// C test program illustrating POSIX shared-memory API.
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include "test.h"

// ============================================================================
// Helper macros
// ============================================================================

#define SHM_OBJ "shm_test" // Name of shared memory object
#define SHM_SIZE 0x1000 // Size (in bytes) of shared memory object

/* Messages to communicate through shared memory */
#define MSG0 "1st Hello"
#define MSG1 "2nd Hello"
#define MSG2 "3rd Hello"
#define MSG3 "4th Hello"
#define MSG_SIZE strlen(MSG0)

// ============================================================================
// Test cases
// ============================================================================

int producer_process() {
    // Shared memory file descriptor
    int shm_fd;
    // Shared memory buffer
    void *shm_buf;

    // Create the shared memory object
    shm_fd = shm_open(SHM_OBJ, O_CREAT | O_RDWR, 0666);
    if (shm_fd < 0) {
        THROW_ERROR("shm_open failed");
    }

    // Configure the size of the shared memory object
    if (ftruncate(shm_fd, SHM_SIZE) < 0) {
        THROW_ERROR("ftruncate error");
    }

    // Memory map the shared memory object
    shm_buf = mmap(NULL, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
    if (shm_buf == MAP_FAILED) {
        THROW_ERROR("mmap(MAP_SHARED) failed");
    }

    // Fork a child and launch consumer process
    pid_t child_pid = vfork();
    if (child_pid < 0) {
        // THROW_ERROR("Spawn a child process failed");
        perror("Spawn a child process failed");
        return -1;
    } else if (child_pid == 0) {
        execl("/bin/posix_shm", NULL, NULL);
        THROW_ERROR("exec failed");
    }

    // Communicate through shared memory
    strncpy(shm_buf, MSG0, MSG_SIZE);
    printf("[Producer] send %s\n", MSG0);
    while (1) {
        if (strncmp(shm_buf, MSG1, MSG_SIZE) != 0) {
            sleep(1);
            continue;
        }
        printf("[Producer] receive %s\n", MSG1);
        strncpy(shm_buf, MSG2, MSG_SIZE);
        printf("[Producer] send %s\n", MSG2);
        while (1) {
            if (strncmp(shm_buf, MSG3, MSG_SIZE) != 0) {
                sleep(1);
                continue;
            }
            printf("[Producer] receive %s\n", MSG3);
            break;
        }
        break;
    }

    // Unmap the shared memory
    if (munmap(shm_buf, SHM_SIZE) < 0) {
        THROW_ERROR("munmap failed");
    }

    // Unlink the shared memory object
    shm_unlink(SHM_OBJ);
    return 0;
}

int consumer_process() {
    // Shared memory file descriptor
    int shm_fd;
    // Shared memory buffer
    void *shm_buf;

    // Create the shared memory object
    shm_fd = shm_open(SHM_OBJ, O_CREAT | O_RDWR, 0666);
    if (shm_fd < 0) {
        THROW_ERROR("shm_open failed");
    }

    // Configure the size of the shared memory object
    if (ftruncate(shm_fd, SHM_SIZE) < 0) {
        THROW_ERROR("ftruncate error");
    }

    // Memory map the shared memory object
    shm_buf = mmap(NULL, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
    if (shm_buf == MAP_FAILED) {
        THROW_ERROR("mmap(MAP_SHARED) failed");
    }

    while (1) {
        if (strncmp(shm_buf, MSG0, MSG_SIZE) != 0) {
            sleep(1);
            continue;
        }
        printf("[Consumer] receive %s\n", MSG0);
        strncpy(shm_buf, MSG1, MSG_SIZE);
        printf("[Consumer] send %s\n", MSG1);
        while (1) {
            if (strncmp(shm_buf, MSG2, MSG_SIZE) != 0) {
                sleep(1);
                continue;
            }
            printf("[Consumer] receive %s\n", MSG2);
            strncpy(shm_buf, MSG3, MSG_SIZE);
            printf("[Consumer] send %s\n", MSG3);
            break;
        }
        break;
    }

    // Unmap the shared memory
    if (munmap(shm_buf, SHM_SIZE) < 0) {
        THROW_ERROR("munmap failed");
    }

    // Unlink the shared memory object
    shm_unlink(SHM_OBJ);
    return 0;
}

int test_posix_shm() {
    return producer_process();
}

// ============================================================================
// Test suite main
// ============================================================================

static test_case_t test_cases[] = {
    TEST_CASE(test_posix_shm),
};

int main(int argc, const char *argv[]) {
    if (argc == 1) {
        // Producer process
        return test_suite_run(test_cases, ARRAY_SIZE(test_cases));
    } else {
        // Consumer process
        return consumer_process();
    }
}