/*
 * Copyright (C) 2014 Johannes Schauer <j.schauer@email.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2, as published by 
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with 
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include <curl/easy.h>
#include <stdbool.h>
#include <stdio.h>

#include "http.h"

static int      http_progress_cb(void *user_ptr, double dltotal, double dlnow,
                                 double ultotal, double ulnow);
static size_t   http_read_buf_cb(char *data, size_t size, size_t nmemb,
                                 void *user_ptr);
static size_t   http_read_file_cb(char *data, size_t size, size_t nmemb,
                                  void *user_ptr);
static size_t   http_write_buf_cb(char *data, size_t size, size_t nmemb,
                                  void *user_ptr);
static size_t   http_write_file_cb(char *data, size_t size, size_t nmemb,
                                   void *user_ptr);

struct mfhttp {
    CURL           *curl_handle;
    char           *write_buf;
    size_t          write_buf_len;
    double          ul_len;
    double          ul_now;
    double          dl_len;
    double          dl_now;
    bool            show_progress;
    char            error_buf[CURL_ERROR_SIZE];
    FILE           *stream;
};

/*
 * This set of functions is made such that the mfhttp struct and the curl
 * handle it stores can be reused for multiple operations
 *
 * We do not use a single global instance because mediafire does not support
 * keep-alive anyways.
 */

static void http_curl_reset(mfhttp * conn)
{
    curl_easy_reset(conn->curl_handle);
    curl_easy_setopt(conn->curl_handle, CURLOPT_NOPROGRESS, 0);
    curl_easy_setopt(conn->curl_handle, CURLOPT_PROGRESSFUNCTION,
                     http_progress_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_PROGRESSDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_FOLLOWLOCATION, 1);
    curl_easy_setopt(conn->curl_handle, CURLOPT_SSLENGINE, NULL);
    curl_easy_setopt(conn->curl_handle, CURLOPT_SSLENGINE_DEFAULT, 1L);
    curl_easy_setopt(conn->curl_handle, CURLOPT_ERRORBUFFER, conn->error_buf);
    curl_easy_setopt(conn->curl_handle, CURLOPT_PROXY, getenv("http_proxy"));
    curl_easy_setopt(conn->curl_handle, CURLOPT_VERBOSE, 0L);

    // it should never take 5 seconds to establish a connection to the server
    curl_easy_setopt(conn->curl_handle, CURLOPT_CONNECTTIMEOUT, 5);

    //curl_easy_setopt(conn->curl_handle, CURLOPT_SSL_VERIFYPEER, 0L);
}

mfhttp         *http_create(void)
{
    mfhttp         *conn;
    CURL           *curl_handle;

    curl_handle = curl_easy_init();
    if (curl_handle == NULL)
        return NULL;

    conn = (mfhttp *) calloc(1, sizeof(mfhttp));
    conn->curl_handle = curl_handle;

    conn->show_progress = false;
    return conn;
}

json_t         *http_parse_buf_json(mfhttp * conn, size_t flags,
                                    json_error_t * error)
{
    return json_loadb(conn->write_buf, conn->write_buf_len, flags, error);
}

void http_destroy(mfhttp * conn)
{
    curl_easy_cleanup(conn->curl_handle);
    free(conn->write_buf);
    free(conn);
}

static int
http_progress_cb(void *user_ptr, double dltotal, double dlnow,
                 double ultotal, double ulnow)
{
    mfhttp         *conn;

    if (user_ptr == NULL)
        return 0;

    conn = (mfhttp *) user_ptr;

    conn->ul_len = ultotal;
    conn->ul_now = ulnow;

    conn->dl_len = dltotal;
    conn->dl_now = dlnow;

    return 0;
}

int
http_get_buf(mfhttp * conn, const char *url,
             int (*data_handler) (mfhttp * conn, void *data), void *data)
{
    int             retval;

    http_curl_reset(conn);
    conn->write_buf_len = 0;
    curl_easy_setopt(conn->curl_handle, CURLOPT_URL, url);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READFUNCTION,
                     http_read_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEFUNCTION,
                     http_write_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEDATA, (void *)conn);
    fprintf(stderr, "GET: %s\n", url);
    retval = curl_easy_perform(conn->curl_handle);
    if (retval != CURLE_OK) {
        fprintf(stderr, "error curl_easy_perform %s\n\r", conn->error_buf);
        return retval;
    }
    if (data_handler != NULL)
        retval = data_handler(conn, data);
    return retval;
}

static          size_t
http_read_buf_cb(char *data, size_t size, size_t nmemb, void *user_ptr)
{
    size_t          data_len;

    if (user_ptr == NULL)
        return 0;

    data_len = size * nmemb;

    if (data_len > 0) {
        fwrite(data, size, nmemb, stderr);
        fprintf(stderr, "Not implemented");
        exit(1);
    }

    return 0;
}

static          size_t
http_write_buf_cb(char *data, size_t size, size_t nmemb, void *user_ptr)
{
    mfhttp         *conn;
    size_t          data_len;

    if (user_ptr == NULL)
        return 0;

    conn = (mfhttp *) user_ptr;
    data_len = size * nmemb;

    if (data_len > 0) {
        fwrite(data, size, nmemb, stderr);
        conn->write_buf = (char *)realloc(conn->write_buf,
                                          conn->write_buf_len + data_len);
        memcpy(conn->write_buf + conn->write_buf_len, data, data_len);
        conn->write_buf_len += data_len;
    }

    return data_len;
}

int
http_post_buf(mfhttp * conn, const char *url, const char *post_args,
              int (*data_handler) (mfhttp * conn, void *data), void *data)
{
    int             retval;

    http_curl_reset(conn);
    conn->write_buf_len = 0;
    curl_easy_setopt(conn->curl_handle, CURLOPT_URL, url);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READFUNCTION,
                     http_read_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEFUNCTION,
                     http_write_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_POSTFIELDS, post_args);
    fprintf(stderr, "POST: %s\n", url);
    retval = curl_easy_perform(conn->curl_handle);
    if (retval != CURLE_OK) {
        fprintf(stderr, "error curl_easy_perform \"%s\" \"%s\"\n\r",
                curl_easy_strerror(retval), conn->error_buf);
        return retval;
    }
    if (data_handler != NULL)
        retval = data_handler(conn, data);
    return retval;
}

int http_get_file(mfhttp * conn, const char *url, const char *path)
{
    int             retval;

    http_curl_reset(conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_URL, url);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READFUNCTION,
                     http_read_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEFUNCTION,
                     http_write_file_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEDATA, (void *)conn);
    // FIXME: handle fopen() return value
    conn->stream = fopen(path, "w+");
    fprintf(stderr, "GET: %s\n", url);
    retval = curl_easy_perform(conn->curl_handle);
    fclose(conn->stream);
    if (retval != CURLE_OK) {
        fprintf(stderr, "error curl_easy_perform %s\n\r", conn->error_buf);
        return retval;
    }
    return retval;
}

static          size_t
http_write_file_cb(char *data, size_t size, size_t nmemb, void *user_ptr)
{
    mfhttp         *conn;
    size_t          ret;

    if (user_ptr == NULL)
        return 0;
    conn = (mfhttp *) user_ptr;

    ret = fwrite(data, size, nmemb, conn->stream);

    fprintf(stderr, "\r   %.0f / %.0f", conn->dl_now, conn->dl_len);

    return size * ret;
}

static          size_t
http_read_file_cb(char *data, size_t size, size_t nmemb, void *user_ptr)
{
    mfhttp         *conn;
    size_t          ret;

    if (user_ptr == NULL)
        return 0;
    conn = (mfhttp *) user_ptr;

    ret = fread(data, size, nmemb, conn->stream);

    fprintf(stderr, "\r   %.0f / %.0f", conn->ul_now, conn->ul_len);

    return size * ret;
}

int
http_post_file(mfhttp * conn, const char *url, FILE * fh,
               struct curl_slist **custom_headers, uint64_t filesize,
               int (*data_handler) (mfhttp * conn, void *data), void *data)
{
    int             retval;
    struct curl_slist *fallback_headers;

    http_curl_reset(conn);
    conn->write_buf_len = 0;

    if (custom_headers == NULL) {
        custom_headers = &fallback_headers;
        *custom_headers = NULL;
    }
    // when using POST, curl implicitly sets
    // Content-Type: application/x-www-form-urlencoded
    // make sure it is set to application/octet-stream instead
    *custom_headers =
        curl_slist_append(*custom_headers,
                          "Content-Type: application/octet-stream");
    // when using POST, curl implicitly sets Expect: 100-continue
    // make sure it is not set
    *custom_headers = curl_slist_append(*custom_headers, "Expect:");
    curl_easy_setopt(conn->curl_handle, CURLOPT_POST, 1);
    curl_easy_setopt(conn->curl_handle, CURLOPT_HTTPHEADER, *custom_headers);
    curl_easy_setopt(conn->curl_handle, CURLOPT_URL, url);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READFUNCTION,
                     http_read_file_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_READDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEFUNCTION,
                     http_write_buf_cb);
    curl_easy_setopt(conn->curl_handle, CURLOPT_WRITEDATA, (void *)conn);
    curl_easy_setopt(conn->curl_handle, CURLOPT_POSTFIELDSIZE, filesize);

    conn->stream = fh;
    fprintf(stderr, "POST: %s\n", url);
    retval = curl_easy_perform(conn->curl_handle);
    curl_slist_free_all(*custom_headers);
    *custom_headers = NULL;
    if (retval != CURLE_OK) {
        fprintf(stderr, "error curl_easy_perform %s\n\r", conn->error_buf);
        return retval;
    }
    if (data_handler != NULL)
        retval = data_handler(conn, data);
    return retval;
}

// we roll our own urlencode function because curl_easy_escape requires a curl
// handle
char           *urlencode(const char *inp)
{
    char           *buf;
    char           *bufp;
    char            hex[] = "0123456789abcdef";

    // allocating three times the length of the input because in the worst
    // case each character must be urlencoded and add a byte for the
    // terminating zero
    bufp = buf = (char *)malloc(strlen(inp) * 3 + 1);

    if (buf == NULL) {
        fprintf(stderr, "malloc failed\n");
        return NULL;
    }

    while (*inp) {
        if ((*inp >= '0' && *inp <= '9')
            || (*inp >= 'A' && *inp <= 'Z')
            || (*inp >= 'a' && *inp <= 'z')
            || *inp == '-' || *inp == '_' || *inp == '.' || *inp == '~') {
            *bufp++ = *inp;
        } else {
            *bufp++ = '%';
            *bufp++ = hex[(*inp >> 4) & 0xf];
            *bufp++ = hex[*inp & 0xf];
        }
        inp++;
    }
    *bufp = '\0';

    return buf;
}