/*
 * HTTP authentication
 * Copyright (c) 2010 Martin Storsjo
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "httpauth.h"
#include "libavutil/base64.h"
#include "libavutil/avstring.h"
#include "avformat.h"
#include <ctype.h>

static void parse_key_value(const char *params,
                            void (*callback_get_buf)(HTTPAuthState *state,
                            const char *key, int key_len,
                            char **dest, int *dest_len), HTTPAuthState *state)
{
    const char *ptr = params;

    /* Parse key=value pairs. */
    for (;;) {
        const char *key;
        char *dest = NULL, *dest_end;
        int key_len, dest_len = 0;

        /* Skip whitespace and potential commas. */
        while (*ptr && (isspace(*ptr) || *ptr == ','))
            ptr++;
        if (!*ptr)
            break;

        key = ptr;

        if (!(ptr = strchr(key, '=')))
            break;
        ptr++;
        key_len = ptr - key;

        callback_get_buf(state, key, key_len, &dest, &dest_len);
        dest_end = dest + dest_len - 1;

        if (*ptr == '\"') {
            ptr++;
            while (*ptr && *ptr != '\"') {
                if (*ptr == '\\') {
                    if (!ptr[1])
                        break;
                    if (dest && dest < dest_end)
                        *dest++ = ptr[1];
                    ptr += 2;
                } else {
                    if (dest && dest < dest_end)
                        *dest++ = *ptr;
                    ptr++;
                }
            }
            if (*ptr == '\"')
                ptr++;
        } else {
            for (; *ptr && !(isspace(*ptr) || *ptr == ','); ptr++)
                if (dest && dest < dest_end)
                    *dest++ = *ptr;
        }
        if (dest)
            *dest = 0;
    }
}

static void handle_basic_params(HTTPAuthState *state, const char *key,
                                int key_len, char **dest, int *dest_len)
{
    if (!strncmp(key, "realm=", key_len)) {
        *dest     =        state->realm;
        *dest_len = sizeof(state->realm);
    }
}

void ff_http_auth_handle_header(HTTPAuthState *state, const char *key,
                                const char *value)
{
    if (!state)
        return;

    if (!strcmp(key, "WWW-Authenticate")) {
        const char *p;
        if (av_stristart(value, "Basic ", &p) &&
            state->auth_type <= HTTP_AUTH_BASIC) {
            state->auth_type = HTTP_AUTH_BASIC;
            state->realm[0] = 0;
            parse_key_value(p, handle_basic_params, state);
        }
    }
}

char *ff_http_auth_create_response(HTTPAuthState *state, const char *auth,
                                   const char *path, const char *method)
{
    char *authstr = NULL;

    if (!auth || !strchr(auth, ':'))
        return NULL;

    if (state->auth_type == HTTP_AUTH_BASIC) {
        int auth_b64_len = (strlen(auth) + 2) / 3 * 4 + 1;
        int len = auth_b64_len + 30;
        char *ptr;
        authstr = av_malloc(len);
        if (!authstr)
            return NULL;
        snprintf(authstr, len, "Authorization: Basic ");
        ptr = authstr + strlen(authstr);
        av_base64_encode(ptr, auth_b64_len, auth, strlen(auth));
        av_strlcat(ptr, "\r\n", len);
    }
    return authstr;
}