/*
 * test_xcetest_process_entry.c -- xce-test-cli-ux task 1.6, Requirements
 * 4.1, 4.2, 4.3 (Process-Level Help and Version Discovery).
 *
 * These are black-box, subprocess tests: they exec the REAL, built
 * xce_test binary (a sibling of this test binary in the same build
 * directory -- see resolve_xce_test_path()) with a process-level flag and
 * inspect its exit code and captured stdout. This is deliberately NOT a
 * plain unit test that calls argp_parse()/parse_opt() in-process: what's
 * under test is main()'s own process-level argv handling, including
 * whether it reaches the interactive/scripted REPL loop at all, which can
 * only be observed by actually running the process to completion.
 *
 * This is a small, self-contained subprocess harness scoped to this one
 * task's needs (process-level -h/--help/--version) -- NOT the reusable
 * pty-driven black-box CLI harness that task 1.7 builds separately (that
 * one will live in test_test_cli.c and is needed for interactive-only
 * surfaces like tab completion that a plain pipe can't exercise).
 *
 * resolve_xce_test_path() below is deliberately non-static (task 1.7):
 * test_test_cli.c's pty-driven harness needs the exact same "find the real
 * built xce_test binary next to this test binary" logic and reuses this
 * copy via an `extern` declaration rather than duplicating it -- see this
 * project's own consolidation-over-copy-paste convention.
 */
#define _GNU_SOURCE
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

#include <unity/unity.h>

#define CAPTURE_BUF_SIZE     16384
#define CHILD_TIMEOUT_TENTHS 50 /* 5 seconds, polled every 100ms */

/* xce_test is always built as a sibling of this test binary in the same
 * meson build directory (src/controller/meson.build builds both `xce_test`
 * and `controller_unit_test` into the same target dir) -- resolving via
 * /proc/self/exe's directory avoids depending on the caller's cwd or an
 * env var that could go stale. */
int resolve_xce_test_path(char* out, size_t outsz)
{
    char    self[PATH_MAX];
    ssize_t n;
    char*   dir;

    n = readlink("/proc/self/exe", self, sizeof(self) - 1);
    if (n <= 0) {
        return -1;
    }
    self[n] = '\0';

    dir = dirname(self); /* dirname() may modify its argument in place;
                           * `self` is a disposable local copy, so that's
                           * fine here. */

    if (snprintf(out, outsz, "%s/xce_test", dir) >= (int)outsz) {
        return -1;
    }
    return 0;
}

/* Runs xce_test_path with argv (NULL-terminated; argv[0] conventionally
 * the program name) with stdin attached to /dev/null -- so that if a
 * regression makes it fall through into the interactive REPL instead of
 * exiting, readline() sees immediate EOF rather than hanging -- and
 * captures its stdout into out_buf. Kills and fails the test if the child
 * does not exit within CHILD_TIMEOUT_TENTHS/10 seconds, so a genuine hang
 * can't wedge the whole suite. */
static void run_and_capture(const char* xce_test_path, char* const argv[],
                             char* out_buf, size_t out_buf_size,
                             int* exit_code)
{
    int   outpipe[2];
    pid_t pid;
    int   status  = 0;
    int   elapsed = 0;
    pid_t waited;

    TEST_ASSERT_EQUAL_INT(0, pipe(outpipe));

    pid = fork();
    TEST_ASSERT_TRUE(pid >= 0);

    if (pid == 0) {
        int devnull = open("/dev/null", O_RDONLY);

        if (devnull >= 0) {
            dup2(devnull, STDIN_FILENO);
            close(devnull);
        }
        dup2(outpipe[1], STDOUT_FILENO);
        close(outpipe[0]);
        close(outpipe[1]);

        execv(xce_test_path, argv);
        _exit(127); /* only reached if execv() itself failed */
    }

    close(outpipe[1]);

    for (;;) {
        waited = waitpid(pid, &status, WNOHANG);
        if (waited == pid) {
            break;
        }
        if (elapsed >= CHILD_TIMEOUT_TENTHS) {
            kill(pid, SIGKILL);
            waitpid(pid, &status, 0);
            close(outpipe[0]);
            TEST_FAIL_MESSAGE(
                "xce_test did not exit within timeout -- it likely fell "
                "through into the REPL instead of exiting after a "
                "process-level help/version flag");
        }
        usleep(100000);
        elapsed++;
    }

    {
        ssize_t total = 0;
        ssize_t r;

        while (total < (ssize_t)out_buf_size - 1) {
            r = read(outpipe[0], out_buf + total,
                      out_buf_size - 1 - (size_t)total);
            if (r <= 0) {
                break;
            }
            total += r;
        }
        out_buf[total] = '\0';
    }
    close(outpipe[0]);

    TEST_ASSERT_TRUE(WIFEXITED(status));
    *exit_code = WEXITSTATUS(status);
}

/* Word-wrapped help text can break a multi-word phrase across lines at any
 * space -- argp wraps the doc string to the terminal width. Folding
 * newlines to spaces before substring-matching makes assertions robust to
 * exactly where those wraps land. */
static void flatten_newlines(char* s)
{
    for (; *s; s++) {
        if (*s == '\n') {
            *s = ' ';
        }
    }
}

static void test_help_flag_prints_usage_and_exits_without_repl(void)
{
    char        xce_test_path[PATH_MAX];
    char        out[CAPTURE_BUF_SIZE];
    int         exit_code;
    char* const argv[] = { "xce_test", "--help", NULL };

    TEST_ASSERT_EQUAL_INT(
        0, resolve_xce_test_path(xce_test_path, sizeof(xce_test_path)));

    run_and_capture(xce_test_path, argv, out, sizeof(out), &exit_code);

    TEST_ASSERT_EQUAL_INT(0, exit_code);
    TEST_ASSERT_NOT_NULL(strstr(out, "Usage:"));
    /* Never reached the interactive session's top-level prompt. */
    TEST_ASSERT_NULL(strstr(out, "xce>"));
}

/* Requirement 4.3: the process-level help output must describe the
 * in-session `help` command as the way to list/learn available commands
 * -- not just document its own --help/-?/-h flags. */
static void test_help_flag_describes_insession_help_command(void)
{
    char        xce_test_path[PATH_MAX];
    char        out[CAPTURE_BUF_SIZE];
    int         exit_code;
    char* const argv[] = { "xce_test", "--help", NULL };

    TEST_ASSERT_EQUAL_INT(
        0, resolve_xce_test_path(xce_test_path, sizeof(xce_test_path)));

    run_and_capture(xce_test_path, argv, out, sizeof(out), &exit_code);
    TEST_ASSERT_EQUAL_INT(0, exit_code);

    flatten_newlines(out);
    TEST_ASSERT_NOT_NULL_MESSAGE(
        strstr(out, "type `help' at the prompt to list"),
        "xce_test --help must describe the in-session `help' command as "
        "the way to list/learn available commands (Requirement 4.3)");
}

/* Requirement 4.1 explicitly calls out `-h` alongside `--help`. GNU argp's
 * OWN built-in short help alias is `-?`, not `-h` -- so unlike --help/-?,
 * this is not automatic and must be verified (and, if missing, added). */
static void test_dash_h_flag_prints_usage_and_exits_without_repl(void)
{
    char        xce_test_path[PATH_MAX];
    char        out[CAPTURE_BUF_SIZE];
    int         exit_code;
    char* const argv[] = { "xce_test", "-h", NULL };

    TEST_ASSERT_EQUAL_INT(
        0, resolve_xce_test_path(xce_test_path, sizeof(xce_test_path)));

    run_and_capture(xce_test_path, argv, out, sizeof(out), &exit_code);

    TEST_ASSERT_EQUAL_INT(0, exit_code);
    TEST_ASSERT_NOT_NULL(strstr(out, "Usage:"));
    TEST_ASSERT_NULL(strstr(out, "xce>"));
}

static void test_version_flag_prints_version_and_exits_without_repl(void)
{
    char        xce_test_path[PATH_MAX];
    char        out[CAPTURE_BUF_SIZE];
    int         exit_code;
    char* const argv[] = { "xce_test", "--version", NULL };

    TEST_ASSERT_EQUAL_INT(
        0, resolve_xce_test_path(xce_test_path, sizeof(xce_test_path)));

    run_and_capture(xce_test_path, argv, out, sizeof(out), &exit_code);

    TEST_ASSERT_EQUAL_INT(0, exit_code);
    TEST_ASSERT_NOT_NULL(strstr(out, "xce"));
    /* xce_compose_version_ex()'s output includes a "built <timestamp>"
     * segment -- distinguishes real version info from a coincidental
     * "xce" substring elsewhere. */
    TEST_ASSERT_NOT_NULL(strstr(out, "built"));
    TEST_ASSERT_NULL(strstr(out, "Usage:"));
    TEST_ASSERT_NULL(strstr(out, "xce>"));
}

void test_xcetest_process_entry(void)
{
    UnitySetTestFile(__FILE__);
    RUN_TEST(test_help_flag_prints_usage_and_exits_without_repl);
    RUN_TEST(test_help_flag_describes_insession_help_command);
    RUN_TEST(test_dash_h_flag_prints_usage_and_exits_without_repl);
    RUN_TEST(test_version_flag_prints_version_and_exits_without_repl);
}