extern	NR_write
extern	strlen
extern	strcat
extern	itoa

section .rodata
	NL		db	0xA
	bufferLength	equ	4096
	ERR_buffLen	db	"<!> ERROR: Failed to complete printf(), reached buffer length!",0xA,0x0
	lERR_buffLen	equ	$-ERR_buffLen-1
section .bss
	printfBuff	resb	bufferLength
	printfNBuff	resb	32
section .text
	global	print
	global	puts
	global	printf

;----- print (char* string) -----;
; return value: N/A
print:
	call	strlen
	mov	rdx, rax
	mov	rax, NR_write
	mov	rsi, rdi
	mov	rdi, 1
	syscall
	ret
;----- puts (char* string) -----;
; return  value: N/A
puts:
	mov	r10, rdi
	call	print
	mov	rdi, r10
	mov	rax, NR_write
	mov	rdi, 1
	mov	rsi, NL
	mov	rdx, 1
	syscall
	ret
;----- printf(const char* string, ...) -----;
; Currently only supports specifiers: %d, %c, %s, %%
; Return value: Amount of printed characters
printf:
	push	rbp
	mov	rbp, rsp

	push	r12 
	push	r14

	xor	r10, r10
	xor	r14, r14
	lea	r11, [rel printfBuff]
	.makeStr:
		cmp	byte [rdi], 0x0
		je	.finish
		cmp	r14, bufferLength-1
		je	.finish
		cmp	byte [rdi], '%'
		je	.replaceArg
		mov	r12b, byte [rdi]
		mov	byte [r11], r12b
		inc	r14
		jmp	.continue
		.replaceArg:
			cmp	byte [rdi+1], 0x0
			je	.continue
			push	rdi
			cmp	byte [rdi+1], 'd'
			je	.rep_d
			cmp	byte [rdi+1], '%'
			je	.rep_pct
			cmp	byte [rdi+1], 'c'
			je	.rep_c
			cmp	byte [rdi+1], 's'
			je	.rep_s
			
			;--- invalid specifier ---;
			mov	byte [r11], '%'
			inc	r14
			inc	r10 
			jmp	.continue

			;--- %d ---;
			.rep_d:
			cmp	r10, 0
			cmove	rdi, rsi
			je	.convertInt
			cmp	r10, 1
			cmove	rdi, rdx
			je	.convertInt
			cmp	r10, 2
			cmove	rdi, rcx
			je	.convertInt
			cmp	r10, 3
			cmove	rdi, r8
			je	.convertInt
			cmp	r10, 4
			cmove	rdi, r9
			je	.convertInt

			mov	rdi, qword [rbp + 16 + (r10-5)*8]

			.convertInt:
				lea	rsi, [rel printfNBuff]
				push	rcx
				push	rdx
				push	r8
				push	r10
				call	itoa
				pop	r10
				pop	r8
				pop	rdx
				pop	rcx
				mov	rsi, rax
				jmp	.insertLoop

			;--- %% ---;
			.rep_pct:
				mov	rdi, '%'
				dec	r10 
				jmp	.charToStr

			;--- %c ---;
			.rep_c:
			cmp	r10, 0
			cmove	rdi, rsi
			je	.charToStr
			cmp	r10, 1
			cmove	rdi, rdx
			je	.charToStr
			cmp	r10, 2
			cmove	rdi, rcx
			je	.charToStr
			cmp	r10, 3
			cmove	rdi, r8
			je	.charToStr
			cmp	r10, 4
			cmove	rdi, r9
			je	.charToStr
		
			mov	rdi, qword [rbp + 16 + (r10-5)*8]

			.charToStr:
			mov	[printfNBuff], dil
			mov	dil, 0
			mov	[printfNBuff+1], dil
			lea	rsi, [rel printfNBuff]
			jmp	.insertLoop

			;--- %s ---;
			.rep_s:
			cmp	r10, 0
			je	.insertLoop
			cmp	r10, 1
			cmove	rsi, rdx
			je	.insertLoop
			cmp	r10, 2
			cmove	rsi, rcx
			je	.insertLoop
			cmp	r10, 3
			cmove	rsi, r8
			je	.insertLoop
			cmp	r10, 4
			cmove	rsi, r9
			je	.insertLoop

			mov	rsi, qword [rbp + 16 + (r10-5)*8]

			;--- Move fetched data to buffer ---;
			.insertLoop:
				cmp	r14, bufferLength-1
				je	.finish
				cmp	byte [rsi], 0x0
				je	.s0f
				mov	r12b, byte [rsi]
				mov	byte [r11], r12b
				inc	r14
				inc	rsi
				inc	r11
				jmp	.insertLoop
			.s0f:
			inc	r10
			pop	rdi
			add	rdi, 2
			jmp	.makeStr
		.continue:
		inc	rdi
		inc	r11
		jmp	.makeStr
	
	.finish:
	mov	byte [r11], 0x0
	mov	rax, NR_write
	mov	rdi, 1
	lea	rsi, [rel printfBuff]
	mov	rdx, r14
	syscall
	mov	rax, r14
	cmp	r14, bufferLength-1
	jl	.final

	mov	rax, NR_write
	mov	rdi, 2
	lea	rsi, [rel ERR_buffLen]
	mov	rdx, lERR_buffLen
	syscall

	.final:
	pop	r14
	pop	r12

	leave
	ret