#include "apr_buckets.h"
#include "apr_strings.h"
#include "ap_config.h"
#include "util_filter.h"
#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_log.h"
#include "http_main.h"
#include "util_script.h"
#include "http_core.h"                                                             

module AP_MODULE_DECLARE_DATA swap_module;

typedef struct swap_struct {
    apr_bucket_brigade *bb;
    char *word;
} swap_struct;

static int swap_filter(ap_filter_t *f, apr_bucket_brigade *bb)
{
    swap_struct *ctx = f->ctx;
    apr_bucket *e;
    apr_pool_t *p = f->r->pool;
    char *word1 = NULL, *word2 = NULL;

    if (ctx == NULL) {
        f->ctx = ctx = apr_pcalloc(f->r->pool, sizeof(*ctx));
        ctx->bb = apr_brigade_create(f->r->pool);
    }
    else {
        word1 = ctx->word;
    }

    APR_BRIGADE_FOREACH(e, bb) {
        const char *str;
        apr_size_t len;

        if (APR_BUCKET_IS_EOS(e) || APR_BUCKET_IS_FLUSH(e)) {
            APR_BUCKET_REMOVE(e);
            APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
            ap_pass_brigade(f->next, ctx->bb);
            return APR_SUCCESS;
        }
        apr_bucket_read(e, &str, &len, APR_NONBLOCK_READ);
        while (str && strcmp(str, "")) {
            if (word1 == NULL) {
                word1 = ap_getword_white(p, &str);
                if (!strcmp(str, "")) {
                    break;
                }
            }
            word2 = ap_getword_white(p, &str);
            ap_fputstrs(f->next, ctx->bb, word2, " ", word1, NULL);
            word1 = word2 = NULL;
        }
    } 
    if (word1) {
        ctx->word = apr_pstrdup(p, word1);
    }
    return APR_SUCCESS;	
}

static void swap_register_hook(apr_pool_t *p)
{
    ap_register_output_filter("SWAP", swap_filter, AP_FTYPE_CONTENT);
}

module AP_MODULE_DECLARE_DATA swap_module = 
{
    STANDARD20_MODULE_STUFF,
    NULL,			/* create per-directory config structure */
    NULL,        		/* merge per-directory config structures */
    NULL,			/* create per-server config structure */
    NULL,			/* merge per-server config structures */
    NULL,			/* command apr_table_t */
    swap_register_hook		/* register hooks */
};