#include <algorithm>
#include <cctype>
#include <fstream>
#include <ranges>
#include <string>
#include <utility>

#include "defs.hpp"

bool is_num(char c) { return c >= '0' && c <= '9'; }
bool is_alpha(char c) { return std::isalpha(c); }

std::string tolower(const std::string &raw) {
    auto ret = raw;
    std::transform(ret.begin(), ret.end(), ret.begin(), [](unsigned char c) { return std::tolower(c); });
    return ret;
}

static std::vector<std::string> data_buf[2];
enum class BufStatus { INIT, FILLING, DONE };
static BufStatus data_buf_ok[2] = {BufStatus::INIT, BufStatus::INIT};

std::generator<std::string> passwords(const DataSource &source) {
    if (data_buf_ok[magic_enum::enum_integer(source)] == BufStatus::DONE) {
        for (auto const &password : data_buf[magic_enum::enum_integer(source)]) co_yield password;
        co_return;
    }

    if (data_buf_ok[magic_enum::enum_integer(source)] == BufStatus::INIT)
        data_buf_ok[magic_enum::enum_integer(source)] = BufStatus::FILLING;

    auto          filename = "data/"s + (source == DataSource::CSDN ? "www.csdn.net.sql"s : "plaintxt_yahoo.txt"s);
    std::ifstream is(filename);

    if (!is.is_open()) {
        spdlog::error("failed to open {}", filename);
        co_return;
    }

    switch (source) {
        case DataSource::CSDN: {
            constexpr auto delim{" # "sv};
            std::string    line;
            while (std::getline(is, line)) {
                auto segments = line | std::views::split(delim);
                auto second   = *std::ranges::next(segments.begin(), 1);
                auto password = std::string(second.begin(), second.end());

                if (data_buf_ok[magic_enum::enum_integer(source)] == BufStatus::FILLING)
                    data_buf[magic_enum::enum_integer(source)].push_back(password);

                co_yield password;
            }
        } break;
        case DataSource::YAHOO: {
            constexpr auto delim{":"sv};
            std::string    line;
            while (std::getline(is, line)) {
                std::erase(line, '\r');
                if (line.empty() || !is_num(line[0])) continue;
                if (is_num(line[0]) && line[1] == '.') continue;

                auto segments = line | std::views::split(delim);
                auto third    = *std::ranges::next(segments.begin(), 2);
                auto password = std::string(third.begin(), third.end());

                if (password.empty()) continue;
                if (data_buf_ok[magic_enum::enum_integer(source)] == BufStatus::FILLING)
                    data_buf[magic_enum::enum_integer(source)].push_back(password);

                co_yield password;
            }
        } break;
        default: std::unreachable();
    }

    data_buf_ok[magic_enum::enum_integer(source)] = BufStatus::DONE;

    is.close();
    co_return;
}