// server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <semaphore.h>
#include <unistd.h>

#define SHM_BUFFER_SIZE 1024

typedef struct {
    int has_data;
    int result_code;
    char buffer[SHM_BUFFER_SIZE];
} shared_block_t;

static void process_line(char *s) {
    if (!s) return;
    for (size_t i = 0; s[i] != '\0'; ++i) {
        if ((i + 1) % 3 == 0) {
            s[i] = ' ';
        }
    }
}

int main(int argc, char *argv[]) {
    if (argc < 4) {
        fprintf(stderr,
                "Usage: %s <shm_name> <sem_client_name> <sem_server_name> [iterations]\n",
                argv[0]);
        return -1;
    }

    const char *shm_name = argv[1];
    const char *sem_client_name = argv[2];
    const char *sem_server_name = argv[3];

    int iterations = -1;
    if (argc >= 5) {
        char *endptr = NULL;
        unsigned long tmp = strtoul(argv[4], &endptr, 10);
        if (endptr == argv[4] || *endptr != '\0') {
            fprintf(stderr, "Invalid iterations value: '%s'\n", argv[4]);
            return -1;
        }
        iterations = (int) tmp;
    }

    shm_unlink(shm_name);
    sem_unlink(sem_client_name);
    sem_unlink(sem_server_name);

    int shm_fd = shm_open(shm_name,
                          O_CREAT | O_EXCL | O_RDWR,
                          S_IRUSR | S_IWUSR);
    if (shm_fd == -1) {
        perror("shm_open");
        return -1;
    }

    if (ftruncate(shm_fd, sizeof(shared_block_t)) == -1) {
        perror("ftruncate");
        close(shm_fd);
        shm_unlink(shm_name);
        return -1;
    }

    shared_block_t *shm_ptr = mmap(NULL,
                                   sizeof(shared_block_t),
                                   PROT_READ | PROT_WRITE,
                                   MAP_SHARED,
                                   shm_fd,
                                   0);
    if (shm_ptr == MAP_FAILED) {
        perror("mmap");
        close(shm_fd);
        shm_unlink(shm_name);
        return -1;
    }

    if (close(shm_fd) == -1) {
        perror("close");
    }

    shm_ptr->has_data = 0;
    shm_ptr->result_code = 0;
    memset(shm_ptr->buffer, 0, sizeof(shm_ptr->buffer));

    sem_t *sem_client = sem_open(sem_client_name,
                                 O_CREAT | O_EXCL,
                                 S_IRUSR | S_IWUSR,
                                 0);
    if (sem_client == SEM_FAILED) {
        perror("sem_open(sem_client)");
        munmap(shm_ptr, sizeof(shared_block_t));
        shm_unlink(shm_name);
        return -1;
    }

    sem_t *sem_server = sem_open(sem_server_name,
                                 O_CREAT | O_EXCL,
                                 S_IRUSR | S_IWUSR,
                                 0);
    if (sem_server == SEM_FAILED) {
        perror("sem_open(sem_server)");
        sem_close(sem_client);
        sem_unlink(sem_client_name);
        munmap(shm_ptr, sizeof(shared_block_t));
        shm_unlink(shm_name);
        return -1;
    }

    FILE *fout = fopen("output.txt", "w");
    if (!fout) {
        perror("fopen(output.txt)");
    }

    int processed_count = 0;

    while (iterations < 0 || processed_count < iterations) {
        if (sem_wait(sem_client) == -1) {
            perror("sem_wait(sem_client)");
            processed_count = -1;
            break;
        }

        if (!shm_ptr->has_data) {
            fprintf(stderr, "Warning: sem_client posted, but has_data == 0\n");
            shm_ptr->result_code = -1;
        } else {
            process_line(shm_ptr->buffer);
            shm_ptr->result_code = 0;
            shm_ptr->has_data = 0;
            processed_count++;

            if (fout) {
                fprintf(fout, "%s\n", shm_ptr->buffer);
                fflush(fout);
            }
        }

        if (sem_post(sem_server) == -1) {
            perror("sem_post(sem_server)");
            processed_count = -1;
            break;
        }
    }

    if (fout && fclose(fout) == EOF) {
        perror("fclose(output.txt)");
    }

    if (processed_count >= 0) {
        printf("%d\n", processed_count);
    } else {
        printf("-1\n");
    }

    if (sem_close(sem_client) == -1) {
        perror("sem_close(sem_client)");
    }
    if (sem_close(sem_server) == -1) {
        perror("sem_close(sem_server)");
    }

    if (sem_unlink(sem_client_name) == -1) {
        perror("sem_unlink(sem_client)");
    }
    if (sem_unlink(sem_server_name) == -1) {
        perror("sem_unlink(sem_server)");
    }

    if (munmap(shm_ptr, sizeof(shared_block_t)) == -1) {
        perror("munmap");
    }
    if (shm_unlink(shm_name) == -1) {
        perror("shm_unlink");
    }

    return 0;
}