/*
 * ai_http_stub.c
 *
 * Spawns tests/functionaltests/ai_http_stub.py as a child process for
 * functional tests that exercise the AI client's HTTP code path. The
 * stub listens on 127.0.0.1 on an OS-chosen port and prints "PORT=<n>"
 * as its first line; we read it back and hand the port to the caller.
 */

#include "ai_http_stub.h"

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

#define STUB_SCRIPT "../tests/functionaltests/ai_http_stub.py"
#define READLINE_MAX 64

static pid_t stub_pid = 0;

int
ai_http_stub_start(const char* mode, const char* reply)
{
    int pipefd[2];
    if (pipe(pipefd) != 0) {
        return 0;
    }

    pid_t pid = fork();
    if (pid < 0) {
        close(pipefd[0]);
        close(pipefd[1]);
        return 0;
    }

    if (pid == 0) {
        /* Child: redirect stdout to the pipe write end, then exec the stub. */
        close(pipefd[0]);
        dup2(pipefd[1], STDOUT_FILENO);
        close(pipefd[1]);

        if (mode) {
            setenv("AI_STUB_MODE", mode, 1);
        }
        if (reply) {
            setenv("AI_STUB_REPLY", reply, 1);
        }
        /* Argument "0" -> let the OS pick a free port. */
        execlp("python3", "python3", STUB_SCRIPT, "0", (char*)NULL);
        /* Falls through on exec failure. */
        _exit(127);
    }

    /* Parent: read "PORT=<n>\n" from the child's stdout. */
    close(pipefd[1]);

    char buf[READLINE_MAX] = { 0 };
    ssize_t total = 0;
    while (total < (ssize_t)sizeof(buf) - 1) {
        ssize_t n = read(pipefd[0], buf + total, sizeof(buf) - 1 - total);
        if (n <= 0) {
            break;
        }
        total += n;
        if (memchr(buf, '\n', total)) {
            break;
        }
    }
    close(pipefd[0]);

    int port = 0;
    if (sscanf(buf, "PORT=%d", &port) != 1 || port <= 0) {
        kill(pid, SIGTERM);
        waitpid(pid, NULL, 0);
        return 0;
    }

    stub_pid = pid;
    return port;
}

void
ai_http_stub_stop(void)
{
    if (stub_pid <= 0) {
        return;
    }
    kill(stub_pid, SIGTERM);
    /* Give the stub a moment to exit cleanly, then reap. */
    int status = 0;
    pid_t waited = waitpid(stub_pid, &status, 0);
    (void)waited;
    (void)status;
    stub_pid = 0;
}