower; ++i) {
            password += sc::random::choice<char>(lower.begin(), lower.end());
        }
        for (int i = 0; i < min_upper; ++i) {
            password += sc::random::choice<char>(upper.begin(), upper.end());
        }
        for (int i = 0; i < min_symbols; ++i) {
            password += sc::random::choice<char>(symbols.begin(), symbols.end());
        }
        if (min_special) {
            password += sc::random::choice<char>(special.begin(), special.end());
        }
        for (int i = 0; i < num_free_choice; ++i) {
            password += sc::random::choice<char>(valid.begin(), valid.end());
        }
        std::shuffle(password.begin(), password.end(), sc::random::instance().engine());
        std::cout << password << std::endl;
    } catch (const std::exception& ex) {
        std::cerr << "pw: " << ex.what() << '\n';
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}