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

#include "../include/servers/fcgi.h"
#include "../c/utils.h"
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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

typedef struct {
    rpd_app *app;
    int sock_id;
} thread_data;

/*!
 * \brief Run FastCGI requests listening in loop.
 * \param data \see thread_data.
 * \return NULL;
 */
static void *listen_requests(void *data);

/*!
 * \brief Handle Request.
 *
 * This function converts FastCGI request into the Rapida request
 * and calls Rapida request handler.
 *
 * \param app Application instance.
 * \param fcgx_req FastCGI Request.
 */
static void handle_request(rpd_app *app, FCGX_Request *fcgx_req);

/*!
 * \brief Convert FastCGI request into the Rapida request.
 *
 * \param dest Rapida request.
 * \param req FastCGI request.
 *
 * \return Status code. 0 is success.
 */
static int fcgx_to_rpd_req(rpd_req *dest, FCGX_Request *req);

/*!
 * Read FastCGI request body.
 * \param dest Destination buffer.
 * \param req FastCGI request.
 * \return Status code. 0 is success.
 */
static int read_fcgx_req_body(char **dest, FCGX_Request *req);

/*!
 * \brief Sends response to client.
 * \param res Response instance.
 * \param out Output stream.
 */
static void send_response(rpd_res *res, FCGX_Stream *out);

static int env_to_req_header(char **key, char **val, const char *envp);

int rpd_fcgi_server_start(rpd_app *app, const char *sock_path)
{
    FCGX_Init();
    int sock_id = 0;
    if ((sock_id = FCGX_OpenSocket(sock_path, 10)) < 0) {
        return 1;
    }

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

    return 0;
}

static void *listen_requests(void *data)
{
    thread_data *hdata = (thread_data *) data;
    FCGX_Request req;
    if (FCGX_InitRequest(&req, hdata->sock_id, 0))
        return 0;

    hdata->app->running = 1;
    while (hdata->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(hdata->app, &req);

#ifdef MT_ENABLED
        pthread_mutex_unlock(&handle_mutex);
#endif

        FCGX_Finish_r(&req);
    }
    return NULL;
}

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

    req = (rpd_req *) malloc(sizeof(rpd_req));
    res = (rpd_res *) malloc(sizeof(rpd_res));

    fcgx_to_rpd_req(req, fcgx_req);
    rpd_res_init(res);

    rpd_app_handle_request(app, req, res);
    send_response(res, fcgx_req->out);

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

static void send_response(rpd_res *res, FCGX_Stream *out)
{
    char *buff;
    if (rpd_res_str(&buff, res)) {
        FCGX_PutS("Status: 500\r\n\r\n", out);
        return;
    }

    FCGX_PutS(buff, out);
    free(buff);
}

static int fcgx_to_rpd_req(rpd_req *dest, FCGX_Request *req)
{
    rpd_query_parse(&dest->query, FCGX_GetParam("QUERY_STRING", req->envp));

    dest->method = rpd_req_smethod(FCGX_GetParam("REQUEST_METHOD", req->envp));
    rpd_url_parse(&dest->path, FCGX_GetParam("DOCUMENT_URI", req->envp));
    // dest->auth = FCGX_GetParam("HTTP_AUTHORIZATION", req->envp);
    // dest->cookie = FCGX_GetParam("HTTP_COOKIE", req->envp);
    rpd_keyval_init(&dest->params, 0);
    rpd_keyval_init(&dest->headers, 0);

    char **env = req->envp;
    char *key = NULL, *val = NULL;
    while (*(++env)) {
        char *ptr = NULL;

        /* keep only http request fields */
        ptr = strstr(*env, "HTTP");
        if (ptr == NULL || ptr - *env != 0)
            continue;

        env_to_req_header(&key, &val, *env);
        if (!val || !key)
            continue;
        rpd_strerase(key, 5);
        ptr = key;
        while (*ptr) {
            *ptr = tolower(*ptr);
            if (ptr == key || *(ptr - 1) == '-')
                *ptr = toupper(*ptr);
            if (*ptr == '_')
                *ptr = '-';
            ptr++;
        }

        rpd_keyval_insert(&dest->headers, key, val);
        free(key);
        free(val);
    }

    if (dest->method != GET) {
        if (read_fcgx_req_body(&dest->body, req)) {
            return 2;
        }
    } else {
        dest->body = NULL;
    }

    return 0;
}

static int read_fcgx_req_body(char **dest, FCGX_Request *req)
{
    char *clen = FCGX_GetParam("CONTENT_LENGTH", req->envp);
    if (!clen)
        return 1;
    size_t len = atoll(clen);

    *dest = (char *) malloc(sizeof(char) * (len + 1));
    if (!*dest)
        return 2;

    *dest[len] = '\0';
    FCGX_GetStr(*dest, len, req->in);

    return 0;
}

static int env_to_req_header(char **key, char **val, const char *env)
{
    const char *ptr = NULL;

    rpd_splitbyc(key, val, env, '=');
    if (!*key || !*val) {
        if (*key)
            free(*key);
        if (*val)
            free(*val);
        return 1;
    }

    return 0;
}