/* mzstrm_mem.c -- Stream for memory access

   This interface is designed to access memory rather than files.
   We do use a region of memory to put data in to and take it out of. 

   Based on Unzip ioapi.c version 0.22, May 19th, 2003

   Copyright (C) 2012-2017 Nathan Moinvaziri
     https://github.com/nmoinvaz/minizip
   Copyright (C) 2003 Justin Fletcher
   Copyright (C) 1998-2003 Gilles Vollant
     http://www.winimage.com/zLibDll/minizip.html

   This file is under the same license as the Unzip tool it is distributed
   with.
*/


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

#include "mzstrm.h"
#include "mzstrm_mem.h"

/***************************************************************************/

typedef struct mz_stream_mem_s {
    mz_stream   stream;
    char        *buffer;    // Memory buffer pointer 
    uint32_t    size;       // Size of the memory buffer
    uint32_t    limit;      // Furthest we've written
    uint32_t    position;   // Current positoin in the memory
    int8_t      grow;       // Memory buffer can grow
    uint32_t    grow_size;  // Size to grow when full
} mz_stream_mem;

/***************************************************************************/

int32_t mz_stream_mem_open(void *stream, const char *path, int mode)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;

    if (mode & MZ_STREAM_MODE_CREATE)
    {
        if (mem->grow)
        {
            mem->size = mem->grow_size;
            mem->buffer = (char *)malloc(mem->size);
        }

        // When writing we start with 0 bytes written
        mem->limit = 0;
    }
    else
    {
        mem->limit = mem->size;
    }

    mem->position = 0;

    return MZ_OK;
}

int32_t mz_stream_mem_is_open(void *stream)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    if (mem->buffer == NULL)
        return MZ_STREAM_ERROR;
    return MZ_OK;
}

int32_t mz_stream_mem_read(void *stream, void *buf, uint32_t size)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;

    if (size > mem->size - mem->position)
        size = mem->size - mem->position;

    memcpy(buf, mem->buffer + mem->position, size);
    mem->position += size;

    return size;
}

int32_t mz_stream_mem_write(void *stream, const void *buf, uint32_t size)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    uint32_t new_size = 0;
    char *new_buf = NULL;

    if (size == 0)
        return size;

    if (size > mem->size - mem->position)
    {
        if (mem->grow)
        {
            new_size = mem->size;
            if (size < mem->grow_size)
                new_size += mem->grow_size;
            else
                new_size += size;

            new_buf = (char *)malloc(new_size);

            memcpy(new_buf, mem->buffer, mem->size);
            free(mem->buffer);

            mem->buffer = new_buf;
            mem->size = new_size;
        }
        else
        {
            size = mem->size - mem->position;
        }
    }

    memcpy(mem->buffer + mem->position, buf, size);

    mem->position += size;
    if (mem->position > mem->limit)
        mem->limit = mem->position;

    return size;
}

int64_t mz_stream_mem_tell(void *stream)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    return mem->position;
}

int32_t mz_stream_mem_seek(void *stream, uint64_t offset, int origin)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    uint64_t new_pos = 0;

    switch (origin)
    {
        case MZ_STREAM_SEEK_CUR:
            new_pos = mem->position + offset;
            break;
        case MZ_STREAM_SEEK_END:
            new_pos = mem->limit + offset;
            break;
        case MZ_STREAM_SEEK_SET:
            new_pos = offset;
            break;
        default:
            return MZ_STREAM_ERROR;
    }

    if (new_pos > mem->size)
        return MZ_STREAM_ERROR;

    mem->position = (uint32_t)new_pos;
    return MZ_OK;
}

int32_t mz_stream_mem_close(void *stream)
{
    // We never return errors
    return MZ_OK;
}

int32_t mz_stream_mem_error(void *stream)
{
    // We never return errors
    return MZ_OK;
}

void mz_stream_mem_set_buffer(void *stream, void *buf, uint32_t size)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    mem->buffer = buf;
    mem->size = size;
}

int8_t mz_stream_mem_get_buffer(void *stream, void **buf)
{
    return mz_stream_mem_get_buffer_at(stream, 0, buf);
}

int8_t mz_stream_mem_get_buffer_at(void *stream, int64_t position, void **buf)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    if (buf == NULL || position < 0 || mem->size < position || mem->buffer == NULL)
        return MZ_STREAM_ERROR;
    *buf = mem->buffer + position;
    return MZ_OK;
}

void mz_stream_mem_set_grow(void *stream, int8_t grow)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    mem->grow = grow;
}

void mz_stream_mem_set_grow_size(void *stream, uint32_t grow_size)
{
    mz_stream_mem *mem = (mz_stream_mem *)stream;
    mem->grow_size = grow_size;
}

void *mz_stream_mem_create(void **stream)
{
    mz_stream_mem *mem = NULL;

    mem = (mz_stream_mem *)malloc(sizeof(mz_stream_mem));
    if (mem != NULL)
    {
        memset(mem, 0, sizeof(mz_stream_mem));

        mem->stream.open = mz_stream_mem_open;
        mem->stream.is_open = mz_stream_mem_is_open;
        mem->stream.read = mz_stream_mem_read;
        mem->stream.write = mz_stream_mem_write;
        mem->stream.tell = mz_stream_mem_tell;
        mem->stream.seek = mz_stream_mem_seek;
        mem->stream.close = mz_stream_mem_close;
        mem->stream.error = mz_stream_mem_error;
        mem->stream.create = mz_stream_mem_create;
        mem->stream.delete = mz_stream_mem_delete;
        mem->grow_size = 16384;
    }
    if (stream != NULL)
        *stream = mem;

    return mem;
}

void mz_stream_mem_delete(void **stream)
{
    mz_stream_mem *mem = NULL;
    if (stream == NULL)
        return;
    mem = (mz_stream_mem *)*stream;
    if (mem != NULL)
    {
        if (mem->grow && mem->buffer != NULL)
            free(mem->buffer);
        free(mem);
    }
}