#include <ngx_core.h>
#include <ngx_files.h>
#include <ngx_string.h>
#include <ngx_hunk.h>
#include <ngx_http.h>
#include <ngx_http_output_filter.h>


static int ngx_http_output_filter_copy_hunk(ngx_hunk_t *dst, ngx_hunk_t *src);
static int ngx_http_output_filter_init(
            int (*next_filter)(ngx_http_request_t *r, ngx_chain_t *ch));
static void *ngx_http_output_filter_create_conf(ngx_pool_t *pool);
static void *ngx_http_output_filter_set_hunk_size(ngx_pool_t *pool, void *conf,
                                                  char *size);


ngx_http_module_t  ngx_http_output_filter_module = {
    NGX_HTTP_MODULE
};


static int (*ngx_http_output_next_filter)(ngx_http_request_t *r,
                                          ngx_chain_t *ch);

/* STUB */
int ngx_http_write_filter(ngx_http_request_t *r, ngx_chain_t *ch);

int ngx_http_output_filter_stub_init(ngx_pool_t *pool, void *loc_conf)
{
    ngx_http_output_filter_conf_t *conf;

    ngx_http_output_filter_init(ngx_http_write_filter);
    conf = ngx_http_output_filter_create_conf(pool);
    ngx_http_output_filter_set_hunk_size(pool, conf, "32");

    loc_conf = conf;
}
/* */


int ngx_http_output_filter(ngx_http_request_t *r, ngx_hunk_t *hunk)
{
    int      rc, once;
    size_t   size;
    ssize_t  n;
    ngx_chain_t  *ce;
    ngx_http_output_filter_ctx_t  *ctx;
    ngx_http_output_filter_conf_t *conf;

    ctx = (ngx_http_output_filter_ctx_t *)
                            ngx_get_module_ctx(r->main ? r->main : r,
                                                ngx_http_output_filter_module);

    if (ctx == NULL) {
        ngx_test_null(ctx,
                    ngx_pcalloc(r->pool, sizeof(ngx_http_output_filter_ctx_t)),
                    NGX_ERROR);

        ctx->next_filter = ngx_http_output_next_filter;
    }

    ngx_log_debug(r->connection->log, "HUNK: x%x CTX-IN: x%x CTX->HUNK: x%x" _
                  hunk _ ctx->in _ ctx->hunk);

    if (hunk && (hunk->type & NGX_HUNK_LAST))
        ctx->last = 1;

    for (once = 1; once || ctx->in; once--) {

         /* input chain is not empty */
        if (ctx->in) {

            /* add hunk to input chain */
            if (once && hunk) {
                for (ce = ctx->in; ce->next; ce = ce->next)
                    /* void */ ;

                ngx_add_hunk_to_chain(ce->next, hunk, r->pool, NGX_ERROR);
            }

            /* our hunk is still busy */
            if (ctx->hunk->pos.mem < ctx->hunk->last.mem) {
                rc = ctx->next_filter(r, NULL);

            /* our hunk is free */
            } else {
                ctx->out.hunk = ctx->hunk;

                rc = ngx_http_output_filter_copy_hunk(ctx->hunk, ctx->in->hunk);
#if (NGX_FILE_AIO)
                if (rc == NGX_AGAIN)
                    return rc;
#endif
                if (rc == NGX_ERROR)
                    return rc;

                /* whole hunk is copied so we send to next filter chain part
                   up to next hunk that need to be copied */
                if (ctx->in->hunk->pos.mem == ctx->in->hunk->last.mem) {
                    ctx->out.next = ctx->in->next;

                    for (ce = ctx->in->next; ce; ce = ce->next) {
                        if (ce->hunk->type & NGX_HUNK_FILE)
                            break;

                        if ((ce->hunk->type & NGX_HUNK_MEMORY|NGX_HUNK_MMAP)
                            && (r->filter & NGX_HTTP_FILTER_NEED_TEMP))
                            break;
                    }

                    ctx->out.next = ce;

                } else {
                    ctx->out.next = NULL;
                }

                rc = ctx->next_filter(r, &ctx->out);
            }

            /* delete completed hunks from input chain */
            for (ce = ctx->in; ce; ce = ce->next) {
                 if (ce->hunk->pos.file == ce->hunk->last.file)
                     ctx->in = ce->next;
            }

            if (rc == NGX_OK)
                ctx->hunk->pos.mem = ctx->hunk->last.mem = ctx->hunk->start;
            else
                return rc;

        /* input chain is empty */
        } else {

            if (hunk == NULL) {
                rc = ctx->next_filter(r, NULL);

            } else {

                /* we need to copy hunk to our hunk */
                if (((r->filter & NGX_HTTP_FILTER_NEED_IN_MEMORY)
                        && (hunk->type & NGX_HUNK_FILE))
                    || ((r->filter & NGX_HTTP_FILTER_NEED_TEMP)
                        && (hunk->type & NGX_HUNK_MEMORY|NGX_HUNK_MMAP))
                   ) {

                    /* out hunk is still busy */
                    if (ctx->hunk && ctx->hunk->pos.mem < ctx->hunk->last.mem) {
                        ngx_add_hunk_to_chain(ctx->in, hunk, r->pool,
                                              NGX_ERROR);

                        rc = ctx->next_filter(r, NULL);

                    } else {
                        if (ctx->hunk == NULL) {

                            if (hunk->type & NGX_HUNK_LAST) {

                                conf = (ngx_http_output_filter_conf_t *)
                                 ngx_get_module_loc_conf(r->main ? r->main : r,
                                                ngx_http_output_filter_module);

                                size = hunk->last.mem - hunk->pos.mem;
                                if (size > conf->hunk_size)
                                    size = conf->hunk_size;

                            } else {
                                size = conf->hunk_size;
                            }

                            ngx_test_null(ctx->hunk,
                                          ngx_create_temp_hunk(r->pool, size,
                                                               50, 50),
                                          NGX_ERROR);
                            ctx->hunk->type |= NGX_HUNK_RECYCLED;

                            rc = ngx_http_output_filter_copy_hunk(ctx->hunk,
                                                                  hunk);
#if (NGX_FILE_AIO)
                            if (rc == NGX_AGAIN) {
                                /* add hunk to input chain */
                                ngx_add_hunk_to_chain(ctx->in, hunk, r->pool,
                                                      NGX_ERROR);

                                return rc;
                            }
#endif
                            if (rc == NGX_ERROR)
                                return rc;

                            if (hunk->pos.mem < hunk->last.mem)
                                ngx_add_hunk_to_chain(ctx->in, hunk, r->pool,
                                                      NGX_ERROR);

                            ctx->out.hunk = ctx->hunk;
                            ctx->out.next = NULL;

                            rc = ctx->next_filter(r, &ctx->out);
                        }
                    }

                } else {
                    ctx->out.hunk = hunk;
                    ctx->out.next = NULL;

                    rc = ctx->next_filter(r, &ctx->out);
                }
            }
        }

        if (rc == NGX_OK && ctx->hunk)
            ctx->hunk->pos.mem = ctx->hunk->last.mem = ctx->hunk->start;
    }

    if (rc == NGX_OK && ctx->last)
        return NGX_OK;

    if (rc == NGX_OK) {
        ctx->hunk->pos.mem = ctx->hunk->last.mem = ctx->hunk->start;
#if level_event
        ngx_del_event(r->connection->write, NGX_WRITE_EVENT);
#endif
    }

    return rc;
}


static int ngx_http_output_filter_copy_hunk(ngx_hunk_t *dst, ngx_hunk_t *src)
{
    size_t   size;
    ssize_t  n;

    size = src->last.mem - src->pos.mem;
    if (size > dst->end - dst->pos.mem)
        size = dst->end - dst->pos.mem;

    if (src->type & NGX_HUNK_FILE) {
        n = ngx_read_file(src->file, dst->pos.mem, size, src->pos.file);

        if (n == NGX_ERROR) {
            return n;

#if (NGX_FILE_AIO)
        } else if (n == NGX_AGAIN) {
            return n;
#endif

        } else {
            ngx_assert((n == size), /* void */ ; , src->file->log,
                       ngx_read_file_n " reads only %d of %d" _
                       n _ size);
        }

        src->pos.mem += n;
        dst->last.mem += n;

    } else {
        ngx_memcpy(src->pos.mem, dst->pos.mem, size);

        src->pos.mem += size;
        dst->last.mem += size;
    }

    return NGX_OK;
}


static int ngx_http_output_filter_init(
            int (*next_filter)(ngx_http_request_t *r, ngx_chain_t *ch))
{
    ngx_http_output_next_filter = next_filter;

    return NGX_OK;
}

static void *ngx_http_output_filter_create_conf(ngx_pool_t *pool)
{
    ngx_http_output_filter_conf_t *conf;

    ngx_test_null(conf,
                  ngx_pcalloc(pool, sizeof(ngx_http_output_filter_conf_t)),
                  NULL);

    conf->hunk_size = 16384;
}

static void *ngx_http_output_filter_set_hunk_size(ngx_pool_t *pool, void *conf,
                                                  char *size)
{
    ngx_http_output_filter_conf_t *cf = (ngx_http_output_filter_conf_t *) conf;

    cf->hunk_size = atoi(size);
    if (cf->hunk_size <= 0)
        return "Error";

    cf->hunk_size *= 1024;
    return NULL;
}