/**
 ******************************************************************************
 * Xenia : Xbox 360 Emulator Research Project                                 *
 ******************************************************************************
 * Copyright 2013 Ben Vanik. All rights reserved.                             *
 * Released under the BSD license - see LICENSE in the root for more details. *
 ******************************************************************************
 * Major contributions to this file from:
 * - abgx360
 */

#include <xenia/kernel/fs/gdfx.h>

#include <poly/math.h>

using namespace xe;
using namespace xe::kernel;
using namespace xe::kernel::fs;


namespace {

#define kXESectorSize   2048

}


GDFXEntry::GDFXEntry() :
    attributes(X_FILE_ATTRIBUTE_NONE), offset(0), size(0) {
}

GDFXEntry::~GDFXEntry() {
  for (std::vector<GDFXEntry*>::iterator it = children.begin();
       it != children.end(); ++it) {
    delete *it;
  }
}

GDFXEntry* GDFXEntry::GetChild(const char* name) {
  // TODO(benvanik): a faster search
  for (std::vector<GDFXEntry*>::iterator it = children.begin();
       it != children.end(); ++it) {
    GDFXEntry* entry = *it;
    if (strcasecmp(entry->name.c_str(), name) == 0) {
      return entry;
    }
  }
  return NULL;
}

void GDFXEntry::Dump(int indent) {
  printf("%s%s\n", std::string(indent, ' ').c_str(), name.c_str());
  for (std::vector<GDFXEntry*>::iterator it = children.begin();
       it != children.end(); ++it) {
    GDFXEntry* entry = *it;
    entry->Dump(indent + 2);
  }
}


GDFX::GDFX(xe_mmap_ref mmap) {
  mmap_ = xe_mmap_retain(mmap);

  root_entry_ = NULL;
}

GDFX::~GDFX() {
  delete root_entry_;

  xe_mmap_release(mmap_);
}

GDFXEntry* GDFX::root_entry() {
  return root_entry_;
}

GDFX::Error GDFX::Load() {
  Error result = kErrorOutOfMemory;

  ParseState state;
  xe_zero_struct(&state, sizeof(state));

  state.ptr   = (uint8_t*)xe_mmap_get_addr(mmap_);
  state.size  = xe_mmap_get_length(mmap_);

  result = Verify(state);
  XEEXPECTZERO(result);

  result = ReadAllEntries(state, state.ptr + state.root_offset);
  XEEXPECTZERO(result);

  result = kSuccess;
XECLEANUP:
  return result;
}

void GDFX::Dump() {
  if (root_entry_) {
    root_entry_->Dump(0);
  }
}

GDFX::Error GDFX::Verify(ParseState& state) {
  // Find sector 32 of the game partition - try at a few points.
  const static size_t likely_offsets[] = {
    0x00000000, 0x0000FB20, 0x00020600, 0x0FD90000,
  };
  bool magic_found = false;
  for (size_t n = 0; n < poly::countof(likely_offsets); n++) {
    state.game_offset = likely_offsets[n];
    if (VerifyMagic(state, state.game_offset + (32 * kXESectorSize))) {
      magic_found = true;
      break;
    }
  }
  if (!magic_found) {
    // File doesn't have the magic values - likely not a real GDFX source.
    return kErrorFileMismatch;
  }

  // Read sector 32 to get FS state.
  if (state.size < state.game_offset + (32 * kXESectorSize)) {
    return kErrorReadError;
  }
  uint8_t* fs_ptr = state.ptr + state.game_offset + (32 * kXESectorSize);
  state.root_sector = poly::load<uint32_t>(fs_ptr + 20);
  state.root_size   = poly::load<uint32_t>(fs_ptr + 24);
  state.root_offset = state.game_offset + (state.root_sector * kXESectorSize);
  if (state.root_size < 13 ||
      state.root_size > 32 * 1024 * 1024) {
    return kErrorDamagedFile;
  }

  return kSuccess;
}

bool GDFX::VerifyMagic(ParseState& state, size_t offset) {
  // Simple check to see if the given offset contains the magic value.
  return memcmp(state.ptr + offset, "MICROSOFT*XBOX*MEDIA", 20) == 0;
}

GDFX::Error GDFX::ReadAllEntries(ParseState& state,
                                 const uint8_t* root_buffer) {
  root_entry_ = new GDFXEntry();
  root_entry_->offset = 0;
  root_entry_->size   = 0;
  root_entry_->name   = "";
  root_entry_->attributes = X_FILE_ATTRIBUTE_DIRECTORY;

  if (!ReadEntry(state, root_buffer, 0, root_entry_)) {
    return kErrorOutOfMemory;
  }

  return kSuccess;
}

bool GDFX::ReadEntry(ParseState& state, const uint8_t* buffer,
                     uint16_t entry_ordinal, GDFXEntry* parent) {
  const uint8_t* p = buffer + (entry_ordinal * 4);

  uint16_t  node_l      = poly::load<uint16_t>(p + 0);
  uint16_t  node_r      = poly::load<uint16_t>(p + 2);
  size_t    sector      = poly::load<uint32_t>(p + 4);
  size_t    length      = poly::load<uint32_t>(p + 8);
  uint8_t   attributes  = poly::load<uint8_t>(p + 12);
  uint8_t   name_length = poly::load<uint8_t>(p + 13);
  char*     name        = (char*)(p + 14);

  if (node_l && !ReadEntry(state, buffer, node_l, parent)) {
    return false;
  }

  GDFXEntry* entry = new GDFXEntry();
  entry->name = std::string(name, name_length);
  entry->name.append(1, '\0');
  entry->attributes = (X_FILE_ATTRIBUTES)attributes;

  // Add to parent.
  parent->children.push_back(entry);

  if (attributes & X_FILE_ATTRIBUTE_DIRECTORY) {
    // Folder.
    entry->offset = 0;
    entry->size   = 0;
    if (length) {
      // Not a leaf - read in children.
      if (state.size < state.game_offset + (sector * kXESectorSize)) {
        // Out of bounds read.
        return false;
      }
      // Read child list.
      uint8_t* folder_ptr =
          state.ptr + state.game_offset + (sector * kXESectorSize);
      if (!ReadEntry(state, folder_ptr, 0, entry)) {
        return false;
      }
    }
  } else {
    // File.
    entry->offset = state.game_offset + (sector * kXESectorSize);
    entry->size   = length;
  }

  // Read next file in the list.
  if (node_r && !ReadEntry(state, buffer, node_r, parent)) {
    return false;
  }

  return true;
}