; THIS CODE HAS NOT BEEN TESTED AND IS NOT FULLY OPERATIONAL.

; Problem Statement: Write X86 Assembly Language Program (ALP) to implement following OS commands: i. TYPE, ii. COPY and iii. DELETE
; Using file operations. User is supposed to provide command line arguments in all cases.

; Code from Microprocessor (SPPU - Second Year - Computer Engineering - Content) repository on KSKA Git: https://git.kska.io/sppu-se-comp-content/Microprocessor/

; BEGINNING OF CODE
%macro cmn 4    ;input/output
mov rax,%1
mov rdi,%2
mov rsi,%3
mov rdx,%4
syscall
%endmacro

%macro exit 0
mov rax,60
mov rdi,0
syscall
%endmacro

%macro fopen 1
mov rax,2       ;open
mov rdi,%1      ;filename
mov rsi,2       ;mode RW
mov rdx,0777o   ;file permissions
syscall
%endmacro

%macro fread 3
mov rax,0       ;read
mov rdi,%1      ;filehandle
mov rsi,%2      ;buf
mov rdx,%3      ;buf_len
syscall
%endmacro

%macro fwrite 3
mov rax,1       ;write/print
mov rdi,%1      ;filehandle
mov rsi,%2      ;buf
mov rdx,%3      ;buf_len
syscall
%endmacro

%macro fclose 1
mov rax,3       ;close
mov rdi,%1      ;file handle
syscall
%endmacro

section .data
menu db 'MENU:',0Ah
  db "1 -> TYPE",0Ah
  db "2 -> COPY",0Ah
  db "3 -> DELETE",0Ah
  db "4 -> EXIT",0Ah
  db "Choose an option (1-4): "
menulen equ $-menu
msg db "Command: "
msglen equ $-msg
cpysc db "Successfully copied the file.",0Ah
cpysclen equ $-cpysc

delsc db "File deletion successful.",0Ah
delsclen equ $-delsc

err db "Error!",0Ah
errlen equ $-err

cpywr db "Command does not exist.",0Ah
cpywrlen equ $-cpywr

err_par db "Insufficient parameter.",0Ah
err_parlen equ $-err_par

section .bss
 choice resb 2
 buffer resb 50
 name1 resb 15
 name2 resb 15
 cmdlen resb 1
 filehandle1 resq 1
 filehandle2 resq 1
 abuf_len resq 1        ;actual buffer length
 dispnum resb 2
 buf resb 4096
 buf_len equ $-buf      ;buffer initial length

 section .txt
 global _start
 _start:

 again: cmn 1,1,menu,menulen
    cmn 0,0,choice,2

 mov al,byte[choice]
 cmp al,31h
 jbe op1
 cmp al,32h
 jbe op2
 cmp al,33h
 jbe op3

 exit
 ret

op1:
 call tproc
 jmp again

op2:
 call cpproc
 jmp again

op3:
 call delproc
 jmp again

;type command procedure
tproc:
 cmn 1,1,msg,msglen
 cmn 0,0,buffer,50
 mov byte[cmdlen],al
 dec byte[cmdlen]

 mov rsi,buffer
 mov al,[rsi]      ;search for correct type command
 cmp al,'t'
 jne skipt
 inc rsi
 dec byte[cmdlen]
 jz skipt
 mov al,[rsi]
 cmp al,'y'
 jne skipt
 inc rsi
 dec byte[cmdlen]
 jz skipt
 mov al,[rsi]
 cmp al,'p'
 jne skipt
 inc rsi
 dec byte[cmdlen]
 jz skipt
 mov al,[rsi]
 cmp al,'e'
 jne skipt
 inc rsi
 dec byte[cmdlen]
 jnz correctt
 cmn 1,1,err_par,err_parlen
 call exit

skipt: cmn 1,1,cpywr,cpywrlen
exit
correctt:
  mov rdi,name1      ;finding file name
  call find_name
  
  fopen name1        ;on success returns handle
  cmp rax,-1H             ;on failure returns -1
  jle error
  mov [filehandle1],rax
  
  xor rax,rax
  fread [filehandle1],buf,buf_len
  mov [abuf_len],rax
  dec byte[abuf_len]

  cmn 1,1,buf,abuf_len    ;printing file content on screen
 ret

;copy command procedure
cpproc:
 cmn 1,1,msg,msglen
 cmn 0,0,buffer,50  ;accept command
 mov byte[cmdlen],al
 dec byte[cmdlen]

 mov rsi,buffer
 mov al,[rsi]  ;search for copy
 cmp al,'c'
 jne skip
 inc rsi
 dec byte[cmdlen]
 jz skip
 mov al,[rsi]
 cmp al,'o'
 jne skip
 inc rsi
 dec byte[cmdlen]
 jz skip
 mov al,[rsi]
 cmp al,'p'
 jne skip
 inc rsi
 dec byte[cmdlen]
 jz skip
 mov al,[rsi]
 cmp al,'y'
 jne skip
 inc rsi 
 dec byte[cmdlen]
 jnz correct
 cmn 1,1,err_par,err_parlen
 exit

skip:  cmn 1,1,cpywr,cpywrlen
exit
correct:
  mov rdi,name1           ;finding first file name
  call find_name
  
  mov rdi,name2           ;finding second file name
  call find_name

skip3:  fopen name1       ;on success returns handle
      cmp rax,-1H         ;on failure returns -1
      jle error
      mov [filehandle1],rax
      
     fopen name2          ;on success returns handle
     cmp rax,-1H          ;on failure returns -1
     jle error
     mov [filehandle2],rax
     xor rax,rax
     fread [filehandle1],buf,buf_len
     mov [abuf_len],rax
     dec byte[abuf_len]
  
 fwrite [filehandle2],buf,[abuf_len] ;write to file
 fclose [filehandle1]
 fclose [filehandle2]
 cmn 1,1,cpysc,cpysclen

 jmp again
error:
  cmn 1,1,err,errlen
  exit
ret

;delete command procedure
delproc:
  cmn 1,1,msg,msglen
  cmn 0,0,buffer,50     ;accept command
  mov byte[cmdlen],al
  dec byte[cmdlen]

  mov rsi,buffer
  mov al,[rsi]          ;search for copy
  cmp al,'d'
  jne skipr
  inc rsi
  dec byte[cmdlen]
  jz skipr
  mov al,[rsi]
  cmp al,'e'
  jne skipr
  inc rsi
  dec byte[cmdlen]
  jz skipr
  mov al,[rsi]
  cmp al,'l'
  jne skipr
  inc rsi
  dec byte[cmdlen]
  jnz correctr
  cmn 1,1,err_par,err_parlen
  exit

skipr:  cmn 1,1,cpywr,cpywrlen
  exit

correctr:
   mov rdi,name1        ;finding first file name
   call find_name
   mov rax,87           ;unlink system call
   mov rdi,name1
   syscall
  
  cmp rax,-1H           ;on failure returns -1
  jle errord
  cmn 1,1,delsc,delsclen
  jmp again

errord:
  cmn 1,1,err,errlen
  exit
ret

find_name:              ;finding file name from command
  inc rsi
  dec byte[cmdlen]

cont1: mov al,[rsi]
       mov [rdi],al
       inc rdi
       inc rsi
       mov al,[rsi]
       cmp al,20h       ;searching for space
       je skip2
       cmp al,0Ah       ;searching for enter key
       je skip2
       dec byte[cmdlen]
       jnz cont1
       cmn 1,1,err,errlen
       exit

skip2:
 ret
; END OF CODE