global _start

extern itos, stoi, print, getInput, exit

section .data
	intro_msg: db 0x0a,0x0a,"Welcome to Hangman!",0x0a,"The object of the game is to guess all the letters in the hidden word.",0x0a,"If you guess incorrectly 5 times, you lose.",0x0a,0x00
	intro_msg_len: equ $ - intro_msg

	bad_letter_msg: db "Please input a valid letter (a-z.)",0x0a,0x00
	bad_letter_msg_len: equ $ - bad_letter_msg

	guess_msg: db "Guess a letter: ",0x00
	guess_msg_len: equ $ - guess_msg

	prior_guess_msg: db "You've already guessed that letter before.",0x0a,"Please try again.",0x0a,0x00
	prior_guess_msg_len: equ $ - prior_guess_msg

	win_msg: db 0x0a,"You win!",0x0a,0x00
	win_msg_len: equ $ - win_msg

	lose_msg: db 0x0a,"You lose! Try harder next time.",0x0a,0x00
	lose_msg_len: equ $ - lose_msg

	wrong_msg: db "That letter does not exist in the word.",0x0a,"You have this many tries left: ",0x00
	wrong_msg_len: equ $ - wrong_msg

	guess_word: db "juxtaposition",0x00		;modify this to change the word to be guessed (as of now)
	guess_word_len: equ $ - guess_word

	alphabet: db "abcdefghijklmnopqrstuvwxyz",0x00
	alphabet_len: equ $ - alphabet

	guess_list_msg: db "Previously guessed letters: ",0x00
	guess_list_msg_len: equ $ - guess_list_msg

	newline: db 0x0a,0x00
	space: db " ",0x00
	underscore: db "_",0x00

section .bss
	input: resd 1
	curletter: resb 1
	guessed: resb 1
	remguesses: resd 16
	guessleft: resb 4
	
section .text
	checkletter:
	mov dl, 0		;no guesses were correct
	mov cl, 0		;letters remain unguessed if 0 after return below
	mov esi, 0
	mov bl, byte [guessed]
	check_loop:
		mov al, byte [guess_word + esi]
		cmp al, 0
		je check_end
		inc esi
		mov [curletter], al
		cmp al, 0x60
		jl check_loop
		cmp al, bl
		je mark
		or cl, 1
		jne check_loop
	mark:
		or dl, 1
		and byte [guessed], 0xDF
		mov al, [guessed]
		mov byte [guess_word + (esi-1)], al
		jmp check_loop
	check_end:
		mov byte [guessed], 0
		ret
	draw_guesses:
	mov esi, 0
	loop_guesses:
		mov al, byte [alphabet + esi]
		cmp al, 0
		je loop_guesses_end
		add esi, 1
		mov [curletter], al
		cmp al, 0x60
		ja loop_guesses
		push curletter
		push 1
		call print
		add esp, 8
		push space
		push 1
		call print
		add esp, 8
		jmp loop_guesses
	loop_guesses_end:
		ret
	check_alpha:
	mov esi, 0
	mov cl, 0
	mov dl, 0
	mov bl, byte [guessed]
	check_range:
		cmp bl, 0x61		;if the guessed letter is not between 'a' and 'z' then it's bad input
		jl bad_input
		cmp bl, 0x7A
		ja bad_input
		jmp loop_alpha
	bad_input:
		cmp cl, 1
		je failed_input
		add bl, 32
		add byte [guessed], 32
		mov cl, 1
		jmp check_range
	failed_input:
		push bad_letter_msg
		push bad_letter_msg_len
		call print
		add esp, 8
		mov dl, 2		
		ret
	loop_alpha:
		mov al, byte [alphabet + esi]
		cmp al, 0
		je loop_alpha_end
		add esi, 1
		mov [curletter], al
		cmp al, 0x60
		jl loop_alpha
		cmp al, bl
		jne loop_alpha
		mov dl, 1
		and al, 0xDF
		mov byte [alphabet + (esi-1)], al
		ret
	loop_alpha_end:
		ret
	displayword:
	mov esi, 0
	push newline
	push 1
	call print
	add esp, 8
	loop_word:
		push space
		push 1
		call print
		add esp, 8
		mov al, byte [guess_word + esi]
		cmp al, 0
		je loop_word_end
		add esi, 1
		mov [curletter], al
		cmp al, 0x60
		ja undiscovered
		push curletter
		push 1
		call print
		add esp, 8
		jmp loop_word
		undiscovered:
  		  push underscore
		  push 1
		  call print
		  add esp, 8
		  jmp loop_word
		loop_word_end:
		  push newline
		  push 1
		  call print
		  add esp, 8
		  ret
	finished:
		call displayword
		push win_msg
		push win_msg_len
		call print
		add esp, 8
		call exit
	_start:	
		push intro_msg
		push intro_msg_len
		call print
		add esp, 8
		pop eax
		mov cl, 1		;set unguessed letters flag in cl to 1
		mov word [guessleft], 5
	guess:
		cmp cl, 0		;check if checkletter has set this flag to 0 (all letters guessed)
		je finished
		call displayword

		push newline
		push 1
		call print
		add esp, 8

		push guess_list_msg
		push guess_list_msg_len
		call print
		add esp, 8
		call draw_guesses
		push newline
		push 1
		call print
		add esp, 8

		  ;Prompt user for first number
		push guess_msg
		push guess_msg_len
		call print
		add esp, 8

		;Get character from user
		push guessed
		push 4
		call getInput
		add esp, 8

		call check_alpha
		cmp dl, 2
		je guess
		cmp dl, 1
		je check_word
		push prior_guess_msg
		push prior_guess_msg_len
		call print
		add esp, 8

		jmp guess
		
	check_word:
		call checkletter
		cmp dl, 1
		je guess

		dec byte [guessleft]
		mov eax, [guessleft]
		cmp word [guessleft], 0
		je lose
		push eax

		push wrong_msg
		push wrong_msg_len
		call print
		add esp, 8

		pop eax
		mov ebx, remguesses
		mov ecx, 16
		call itos
		push remguesses
		push 16
		call print
		add esp, 8
		jmp guess
	lose:
		push lose_msg
		push lose_msg_len
		call print
		add esp, 8
		call exit