/** @file
  Copyright (C) 2019-2021, vit9696, Goldfish64, mikebeaton. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-3-Clause
**/

#include <Uefi.h>
#include <Guid/FileInfo.h>
#include <Protocol/OcBootstrap.h>
#include <Protocol/SimpleFileSystem.h>

#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/OcFileLib.h>
#include <Library/UefiBootServicesTableLib.h>

// Define EPOCH (1970-JANUARY-01) in the Julian Date representation
#define EPOCH_JULIAN_DATE                               2440588

// Seconds per unit
#define SEC_PER_MIN                                     ((UINTN)    60)
#define SEC_PER_HOUR                                    ((UINTN)  3600)
#define SEC_PER_DAY                                     ((UINTN) 86400)
#define SEC_PER_MONTH                                   ((UINTN)  2,592,000)
#define SEC_PER_YEAR                                    ((UINTN) 31,536,000)

STATIC
UINT32
EfiGetEpochDays (
  IN  EFI_TIME  *Time
  )
{
  UINT8  a;
  UINT32 y;
  UINT8  m;
  UINT32 JulianDate;  // Absolute Julian Date representation of the supplied Time
  UINT32 EpochDays;   // Number of days elapsed since EPOCH_JULIAN_DAY

  a = (14 - Time->Month) / 12 ;
  y = Time->Year + 4800 - a;
  m = Time->Month + (12*a) - 3;

  JulianDate = Time->Day + ((153*m + 2)/5) + (365*y) + (y/4) - (y/100) + (y/400) - 32045;

  ASSERT (JulianDate >= EPOCH_JULIAN_DATE);
  EpochDays = JulianDate - EPOCH_JULIAN_DATE;

  return EpochDays;
}

STATIC
UINT32
EfiTimeToEpoch (
  IN  EFI_TIME  *Time
  )
{
  UINT32 EpochDays;   // Number of days elapsed since EPOCH_JULIAN_DAY
  UINT32 EpochSeconds;

  EpochDays = EfiGetEpochDays (Time);

  EpochSeconds = (EpochDays * SEC_PER_DAY) + (Time->Hour * SEC_PER_HOUR) + (Time->Minute * SEC_PER_MIN) + Time->Second;

  return EpochSeconds;
}

EFI_STATUS
OcGetFileData (
  IN  EFI_FILE_PROTOCOL  *File,
  IN  UINT32             Position,
  IN  UINT32             Size,
  OUT UINT8              *Buffer
  )
{
  EFI_STATUS  Status;
  UINTN       ReadSize;
  UINTN       RequestedSize;

  while (Size > 0) {
    Status = File->SetPosition (File, Position);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    //
    // We are required to read in 1 MB portions, because otherwise some
    // systems namely MacBook7,1 will not read file data from APFS volumes
    // but will pretend they did. Repeoduced with BootKernelExtensions.kc.
    //
    ReadSize = RequestedSize = MIN (Size, BASE_1MB);
    Status = File->Read (File, &ReadSize, Buffer);
    if (EFI_ERROR (Status)) {
      File->SetPosition (File, 0);
      return Status;
    }

    if (ReadSize != RequestedSize) {
      File->SetPosition (File, 0);
      return EFI_BAD_BUFFER_SIZE;
    }

    Position += (UINT32) ReadSize;
    Buffer   += ReadSize;
    Size     -= (UINT32) ReadSize;
  }

  File->SetPosition (File, 0);

  return EFI_SUCCESS;
}

EFI_STATUS
OcGetFileSize (
  IN  EFI_FILE_PROTOCOL  *File,
  OUT UINT32             *Size
  )
{
  EFI_STATUS     Status;
  UINT64         Position;
  EFI_FILE_INFO  *FileInfo;

  Status = File->SetPosition (File, 0xFFFFFFFFFFFFFFFFULL);
  if (EFI_ERROR (Status)) {
    //
    // Some drivers, like EfiFs, return EFI_UNSUPPORTED when trying to seek
    // past the file size. Use slow method via attributes for them.
    //
    FileInfo = OcGetFileInfo (File, &gEfiFileInfoGuid, sizeof (*FileInfo), NULL);
    if (FileInfo != NULL) {
      if ((UINT32) FileInfo->FileSize == FileInfo->FileSize) {
        *Size = (UINT32) FileInfo->FileSize;
        Status = EFI_SUCCESS;
      }
      FreePool (FileInfo);
    }
    return Status;
  }

  Status = File->GetPosition (File, &Position);
  File->SetPosition (File, 0);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  if ((UINT32) Position != Position) {
    return EFI_OUT_OF_RESOURCES;
  }

  *Size = (UINT32) Position;

  return EFI_SUCCESS;
}

EFI_STATUS
OcGetFileModificationTime (
  IN  EFI_FILE_PROTOCOL  *File,
  OUT EFI_TIME           *Time
  )
{
  EFI_FILE_INFO  *FileInfo;

  FileInfo = OcGetFileInfo (File, &gEfiFileInfoGuid, 0, NULL);
  if (FileInfo == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  CopyMem (Time, &FileInfo->ModificationTime, sizeof (*Time));
  FreePool (FileInfo);

  return EFI_SUCCESS;
}

BOOLEAN
OcIsWritableFileSystem (
  IN EFI_FILE_PROTOCOL  *Fs
  )
{
  EFI_STATUS         Status;
  EFI_FILE_PROTOCOL  *File;

  //
  // We cannot test if the file system is writeable without attempting to create some file.
  //
  Status = OcSafeFileOpen (
    Fs,
    &File,
    L"octest.fil",
    EFI_FILE_MODE_CREATE | EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE,
    0
    );
  if (EFI_ERROR (Status)) {
    return FALSE;
  }

  //
  // Delete the temporary file and report the found file system.
  //
  Fs->Delete (File);
  return TRUE;
}

EFI_STATUS
OcFindWritableFileSystem (
  IN OUT EFI_FILE_PROTOCOL  **WritableFs
  )
{
  EFI_HANDLE                       *HandleBuffer;
  UINTN                            HandleCount;
  UINTN                            Index;
  EFI_SIMPLE_FILE_SYSTEM_PROTOCOL  *SimpleFs;
  EFI_FILE_PROTOCOL                *Fs;

  //
  // Locate all the simple file system devices in the system.
  //
  EFI_STATUS Status = gBS->LocateHandleBuffer (
    ByProtocol,
    &gEfiSimpleFileSystemProtocolGuid,
    NULL,
    &HandleCount,
    &HandleBuffer
    );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  for (Index = 0; Index < HandleCount; ++Index) {
    Status = gBS->HandleProtocol (
      HandleBuffer[Index],
      &gEfiSimpleFileSystemProtocolGuid,
      (VOID **) &SimpleFs
      );

    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_VERBOSE,
        "OCFS: FindWritableFileSystem gBS->HandleProtocol[%u] returned %r\n",
        (UINT32) Index,
        Status
        ));
      continue;
    }

    Status = SimpleFs->OpenVolume (SimpleFs, &Fs);
    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_VERBOSE,
        "OCFS: FindWritableFileSystem SimpleFs->OpenVolume[%u] returned %r\n",
        (UINT32) Index,
        Status
        ));
      continue;
    }

    if (OcIsWritableFileSystem (Fs)) {
      FreePool (HandleBuffer);
      *WritableFs = Fs;
      return EFI_SUCCESS;
    }

    DEBUG ((
      DEBUG_VERBOSE,
      "OCFS: FindWritableFileSystem Fs->Open[%u] failed\n",
      (UINT32) Index
      ));
  }

  FreePool (HandleBuffer);
  return EFI_NOT_FOUND;
}

EFI_STATUS
OcFindWritableOcFileSystem (
  OUT EFI_FILE_PROTOCOL  **FileSystem
  )
{
  EFI_STATUS             Status;
  OC_BOOTSTRAP_PROTOCOL  *Bootstrap;
  EFI_HANDLE             PreferedHandle;

  PreferedHandle = NULL;

  Status = gBS->LocateProtocol (
    &gOcBootstrapProtocolGuid,
    NULL,
    (VOID **) &Bootstrap
    );
  if (!EFI_ERROR (Status) && Bootstrap->Revision == OC_BOOTSTRAP_PROTOCOL_REVISION) {
    PreferedHandle = Bootstrap->GetLoadHandle (Bootstrap);
  }

  if (PreferedHandle != NULL) {
    *FileSystem = OcLocateRootVolume (PreferedHandle, NULL);
  } else {
    *FileSystem = NULL;
  }

  DEBUG ((DEBUG_INFO, "OCFS: Preferred handle is %p found fs %p\n", PreferedHandle, *FileSystem));

  if (*FileSystem == NULL) {
    return OcFindWritableFileSystem (FileSystem);
  }

  return EFI_SUCCESS;
}

EFI_STATUS
OcSetFileData (
  IN EFI_FILE_PROTOCOL  *WritableFs OPTIONAL,
  IN CONST CHAR16       *FileName,
  IN CONST VOID         *Buffer,
  IN UINT32             Size
  )
{
  EFI_STATUS         Status;
  EFI_FILE_PROTOCOL  *Fs;
  EFI_FILE_PROTOCOL  *File;
  UINTN              WrittenSize;

  ASSERT (FileName != NULL);
  ASSERT (Buffer != NULL);

  if (WritableFs == NULL) {
    Status = OcFindWritableFileSystem (&Fs);
    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_VERBOSE, "OCFS: WriteFileData can't find writable FS\n"));
      return Status;
    }
  } else {
    Fs = WritableFs;
  }

  Status = OcSafeFileOpen (
    Fs,
    &File,
    (CHAR16 *) FileName,
    EFI_FILE_MODE_CREATE | EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE,
    0
    );

  if (!EFI_ERROR (Status)) {
    WrittenSize = Size;
    Status = File->Write (File, &WrittenSize, (VOID *) Buffer);
    Fs->Close (File);

    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_VERBOSE, "OCFS: WriteFileData file->Write returned %r\n", Status));
    } else if (WrittenSize != Size) {
      DEBUG ((
        DEBUG_VERBOSE,
        "WriteFileData: File->Write truncated %u to %u\n",
        Status,
        Size,
        (UINT32) WrittenSize
        ));
      Status = EFI_BAD_BUFFER_SIZE;
    }
  } else {
    DEBUG ((DEBUG_VERBOSE, "OCFS: WriteFileData Fs->Open of %s returned %r\n", FileName, Status));
  }

  if (WritableFs == NULL) {
    Fs->Close (Fs);
  }

  return Status;
}

EFI_STATUS
OcAllocateCopyFileData (
  IN  EFI_FILE_PROTOCOL  *File,
  OUT UINT8              **Buffer,
  OUT UINT32             *BufferSize
  )
{
  EFI_STATUS    Status;
  UINT8         *FileBuffer;
  UINT32        ReadSize;

  //
  // Get full file data.
  //
  Status = OcGetFileSize (File, &ReadSize);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  FileBuffer = AllocatePool (ReadSize);
  if (FileBuffer == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }
  Status = OcGetFileData (File, 0, ReadSize, FileBuffer);
  if (EFI_ERROR (Status)) {
    FreePool (FileBuffer);
    return Status;
  }

  *Buffer     = FileBuffer;
  *BufferSize = ReadSize;
  return EFI_SUCCESS;
}

VOID
OcDirectorySeachContextInit (
  IN OUT DIRECTORY_SEARCH_CONTEXT *Context
  )
{
  ASSERT (Context != NULL);

  ZeroMem (Context, sizeof (*Context));
}

EFI_STATUS
OcEnsureDirectoryFile (
  IN     EFI_FILE_PROTOCOL        *File,
  IN     BOOLEAN                  IsDirectory
  )
{
  EFI_FILE_INFO     *FileInfo;

  //
  // Ensure this is a directory/file.
  //
  FileInfo = OcGetFileInfo (File, &gEfiFileInfoGuid, 0, NULL);
  if (FileInfo == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  if (((FileInfo->Attribute & EFI_FILE_DIRECTORY) != 0) != IsDirectory) {
    FreePool (FileInfo);
    return EFI_INVALID_PARAMETER;
  }
  FreePool (FileInfo);

  return EFI_SUCCESS;
}

EFI_STATUS
OcGetNewestFileFromDirectory (
  IN OUT DIRECTORY_SEARCH_CONTEXT *Context,
  IN     EFI_FILE_PROTOCOL        *Directory,
  IN     CHAR16                   *FileNameStartsWith OPTIONAL,
     OUT EFI_FILE_INFO            **FileInfo
  )
{
  EFI_STATUS        Status;
  EFI_FILE_INFO     *FileInfoCurrent;
  EFI_FILE_INFO     *FileInfoLatest;
  UINTN             FileInfoSize;
  UINT32            EpochCurrent;
  UINTN             Index;

  UINTN             LatestIndex;
  UINT32            LatestEpoch;

  ASSERT (Context != NULL);
  ASSERT (Directory != NULL);
  ASSERT (FileInfo != NULL);

  LatestIndex = 0;
  LatestEpoch = 0;

  Status = OcEnsureDirectoryFile (Directory, TRUE);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Allocate two FILE_INFO structures.
  // The first is used for all entries, and the second is used only for the
  // latest, and eventually returned to the caller.
  //
  FileInfoCurrent = AllocatePool (SIZE_1KB);
  if (FileInfoCurrent == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }
  FileInfoLatest = AllocateZeroPool (SIZE_1KB);
  if (FileInfoLatest == NULL) {
    FreePool (FileInfoCurrent);
    return EFI_OUT_OF_RESOURCES;
  }

  Directory->SetPosition (Directory, 0);
  Index = 0;

  do {
    //
    // Apple's HFS+ driver does not adhere to the spec and will return zero for
    // EFI_BUFFER_TOO_SMALL. EFI_FILE_INFO structures larger than 1KB are
    // unrealistic as the filename is the only variable.
    //
    FileInfoSize = SIZE_1KB - sizeof (CHAR16);
    Status = Directory->Read (Directory, &FileInfoSize, FileInfoCurrent);
    if (EFI_ERROR (Status)) {
      Directory->SetPosition (Directory, 0);
      FreePool (FileInfoCurrent);
      FreePool (FileInfoLatest);
      return Status;
    }

    if (FileInfoSize > 0) {
      //
      // Skip any files that do not start with the desired filename.
      //
      if (FileNameStartsWith != NULL) {
        if (StrnCmp (FileInfoCurrent->FileName, FileNameStartsWith, StrLen (FileNameStartsWith)) != 0) {
          continue;
        }
      }

      //
      // Get time of current entry.
      // We want to skip any entries that have been returned as "latest" in prior calls.
      //
      EpochCurrent = EfiTimeToEpoch (&FileInfoCurrent->ModificationTime);
      DEBUG ((DEBUG_VERBOSE, "OCFS: Current file %s with time %u\n", FileInfoCurrent->FileName, EpochCurrent));

      //
      // Skip any entries that are newer than our previously matched entry.
      //
      if (Context->PreviousTime > 0 && EpochCurrent > Context->PreviousTime) {
        DEBUG ((DEBUG_VERBOSE, "OCFS: Skipping file %s due to time %u > %u\n", FileInfoCurrent->FileName, EpochCurrent, Context->PreviousTime));
        continue;
      }

      //
      // Skip any entries that have the same time as our previously
      // matched entry and were found previously.
      //
      // ASSUMPTION: Entries are in the same order each time the directory is iterated.
      //
      if (EpochCurrent == Context->PreviousTime) {
        if (Index <= Context->PreviousIndex) {
          DEBUG ((DEBUG_VERBOSE, "OCFS: Skipping file %s with due to index %u <= %u\n", FileInfoCurrent->FileName, Index, Context->PreviousIndex));
          Index++;
          continue;
        }
      } else {
        //
        // Reset index counter if the time is different from the last.
        //
        Index = 0;
      }

      //
      // Store latest entry.
      //
      if (FileInfoLatest->FileName[0] == '\0' || EpochCurrent > EfiTimeToEpoch (&FileInfoLatest->ModificationTime)) {
        CopyMem (FileInfoLatest, FileInfoCurrent, FileInfoSize);
        LatestIndex = Index;
        LatestEpoch = EfiTimeToEpoch (&FileInfoLatest->ModificationTime);

        DEBUG ((DEBUG_VERBOSE, "OCFS: Stored newest file %s\n", FileInfoCurrent->FileName));
      }
    }
  } while (FileInfoSize > 0);

  Directory->SetPosition (Directory, 0);
  FreePool (FileInfoCurrent);

  if (FileInfoLatest->FileName[0] == '\0') {
    FreePool (FileInfoLatest);

    DEBUG ((DEBUG_VERBOSE, "OCFS: No matching files found\n"));
    return EFI_NOT_FOUND;
  }

  *FileInfo               = FileInfoLatest;
  Context->PreviousIndex  = LatestIndex;
  Context->PreviousTime   = LatestEpoch;

  return EFI_SUCCESS;
}

//
// TODO: OcGetNewestFileFromDirectory above and ScanExtensions in CachelessContext.c could be redone using this.
// TODO: I am unclear exactly what the Apple 32-bit HFS is being described as doing (see also OcGetFileInfo), so
// have just copied the existing handling.
//
EFI_STATUS
OcScanDirectory (
  IN      EFI_FILE_HANDLE                 Directory,
  IN      OC_PROCESS_DIRECTORY_ENTRY      ProcessEntry,
  IN OUT  VOID                            *Context            OPTIONAL
  )
{
  EFI_STATUS        Status;
  EFI_STATUS        TempStatus;
  EFI_FILE_INFO     *FileInfo;
  UINTN             FileInfoSize;

  ASSERT (Directory != NULL);
  ASSERT (ProcessEntry != NULL);

  Status = OcEnsureDirectoryFile (Directory, TRUE);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Allocate FILE_INFO structure.
  //
  FileInfo = AllocatePool (SIZE_1KB);
  if (FileInfo == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  Status = EFI_NOT_FOUND;
  Directory->SetPosition (Directory, 0);

  do {
    //
    // Apple's HFS+ driver does not adhere to the spec and will return zero for
    // EFI_BUFFER_TOO_SMALL. EFI_FILE_INFO structures larger than 1KB are
    // unrealistic as the filename is the only variable.
    //
    FileInfoSize = SIZE_1KB - sizeof (CHAR16);
    TempStatus = Directory->Read (Directory, &FileInfoSize, FileInfo);
    if (EFI_ERROR (TempStatus)) {
      Status = TempStatus;
      break;
    }

    if (FileInfoSize > 0) {
      TempStatus = ProcessEntry (Directory, FileInfo, FileInfoSize, Context);

      //
      // Act as if no matching file was found.
      //
      if (TempStatus == EFI_NOT_FOUND) {
        continue;
      }

      if (EFI_ERROR (TempStatus)) {
        Status = TempStatus;
        break;
      }

      //
      // At least one file found.
      //
      Status = EFI_SUCCESS;
    }
  } while (FileInfoSize > 0);

  Directory->SetPosition (Directory, 0);
  FreePool (FileInfo);

  return Status;
}