main.cpp

// main.cpp — Interactive multiplication quiz (CLI entry-point)
//
// Pedagogical intent: this file is deliberately simple and heavily commented
// so that stepping through it in the VS Code debugger is instructive.
//
// Suggested breakpoints when debugging for the first time:
//   1. The top of the game loop (while-loop header) to inspect `seed`.
//   2. The check_answer() call to watch `player_answer` vs `q.correct`.
//   3. score.record() (step into quiz_lib) to see the Score state change.

#include <iostream>
#include <limits>
#include <string>

#include "quiz.hpp"   // quiz::generate_question, quiz::check_answer, quiz::Score

namespace {

/// Number of questions in one game session.
/// Kept small so a manual debug session doesn't feel tedious.
constexpr int kQuestionsPerGame = 5;

/// Read a single integer from stdin, discarding any leading whitespace.
/// Returns false (and leaves `out` unchanged) if the input is not a valid int.
bool read_int(int& out) {
    int value{};
    if (std::cin >> value) {
        // Discard remainder of the line (newline, trailing garbage) so the
        // next std::cin >> call starts on a fresh line.
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
        out = value;
        return true;
    }
    // Clear the error flag and discard the bad token so the stream is reusable.
    std::cin.clear();
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    return false;
}

} // anonymous namespace

int main() {
    std::cout << "=== Multiplication Quiz ===\n"
              << "Answer " << kQuestionsPerGame << " multiplication questions.\n\n";

    quiz::Score score;

    // Each iteration of the loop is one question.
    // `seed` drives generate_question(); incrementing it gives a new question
    // each round while keeping the sequence deterministic (useful for demos).
    for (int seed = 0; seed < kQuestionsPerGame; ++seed) {

        // ── Generate question ─────────────────────────────────────────────
        quiz::Question q = quiz::generate_question(seed);

        // Print the question number (1-based for the player) and the prompt.
        std::cout << "Q" << (seed + 1) << ": " << q.prompt();

        // ── Read player answer ────────────────────────────────────────────
        int player_answer{};
        if (!read_int(player_answer)) {
            std::cout << "  [invalid input — skipping]\n";
            score.record(false);  // Count as incorrect
            continue;
        }

        // ── Check answer and give feedback ────────────────────────────────
        bool correct = quiz::check_answer(q, player_answer);
        score.record(correct);

        if (correct) {
            std::cout << "  Correct!\n";
        } else {
            std::cout << "  Wrong. The answer was " << q.correct << ".\n";
        }
    }

    // ── Final score ───────────────────────────────────────────────────────
    std::cout << "\nResult: " << score.summary() << "\n";

    // Return 0 on a perfect score, 1 otherwise — useful for scripting.
    return (score.correct_count() == kQuestionsPerGame) ? 0 : 1;
}