/*
 * Copyright 2014 James Geboski <jgeboski@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <bitlbee.h>
#include <string.h>

#include "facebook-http.h"
#include "facebook-util.h"

/**
 * Gets the error domain for #fb_http.
 *
 * @return The #GQuark of the error domain.
 **/
GQuark fb_http_error_quark(void)
{
    static GQuark q;

    if (G_UNLIKELY(q == 0))
        q = g_quark_from_static_string("fb-http-error-quark");

    return q;
}

/**
 * Creates a new #fb_http. The returned #fb_http should be freed with
 * #fb_http_free() when no longer needed.
 *
 * @param agent The HTTP agent.
 *
 * @return The #fb_http or NULL on error.
 **/
fb_http_t *fb_http_new(const gchar *agent)
{
    fb_http_t *http;

    http = g_new0(fb_http_t, 1);

    http->agent   = g_strdup(agent);
    http->reqs    = g_hash_table_new(g_direct_hash, g_direct_equal);
    http->cookies = g_hash_table_new_full(g_str_hash,
                                          (GEqualFunc) fb_util_str_iequal,
                                          g_free, g_free);
    return http;
}

/**
 * Frees all #fb_http_req inside a #fb_http.
 *
 * @param http The #fb_http.
 **/
void fb_http_free_reqs(fb_http_t *http)
{
    GHashTableIter iter;
    gpointer       key;

    if (G_UNLIKELY(http == NULL))
        return;

    g_hash_table_iter_init(&iter, http->reqs);

    while (g_hash_table_iter_next(&iter, &key, NULL)) {
        g_hash_table_iter_remove(&iter);
        fb_http_req_free(key);
    }
}

/**
 * Frees all memory used by a #fb_http.
 *
 * @param http The #fb_http.
 **/
void fb_http_free(fb_http_t *http)
{
    if (G_UNLIKELY(http == NULL))
        return;

    fb_http_free_reqs(http);
    g_hash_table_destroy(http->reqs);
    g_hash_table_destroy(http->cookies);

    g_free(http->agent);
    g_free(http);
}

/**
 * Inserts a #va_list into a #GHashTable.
 *
 * @param table The #GHashTable.
 * @param pair  The first #fb_http_pair.
 * @param ap    The #va_list.
 **/
static void fb_http_tree_ins(GHashTable *table, const fb_http_pair_t *pair,
                             va_list ap)
{
    const fb_http_pair_t *p;
    gchar *key;
    gchar *val;

    for (p = pair; p != NULL; ) {
        if (p->key == NULL)
            continue;

        key = g_strdup(p->key);
        val = g_strdup(p->val);

        g_hash_table_replace(table, key, val);
        p = va_arg(ap, const fb_http_pair_t*);
    }
}

/**
 * Sets cookies from #fb_http_pair. If a cookie already exists, it is
 * overwritten with the new value.
 *
 * @param http The #fb_http.
 * @param pair The first #fb_http_pair.
 * @param ...  The additional #fb_http_pair.
 **/
void fb_http_cookies_set(fb_http_t *http, const fb_http_pair_t *pair, ...)
{
    va_list ap;

    g_return_if_fail(http != NULL);

    va_start(ap, pair);
    fb_http_tree_ins(http->cookies, pair, ap);
    va_end(ap);
}

/**
 * Parses cookies from a #fb_http_req. If a cookie already exists, it
 * is overwritten with the new value.
 *
 * @param http The #fb_http.
 * @param req  The #fb_http_req.
 **/
void fb_http_cookies_parse_req(fb_http_t *http, const fb_http_req_t *req)
{
    gchar **hdrs;
    gchar **kv;
    gchar  *str;
    gsize   i;
    gsize   j;

    g_return_if_fail(http != NULL);
    g_return_if_fail(req  != NULL);

    if (req->request == NULL)
        return;

    hdrs = g_strsplit(req->request->reply_headers, "\r\n", 0);

    for (i = 0; hdrs[i] != NULL; i++) {
        if (g_ascii_strncasecmp(hdrs[i], "Set-Cookie", 10) != 0)
            continue;

        str = strchr(hdrs[i], ';');

        if (str != NULL)
            str[0] = 0;

        str = strchr(hdrs[i], ':');

        if (str == NULL)
            continue;

        str = g_strstrip(++str);
        kv  = g_strsplit(str, "=", 2);

        for (j = 0; kv[j] != NULL; j++) {
            str = fb_http_uri_unescape(kv[j]);
            g_free(kv[j]);
            kv[j] = str;
        }

        if (g_strv_length(kv) > 1)
            fb_http_cookies_set(http, FB_HTTP_PAIR(kv[0], kv[1]), NULL);

        g_strfreev(kv);
    }

    g_strfreev(hdrs);
}

/**
 * Parses cookies from a string. If a cookie already exists, it is
 * overwritten with the new value.
 *
 * @param http The #fb_http.
 * @param data The string.
 **/
void fb_http_cookies_parse_str(fb_http_t *http, const gchar *data)
{
    gchar **ckis;
    gchar **kv;
    gchar  *str;
    gsize   i;
    gsize   j;

    g_return_if_fail(http != NULL);
    g_return_if_fail(data != NULL);

    ckis = g_strsplit(data, ";", 0);

    for (i = 0; ckis[i] != NULL; i++) {
        str = g_strstrip(ckis[i]);
        kv  = g_strsplit(str, "=", 2);

        for (j = 0; kv[j] != NULL; j++) {
            str = fb_http_uri_unescape(kv[j]);
            g_free(kv[j]);
            kv[j] = str;
        }

        if (g_strv_length(kv) > 1)
            fb_http_cookies_set(http, FB_HTTP_PAIR(kv[0], kv[1]), NULL);

        g_strfreev(kv);
    }

    g_strfreev(ckis);
}

/**
 * Gets a string representation of the cookies of a #fb_http. The
 * returned string should be freed with #g_free() when no longer
 * needed.
 *
 * @param http The #fb_http.
 *
 * @return The string representation of the cookies.
 **/
gchar *fb_http_cookies_str(fb_http_t *http)
{
    GHashTableIter  iter;
    GString        *gstr;
    gchar          *key;
    gchar          *val;
    gchar          *str;

    g_return_val_if_fail(http != NULL, NULL);

    gstr = g_string_sized_new(128);
    g_hash_table_iter_init(&iter, http->cookies);

    while (g_hash_table_iter_next(&iter, (gpointer*) &key, (gpointer*) &val)) {
        if (val == NULL)
            val = "";

        key = fb_http_uri_escape(key);
        val = fb_http_uri_escape(val);

        str = (gstr->len > 0) ? "; " : "";
        g_string_append_printf(gstr, "%s%s=%s", str, key, val);

        g_free(key);
        g_free(val);
    }

    str = g_strdup(gstr->str);
    g_string_free(gstr, TRUE);

    return str;
}

/**
 * Creates a new #fb_http_req. The returned #fb_http_req should be
 * freed with #fb_http_req_free() when no longer needed.
 *
 * @param http The #fb_http.
 * @param host The hostname.
 * @param port The port number.
 * @param path The pathname.
 * @param func The user callback function or NULL.
 * @param data The user define data or NULL.
 *
 * @return The #fb_http_req or NULL on error.
 **/
fb_http_req_t *fb_http_req_new(fb_http_t *http, const gchar *host,
                               gint port, const gchar *path,
                               fb_http_func_t func, gpointer data)
{
    fb_http_req_t *req;

    req = g_new0(fb_http_req_t, 1);

    req->http = http;
    req->host = g_strdup(host);
    req->port = port;
    req->path = g_strdup(path);
    req->func = func;
    req->data = data;

    req->headers = g_hash_table_new_full(g_str_hash,
                                         (GEqualFunc) fb_util_str_iequal,
                                         g_free, g_free);
    req->params  = g_hash_table_new_full(g_str_hash,
                                         (GEqualFunc) fb_util_str_iequal,
                                         g_free, g_free);

    fb_http_req_headers_set(req,
        FB_HTTP_PAIR("User-Agent", http->agent),
        FB_HTTP_PAIR("Host",       host),
        FB_HTTP_PAIR("Accept",     "*/*"),
        FB_HTTP_PAIR("Connection", "Close"),
        NULL
    );

    return req;
}

/**
 * Implemented #http_input_function for nulling the callback operation.
 *
 * @param request The #http_request.
 **/
static void fb_http_req_close_nuller(struct http_request *request)
{

}

/**
 * Closes the underlying #http_request.
 *
 * @param callback TRUE to execute the callback, otherwise FALSE.
 *
 * @param req The #fb_http_req.
 **/
static void fb_http_req_close(fb_http_req_t *req, gboolean callback)
{
    g_return_if_fail(req != NULL);

    b_event_remove(req->toid);

    if ((req->err == NULL) && (req->scode == 0)) {
        g_set_error(&req->err, FB_HTTP_ERROR, FB_HTTP_ERROR_CLOSED,
                    "Request closed");
    }

    if (callback && (req->func != NULL))
        req->func(req, req->data);

    if (req->request != NULL) {
        /* Prevent more than one call to request->func() */
        req->request->func = fb_http_req_close_nuller;
        req->request->data = NULL;

        if (!(req->request->flags & FB_HTTP_CLIENT_FREED))
            http_close(req->request);
    }

    req->status    = NULL;
    req->scode     = 0;
    req->header    = NULL;
    req->body      = NULL;
    req->body_size = 0;
    req->toid      = 0;
    req->request   = NULL;
}

/**
 * Frees all memory used by a #fb_http_req.
 *
 * @param req The #fb_http_req.
 **/
void fb_http_req_free(fb_http_req_t *req)
{
    if (G_UNLIKELY(req == NULL))
        return;

    fb_http_req_close(req, TRUE);

    if (req->err != NULL)
        g_error_free(req->err);

    g_hash_table_destroy(req->headers);
    g_hash_table_destroy(req->params);

    g_free(req->path);
    g_free(req->host);
    g_free(req);
}

#ifdef DEBUG_FACEBOOK
static void fb_http_req_debug(fb_http_req_t *req, gboolean response,
                              const gchar *header, const gchar *body)
{
    const gchar  *act;
    const gchar  *type;
    const gchar  *prot;
    gchar        *str;
    gchar       **ls;
    guint         i;

    if (req->err != NULL)
        str = g_strdup_printf(" (%s)", req->err->message);
    else if (req->status != NULL)
        str = g_strdup_printf(" (%s)", req->status);
    else
        str = g_strdup("");

    act  = response ? "Response" : "Request";
    type = (req->flags & FB_HTTP_REQ_FLAG_POST) ? "POST"  : "GET";
    prot = (req->flags & FB_HTTP_REQ_FLAG_SSL)  ? "https" : "http";

    FB_UTIL_DEBUGLN("%s %s (%p): %s://%s:%d%s%s",
                    type, act, req, prot,
                    req->host, req->port,
                    req->path, str);
    g_free(str);

    if (req->rsc > 0)
        FB_UTIL_DEBUGLN("Reattempt: #%u", req->rsc);

    if ((header != NULL) && (strlen(header) > 0)) {
        ls = g_strsplit(header, "\n", 0);

        for (i = 0; ls[i] != NULL; i++)
            FB_UTIL_DEBUGLN("  %s", ls[i]);

        g_strfreev(ls);
    } else {
        FB_UTIL_DEBUGLN("  ** No header data **");
        FB_UTIL_DEBUGLN("");
    }

    if ((body != NULL) && (strlen(body) > 0)) {
        ls = g_strsplit(body, "\n", 0);

        for (i = 0; ls[i] != NULL; i++)
            FB_UTIL_DEBUGLN("  %s", ls[i]);

        g_strfreev(ls);
    } else {
        FB_UTIL_DEBUGLN("  ** No body data **");
    }
}
#endif /* DEBUG_FACEBOOK */

/**
 * Sets headers from #fb_http_pair. If a header already exists, it is
 * overwritten with the new value.
 *
 * @param req  The #fb_http_req.
 * @param pair The first #fb_http_pair.
 * @param ...  The additional #fb_http_pair.
 **/
void fb_http_req_headers_set(fb_http_req_t *req, const fb_http_pair_t *pair,
                             ...)
{
    va_list ap;

    g_return_if_fail(req != NULL);

    va_start(ap, pair);
    fb_http_tree_ins(req->headers, pair, ap);
    va_end(ap);
}

/**
 * Sets parameters from #fb_http_pair. If a parameter already exists,
 * it is overwritten with the new value.
 *
 * @param req  The #fb_http_req.
 * @param pair The first #fb_http_pair.
 * @param ...  The additional #fb_http_pair.
 **/
void fb_http_req_params_set(fb_http_req_t *req, const fb_http_pair_t *pair,
                            ...)
{
    va_list ap;

    g_return_if_fail(req != NULL);

    va_start(ap, pair);
    fb_http_tree_ins(req->params, pair, ap);
    va_end(ap);
}

/**
 * Implemented #b_event_handler for resending failed a #fb_http_req.
 *
 * @param data The user defined data, which is a #fb_http_req.
 * @param fd   The file descriptor.
 * @param cond The #b_input_condition.
 *
 * @return FALSE to kill the timer.
 **/
static gboolean fb_http_req_done_error(gpointer data, gint fd,
                                       b_input_condition cond)
{
    fb_http_req_t *req = data;

    fb_http_req_send(req);
    return FALSE;
}

/**
 * Processes all #fb_http_req by resending, queuing, and freeing.
 *
 * @param req The #fb_http_req.
 **/
static void fb_http_req_done(fb_http_req_t *req)
{
#ifdef DEBUG_FACEBOOK
    fb_http_req_debug(req, TRUE, req->header, req->body);
#endif /* DEBUG_FACEBOOK */

    if (req->err != NULL) {
        if (req->rsc < FB_HTTP_RESEND_MAX) {
            fb_http_req_close(req, FALSE);
            g_error_free(req->err);
            req->err = NULL;

            req->toid = b_timeout_add(FB_HTTP_RESEND_TIMEOUT,
                                      fb_http_req_done_error, req);
            req->rsc++;
            return;
        }

        g_prefix_error(&req->err, "HTTP: ");
    }

    g_hash_table_remove(req->http->reqs, req);
    fb_http_req_free(req);
}

/**
 * Implemented #http_input_function for all #fb_http_req.
 *
 * @param request The #http_request.
 **/
static void fb_http_req_cb(struct http_request *request)
{
    fb_http_req_t *req = request->data;

    /* Shortcut request elements */
    req->status    = request->status_string;
    req->scode     = request->status_code;
    req->header    = request->reply_headers;
    req->body      = request->reply_body;
    req->body_size = request->body_size;

    switch (req->scode) {
    case 200:
    case 301:
    case 302:
    case 303:
    case 307:
        break;

    default:
        g_set_error(&req->err, FB_HTTP_ERROR, req->scode, "%s", req->status);
    }

    req->request->flags |= FB_HTTP_CLIENT_FREED;
    fb_http_req_done(req);
}

/**
 * Implemented #b_event_handler for handling a timed out #fb_http_req.
 *
 * @param data The user defined data, which is a #fb_http_req.
 * @param fd   The file descriptor.
 * @param cond The #b_input_condition.
 *
 * @return FALSE to kill the timer.
 **/
static gboolean fb_http_req_send_timeout(gpointer data, gint fd,
                                         b_input_condition cond)
{
    fb_http_req_t *req = data;

    g_set_error(&req->err, FB_HTTP_ERROR, FB_HTTP_ERROR_TIMEOUT,
                "Request timed out");

    req->toid = 0;
    fb_http_req_done(req);
    return FALSE;
}

/**
 * Assembles a #fb_http_req. The returned strings should be freed with
 * #g_free() when no longer needed.
 *
 * @param req The #fb_http_req.
 * @param hs  The return location for the header string.
 * @param ps  The return location for the param string.
 * @param fs  The return location for the full string.
 **/
static void fb_http_req_asm(fb_http_req_t *req, gchar **hs, gchar **ps,
                            gchar **fs)
{
    GHashTableIter  iter;
    GString        *hgs;
    GString        *pgs;
    gchar          *str;
    gchar          *key;
    gchar          *val;

    g_hash_table_iter_init(&iter, req->params);
    pgs = g_string_sized_new(128);

    while (g_hash_table_iter_next(&iter, (gpointer*) &key, (gpointer*) &val)) {
        if (val == NULL)
            val = "";

        key = fb_http_uri_escape(key);
        val = fb_http_uri_escape(val);

        str = (pgs->len > 0) ? "&" : "";
        g_string_append_printf(pgs, "%s%s=%s", str, key, val);

        g_free(key);
        g_free(val);
    }

    if (g_hash_table_size(req->http->cookies) > 0) {
        str = fb_http_cookies_str(req->http);
        fb_http_req_headers_set(req, FB_HTTP_PAIR("Cookie", str), NULL);
        g_free(str);
    }

    if (req->flags & FB_HTTP_REQ_FLAG_POST) {
        str = g_strdup_printf("%" G_GSIZE_FORMAT, pgs->len);

        fb_http_req_headers_set(req,
            FB_HTTP_PAIR("Content-Type",   "application/"
                                           "x-www-form-urlencoded"),
            FB_HTTP_PAIR("Content-Length", str),
            NULL
        );

        g_free(str);
    }

    g_hash_table_iter_init(&iter, req->headers);
    hgs = g_string_sized_new(128);

    while (g_hash_table_iter_next(&iter, (gpointer*) &key, (gpointer*) &val)) {
        if (val == NULL)
            val = "";

        g_string_append_printf(hgs, "%s: %s\r\n", key, val);
    }

    if (req->flags & FB_HTTP_REQ_FLAG_POST) {
        *fs = g_strdup_printf("POST %s HTTP/1.1\r\n%s\r\n%s",
                              req->path, hgs->str, pgs->str);
    } else {
        *fs = g_strdup_printf("GET %s?%s HTTP/1.1\r\n%s\r\n",
                              req->path, pgs->str, hgs->str);
    }

    *hs = g_string_free(hgs, FALSE);
    *ps = g_string_free(pgs, FALSE);
}

/**
 * Sends a #fb_http_req.
 *
 * @param req The #fb_http_req.
 **/
void fb_http_req_send(fb_http_req_t *req)
{
    gchar *str;
    gchar *hs;
    gchar *ps;

    g_return_if_fail(req != NULL);

    fb_http_req_asm(req, &hs, &ps, &str);

#ifdef DEBUG_FACEBOOK
    fb_http_req_debug(req, FALSE, hs, ps);
#endif /* DEBUG_FACEBOOK */

    req->request = http_dorequest(req->host, req->port,
                                  (req->flags & FB_HTTP_REQ_FLAG_SSL),
                                  str, fb_http_req_cb, req);
    g_hash_table_add(req->http->reqs, req);

    g_free(hs);
    g_free(ps);
    g_free(str);

    if (G_UNLIKELY(req->request == NULL)) {
        g_set_error(&req->err, FB_HTTP_ERROR, FB_HTTP_ERROR_INIT,
                    "Failed to init request");
        fb_http_req_done(req);
        return;
    }

    /* Prevent automatic redirection */
    req->request->redir_ttl = 0;

    if (req->timeout > 0) {
        req->toid = b_timeout_add(req->timeout, fb_http_req_send_timeout,
                                  req);
    }
}

/**
 * Escapes the characters of a string to make it URL safe. The returned
 * string should be freed with #g_free() when no longer needed.
 *
 * @param unescaped The string.
 *
 * @return The escaped string or NULL on error.
 **/
gchar *fb_http_uri_escape(const gchar *unescaped)
{
    gchar *ret;
    gchar *str;

    g_return_val_if_fail(unescaped != NULL, NULL);

    str = g_strndup(unescaped, (strlen(unescaped) * 3) + 1);
    http_encode(str);

    ret = g_strdup(str);
    g_free(str);

    return ret;
}

/**
 * Unescapes the characters of a string to make it a normal string. The
 * returned string should be freed with #g_free() when no longer needed.
 *
 * @param escaped The string.
 *
 * @return The unescaped string or NULL on error.
 **/
gchar *fb_http_uri_unescape(const gchar *escaped)
{
    gchar *ret;
    gchar *str;

    g_return_val_if_fail(escaped != NULL, NULL);

    str = g_strdup(escaped);
    http_decode(str);

    ret = g_strdup(str);
    g_free(str);

    return ret;
}