// Copyright (c) 2023 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "AssetLoader.hpp"
#include "util/mathutils.hpp"

using namespace Dawn;

ssize_t assetLoaderArchiveRead(
  struct archive *archive,
  void *d,
  const void **buffer
) {
  assertNotNull(archive, "assetArchiveRead: Archive is NULL!");
  assertNotNull(d, "assetArchiveRead: Data is NULL!");
  assertNotNull(buffer, "assetArchiveRead: Buffer is NULL!");
  AssetLoader *loader = (AssetLoader*)d;

  *buffer = loader->buffer;
  size_t read = fread(
    loader->buffer, 1, ASSET_LOADER_BUFFER_SIZE, loader->assetArchiveFile
  );
  if(ferror(loader->assetArchiveFile)) return ARCHIVE_FATAL;
  return read;
}

int64_t assetLoaderArchiveSeek(
  struct archive *archive,
  void *d,
  int64_t offset,
  int32_t whence
) {
  assertNotNull(archive, "assetArchiveSeek: Archive is NULL!");
  assertNotNull(d, "assetArchiveSeek: Data is NULL!");
  assertTrue(offset > 0, "assetArchiveSeek: Offset must be greater than 0!");
  AssetLoader *loader = (AssetLoader*)d;
  int32_t ret = fseek(loader->assetArchiveFile, offset, whence);
  assertTrue(ret == 0, "assetArchiveSeek: Failed to seek!");
  return ftell(loader->assetArchiveFile);
}

int32_t assetLoaderArchiveOpen(struct archive *a, void *d) {
  assertNotNull(a, "assetArchiveOpen: Archive is NULL!");
  assertNotNull(d, "assetArchiveOpen: Data is NULL!");
  AssetLoader *loader = (AssetLoader*)d;

  int32_t ret = fseek(loader->assetArchiveFile, 0, SEEK_SET);
  assertTrue(ret == 0, "assetArchiveOpen: Failed to seek to start of file!");
  return ARCHIVE_OK;
}

int32_t assetLoaderArchiveClose(struct archive *a, void *d) {
  assertNotNull(a, "assetArchiveClose: Archive is NULL!");
  assertNotNull(d, "assetArchiveClose: Data is NULL!");
  return assetLoaderArchiveOpen(a, d);
}

AssetLoader::AssetLoader(std::string fileName) : IAssetLoader(fileName) {}

void AssetLoader::open() {
  assertNull(this->assetArchiveFile, "AssetLoader::open: File is already open");
  assertNull(this->assetArchive, "AssetLoader::open: Archive is already open");
  assertNull(this->assetArchiveEntry, "AssetLoader::open: Entry is already open");

  this->assetArchiveFile = fopen(DAWN_ASSET_LOCATION, "rb");
  assertNotNull(this->assetArchiveFile, "AssetLoader::open: Failed to open file %s", DAWN_ASSET_LOCATION);

  // Open archive reader
  assetArchive = archive_read_new();
  assertNotNull(assetArchive, "AssetLoader::open: Failed to create archive reader");

  // Set up the reader
  archive_read_support_format_tar(assetArchive);

  // Open reader
  archive_read_set_open_callback(assetArchive, &assetLoaderArchiveOpen);
  archive_read_set_read_callback(assetArchive, &assetLoaderArchiveRead);
  archive_read_set_seek_callback(assetArchive, &assetLoaderArchiveSeek);
  archive_read_set_close_callback(assetArchive, &assetLoaderArchiveClose);
  archive_read_set_callback_data(assetArchive, this);

  int32_t ret =  archive_read_open1(assetArchive);
  assertTrue(ret == ARCHIVE_OK, "AssetLoader::open: Failed to open archive!");
  position = 0;

  // Iterate over each file to find the one for this asset loader.
  while(archive_read_next_header(assetArchive, &assetArchiveEntry) == ARCHIVE_OK) {
    const char_t *headerFile = (char_t*)archive_entry_pathname(assetArchiveEntry);
    if(std::string(headerFile) == this->fileName) return;
    int32_t ret = archive_read_data_skip(assetArchive);
    assertTrue(ret == ARCHIVE_OK, "AssetLoader::open: Failed to skip data!");
  }

  assertUnreachable("AssetLoader::open: Failed to find file!");
}

int32_t AssetLoader::close() {
  assertNotNull(this->assetArchiveFile, "AssetLoader::close: File is NULL");
  assertNotNull(this->assetArchive, "AssetLoader::close: Archive is NULL!");
  assertNotNull(this->assetArchiveEntry, "AssetLoader::close: Entry is NULL!");
  
  // Close the archive
  int32_t ret = archive_read_free(this->assetArchive);
  assertTrue(ret == ARCHIVE_OK, "AssetLoader::close: Failed to close archive!");

  this->assetArchive = nullptr;
  this->assetArchiveEntry = nullptr;

  // Close the file
  int32_t res = fclose(this->assetArchiveFile);
  this->assetArchiveFile = nullptr;
  return res;
}

size_t AssetLoader::read(uint8_t *buffer, size_t size) {
  assertNotNull(buffer, "assetArchiveRead: Buffer is NULL!");
  assertTrue(size > 0, "assetArchiveRead: Size must be greater than 0!");
  assertNotNull(this->assetArchive, "assetRead: Archive is NULL!");
  assertNotNull(this->assetArchiveEntry, "assetRead: Entry is NULL!");

  ssize_t read = archive_read_data(this->assetArchive, buffer, size);
  this->position += read;
  
  if(read == ARCHIVE_FATAL) {
    assertUnreachable(archive_error_string(this->assetArchive));
  }
  
  assertTrue(read != ARCHIVE_RETRY, "assetRead: Failed to read data (RETRY)!");
  assertTrue(read != ARCHIVE_WARN, "assetRead: Failed to read data (WARN)!");

  return read;
}

size_t AssetLoader::getSize() {
  assertTrue(this->assetArchiveEntry != nullptr, "AssetLoader::getSize: Entry is NULL!");
  assertTrue(archive_entry_size_is_set(assetArchiveEntry), "assetGetSize: Entry size is not set!");
  return archive_entry_size(assetArchiveEntry);
}

size_t AssetLoader::skip(size_t n) {
  assertTrue(n >= 0, "AssetLoader::skip: Byte count must be greater than 0.");

  uint8_t dumpBuffer[ASSET_LOADER_BUFFER_SIZE];
  size_t skipped = 0;
  size_t n2, n3;
  while(n != 0) {
    n2 = mathMin<size_t>(n, ASSET_LOADER_BUFFER_SIZE);
    n3 = this->read(dumpBuffer, n2);
    assertTrue(n3 == n2, "AssetLoader::skip: Failed to skip bytes!");
    n -= n3;
  }

  return skipped;
}

void AssetLoader::rewind() {
  // TODO: See if I can optimize this
  this->close();
  this->open();
}

size_t AssetLoader::getPosition() {
  assertNotNull(this->assetArchiveFile, "AssetLoader::getPosition: File is not open!");
  return this->position;
}

AssetLoader::~AssetLoader() {
  if(this->assetArchiveFile != nullptr) this->close();
}