#include "test_utils.h"

static int test_two_files(const char *path_a, const char *path_b)
{
    printf("\n=== test_two_files ===\n");

    int fd_a = open(path_a, O_CREAT | O_RDWR | O_TRUNC, 0644);
    if (fd_a < 0) { perror("open A"); return 1; }

    int fd_b = open(path_b, O_CREAT | O_RDWR | O_TRUNC, 0644);
    if (fd_b < 0) { perror("open B"); return 2; }

    printf("fd_a=%d  fd_b=%d\n", fd_a, fd_b);

    const char *data_a = "File-A: Hello World!";
    const char *data_b = "File-B: Goodbye World!";
    if (write(fd_a, data_a, strlen(data_a)) < 0) { perror("write A"); return 3; }
    if (write(fd_b, data_b, strlen(data_b)) < 0) { perror("write B"); return 4; }
    printf("write A: %s\n", data_a);
    printf("write B: %s\n", data_b);

    lseek(fd_a, 0, SEEK_SET);
    lseek(fd_b, 0, SEEK_SET);

    char buf_a[64] = {0};
    char buf_b[64] = {0};
    ssize_t r_a = read(fd_a, buf_a, sizeof(buf_a));
    ssize_t r_b = read(fd_b, buf_b, sizeof(buf_b));

    printf("read A: %zd bytes: %.*s\n", r_a, (int)r_a, buf_a);
    printf("read B: %zd bytes: %.*s\n", r_b, (int)r_b, buf_b);

    int ok = 1;
    if (strncmp(buf_a, data_a, strlen(data_a)) != 0) {
        printf("FAIL: A content mismatch!\n");
        ok = 0;
    }
    if (strncmp(buf_b, data_b, strlen(data_b)) != 0) {
        printf("FAIL: B content mismatch!\n");
        ok = 0;
    }
    if (ok) {
        printf("PASS: both files read back correctly\n");
    }

    lseek(fd_a, 0, SEEK_END);
    if (write(fd_a, "[A-TAIL]", 8) != 8) { perror("append A"); return 5; }

    lseek(fd_b, 8, SEEK_SET);
    if (write(fd_b, "Hi!    ", 7) != 7) { perror("overwrite B"); return 6; }

    lseek(fd_a, 0, SEEK_SET);
    lseek(fd_b, 0, SEEK_SET);
    memset(buf_a, 0, sizeof(buf_a));
    memset(buf_b, 0, sizeof(buf_b));
    r_a = read(fd_a, buf_a, sizeof(buf_a));
    r_b = read(fd_b, buf_b, sizeof(buf_b));
    printf("after cross-write:\n");
    printf("  A: %.*s\n", (int)r_a, buf_a);
    printf("  B: %.*s\n", (int)r_b, buf_b);

    close(fd_a);
    close(fd_b);
    unlink(path_a);
    unlink(path_b);
    return 0;
}

int main(int argc, char **argv)
{
    char path_a[PATH_MAX];
    char path_b[PATH_MAX];
    const char *dir = argc >= 2 ? argv[1] : NULL;
    make_path(path_a, sizeof(path_a), dir, "file_a.dat");
    make_path(path_b, sizeof(path_b), dir, "file_b.dat");
    int rc = test_two_files(path_a, path_b);
    return report_result("test_two_files", rc);
}