#include "../../unity/unity.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <locale.h>

#include "progname.h" /* for set_program_name */

static bool str_contains(const char *haystack, const char *needle)
{
    if (!haystack || !needle) return false;
    return strstr(haystack, needle) != NULL;
}

static char *read_all_from_fd(int fd, size_t *out_len)
{
    size_t cap = 1024;
    size_t len = 0;
    char *buf = (char *)malloc(cap + 1);
    if (!buf) return NULL;

    for (;;)
    {
        if (len == cap)
        {
            cap *= 2;
            char *nb = (char *)realloc(buf, cap + 1);
            if (!nb) { free(buf); return NULL; }
            buf = nb;
        }
        ssize_t n = read(fd, buf + len, cap - len);
        if (n < 0)
        {
            if (errno == EINTR) continue;
            free(buf);
            return NULL;
        }
        if (n == 0)
            break;
        len += (size_t)n;
    }
    buf[len] = '\0';
    if (out_len) *out_len = len;
    return buf;
}

/* Run usage(status) in a child process, capturing stdout and stderr.
   Returns 0 on success, -1 on failure to set up/run. */
static int run_usage_and_capture(int status,
                                 char **out_stdout, size_t *out_stdout_len,
                                 char **out_stderr, size_t *out_stderr_len,
                                 int *out_exit_status)
{
    int out_pipe[2] = {-1, -1};
    int err_pipe[2] = {-1, -1};
    if (pipe(out_pipe) != 0) return -1;
    if (pipe(err_pipe) != 0) {
        close(out_pipe[0]); close(out_pipe[1]);
        return -1;
    }

    fflush(stdout);
    fflush(stderr);
    pid_t pid = fork();
    if (pid < 0)
    {
        close(out_pipe[0]); close(out_pipe[1]);
        close(err_pipe[0]); close(err_pipe[1]);
        return -1;
    }
    else if (pid == 0)
    {
        /* Child: redirect stdout/stderr to pipes and call usage(status). */
        /* Ensure our stdio streams go to the pipes. */
        if (dup2(out_pipe[1], STDOUT_FILENO) < 0) _exit(127);
        if (dup2(err_pipe[1], STDERR_FILENO) < 0) _exit(127);

        /* Close all pipe fds now in child. */
        close(out_pipe[0]); close(out_pipe[1]);
        close(err_pipe[0]); close(err_pipe[1]);

        /* Call usage; it will exit(status). */
        usage(status);
        _exit(127); /* Should not reach here */
    }
    else
    {
        /* Parent: close write ends, read outputs, and wait. */
        close(out_pipe[1]);
        close(err_pipe[1]);

        size_t out_len = 0, err_len = 0;
        char *out_buf = read_all_from_fd(out_pipe[0], &out_len);
        char *err_buf = read_all_from_fd(err_pipe[0], &err_len);

        close(out_pipe[0]);
        close(err_pipe[0]);

        int wstatus = 0;
        if (waitpid(pid, &wstatus, 0) < 0)
        {
            free(out_buf);
            free(err_buf);
            return -1;
        }

        if (out_stdout) *out_stdout = out_buf; else free(out_buf);
        if (out_stdout_len) *out_stdout_len = out_len;
        if (out_stderr) *out_stderr = err_buf; else free(err_buf);
        if (out_stderr_len) *out_stderr_len = err_len;

        if (out_exit_status)
        {
            if (WIFEXITED(wstatus))
                *out_exit_status = WEXITSTATUS(wstatus);
            else
                *out_exit_status = -1;
        }

        return 0;
    }
}

/* Unity fixtures */
void setUp(void) {
    /* Ensure stable, English output. */
    setenv("LC_ALL", "C", 1);
    setlocale(LC_ALL, "C");

    /* Ensure program_name is set to "fold" for usage output. */
    set_program_name("fold");
}

void tearDown(void) {
    /* No-op */
}

/* Tests */

void test_usage_failure_emits_try_help_on_stderr(void)
{
    char *out = NULL, *err = NULL;
    size_t out_len = 0, err_len = 0;
    int exit_code = -1;

    int rc = run_usage_and_capture(EXIT_FAILURE, &out, &out_len, &err, &err_len, &exit_code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Failed to run usage() in child.");

    /* Should exit with EXIT_FAILURE */
    TEST_ASSERT_EQUAL_INT(EXIT_FAILURE, exit_code);

    /* stdout should be empty; stderr should contain the try-help hint with program name and --help */
    TEST_ASSERT_TRUE_MESSAGE(out_len == 0 || (out && out[0] == '\0'), "stdout should be empty on failure.");
    TEST_ASSERT_TRUE_MESSAGE(err && err_len > 0, "stderr should not be empty on failure.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "Try"), "stderr should contain 'Try' hint.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "--help"), "stderr should mention --help.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "fold"), "stderr should include the program name.");

    free(out);
    free(err);
}

void test_usage_success_prints_help_to_stdout_and_exits_zero(void)
{
    char *out = NULL, *err = NULL;
    size_t out_len = 0, err_len = 0;
    int exit_code = -1;

    int rc = run_usage_and_capture(EXIT_SUCCESS, &out, &out_len, &err, &err_len, &exit_code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Failed to run usage() in child.");

    /* Should exit with 0 */
    TEST_ASSERT_EQUAL_INT(EXIT_SUCCESS, exit_code);

    /* stdout should contain the usage banner and options; stderr should be empty */
    TEST_ASSERT_TRUE_MESSAGE(out && out_len > 0, "stdout should not be empty on success.");
    TEST_ASSERT_TRUE_MESSAGE(err_len == 0 || (err && err[0] == '\0'), "stderr should be empty on success.");

    /* Check for key substrings from the help text */
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "Usage: fold"), "Help should include 'Usage: fold'.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "Wrap input lines"), "Help should describe wrapping input lines.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-b, --bytes"), "Help should list --bytes option.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-c, --characters"), "Help should list --characters option.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-s, --spaces"), "Help should list --spaces option.");
    TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-w, --width"), "Help should list --width option.");

    free(out);
    free(err);
}

int main(void)
{
    UNITY_BEGIN();
    RUN_TEST(test_usage_failure_emits_try_help_on_stderr);
    RUN_TEST(test_usage_success_prints_help_to_stdout_and_exits_zero);
    return UNITY_END();
}