// SPDX-License-Identifier: 0BSD

///////////////////////////////////////////////////////////////////////////////

//

/// \file       alone_encoder.c

/// \brief      Encoder for LZMA_Alone files

//

//  Author:     Lasse Collin

//

///////////////////////////////////////////////////////////////////////////////

#include "common.h"

#include "lzma_encoder.h"

#define ALONE_HEADER_SIZE (1 + 4 + 8)

typedef struct {

  lzma_next_coder next;

  enum {

    SEQ_HEADER,

    SEQ_CODE,

  } sequence;

  size_t header_pos;

  uint8_t header[ALONE_HEADER_SIZE];

} lzma_alone_coder;

static lzma_ret

alone_encode(void *coder_ptr, const lzma_allocator *allocator,

    const uint8_t *restrict in, size_t *restrict in_pos,

    size_t in_size, uint8_t *restrict out,

    size_t *restrict out_pos, size_t out_size,

    lzma_action action)

{

  lzma_alone_coder *coder = coder_ptr;

  while (*out_pos < out_size)

  switch (coder->sequence) {

  case SEQ_HEADER:

    lzma_bufcpy(coder->header, &coder->header_pos,

        ALONE_HEADER_SIZE,

        out, out_pos, out_size);

    if (coder->header_pos < ALONE_HEADER_SIZE)

      return LZMA_OK;

    coder->sequence = SEQ_CODE;

    break;

  case SEQ_CODE:

    return coder->next.code(coder->next.coder,

        allocator, in, in_pos, in_size,

        out, out_pos, out_size, action);

  default:

    assert(0);

    return LZMA_PROG_ERROR;

  }

  return LZMA_OK;

}

static void

alone_encoder_end(void *coder_ptr, const lzma_allocator *allocator)

{

  lzma_alone_coder *coder = coder_ptr;

  lzma_next_end(&coder->next, allocator);

  lzma_free(coder, allocator);

  return;

}

static lzma_ret

alone_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,

    const lzma_options_lzma *options)

{

  lzma_next_coder_init(&alone_encoder_init, next, allocator);

  lzma_alone_coder *coder = next->coder;

  if (coder == NULL) {

    coder = lzma_alloc(sizeof(lzma_alone_coder), allocator);

    if (coder == NULL)

      return LZMA_MEM_ERROR;

    next->coder = coder;

    next->code = &alone_encode;

    next->end = &alone_encoder_end;

    coder->next = LZMA_NEXT_CODER_INIT;

  }

  // Basic initializations

  coder->sequence = SEQ_HEADER;

  coder->header_pos = 0;

  // Encode the header:

  // - Properties (1 byte)

  if (lzma_lzma_lclppb_encode(options, coder->header))

    return LZMA_OPTIONS_ERROR;

  // - Dictionary size (4 bytes)

  if (options->dict_size < LZMA_DICT_SIZE_MIN)

    return LZMA_OPTIONS_ERROR;

  // Round up to the next 2^n or 2^n + 2^(n - 1) depending on which

  // one is the next unless it is UINT32_MAX. While the header would

  // allow any 32-bit integer, we do this to keep the decoder of liblzma

  // accepting the resulting files.

  uint32_t d = options->dict_size - 1;

  d |= d >> 2;

  d |= d >> 3;

  d |= d >> 4;

  d |= d >> 8;

  d |= d >> 16;

  if (d != UINT32_MAX)

    ++d;

  write32le(coder->header + 1, d);

  // - Uncompressed size (always unknown and using EOPM)

  memset(coder->header + 1 + 4, 0xFF, 8);

  // Initialize the LZMA encoder.

  const lzma_filter_info filters[2] = {

    {

      .id = LZMA_FILTER_LZMA1,

      .init = &lzma_lzma_encoder_init,

      .options = (void *)(options),

    }, {

      .init = NULL,

    }

  };

  return lzma_next_filter_init(&coder->next, allocator, filters);

}

extern LZMA_API(lzma_ret)

lzma_alone_encoder(lzma_stream *strm, const lzma_options_lzma *options)

{

  lzma_next_strm_init(alone_encoder_init, strm, options);

  strm->internal->supported_actions[LZMA_RUN] = true;

  strm->internal->supported_actions[LZMA_FINISH] = true;

  return LZMA_OK;

}