#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_event_pipe.h>


static int ngx_event_pipe_read_upstream(ngx_event_pipe_t *p);
static int ngx_event_pipe_write_to_downstream(ngx_event_pipe_t *p);

static int ngx_event_pipe_write_chain_to_temp_file(ngx_event_pipe_t *p);
ngx_inline static void ngx_remove_shadow_links(ngx_hunk_t *hunk);
ngx_inline static void ngx_remove_shadow_free_raw_hunk(ngx_chain_t **free,
                                                       ngx_hunk_t *h);
ngx_inline static void ngx_add_after_partially_filled_hunk(ngx_chain_t **chain,
                                                           ngx_chain_t *ce);
static int ngx_drain_chains(ngx_event_pipe_t *p);


int ngx_event_pipe(ngx_event_pipe_t *p, int do_write)
{
    for ( ;; ) {
        if (do_write) {
            if (ngx_event_pipe_write_to_downstream(p) == NGX_ABORT) {
                return NGX_ABORT;
            }
        }

        p->read = 0;
        p->upstream_blocked = 0;

        if (ngx_event_pipe_read_upstream(p) == NGX_ABORT) {
            return NGX_ABORT;
        }

        if (!p->read && !p->upstream_blocked) {
            break;
        }

        do_write = 1;
    }

    if (ngx_handle_read_event(p->upstream->read) == NGX_ERROR) {
        return NGX_ABORT;
    }

    if (ngx_handle_write_event(p->downstream->write,
                                           /* TODO: lowat */ 0) == NGX_ERROR) {
        return NGX_ABORT;
    }

    return NGX_OK;
}


int ngx_event_pipe_read_upstream(ngx_event_pipe_t *p)
{
    int           n, rc, size;
    ngx_hunk_t   *h;
    ngx_chain_t  *chain, *ce, *te;

    if (p->upstream_eof || p->upstream_error || p->upstream_done) {
        return NGX_OK;
    }

    ngx_log_debug(p->log, "read upstream: %d" _ p->upstream->read->ready);

    for ( ;; ) {

        if (p->upstream_eof || p->upstream_error || p->upstream_done) {
            break;
        }

        if (p->preread_hunks == NULL && !p->upstream->read->ready) {
            break;
        }

        if (p->preread_hunks) {

            /* use the pre-read hunks if they exist */

            p->read = 1;
            chain = p->preread_hunks;
            p->preread_hunks = NULL;
            n = p->preread_size;

            ngx_log_debug(p->log, "preread: %d" _ n);

        } else {

#if (HAVE_KQUEUE)

            /*
             * kqueue notifies about the end of file or a pending error.
             * This test allows not to allocate a hunk on these conditions
             * and not to call ngx_recv_chain().
             */

            if (ngx_event_flags == NGX_HAVE_KQUEUE_EVENT) {

                if (p->upstream->read->error) {
                    ngx_log_error(NGX_LOG_ERR, p->log, p->upstream->read->error,
                                  "readv() failed");
                    p->upstream_error = 1;

                    break;

                } else if (p->upstream->read->eof
                           && p->upstream->read->available == 0) {
                    p->upstream_eof = 1;
                    p->read = 1;

                    break;
                }
            }
#endif

            if (p->free_raw_hunks) {

                /* use the free hunks if they exist */

                chain = p->free_raw_hunks;
                p->free_raw_hunks = NULL;

            } else if (p->hunks < p->bufs.num) {

                /* allocate a new hunk if it's still allowed */

                ngx_test_null(h, ngx_create_temp_hunk(p->pool,
                                                      p->bufs.size, 0, 0),
                              NGX_ABORT);
                p->hunks++;

                ngx_alloc_ce_and_set_hunk(te, h, p->pool, NGX_ABORT);
                chain = te;

            } else if (!p->cachable && p->downstream->write->ready) {

                /*
                 * if the hunks are not needed to be saved in a cache and
                 * a downstream is ready then write the hunks to a downstream
                 */

                p->upstream_blocked = 1;

                ngx_log_debug(p->log, "downstream ready");

                break;

            } else if (p->cachable || p->temp_offset < p->max_temp_file_size) {

                /*
                 * if it's allowed then save some hunks from r->in
                 * to a temporary file, and add them to a r->out chain
                 */

                rc = ngx_event_pipe_write_chain_to_temp_file(p);

                ngx_log_debug(p->log, "temp offset: %d" _ p->temp_offset);

                if (rc == NGX_AGAIN) {
                    if (ngx_event_flags & NGX_USE_LEVEL_EVENT
                        && p->upstream->read->active
                        && p->upstream->read->ready)
                    {
                        if (ngx_del_event(p->upstream->read, NGX_READ_EVENT, 0)
                                                                  == NGX_ERROR)
                        {
                            return NGX_ABORT;
                        }
                    }
                }

                if (rc != NGX_OK) {
                    return rc;
                }

                chain = p->free_raw_hunks;
                p->free_raw_hunks = NULL;

            } else {

                /* if there're no hunks to read in then disable a level event */

                ngx_log_debug(p->log, "no hunks to read in");
    
                break;
            }

            ngx_log_debug(p->log, "HUNK_FREE: %d" _ chain->hunk->num);

            n = ngx_recv_chain(p->upstream, chain);

            ngx_log_debug(p->log, "recv_chain: %d" _ n);

            p->free_raw_hunks = chain;

            if (n == NGX_ERROR) {
                p->upstream_error = 1;
                return NGX_ERROR;
            }

            if (n == NGX_AGAIN) {
                break;
            }

            p->read = 1;

            if (n == 0) {
                p->upstream_eof = 1;
                break;
            }
        }

        ce = chain;

        while (ce && n > 0) {

            ngx_remove_shadow_links(ce->hunk);

            size = ce->hunk->end - ce->hunk->last;

            if (n >= size) {
                ce->hunk->last = ce->hunk->end;

    /* STUB */ ce->hunk->num = p->num++;

                if (p->input_filter(p, ce->hunk) == NGX_ERROR) {
                    return NGX_ABORT;
                }

                n -= size;
                ce = ce->next;

            } else {
                ce->hunk->last += n;
                n = 0;
            }
        }

        p->free_raw_hunks = ce;
    }

    if ((p->upstream_eof || p->upstream_error) && p->free_raw_hunks) {
    /* STUB */ p->free_raw_hunks->hunk->num = p->num++;
        if (p->input_filter(p, p->free_raw_hunks->hunk) == NGX_ERROR) {
            return NGX_ABORT;
        }

        /* TODO: p->free_raw_hunk->next can be free()ed */
        p->free_raw_hunks = p->free_raw_hunks->next;
    }

    if (p->cachable && p->in) {
        if (ngx_event_pipe_write_chain_to_temp_file(p) == NGX_ABORT) {
            return NGX_ABORT;
        }
    }

    return NGX_OK;
}


int ngx_event_pipe_write_to_downstream(ngx_event_pipe_t *p)
{
    size_t        busy_len;
    ngx_hunk_t   *h;
    ngx_chain_t  *out, **le, *ce, *te;

    ngx_log_debug(p->log, "write downstream: %d" _ p->downstream->write->ready);

    for ( ;; ) {
        if (p->downstream_error) {
            return ngx_drain_chains(p);
        }

        if ((p->upstream_eof || p->upstream_error || p->upstream_done)
            && p->out == NULL && p->in == NULL)
        {
            p->downstream_done = 1;
            break;
        }

        if (!p->downstream->write->ready) {
            break;
        }

        busy_len = 0;

        if (!(p->upstream_eof || p->upstream_error || p->upstream_done)) {
            /* calculate p->busy_len */
            for (ce = p->busy; ce; ce = ce->next) {
                busy_len += ngx_hunk_size(ce->hunk);
            }
        }

        out = NULL;
        le = NULL;

        for ( ;; ) {
            if (p->out) {
                ce = p->out;

                if (!(p->upstream_eof || p->upstream_error || p->upstream_done)
                    && (busy_len + ngx_hunk_size(ce->hunk) > p->max_busy_len))
                {
                    break;
                }

                p->out = p->out->next;
                ngx_remove_shadow_free_raw_hunk(&p->free_raw_hunks, ce->hunk);

ngx_log_debug(p->log, "HUNK OUT: %d %x" _ ce->hunk->num _ ce->hunk->type);

            } else if (!p->cachable && p->in) {
                ce = p->in;

                if (!(p->upstream_eof || p->upstream_error || p->upstream_done)
                    && (busy_len + ngx_hunk_size(ce->hunk) > p->max_busy_len))
                {
                    break;
                }

                p->in = p->in->next;

ngx_log_debug(p->log, "HUNK IN: %d" _ ce->hunk->num);

            } else {
                break;
            }

            busy_len += ngx_hunk_size(ce->hunk);
            ce->next = NULL;
            ngx_chain_add_ce(out, le, ce);
        }

        if (out == NULL) {
            ngx_log_debug(p->log, "no hunks to write BUSY: %d" _ busy_len);

            if (!p->upstream_blocked || busy_len == 0) {
                break;
            }

            /* if the upstream is blocked then write the busy hunks */
        }

        if (p->output_filter(p->output_ctx, out) == NGX_ERROR) {
            p->downstream_error = 1;

            /* handle the downstream error at the begin of the cycle.  */

            continue;
        }

        ngx_chain_update_chains(&p->free, &p->busy, &out, p->tag);

        for (ce = p->free; ce; ce = ce->next) {

            /* add the free shadow raw hunk to p->free_raw_hunks */

            if (ce->hunk->type & NGX_HUNK_LAST_SHADOW) {
                h = ce->hunk->shadow;
                h->pos = h->last = h->start;
                h->shadow = NULL;
                ngx_alloc_ce_and_set_hunk(te, h, p->pool, NGX_ABORT);
                ngx_add_after_partially_filled_hunk(&p->free_raw_hunks, te);

                ce->hunk->type &= ~NGX_HUNK_LAST_SHADOW;
            }
            ce->hunk->shadow = NULL;

            if (p->cyclic_temp_file && (ce->hunk->type & NGX_HUNK_TEMP_FILE)) {

                /* reset p->temp_offset if all hunks had been sent */

                if (ce->hunk->file_last == p->temp_offset) {
                    p->temp_offset = 0;
                }
            }
        }
    }

    return NGX_OK;
}


static int ngx_event_pipe_write_chain_to_temp_file(ngx_event_pipe_t *p)
{
    int           rc, size, hsize;
    ngx_hunk_t   *h;
    ngx_chain_t  *ce, *te, *next, *out, **le, **last_free;

    ngx_log_debug(p->log, "write to file");

    if (p->temp_file->fd == NGX_INVALID_FILE) {
        rc = ngx_create_temp_file(p->temp_file, p->temp_path, p->pool,
                                  p->cachable);

        if (rc == NGX_ERROR) {
            return NGX_ABORT;
        }

        if (rc == NGX_AGAIN) {
            return NGX_AGAIN;
        }

        if (!p->cachable && p->temp_file_warn) {
            ngx_log_error(NGX_LOG_WARN, p->log, 0, p->temp_file_warn);
        }
    }

    out = p->in;

    if (!p->cachable) {

        size = 0;
        ce = p->in;
        le = NULL;

ngx_log_debug(p->log, "offset: %d" _ p->temp_offset);

        do {
            hsize = ce->hunk->last - ce->hunk->pos;

ngx_log_debug(p->log, "hunk size: %d" _ hsize);

            if ((size + hsize > p->temp_file_write_size)
                || (p->temp_offset + size + hsize > p->max_temp_file_size))
            {
                break;
            }

            size += hsize;
            le = &ce->next;
            ce = ce->next;

        } while (ce);

ngx_log_debug(p->log, "size: %d" _ size);

        if (ce) {
           p->in = ce;
           *le = NULL;

        } else {
           p->in = NULL;
           p->last_in = &p->in;
        }

    } else {
        p->in = NULL;
        p->last_in = &p->in;
    }

    if (ngx_write_chain_to_file(p->temp_file, out, p->temp_offset,
                                                       p->pool) == NGX_ERROR) {
        return NGX_ABORT;
    }

    for (last_free = &p->free_raw_hunks;
         *last_free != NULL;
         last_free = &(*last_free)->next)
    {
        /* void */
    }

    for (ce = out; ce; ce = next) {
        next = ce->next;
        ce->next = NULL;

        h = ce->hunk;
        h->file = p->temp_file;
        h->file_pos = p->temp_offset;
        p->temp_offset += h->last - h->pos;
        h->file_last = p->temp_offset;

        if (p->cachable) {
            h->type |= NGX_HUNK_FILE;
        } else {
            h->type |= NGX_HUNK_FILE|NGX_HUNK_TEMP_FILE;
        }

        ngx_chain_add_ce(p->out, p->last_out, ce);

        if (h->type & NGX_HUNK_LAST_SHADOW) {
            h->shadow->last = h->shadow->pos = h->shadow->start;
            ngx_alloc_ce_and_set_hunk(te, h->shadow, p->pool, NGX_ABORT);
            *last_free = te;
            last_free = &te->next;
        }
    }

    return NGX_OK;
}


/* the copy input filter */

int ngx_event_pipe_copy_input_filter(ngx_event_pipe_t *p, ngx_hunk_t *hunk)
{
    ngx_hunk_t   *h;
    ngx_chain_t  *ce;

    if (hunk->pos == hunk->last) {
        return NGX_OK;
    }

    if (p->free) {
        h = p->free->hunk;
        p->free = p->free->next;

    } else {
        ngx_test_null(h, ngx_alloc_hunk(p->pool), NGX_ERROR);
    }

    ngx_memcpy(h, hunk, sizeof(ngx_hunk_t));
    h->shadow = hunk;
    h->tag = p->tag;
    h->type |= NGX_HUNK_LAST_SHADOW|NGX_HUNK_RECYCLED;
    hunk->shadow = h;

    ngx_alloc_ce_and_set_hunk(ce, h, p->pool, NGX_ERROR);
ngx_log_debug(p->log, "HUNK %d" _ h->num);
    ngx_chain_add_ce(p->in, p->last_in, ce);

    return NGX_OK;
}


ngx_inline static void ngx_remove_shadow_links(ngx_hunk_t *hunk)
{
    ngx_hunk_t  *h, *next;

    if (hunk->shadow == NULL) {
        return;
    }

    h = hunk->shadow;

    while (!(h->type & NGX_HUNK_LAST_SHADOW)) {
        next = h->shadow;
        h->type &= ~(NGX_HUNK_TEMP|NGX_HUNK_IN_MEMORY|NGX_HUNK_RECYCLED);
        h->shadow = NULL;
        h = next;
    }

    h->type &= ~(NGX_HUNK_TEMP
                 |NGX_HUNK_IN_MEMORY
                 |NGX_HUNK_RECYCLED
                 |NGX_HUNK_LAST_SHADOW);
    h->shadow = NULL;

    hunk->shadow = NULL;
}


ngx_inline static void ngx_remove_shadow_free_raw_hunk(ngx_chain_t **free,
                                                       ngx_hunk_t *h)
{
    ngx_hunk_t   *s;
    ngx_chain_t  *ce, **le;

    if (h->shadow == NULL) {
        return;
    }

    for (s = h->shadow; !(s->type & NGX_HUNK_LAST_SHADOW); s = s->shadow) {
        /* void */
    }

    le = free;

    for (ce = *free ; ce; ce = ce->next) {
        if (ce->hunk == s) {
            *le = ce->next;
            break;
        }

        if (ce->hunk->shadow) {
            break;
        }

        le = &ce->next;
    }
}


ngx_inline static void ngx_add_after_partially_filled_hunk(ngx_chain_t **chain,
                                                           ngx_chain_t *ce)
{
    if (*chain == NULL) {
        *chain = ce;
        return;
    }

    if ((*chain)->hunk->pos != (*chain)->hunk->last) {
        ce->next = (*chain)->next;
        (*chain)->next = ce;

    } else {
        ce->next = (*chain);
        (*chain) = ce;
    }
}


static int ngx_drain_chains(ngx_event_pipe_t *p)
{
    ngx_hunk_t   *h;
    ngx_chain_t  *ce, *te;

    for ( ;; ) {
        if (p->busy) {
            ce = p->busy;

        } else if (p->out) {
            ce = p->out;

        } else if (p->in) {
            ce = p->in;

        } else {
            return NGX_OK;
        }

        while (ce) {
            if (ce->hunk->type & NGX_HUNK_LAST_SHADOW) {
                h = ce->hunk->shadow;
                /* THINK NEEDED ??? */ h->pos = h->last = h->start;
                h->shadow = NULL;
                ngx_alloc_ce_and_set_hunk(te, h, p->pool, NGX_ABORT);
                ngx_add_after_partially_filled_hunk(&p->free_raw_hunks, te);

                ce->hunk->type &= ~NGX_HUNK_LAST_SHADOW;
            }

            ce->hunk->shadow = NULL;
            te = ce->next;
            ce->next = p->free;
            p->free = ce;
            ce = te;
        }
    }
}