#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include "al.h"
#include "sio.h"

#include <zlib.h>

typedef struct {
    z_stream     zs;
    int          lvl;
    al_t        *ibuf;
    char        *obuf;
    size_t       olen;
    al_t        *al;
    void        *u;
} data_t;

typedef struct {
    data_t       input;
    data_t       output;
    int          inputlevel;
    int          outputlevel;
    size_t       inputsize;
    size_t       outputsize;
    al_label_t   data_label;
} private_t;

/*
 * create stage
 *
 * allocate private instance data
 */
static
sio_rc_t zlib_init(sio_t *sio, void **up)
{
    private_t *my;
    
    my = (private_t *)malloc(sizeof(private_t));
    if (my == NULL)
        return SIO_ERR_MEM;

    my->inputsize    = 0;
    my->outputsize   = 0;
    my->inputlevel   = 0;
    my->outputlevel  = 0;

    sio_label(sio, SIO_LN_DATA, &my->data_label);

    *up = my;

    return SIO_OK;
}

/*
 * configure stage
 *
 * pass two void pointers
 */
static
sio_rc_t zlib_configure(sio_t *sio, void *u, void *obj, void *val)
{
    private_t *my = (private_t *)u;
    const char *name = (const char *)obj;

    if (!strcmp(name, "inputlevel")) {
        my->inputlevel = *(int *)val;
    } else if (!strcmp(name, "outputlevel")) {
        my->outputlevel = *(int *)val;
    } else if (!strcmp(name, "inputsize")) {
        my->inputsize = *(size_t *)val;
    } else if (!strcmp(name, "outputsize")) {
        my->outputsize = *(size_t *)val;
    } else {
        return SIO_ERR_ARG;
    }

    return SIO_OK;
}

/*
 * destroy stage
 */
static
sio_rc_t zlib_cleanup(sio_t *sio, void *u)
{
    private_t *my = (private_t *)u;

    free(my);

    return SIO_OK;
}

static
int zlib_alloc_data(private_t *my, data_t *dt)
{
    al_rc_t arc;
    int zrc;

    dt->u = (void *)my;

    if (dt->lvl >= 0)
        zrc = deflateInit(&dt->zs, dt->lvl);
    else
        zrc = inflateInit(&dt->zs);
    if (zrc != Z_OK)
        return -1;

    arc = al_create(&dt->ibuf);
    if (arc != AL_OK)
        return -1;

    dt->obuf = NULL;

    return 0;
}

static
void zlib_free_data(data_t *dt)
{
    al_destroy(dt->ibuf);
    dt->ibuf = NULL;

    if (dt->obuf != NULL) {
        free(dt->obuf);
        dt->obuf = NULL;
    }

    if (dt->lvl >= 0)
        deflateEnd(&dt->zs);
    else
        inflateEnd(&dt->zs);
}

static
sio_rc_t zlib_openr(sio_t *sio, al_t *al, void *u)
{
    private_t *my = (private_t *)u;

    if (my->inputsize <= 0)
        return SIO_ERR_ARG;

    my->input.lvl  = my->inputlevel;
    my->input.olen = my->inputsize;
    my->input.al   = al;

    if (zlib_alloc_data(my, &my->input))
        return SIO_ERR_INT;

    return SIO_OK;
}

static
sio_rc_t zlib_closer(sio_t *sio, al_t *al, void *u)
{
    private_t *my = (private_t *)u;

    zlib_free_data(&my->input);

    return SIO_OK;
}

static
sio_rc_t zlib_openw(sio_t *sio, al_t *al, void *u)
{
    private_t *my = (private_t *)u;

    if (my->outputsize <= 0)
        return SIO_ERR_ARG;

    my->output.lvl  = my->outputlevel;
    my->output.olen = my->outputsize;
    my->output.al   = al;

    if (zlib_alloc_data(my, &my->output))
        return SIO_ERR_INT;

    return SIO_OK;
}

static
sio_rc_t zlib_closew(sio_t *sio, al_t *al, void *u)
{
    private_t *my = (private_t *)u;

    if (my->output.lvl >= 0)
        deflateEnd(&my->output.zs);
    else
        inflateEnd(&my->output.zs);

    free(my->output.obuf);
    my->output.obuf = NULL;

    al_destroy(my->output.ibuf);
    my->output.ibuf = NULL;

    return SIO_OK;
}

static
void freezlibbuf(char *p, size_t n, void *u)
{
    free(p);
}

/*
 * buffer logic
 *
 * gather data from producer
 * if buffer size reached or label changes then push data to consumer
 * (read -> downstream, write -> upstream)
 *
 * buffer size depends on label type
 *
 */
static
al_rc_t zlib_inout_cb(al_chunk_t *alcp, void *u)
{
    data_t    *dt = (data_t *)u;
    private_t *my = (private_t *)dt->u;
    z_stream  *zs = &dt->zs;
    int        level = dt->lvl;
    int        zrc, flush;
    al_rc_t    arc;
    char      *p;
    size_t     n;

    arc = AL_OK;

    p = al_chunk_ptr(alcp, 0);
    n = al_chunk_len(alcp);

    if (al_same_label(alcp, my->data_label)) {
        zs->next_in  = (unsigned char *)p;
        zs->avail_in = n;
        flush = 0;
    } else {
        zs->next_in  = (unsigned char *)"";
        zs->avail_in = 0;
        flush = Z_FINISH;
    }

    do {
        if (zs->avail_out == 0) {
            if (dt->obuf == NULL &&
                (dt->obuf = malloc(dt->olen)) == NULL) {
                arc = AL_ERR_INT;
                break;
            }

            zs->next_out  = (unsigned char *)dt->obuf;
            zs->avail_out = dt->olen;
            zs->total_out = 0;
        }
        if (level >= 0)
            zrc = deflate(zs, flush);
        else
            zrc = inflate(zs, flush);
        if (zrc != Z_OK && zrc != Z_STREAM_END) {
            arc = AL_ERR_INT;
            break;
        }
        if (zs->avail_out == 0 || zrc == Z_STREAM_END || flush) {
            if (zs->total_out > 0) {
                arc = al_attach_buffer(dt->al, dt->obuf, zs->total_out,
                                       my->data_label, freezlibbuf, NULL);
                dt->obuf = NULL;
                zs->avail_out = 0;
                if (arc != AL_OK)
                    break;
            }
        }
    } while (zs->avail_in > 0 || (zrc == Z_OK && zs->avail_out == 0));

    if (arc != AL_OK)
        return arc;

    if (flush)
        arc = al_append_bytes(dt->al, p, n, al_chunk_label(alcp));

    return arc;
}

static
sio_rc_t zlib_inout(sio_t *sio, al_t *al, private_t *my, data_t *dt)
{
    al_rc_t arc;

    arc = al_splice(al, 0, al_bytes(al), NULL, dt->ibuf);
    if (arc != AL_OK)
        return SIO_ERR_INT;

    arc = al_traverse_cb(dt->ibuf, 0, al_bytes(dt->ibuf),
                         AL_FORWARD, NULL,
                         zlib_inout_cb, (void *)dt);
    if (arc != AL_OK)
        return SIO_ERR_INT;

    arc = al_splice(dt->ibuf, 0, al_bytes(dt->ibuf), NULL, NULL);
    if (arc != AL_OK)
        return SIO_ERR_INT;

    return SIO_OK;
}

static
sio_rc_t zlib_input(sio_t *sio, al_t *al, void *u, sio_rc_t orc)
{
    private_t *my = (private_t *)u;

    return zlib_inout(sio, al, my, &my->input);
}

static
sio_rc_t zlib_output(sio_t *sio, al_t *al, void *u, sio_rc_t orc)
{
    private_t *my = (private_t *)u;

    return zlib_inout(sio, al, my, &my->output);
}

sio_module_t sio_module_zlib = {
    "zlib",
    zlib_init,
    zlib_configure,
    zlib_cleanup,
    zlib_openr,
    zlib_closer,
    zlib_openw,
    zlib_closew,
    zlib_input,
    zlib_output,
    NULL
};