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

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

/* Helper: read all data from fd into a newly malloc'd, NUL-terminated buffer.
   Returns buffer (caller must free). On error, returns NULL. */
static char* read_all_from_fd(int fd)
{
    size_t cap = 4096;
    size_t len = 0;
    char *buf = (char*)malloc(cap);
    if (!buf) return NULL;

    for (;;)
    {
        if (len == cap)
        {
            size_t ncap = cap * 2;
            char *nbuf = (char*)realloc(buf, ncap);
            if (!nbuf) { free(buf); return NULL; }
            buf = nbuf;
            cap = ncap;
        }
        ssize_t rd = read(fd, buf + len, cap - len);
        if (rd > 0)
        {
            len += (size_t)rd;
            continue;
        }
        else if (rd == 0)
        {
            break;
        }
        else
        {
            if (errno == EINTR) continue;
            free(buf);
            return NULL;
        }
    }

    /* Ensure NUL-terminated */
    if (len == cap)
    {
        char *nbuf = (char*)realloc(buf, cap + 1);
        if (!nbuf) { free(buf); return NULL; }
        buf = nbuf;
    }
    buf[len] = '\0';
    return buf;
}

/* Run usage(status) in a child, capture stdout/stderr, collect exit code.
   Returns 0 on success (able to run and capture), -1 on error (test infra error).
   On success, *out and *err are malloc'd strings (never NULL; empty string if no output).
   Caller must free(*out) and free(*err). */
static int run_usage_and_capture(int status, char **out, char **err, int *exit_code)
{
    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) */
        /* Close read ends */
        close(out_pipe[0]);
        close(err_pipe[0]);

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

        /* Close original write ends after dup */
        close(out_pipe[1]);
        close(err_pipe[1]);

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

        /* Should not reach; just in case */
        _exit(128);
    }
    else
    {
        /* Parent */
        close(out_pipe[1]);
        close(err_pipe[1]);

        char *captured_out = read_all_from_fd(out_pipe[0]);
        char *captured_err = read_all_from_fd(err_pipe[0]);

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

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

        /* Ensure non-NULL strings */
        if (!captured_out) captured_out = (char*)calloc(1, 1);
        if (!captured_err) captured_err = (char*)calloc(1, 1);
        if (!captured_out || !captured_err)
        {
            if (captured_out) free(captured_out);
            if (captured_err) free(captured_err);
            return -1;
        }

        *out = captured_out;
        *err = captured_err;

        if (WIFEXITED(wstatus))
            *exit_code = WEXITSTATUS(wstatus);
        else if (WIFSIGNALED(wstatus))
            *exit_code = 128 + WTERMSIG(wstatus);
        else
            *exit_code = -1;

        return 0;
    }
}

/* Unity fixtures */
void setUp(void) {
    /* Ensure predictable, English messages */
    setlocale(LC_ALL, "C");

    /* Ensure program_name is initialized to "join" */
    /* set_program_name is declared in earlier includes in this translation unit */
    set_program_name("join");
}
void tearDown(void) {
    /* nothing */
}

/* Tests */

static void assert_contains(const char* haystack, const char* needle, const char* ctx)
{
    if (!haystack || !needle) {
        TEST_FAIL_MESSAGE("Internal error: NULL passed to assert_contains");
    }
    if (strstr(haystack, needle) == NULL) {
        char msg[512];
        snprintf(msg, sizeof msg, "Expected output to contain '%s' (%s)", needle, ctx ? ctx : "");
        TEST_FAIL_MESSAGE(msg);
    }
}

void test_usage_exit_success_prints_help_to_stdout(void)
{
    char *out = NULL, *err = NULL;
    int code = -1;

    int rc = run_usage_and_capture(EXIT_SUCCESS, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Failed to invoke/capture usage()");

    TEST_ASSERT_EQUAL_INT(0, code);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_NOT_NULL(err);

    /* stdout should be non-empty, stderr should be empty */
    TEST_ASSERT_TRUE_MESSAGE(strlen(out) > 0, "Expected help text on stdout");
    TEST_ASSERT_EQUAL_UINT_MESSAGE(0u, (unsigned)strlen(err), "Expected no stderr for EXIT_SUCCESS");

    /* Basic sanity checks for content */
    assert_contains(out, "Usage:", "usage header");
    assert_contains(out, "join", "program name in usage");
    assert_contains(out, "--help", "help option description likely present");

    free(out);
    free(err);
}

void test_usage_exit_failure_prints_try_help_to_stderr(void)
{
    char *out = NULL, *err = NULL;
    int code = -1;

    int rc = run_usage_and_capture(EXIT_FAILURE, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Failed to invoke/capture usage()");

    TEST_ASSERT_EQUAL_INT(EXIT_FAILURE, code);
    TEST_ASSERT_NOT_NULL(out);
    TEST_ASSERT_NOT_NULL(err);

    /* stdout should be empty or nearly empty, stderr should have 'Try' message mentioning --help */
    TEST_ASSERT_TRUE_MESSAGE(strlen(out) == 0, "Expected no stdout for non-success status");
    assert_contains(err, "--help", "try-help hint");
    assert_contains(err, "join", "program name in try-help hint");

    free(out);
    free(err);
}

void test_usage_help_contains_key_options(void)
{
    char *out = NULL, *err = NULL;
    int code = -1;

    int rc = run_usage_and_capture(EXIT_SUCCESS, &out, &err, &code);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Failed to invoke/capture usage()");

    TEST_ASSERT_EQUAL_INT(0, code);
    TEST_ASSERT_TRUE_MESSAGE(strlen(out) > 0, "Expected help text on stdout");
    TEST_ASSERT_EQUAL_UINT_MESSAGE(0u, (unsigned)strlen(err), "Expected no stderr for EXIT_SUCCESS");

    /* Check presence of some key options in the help text */
    assert_contains(out, "-a FILENUM", "option -a");
    assert_contains(out, "-i, --ignore-case", "option -i");
    assert_contains(out, "--check-order", "long option");
    assert_contains(out, "--header", "header option");
    assert_contains(out, "-z, --zero-terminated", "zero-terminated option");

    free(out);
    free(err);
}

int main(void)
{
    UNITY_BEGIN();
    RUN_TEST(test_usage_exit_success_prints_help_to_stdout);
    RUN_TEST(test_usage_exit_failure_prints_try_help_to_stderr);
    RUN_TEST(test_usage_help_contains_key_options);
    return UNITY_END();
}