/* SPDX-License-Identifier: GPL-3.0-or-later */
/* Copyright 2022 Ivan Polyakov */

#include "app.h"
#include <stdlib.h>
#include <string.h>

#ifdef MT_ENABLED
#include <pthread.h>
#endif /* MT_ENABLED */

/*!
 * \brief Listens new requests by FastCGI protocol.
 * \param app Pointer to current App instance.
 * \return Always returns NULL.
 */
static void *listen_requests(void *app);

/*!
 * Handle accepted request.
 * \param app Application instance.
 * \param req FastCGI request.
 */
static void handle_request(rpd_app *app, FCGX_Request *fcgx_req);

/*!
 * \brief Selects a route handler based on requested path.
 * \param app Application instance.
 * \param req Request.
 * \return Pointer to route handler.
 */
static rpd_route *routes_fabric(rpd_app *app, rpd_req *req);

int rpd_app_create(rpd_app *app, const char *sock_path)
{
    app->running = app->sock_id = app->routes_len = 0;
    app->routes = NULL;

    app->sock_path = strdup(sock_path);
    if (!app->sock_path)
        return 1;

    FCGX_Init();

    return 0;
}

int rpd_app_start(rpd_app *app)
{
    if ((app->sock_id = FCGX_OpenSocket(app->sock_path, 10)) < 0) {
        return 1;
    }

#ifdef MT_ENABLED
    pthread_t threads[NTHREADS];
    for (int i = 0; i < NTHREADS; i++) {
        pthread_create(&threads[i], 0, listen_requests, (void *) app);
        pthread_join(threads[i], 0);
    }
#else
    listen_requests((void *) app);
#endif

    return 0;
}

int rpd_app_add_route(rpd_app *app, const char *path, rpd_route_cb cb,
    void *userdata)
{
    rpd_route route;
    if (rpd_route_init(&route, path, cb, userdata))
        return 1;

    app->routes = (rpd_route *) realloc(app->routes, sizeof(rpd_route) * (app->routes_len + 1));
    if (!app->routes)
        return 2;

    app->routes[app->routes_len++] = route;
    return 0;
}

static void *listen_requests(void *userdata)
{
    rpd_app *app = (rpd_app *) userdata;

    FCGX_Request req;
    if (FCGX_InitRequest(&req, app->sock_id, 0)) {
        return 0;
    }

    app->running = 1;
    while (app->running) {
#ifdef MT_ENABLED
        static pthread_mutex_t accept_mutex = PTHREAD_MUTEX_INITIALIZER;
        pthread_mutex_lock(&accept_mutex);
#endif

        int rc = FCGX_Accept_r(&req);

#ifdef MT_ENABLED
        pthread_mutex_unlock(&accept_mutex);
#endif

        if (rc < 0) {
            break;
        }

#ifdef MT_ENABLED
        static pthread_mutex_t handle_mutex = PTHREAD_MUTEX_INITIALIZER;
        pthread_mutex_lock(&handle_mutex);
#endif

        handle_request(app, &req);

#ifdef MT_ENABLED
        pthread_mutex_unlock(&handle_mutex);
#endif

        FCGX_Finish_r(&req);
    }

    return 0;
}

static void handle_request(rpd_app *app, FCGX_Request *fcgx_req)
{
    rpd_req req;
    rpd_res res;

    rpd_req_parse(&req, fcgx_req);
    rpd_res_init(&res, fcgx_req);

    // get route and process request
    rpd_route *route = routes_fabric(app, &req);
    if (!route) {
        return;
    }

    route->cb(&req, &res, route->userdata);

    rpd_res_send(&res);

    rpd_req_cleanup(&req);
    rpd_res_cleanup(&res);
}

static rpd_route *routes_fabric(rpd_app *app, rpd_req *req)
{
    const rpd_url *req_path, *route_path = 0;
    req_path = &req->path;

    for (int i = 0; i < app->routes_len; i++) {
        route_path = &app->routes[i].path;
        if (req_path->parts_len != route_path->parts_len)
            continue;

        int match = 1;
        for (int j = 0; j < route_path->parts_len && match; j++) {
            int cur_part_is_dyn = route_path->parts[i][0] == ':';
            if (!cur_part_is_dyn && strcmp(req_path->parts[i], route_path->parts[i])) {
                match = 0;
            }
        }

        if (!match)
            continue;

        rpd_keyval_init(&req->params, 0);
        rpd_url_params_parse_keys(&req->params, route_path);
        rpd_url_params_parse_vals(&req->params, req_path, route_path);
        return &app->routes[i];
    }
    return NULL;
}