// Copyright 2017 The Wuffs Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// ----------------

// Uncomment this line to test and bench miniz instead of zlib-the-library.
// #define WUFFS_MIMICLIB_USE_MINIZ_INSTEAD_OF_ZLIB 1

#ifdef WUFFS_MIMICLIB_USE_MINIZ_INSTEAD_OF_ZLIB
#include "/path/to/your/copy/of/github.com/richgel999/miniz/miniz_tinfl.c"

const char* mimic_bench_adler32(wuffs_base__io_buffer* dst,
                                wuffs_base__io_buffer* src,
                                uint32_t wuffs_initialize_flags,
                                uint64_t wlimit,
                                uint64_t rlimit) {
  return "miniz does not independently compute Adler32";
}

const char* mimic_bench_crc32_ieee(wuffs_base__io_buffer* dst,
                                   wuffs_base__io_buffer* src,
                                   uint32_t wuffs_initialize_flags,
                                   uint64_t wlimit,
                                   uint64_t rlimit) {
  return "miniz does not implement CRC32/IEEE";
}

const char* mimic_deflate_zlib_decode(wuffs_base__io_buffer* dst,
                                      wuffs_base__io_buffer* src,
                                      uint32_t wuffs_initialize_flags,
                                      uint64_t wlimit,
                                      uint64_t rlimit,
                                      bool deflate_instead_of_zlib) {
  if (wlimit || rlimit) {
    // Supporting this would probably mean using tinfl_decompress instead of
    // the simpler tinfl_decompress_mem_to_mem function.
    return "unsupported I/O limit";
  }
  int flags = 0;
  if (!deflate_instead_of_zlib) {
    flags |= TINFL_FLAG_PARSE_ZLIB_HEADER;
  }
  size_t n = tinfl_decompress_mem_to_mem(
      dst->data.ptr + dst->meta.wi, dst->data.len - dst->meta.wi,
      src->data.ptr + src->meta.ri, src->meta.wi - src->meta.ri, flags);
  if (n == TINFL_DECOMPRESS_MEM_TO_MEM_FAILED) {
    return "TINFL_DECOMPRESS_MEM_TO_MEM_FAILED";
  }
  dst->meta.wi += n;
  src->meta.ri = src->meta.wi;
  return NULL;
}

const char* mimic_deflate_decode(wuffs_base__io_buffer* dst,
                                 wuffs_base__io_buffer* src,
                                 uint64_t wlimit,
                                 uint64_t rlimit) {
  return mimic_deflate_zlib_decode(dst, src, wlimit, rlimit, true);
}

const char* mimic_gzip_decode(wuffs_base__io_buffer* dst,
                              wuffs_base__io_buffer* src,
                              uint64_t wlimit,
                              uint64_t rlimit) {
  return "miniz does not implement gzip";
}

const char* mimic_zlib_decode(wuffs_base__io_buffer* dst,
                              wuffs_base__io_buffer* src,
                              uint64_t wlimit,
                              uint64_t rlimit) {
  return mimic_deflate_zlib_decode(dst, src, wlimit, rlimit, false);
}

#else  // WUFFS_MIMICLIB_USE_MINIZ_INSTEAD_OF_ZLIB
#include "zlib.h"

uint32_t global_mimiclib_deflate_unused_u32;

const char* mimic_bench_adler32(wuffs_base__io_buffer* dst,
                                wuffs_base__io_buffer* src,
                                uint32_t wuffs_initialize_flags,
                                uint64_t wlimit,
                                uint64_t rlimit) {
  global_mimiclib_deflate_unused_u32 = 0;
  while (src->meta.ri < src->meta.wi) {
    uint8_t* ptr = src->data.ptr + src->meta.ri;
    size_t len = src->meta.wi - src->meta.ri;
    if (len > 0x7FFFFFFF) {
      return "src length is too large";
    } else if ((len > rlimit) && (rlimit > 0)) {
      len = rlimit;
    }
    global_mimiclib_deflate_unused_u32 =
        adler32(global_mimiclib_deflate_unused_u32, ptr, len);
    src->meta.ri += len;
  }
  return NULL;
}

const char* mimic_bench_crc32_ieee(wuffs_base__io_buffer* dst,
                                   wuffs_base__io_buffer* src,
                                   uint32_t wuffs_initialize_flags,
                                   uint64_t wlimit,
                                   uint64_t rlimit) {
  global_mimiclib_deflate_unused_u32 = 0;
  while (src->meta.ri < src->meta.wi) {
    uint8_t* ptr = src->data.ptr + src->meta.ri;
    size_t len = src->meta.wi - src->meta.ri;
    if (len > 0x7FFFFFFF) {
      return "src length is too large";
    } else if ((len > rlimit) && (rlimit > 0)) {
      len = rlimit;
    }
    global_mimiclib_deflate_unused_u32 =
        crc32(global_mimiclib_deflate_unused_u32, ptr, len);
    src->meta.ri += len;
  }
  return NULL;
}

typedef enum {
  zlib_flavor_raw,
  zlib_flavor_gzip,
  zlib_flavor_zlib,
} zlib_flavor;

const char* mimic_deflate_gzip_zlib_decode(wuffs_base__io_buffer* dst,
                                           wuffs_base__io_buffer* src,
                                           uint64_t wlimit,
                                           uint64_t rlimit,
                                           zlib_flavor flavor) {
  const char* ret = NULL;
  if (dst->data.len > UINT_MAX) {
    ret = "dst length is too large";
    goto cleanup0;
  }
  if (src->data.len > UINT_MAX) {
    ret = "src length is too large";
    goto cleanup0;
  }

  // See inflateInit2 in the zlib manual, or in zlib.h, for details about how
  // the window_bits int also encodes the wire format wrapper.
  int window_bits = 0;
  switch (flavor) {
    case zlib_flavor_raw:
      window_bits = -15;
      break;
    case zlib_flavor_gzip:
      window_bits = +15 | 16;
      break;
    case zlib_flavor_zlib:
      window_bits = +15;
      break;
    default:
      ret = "invalid zlib_flavor";
      goto cleanup0;
  }
  z_stream z = {0};
  int ii2_err = inflateInit2(&z, window_bits);
  if (ii2_err != Z_OK) {
    ret = "inflateInit2 failed";
    goto cleanup0;
  }

  while (true) {
    z.next_in = src->data.ptr + src->meta.ri;
    z.avail_in = src->meta.wi - src->meta.ri;
    if ((z.avail_in > rlimit) && (rlimit > 0)) {
      z.avail_in = rlimit;
    }
    uInt initial_avail_in = z.avail_in;

    z.next_out = dst->data.ptr + dst->meta.wi;
    z.avail_out = dst->data.len - dst->meta.wi;
    if ((z.avail_out > wlimit) && (wlimit > 0)) {
      z.avail_out = wlimit;
    }
    uInt initial_avail_out = z.avail_out;

    // TODO: s/Z_NO_FLUSH/Z_SYNC_FLUSH/ more closely matches Wuffs' behavior.
    int i_err = inflate(&z, Z_NO_FLUSH);

    if (initial_avail_in < z.avail_in) {
      ret = "inconsistent avail_in";
      goto cleanup1;
    }
    src->meta.ri += initial_avail_in - z.avail_in;

    if (initial_avail_out < z.avail_out) {
      ret = "inconsistent avail_out";
      goto cleanup1;
    }
    dst->meta.wi += initial_avail_out - z.avail_out;

    if (i_err == Z_STREAM_END) {
      break;
    } else if (i_err == Z_DATA_ERROR) {
      ret = "inflate failed (data error)";
      goto cleanup1;
    } else if (i_err != Z_OK) {
      ret = "inflate failed";
      goto cleanup1;
    }
  }

cleanup1:;
  int ie_err = inflateEnd(&z);
  if ((ie_err != Z_OK) && !ret) {
    ret = "inflateEnd failed";
  }

cleanup0:;
  return ret;
}

const char* mimic_deflate_decode(wuffs_base__io_buffer* dst,
                                 wuffs_base__io_buffer* src,
                                 uint32_t wuffs_initialize_flags,
                                 uint64_t wlimit,
                                 uint64_t rlimit) {
  return mimic_deflate_gzip_zlib_decode(dst, src, wlimit, rlimit,
                                        zlib_flavor_raw);
}

const char* mimic_gzip_decode(wuffs_base__io_buffer* dst,
                              wuffs_base__io_buffer* src,
                              uint32_t wuffs_initialize_flags,
                              uint64_t wlimit,
                              uint64_t rlimit) {
  return mimic_deflate_gzip_zlib_decode(dst, src, wlimit, rlimit,
                                        zlib_flavor_gzip);
}

const char* mimic_zlib_decode(wuffs_base__io_buffer* dst,
                              wuffs_base__io_buffer* src,
                              uint32_t wuffs_initialize_flags,
                              uint64_t wlimit,
                              uint64_t rlimit) {
  return mimic_deflate_gzip_zlib_decode(dst, src, wlimit, rlimit,
                                        zlib_flavor_zlib);
}

#endif  // WUFFS_MIMICLIB_USE_MINIZ_INSTEAD_OF_ZLIB