/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   race_detector.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: ruiferna <ruiferna@student.42porto.com>    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2025/10/14 00:00:00 by ruiferna          #+#    #+#             */
/*   Updated: 2025/10/14 15:38:47 by ruiferna         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>

typedef enum e_strategy
{
	STRATEGY_A, // Global mutex for all operations
	STRATEGY_B, // Mutex per fork + printf mutex
	STRATEGY_C  // Minimize lock time
}	t_strategy;

typedef struct s_philo
{
	int				id;
	int				meals_eaten;
	long long		last_meal_time;
	int				data_race_count;
	struct s_shared	*shared;
}	t_philo;

typedef struct s_shared
{
	int				num_philos;
	int				time_to_die;
	int				time_to_eat;
	int				time_to_sleep;
	int				simulation_stop;
	int				total_data_races;
	int				total_deaths;
	long long		start_time;
	long long		total_time;
	t_strategy		strategy;
	pthread_mutex_t	*forks;
	pthread_mutex_t	global_mutex;    // Strategy A
	pthread_mutex_t	printf_mutex;    // Strategy B
	t_philo			*philos;
}	t_shared;

typedef struct s_test_result
{
	t_strategy	strategy;
	int			data_races;
	int			deaths;
	long long	time_ms;
}	t_test_result;

long long	get_current_time(void)
{
	struct timeval	tv;

	gettimeofday(&tv, NULL);
	return ((tv.tv_sec * 1000LL) + (tv.tv_usec / 1000LL));
}

void	precise_sleep(int ms)
{
	long long	start_time;

	start_time = get_current_time();
	while ((get_current_time() - start_time) < ms)
		usleep(100);
}

void	print_message(t_shared *shared, int philo_id, char *message)
{
	long long	timestamp;

	if (shared->strategy == STRATEGY_A)
	{
		// Strategy A: Already have global lock
		timestamp = get_current_time() - shared->start_time;
		printf("%lld %d %s\n", timestamp, philo_id, message);
	}
	else
	{
		// Strategy B & C: Use printf mutex
		pthread_mutex_lock(&shared->printf_mutex);
		timestamp = get_current_time() - shared->start_time;
		printf("%lld %d %s\n", timestamp, philo_id, message);
		pthread_mutex_unlock(&shared->printf_mutex);
	}
}

int	check_stop(t_shared *shared)
{
	int	stop;

	if (shared->strategy == STRATEGY_A)
	{
		// Strategy A: Already have global lock
		stop = shared->simulation_stop;
	}
	else
	{
		// Strategy B & C: Need to check atomically
		stop = shared->simulation_stop;
	}
	return (stop);
}

void	detect_data_race(t_philo *philo, char *operation)
{
	// Simple data race detection: count concurrent access to shared data
	philo->data_race_count++;
	philo->shared->total_data_races++;
}

void	philo_eat_strategy_a(t_philo *philo)
{
	int	left_fork;
	int	right_fork;
	int	first;
	int	second;

	left_fork = philo->id - 1;
	right_fork = philo->id % philo->shared->num_philos;
	first = left_fork;
	second = right_fork;
	if (first > second)
	{
		first = right_fork;
		second = left_fork;
	}

	// Strategy A: Global lock for all operations
	pthread_mutex_lock(&philo->shared->global_mutex);
	print_message(philo->shared, philo->id, "has taken a fork");
	if (philo->shared->num_philos == 1)
	{
		pthread_mutex_unlock(&philo->shared->global_mutex);
		return ;
	}
	print_message(philo->shared, philo->id, "has taken a fork");
	philo->last_meal_time = get_current_time();
	detect_data_race(philo, "meal_time_update");
	print_message(philo->shared, philo->id, "is eating");
	precise_sleep(philo->shared->time_to_eat);
	philo->meals_eaten++;
	detect_data_race(philo, "meals_eaten_update");
	pthread_mutex_unlock(&philo->shared->global_mutex);
}

void	philo_eat_strategy_b(t_philo *philo)
{
	int	left_fork;
	int	right_fork;
	int	first;
	int	second;

	left_fork = philo->id - 1;
	right_fork = philo->id % philo->shared->num_philos;
	first = left_fork;
	second = right_fork;
	if (first > second)
	{
		first = right_fork;
		second = left_fork;
	}

	// Strategy B: Mutex per fork + printf mutex
	pthread_mutex_lock(&philo->shared->forks[first]);
	print_message(philo->shared, philo->id, "has taken a fork");
	if (philo->shared->num_philos == 1)
	{
		pthread_mutex_unlock(&philo->shared->forks[first]);
		return ;
	}
	pthread_mutex_lock(&philo->shared->forks[second]);
	print_message(philo->shared, philo->id, "has taken a fork");
	philo->last_meal_time = get_current_time();
	detect_data_race(philo, "meal_time_update");
	print_message(philo->shared, philo->id, "is eating");
	precise_sleep(philo->shared->time_to_eat);
	philo->meals_eaten++;
	detect_data_race(philo, "meals_eaten_update");
	pthread_mutex_unlock(&philo->shared->forks[second]);
	pthread_mutex_unlock(&philo->shared->forks[first]);
}

void	philo_eat_strategy_c(t_philo *philo)
{
	int	left_fork;
	int	right_fork;
	int	first;
	int	second;

	left_fork = philo->id - 1;
	right_fork = philo->id % philo->shared->num_philos;
	first = left_fork;
	second = right_fork;
	if (first > second)
	{
		first = right_fork;
		second = left_fork;
	}

	// Strategy C: Minimize lock time - lock only when necessary
	pthread_mutex_lock(&philo->shared->forks[first]);
	print_message(philo->shared, philo->id, "has taken a fork");
	if (philo->shared->num_philos == 1)
	{
		pthread_mutex_unlock(&philo->shared->forks[first]);
		return ;
	}
	if (pthread_mutex_trylock(&philo->shared->forks[second]) != 0)
	{
		// Couldn't get second fork, release first and retry
		pthread_mutex_unlock(&philo->shared->forks[first]);
		usleep(1000); // Brief pause
		return ;
	}
	print_message(philo->shared, philo->id, "has taken a fork");

	// Update meal time with minimal lock time
	long long current_time = get_current_time();
	philo->last_meal_time = current_time;
	detect_data_race(philo, "meal_time_update");

	print_message(philo->shared, philo->id, "is eating");
	precise_sleep(philo->shared->time_to_eat);

	// Update meals eaten
	philo->meals_eaten++;
	detect_data_race(philo, "meals_eaten_update");

	pthread_mutex_unlock(&philo->shared->forks[second]);
	pthread_mutex_unlock(&philo->shared->forks[first]);
}

void	philo_eat(t_philo *philo)
{
	if (philo->shared->strategy == STRATEGY_A)
		philo_eat_strategy_a(philo);
	else if (philo->shared->strategy == STRATEGY_B)
		philo_eat_strategy_b(philo);
	else
		philo_eat_strategy_c(philo);
}

void	*philo_routine(void *arg)
{
	t_philo	*philo;

	philo = (t_philo *)arg;
	if (philo->id % 2 == 0)
		precise_sleep(50);
	while (!check_stop(philo->shared))
	{
		print_message(philo->shared, philo->id, "is thinking");
		philo_eat(philo);
		if (check_stop(philo->shared))
			break ;
		print_message(philo->shared, philo->id, "is sleeping");
		precise_sleep(philo->shared->time_to_sleep);
	}
	return (NULL);
}

int	check_death(t_shared *shared)
{
	int			i;
	long long	current_time;
	long long	time_since_meal;

	i = 0;
	while (i < shared->num_philos)
	{
		current_time = get_current_time();
		time_since_meal = current_time - shared->philos[i].last_meal_time;
		if (time_since_meal > shared->time_to_die)
		{
			shared->simulation_stop = 1;
			shared->total_deaths++;
			if (shared->strategy == STRATEGY_A)
				pthread_mutex_lock(&shared->global_mutex);
			print_message(shared, shared->philos[i].id, "died");
			if (shared->strategy == STRATEGY_A)
				pthread_mutex_unlock(&shared->global_mutex);
			return (1);
		}
		i++;
	}
	return (0);
}

void	*monitor_routine(void *arg)
{
	t_shared	*shared;

	shared = (t_shared *)arg;
	while (!check_stop(shared))
	{
		if (check_death(shared))
			break ;
		usleep(1000);
	}
	return (NULL);
}

int	ft_atoi(const char *str)
{
	int	result;
	int	i;

	result = 0;
	i = 0;
	while (str[i] >= '0' && str[i] <= '9')
	{
		result = result * 10 + (str[i] - '0');
		i++;
	}
	return (result);
}

int	is_valid_number(const char *str)
{
	int	i;

	i = 0;
	if (!str || str[0] == '\0')
		return (0);
	while (str[i])
	{
		if (str[i] < '0' || str[i] > '9')
			return (0);
		i++;
	}
	return (1);
}

int	parse_arguments(int argc, char **argv, t_shared *shared, int *iterations)
{
	if (argc != 5 && argc != 6)
	{
		printf("Usage: %s number_of_philosophers time_to_die time_to_eat time_to_sleep [iterations]\n",
			argv[0]);
		return (0);
	}
	if (!is_valid_number(argv[1]) || !is_valid_number(argv[2])
		|| !is_valid_number(argv[3]) || !is_valid_number(argv[4]))
		return (0);
	shared->num_philos = ft_atoi(argv[1]);
	shared->time_to_die = ft_atoi(argv[2]);
	shared->time_to_eat = ft_atoi(argv[3]);
	shared->time_to_sleep = ft_atoi(argv[4]);
	if (shared->num_philos <= 0 || shared->time_to_die <= 0
		|| shared->time_to_eat <= 0 || shared->time_to_sleep <= 0)
		return (0);
	*iterations = 10; // Default for testing
	if (argc == 6)
	{
		if (!is_valid_number(argv[5]))
			return (0);
		*iterations = ft_atoi(argv[5]);
		if (*iterations <= 0)
			*iterations = 10;
	}
	return (1);
}

int	init_shared(t_shared *shared)
{
	int	i;

	shared->simulation_stop = 0;
	shared->total_data_races = 0;
	shared->total_deaths = 0;
	shared->forks = malloc(sizeof(pthread_mutex_t) * shared->num_philos);
	if (!shared->forks)
		return (0);
	shared->philos = malloc(sizeof(t_philo) * shared->num_philos);
	if (!shared->philos)
	{
		free(shared->forks);
		return (0);
	}
	i = 0;
	while (i < shared->num_philos)
	{
		pthread_mutex_init(&shared->forks[i], NULL);
		i++;
	}
	if (shared->strategy == STRATEGY_A)
		pthread_mutex_init(&shared->global_mutex, NULL);
	else
		pthread_mutex_init(&shared->printf_mutex, NULL);
	return (1);
}

void	init_philosophers(t_shared *shared)
{
	int			i;
	long long	current_time;

	current_time = get_current_time();
	shared->start_time = current_time;
	i = 0;
	while (i < shared->num_philos)
	{
		shared->philos[i].id = i + 1;
		shared->philos[i].meals_eaten = 0;
		shared->philos[i].last_meal_time = current_time;
		shared->philos[i].data_race_count = 0;
		shared->philos[i].shared = shared;
		i++;
	}
}

void	cleanup(t_shared *shared, pthread_t *threads)
{
	int	i;

	i = 0;
	while (i < shared->num_philos)
	{
		pthread_mutex_destroy(&shared->forks[i]);
		i++;
	}
	if (shared->strategy == STRATEGY_A)
		pthread_mutex_destroy(&shared->global_mutex);
	else
		pthread_mutex_destroy(&shared->printf_mutex);
	free(shared->forks);
	free(shared->philos);
	free(threads);
}

t_test_result	run_simulation(t_strategy strategy, int num_philos, int time_to_die,
	int time_to_eat, int time_to_sleep)
{
	t_shared	shared;
	pthread_t	*threads;
	pthread_t	monitor;
	int			i;
	long long	start_time;
	long long	end_time;

	// Initialize shared data
	memset(&shared, 0, sizeof(t_shared));
	shared.num_philos = num_philos;
	shared.time_to_die = time_to_die;
	shared.time_to_eat = time_to_eat;
	shared.time_to_sleep = time_to_sleep;
	shared.strategy = strategy;

	if (!init_shared(&shared))
		return ((t_test_result){strategy, -1, -1, -1});

	init_philosophers(&shared);
	threads = malloc(sizeof(pthread_t) * shared.num_philos);
	if (!threads)
	{
		cleanup(&shared, NULL);
		return ((t_test_result){strategy, -1, -1, -1});
	}

	start_time = get_current_time();

	// Create philosopher threads
	i = 0;
	while (i < shared.num_philos)
	{
		pthread_create(&threads[i], NULL, philo_routine, &shared.philos[i]);
		i++;
	}

	// Create monitor thread
	pthread_create(&monitor, NULL, monitor_routine, &shared);

	// Wait for threads
	i = 0;
	while (i < shared.num_philos)
	{
		pthread_join(threads[i], NULL);
		i++;
	}
	pthread_join(monitor, NULL);

	end_time = get_current_time();

	t_test_result result = {
		strategy,
		shared.total_data_races,
		shared.total_deaths,
		end_time - start_time
	};

	cleanup(&shared, threads);
	return (result);
}

void	print_strategy_name(t_strategy strategy)
{
	if (strategy == STRATEGY_A)
		printf("Strategy A (Global Mutex)");
	else if (strategy == STRATEGY_B)
		printf("Strategy B (Fork Mutexes + Print)");
	else
		printf("Strategy C (Minimize Locks)");
}

void	run_stress_test(int num_philos, int time_to_die, int time_to_eat, int time_to_sleep, int iterations)
{
	t_test_result	results[3];
	long long		total_times[3] = {0, 0, 0};
	int				total_races[3] = {0, 0, 0};
	int				total_deaths[3] = {0, 0, 0};
	int				i;

	printf("Running stress test with %d iterations...\n", iterations);
	printf("Configuration: %d philosophers, die=%dms, eat=%dms, sleep=%dms\n\n",
		num_philos, time_to_die, time_to_eat, time_to_sleep);

	for (i = 0; i < iterations; i++)
	{
		int strategy;
		for (strategy = 0; strategy < 3; strategy++)
		{
			results[strategy] = run_simulation(strategy, num_philos, time_to_die,
				time_to_eat, time_to_sleep);
			total_times[strategy] += results[strategy].time_ms;
			total_races[strategy] += results[strategy].data_races;
			total_deaths[strategy] += results[strategy].deaths;
		}
		if ((i + 1) % 10 == 0)
			printf("Completed %d/%d iterations\n", i + 1, iterations);
	}

	printf("\n=== STRESS TEST RESULTS ===\n");
	for (i = 0; i < 3; i++)
	{
		printf("\n");
		print_strategy_name(i);
		printf(":\n");
		printf("  Average time: %.2f ms\n", (double)total_times[i] / iterations);
		printf("  Total data races: %d (avg: %.2f per run)\n",
			total_races[i], (double)total_races[i] / iterations);
		printf("  Total deaths: %d (avg: %.2f per run)\n",
			total_deaths[i], (double)total_deaths[i] / iterations);
	}
}

int	main(int argc, char **argv)
{
	t_shared	shared;
	int			iterations;

	memset(&shared, 0, sizeof(t_shared));
	if (!parse_arguments(argc, argv, &shared, &iterations))
	{
		printf("Error: Invalid arguments\n");
		return (1);
	}

	// Run stress test with the provided configuration
	run_stress_test(shared.num_philos, shared.time_to_die,
		shared.time_to_eat, shared.time_to_sleep, iterations);

	return (0);
}