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

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

/* Target function under test: void usage(int status); declared earlier in od.c */

static char *read_all_from_fd(int fd, size_t *out_len)
{
    size_t cap = 4096;
    size_t len = 0;
    char *buf = (char *)malloc(cap);
    if (!buf) return NULL;
    for (;;) {
        if (len + 1024 > cap) {
            size_t ncap = cap * 2;
            char *nb = (char *)realloc(buf, ncap);
            if (!nb) { free(buf); return NULL; }
            buf = nb; cap = ncap;
        }
        ssize_t n = read(fd, buf + len, cap - len - 1);
        if (n < 0) {
            if (errno == EINTR) continue;
            /* read error */
            free(buf);
            return NULL;
        }
        if (n == 0) break; /* EOF */
        len += (size_t)n;
    }
    buf[len] = '\0';
    if (out_len) *out_len = len;
    return buf;
}

/* Helper to run usage(status) in a child, capturing stdout and stderr. */
static int run_usage_and_capture(int status, char **out_str, char **err_str, int *exit_code)
{
    int out_pipe[2];
    int err_pipe[2];
    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) {
        /* fork failed */
        close(out_pipe[0]); close(out_pipe[1]);
        close(err_pipe[0]); close(err_pipe[1]);
        return -1;
    }

    if (pid == 0) {
        /* Child: redirect stdout/stderr, set locale, set program name, call usage */
        /* Ensure English output */
        setenv("LC_ALL", "C", 1);
        setenv("LANGUAGE", "C", 1);
        setlocale(LC_ALL, "C");

        /* Prepare redirection */
        close(out_pipe[0]);
        close(err_pipe[0]);
        if (dup2(out_pipe[1], STDOUT_FILENO) < 0) _exit(127);
        if (dup2(err_pipe[1], STDERR_FILENO) < 0) _exit(127);
        close(out_pipe[1]);
        close(err_pipe[1]);

        /* Ensure program_name is set for formatted messages */
        /* set_program_name is declared via headers included earlier in od.c */
        extern void set_program_name(const char *);
        set_program_name("od");

        /* Call the function under test; it will exit(status). */
        usage(status);

        /* Not reached */
        _exit(255);
    }

    /* Parent: close write ends and read output */
    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 status_wait = 0;
    pid_t w = waitpid(pid, &status_wait, 0);
    if (w < 0) {
        if (out_buf) free(out_buf);
        if (err_buf) free(err_buf);
        return -1;
    }

    int code = -1;
    if (WIFEXITED(status_wait)) code = WEXITSTATUS(status_wait);
    else if (WIFSIGNALED(status_wait)) code = 128 + WTERMSIG(status_wait);

    if (exit_code) *exit_code = code;
    if (out_str) *out_str = out_buf; else if (out_buf) free(out_buf);
    if (err_str) *err_str = err_buf; else if (err_buf) free(err_buf);

    return 0;
}

void setUp(void) {
    /* No global setup required */
}

void tearDown(void) {
    /* No global teardown required */
}

static void assert_substr(const char *haystack, const char *needle)
{
    TEST_ASSERT_NOT_NULL_MESSAGE(haystack, "Captured text is NULL");
    TEST_ASSERT_NOT_NULL_MESSAGE(needle, "Needle is NULL");
    TEST_ASSERT_NOT_NULL_MESSAGE(strstr(haystack, needle), "Expected substring not found");
}

void test_usage_success_outputs_help_and_exits_success(void)
{
    char *out = NULL; char *err = NULL; int code = -1;
    int rc = run_usage_and_capture(EXIT_SUCCESS, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "run_usage_and_capture failed");

    /* Verify exit status */
    TEST_ASSERT_EQUAL_INT(EXIT_SUCCESS, code);

    /* For success case, help goes to stdout, stderr should be empty */
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_TRUE_MESSAGE(out[0] != '\0', "stdout should not be empty for --help");
    TEST_ASSERT_NOT_NULL(err);
    TEST_ASSERT_TRUE_MESSAGE(err[0] == '\0', "stderr should be empty for --help");

    /* Verify some key substrings of the help text */
    assert_substr(out, "Usage: od ");
    assert_substr(out, "--address-radix=");
    assert_substr(out, "--endian=");
    assert_substr(out, "--width");

    free(out);
    free(err);
}

void test_usage_failure_outputs_try_help_to_stderr_and_exits_failure(void)
{
    char *out = NULL; char *err = NULL; int code = -1;
    int rc = run_usage_and_capture(EXIT_FAILURE, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "run_usage_and_capture failed");

    TEST_ASSERT_EQUAL_INT(EXIT_FAILURE, code);

    /* For failure case, try-help goes to stderr */
    TEST_ASSERT_NOT_NULL(out);
    /* stdout should be empty or nearly empty */
    TEST_ASSERT_TRUE_MESSAGE(out[0] == '\0', "stdout should be empty when emitting try-help");

    TEST_ASSERT_NOT_NULL(err);
    assert_substr(err, "Try 'od --help' for more information.");

    free(out);
    free(err);
}

void test_usage_custom_nonzero_status_propagates_exit_code_and_try_help(void)
{
    char *out = NULL; char *err = NULL; int code = -1;
    /* Use a non-standard nonzero exit status */
    int wanted = 77;
    int rc = run_usage_and_capture(wanted, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "run_usage_and_capture failed");

    TEST_ASSERT_EQUAL_INT(wanted, code);

    TEST_ASSERT_NOT_NULL(err);
    assert_substr(err, "Try 'od --help' for more information.");

    free(out);
    free(err);
}

int main(void)
{
    UNITY_BEGIN();
    RUN_TEST(test_usage_success_outputs_help_and_exits_success);
    RUN_TEST(test_usage_failure_outputs_try_help_to_stderr_and_exits_failure);
    RUN_TEST(test_usage_custom_nonzero_status_propagates_exit_code_and_try_help);
    return UNITY_END();
}