/** @file
  A minimal command-line shell.

  Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php.

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Library/ShellLib.h>
#include <Library/ConsoleInLib.h>
#include <Library/ConsoleOutLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/TimerLib.h>
#include "Shell.h"
#include "Parsing.h"

#define ESC   '\x1b'

CONST SHELL_COMMAND *mShellDefaultCommands[] = {
  SHELL_COMMANDS_DEFAULT
  NULL,
};

/**
  Prompt user for command, receive command, run command.

  @param[in]  Shell        shell instance

  @retval EFI_SUCCESS
  @retval RETURN_ABORTED

**/
STATIC
EFI_STATUS
ShellPrompt (
  IN SHELL *Shell
  );

/**
  Find shell command by name.

  @param[in]  Shell        shell instance
  @param[in]  Name         name of command
  @param[in]  Ptr          pointer to string pointer

  @retval EFI_SUCCESS
  @retval EFI_NOT_FOUND

**/
STATIC
EFI_STATUS
FindShellCommand (
  IN       SHELL         *Shell,
  IN CONST CHAR16        *Name,
  IN CONST SHELL_COMMAND **Ptr
  );

/**
  Process and run a command line.

  @param[in] Shell        shell instance
  @param[in] CmdLine      command line to parse

  @retval EFI_SUCCESS     command was completed

**/
STATIC
EFI_STATUS
RunShellCommand (
  IN       SHELL  *Shell,
  IN CONST CHAR16 *CmdLine
  );

/**
  Wait for command line input from the serial port.

  @param[in]  Shell        shell instance
  @param[out] Buffer       buffer to receive command line
  @param[in]  BufferSize   size (in bytes) of the buffer

  @retval EFI_SUCCESS
  @retval EFI_BUFFER_TOO_SMALL
  @retval EFI_TIMEOUT

**/
STATIC
EFI_STATUS
ReadShellCommand (
  IN        SHELL  *Shell,
  OUT       CHAR16 *Buffer,
  IN  CONST UINTN   BufferSize
  );

/**
  Begin a run-time interactive shell.

  @param[in]  Commands      command list (may be NULL for default commands)
  @param[in]  Timeout       seconds to wait for input before returning (0 for no timeout)

  @retval EFI_SUCCESS

**/
EFI_STATUS
EFIAPI
Shell (
  IN CONST SHELL_COMMAND **Commands,
  IN       UINTN           Timeout
  )
{
  BOOLEAN Start;
  UINTN   Index, Index1;
  SHELL   Shell;

  Shell.ShouldExit = FALSE;
  Shell.Commands   = Commands;

  if (Timeout != 0) {
    ShellPrint (L"\n");
    for (Index = Timeout; Index > 0; Index--) {
      ShellPrint (L"Press any key within %d second(s) to enter the command shell", Index);
      for (Index1 = 0; Index1 < 10; Index1++) {
        Start = ConsolePoll ();
        if (Start) {
          break;
        }
        MicroSecondDelay (100 * 1000);
      }
      ShellPrint(L"\r");
      if (Start) {
        break;
      }
    }
    ShellPrint (L"\n");
    if (!Start) {
      return EFI_ABORTED;
    }
  }

  while (! (Shell.ShouldExit)) {
    ShellPrompt (&Shell);
  }

  return EFI_SUCCESS;
}

/**
  Prompt user for command, receive command, run command.

  @param[in]  Shell        shell instance

  @retval EFI_SUCCESS
  @retval RETURN_ABORTED

**/
STATIC
EFI_STATUS
ShellPrompt (
  IN SHELL *Shell
  )
{
  CHAR16     CommandLine[MAX_COMMAND_LINE_LEN];
  EFI_STATUS Status;

  ASSERT (Shell != NULL);
  ShellPrint (L"\nShell> ");

  Status = ReadShellCommand (Shell, CommandLine, sizeof (CommandLine));
  if (EFI_ERROR (Status)) {
    return Status;
  }

  return RunShellCommand (Shell, CommandLine);
}

/**
  Wait for command line input from the serial port.

  @param[in]  Shell        shell instance
  @param[out] Buffer       buffer to receive command line
  @param[in]  BufferSize   size (in bytes) of the buffer

  @retval EFI_SUCCESS
  @retval EFI_BUFFER_TOO_SMALL
  @retval EFI_TIMEOUT

**/
STATIC
EFI_STATUS
ReadShellCommand (
  IN        SHELL  *Shell,
  OUT       CHAR16 *Buffer,
  IN  CONST UINTN   BufferSize
  )
{
  UINTN Count;
  UINT8 Char;

  Count = 0;

  ASSERT (Buffer != NULL);
  ASSERT (BufferSize > sizeof (CHAR16));

  while (1) {
    // Check for buffer overflow
    if (Count >= (BufferSize / sizeof (CHAR16) - 1)) {
      Buffer[0] = CHAR_NULL; // Terminate String
      return EFI_BUFFER_TOO_SMALL;
    }

    // Get next character from serial port
    Char = 0;
    if (ConsoleRead (&Char, 1) < 1) {
      return EFI_TIMEOUT;
    }

    // Check for end of line
    if ((Char == '\r') || (Char == '\n')) {
      Buffer[Count] = CHAR_NULL; // Terminate String
      break;
    }

    // Check for backspace/delete
    if ((Char == 0x7f) || (Char == '\b')) {
      if (Count > 0) {
        // Move cursor back 1 char and clear
        ShellPrint (L"\b \b");
        Count--;
      }
      continue;
    }

    // Handle key codes of the form: ESC [ x
    if (Char == ESC) {
      // Expect '[' character
      if (ConsoleRead (&Char, 1) < 1) {
        return EFI_TIMEOUT;
      }
      if (Char == '[') {
        // Expect command
        if (ConsoleRead (&Char, 1) < 1) {
          return EFI_TIMEOUT;
        }

        if (Char == 'A') { // Up
        } else if (Char == 'B') { // Down
        } else if (Char == 'C') { // Right
        } else if (Char == 'D') { // Left
        }

        // Key code consumed, continue getting input
        continue;
      }
    }

    // Echo character back and save character in buffer
    ShellPrint (L"%c", Char);
    Buffer[Count++] = Char;
  }

  ShellPrint (L"\n");
  TrimSpaces (&Buffer);

  return EFI_SUCCESS;
}

/**
  Read a line of input from the serial port.

  @param[in]  Shell        shell instance
  @param[out] Buffer       buffer to receive command line
  @param[in]  BufferSize   size (in bytes) of the buffer

  @retval EFI_SUCCESS
  @retval EFI_BUFFER_TOO_SMALL
  @retval EFI_TIMEOUT

**/
EFI_STATUS
ShellReadLine (
  IN        SHELL  *Shell,
  OUT       CHAR16 *Buffer,
  IN  CONST UINTN   BufferSize
  )
{
  UINTN Count;
  UINT8 Char;

  Count = 0;

  ASSERT (Buffer != NULL);
  ASSERT (BufferSize > sizeof (CHAR16));

  while (1) {
    // Check for buffer overflow
    if (Count >= (BufferSize / sizeof (CHAR16) - 1)) {
      Buffer[0] = CHAR_NULL; // Terminate String
      return EFI_BUFFER_TOO_SMALL;
    }

    // Get next character from serial port
    Char = 0;
    if (ConsoleRead (&Char, 1) < 1) {
      return EFI_TIMEOUT;
    }

    // Check for end of line
    if ((Char == '\r') || (Char == '\n')) {
      Buffer[Count] = CHAR_NULL; // Terminate String
      break;
    }

    // Check for backspace/delete
    if ((Char == 0x7f) || (Char == '\b')) {
      if (Count > 0) {
        // Move cursor back 1 char and clear
        ShellPrint (L"\b \b");
        Count--;
      }
      continue;
    }

    // Handle key codes of the form: ESC [ x
    if (Char == ESC) {
      // Expect '[' character
      if (ConsoleRead (&Char, 1) < 1) {
        return EFI_TIMEOUT;
      }
      if (Char == '[') {
        // Expect command
        if (ConsoleRead (&Char, 1) < 1) {
          return EFI_TIMEOUT;
        }

        if (Char == 'A') { // Up
        } else if (Char == 'B') { // Down
        } else if (Char == 'C') { // Right
        } else if (Char == 'D') { // Left
        }

        // Key code consumed, continue getting input
        continue;
      }
    }

    // Echo character back and save character in buffer
    ShellPrint (L"%c", Char);
    Buffer[Count++] = Char;
  }

  ShellPrint (L"\n");
  TrimSpaces (&Buffer);

  return EFI_SUCCESS;
}

/**
  Read a UINT value from the serial port.

  @param[in]  Shell        shell instance
  @param[out] Buffer       buffer to receive command line
  @param[in]  BufferSize   size (in bytes) of the buffer
  @param[out] IsHex        determine if the UINT is hex or decimal format

  @retval EFI_SUCCESS
  @retval EFI_BUFFER_TOO_SMALL
  @retval EFI_TIMEOUT

**/
EFI_STATUS
ShellReadUintn (
  IN        SHELL   *Shell,
  OUT       CHAR16  *Buffer,
  IN  CONST UINTN    BufferSize,
  OUT       BOOLEAN *IsHex
  )
{
  UINTN Count;
  UINT8 Char;

  Count = 0;

  ASSERT (Buffer != NULL);
  ASSERT (BufferSize > sizeof (CHAR16));

  *IsHex = FALSE;
  ZeroMem (Buffer, BufferSize);

  while (1) {
    // Check for buffer overflow
    if (Count >= (BufferSize / sizeof (CHAR16) - 1)) {
      return EFI_BUFFER_TOO_SMALL;
    }

    // Get next character from serial port
    Char = 0;
    if (ConsoleRead (&Char, 1) < 1) {
      return EFI_TIMEOUT;
    }

    if ((Char == '\r') || (Char == '\n')) {
      // Check for end of line
      Buffer[Count] = CHAR_NULL; // Terminate String
      break;
    } else if ((Char == 0x7f) || (Char == '\b')) {
      // Check for backspace/delete
      if (Count > 0) {
        if (Buffer[Count - 1] == 'x' || Buffer[Count - 1] == 'X') {
          *IsHex = FALSE;
        }
        // Move cursor back 1 char and clear
        ShellPrint (L"\b \b");
        Count--;
      }
      continue;
    } else if (Char == 'x' || Char == 'X') {
      if (Count != 1) {
        continue;
      }
      *IsHex = TRUE;
    } else if (Char >= '0' && Char <= '9') {
      ;
    } else if (*IsHex && ((Char >= 'a' && Char <= 'f') || (Char >= 'A' && Char <= 'F'))) {
      ;
    } else {
      continue;
    }

    // Echo character back and save character in buffer
    ShellPrint (L"%c", Char);
    Buffer[Count++] = Char;
  }

  ShellPrint (L"\n");
  TrimSpaces (&Buffer);

  return EFI_SUCCESS;
}

/**
  Process and run a command line.

  @param[in] Shell        shell instance
  @param[in] CmdLine      command line to parse

  @retval EFI_SUCCESS     command was completed

**/
STATIC
EFI_STATUS
RunShellCommand (
  IN       SHELL  *Shell,
  IN CONST CHAR16 *CmdLine
  )
{
  CHAR16              Buf[MAX_COMMAND_LINE_LEN];
  CHAR16              *Ptr;
  CONST CHAR16        *Walker;
  UINTN               Index, Count, BufRemaining;
  EFI_STATUS          Status;
  CONST SHELL_COMMAND *Cmd;
  CHAR16              *Argv[8]; // FIXME: Use allocator once that's available

  // Parse the command line parameters
  BufRemaining = sizeof (Buf);
  Ptr          = Buf;
  Walker       = CmdLine;

  for (Count = 0; Walker != NULL && *Walker != CHAR_NULL; Count++) {
    Status = GetNextParameter (&Walker, &Ptr, BufRemaining, TRUE);
    if (EFI_ERROR (Status)) {
      break;
    }
    BufRemaining -= StrSize (Ptr);
    Ptr          += StrLen (Ptr) + 1;
  }

  if (Count == 0) {
    return EFI_SUCCESS;
  }

  ASSERT (Count <= (sizeof (Argv) / sizeof (Argv[0])));
  for (Index = 0, Ptr = Buf; Index < Count; Index++) {
    Argv[Index]  = Ptr;
    Ptr     += StrLen (Ptr) + 1;
  }

  // Locate and execute command
  Cmd = NULL;
  Status = FindShellCommand (Shell, Argv[0], &Cmd);
  if (EFI_ERROR (Status)) {
    if (Status == EFI_NOT_FOUND) {
      ShellPrint (L"Command not found (try help)\n");
    }
  } else {
    ASSERT (Cmd);
    Status = Cmd->Entry (Shell, Count, Argv);
  }

  return Status;
}

/**
  Find shell command by name.

  @param[in]  Shell        shell instance
  @param[in]  Name         name of command
  @param[in]  Ptr          pointer to string pointer

  @retval EFI_SUCCESS
  @retval EFI_NOT_FOUND

**/
STATIC
EFI_STATUS
FindShellCommand (
  IN       SHELL         *Shell,
  IN CONST CHAR16        *Name,
  IN CONST SHELL_COMMAND **Ptr
  )
{
  CONST SHELL_COMMAND **Iter;

  //
  // Add '?' alias for help
  //
  if (Name[0] == '?') {
    Name = L"help";
  }

  //
  // Search the default commands firstly
  //
  for (Iter = mShellDefaultCommands; *Iter != NULL; Iter++) {
    if (StrCmp (Name, (*Iter)->Name) == 0) {
      *Ptr = *Iter;
      return EFI_SUCCESS;
    }
  }

  //
  // Search the extension shell command
  //
  for (Iter = Shell->Commands; *Iter != NULL; Iter++) {
    if (StrCmp (Name, (*Iter)->Name) == 0) {
      *Ptr = *Iter;
      return EFI_SUCCESS;
    }
  }

  return EFI_NOT_FOUND;
}