; multi-segment executable file template.

data segment
    name_contents db "c:\contents.bin", '$'
    string_formula db "Formula",
    string_result db "Result",
    string_menu db "Menu",
    num_hcell dw 04h
    matrix_lenght dw 160 ;estava 240 antes
    matrix_height dw 65
    cell db -128 dup(16)
    ;formula_lenght 88
ends

stack segment
    dw   128  dup(0)
ends

code segment
start:
; set segment registers:
    mov ax, data
    mov ds, ax
    mov es, ax

    ;open contents.bin
        call open_contents

    ;iniciate video mode
        mov ah, 00h
        mov al, 13h
        int 10h

    ;draw spreadsheet
        ;call createMatrix

        call createMenuBox

        call createFormulaBox

        call createResultBox

        call showLetters

        call showNumbers

        mov ax, 00h
        int 33h

    ;wait for user input
    keep_checking:
        mov ax, 03h
        int 33h
        shr cx, 1       ; x/2 - in this mode the value of CX is doubled.
        cmp bx, 1
        jnz keep_checking

        call cANDeCell  ;check and evaluate cell

        ;Preisamos agora de uma funcao para avaliar a celula que foi clicada
        ;ja temos toda a informacao necessaria
        ;devo meter AL para a dizer se a celula e valida
        ;e AH para dizer o tipo de celula

        cmp bl, 0     ;exit to MENU
        jnz keep_checking

    ;saves contents.bin
        call save_contents

    mov ax, 4c00h ; exit to operating system.
    int 21h


;*****************************************************************
; hLine -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************

    hLine proc

        n_hlines:
            push ax
            push cx

            h_change_pixel:
            push ax
            mov ah, 0Ch
            mov al, 0Fh
            int 10h

            pop ax
            dec ax
            jz h_done
            inc cx
            jmp h_change_pixel

        h_done:
        pop cx
        pop ax
        add dx, 16
        dec bx
        jnz n_hlines

        ret
    hLine endp


;*****************************************************************
; vLine -
; descricao: creates vertical lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = matrix_height
; output -
; destroi -
;*****************************************************************

    vLine proc

        n_vlines:
            push ax
            push dx

            v_change_pixel:
            push ax
            mov ah, 0Ch
            mov al, 0Fh
            int 10h

            pop ax
            dec ax
            jz v_done
            inc dx
            jmp v_change_pixel

        v_done:
        pop dx
        pop ax
        add cx, 40
        dec bx
        jnz n_vlines

        ret
    vLine endp



;*****************************************************************
; createMatrix -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************

  createMatrix proc
    mov bx, 05h ; se calhar temos de remover isto
    mov dx, 28
    mov cx, 20
    mov ax, matrix_lenght
    call hLine

    mov bx, 05h
    mov cx, 20
    mov dx, 28
    mov ax, matrix_height
    call vLine

    ret

  createMatrix endp

;*****************************************************************
; createMatrix -
; descricao: creates horizontal lines for the matrix
; input - bx= numero de linhas ; cx = horizontal margin ; dx = vertical margin ; ax = line lenght
; output -
; destroi -
;*****************************************************************


  createMenuBox proc

    mov bx, 2
    mov ax, 40
    mov cx, 20
    mov dx, 164
    call hLine

    mov bx, 2
    mov ax, 17
    mov cx, 20
    mov dx, 164
    call vLine

    ;writes "Menu" inside the cell
        mov al, 1
        mov bl, 0Fh
        mov cx, 4    ;string lenght
        mov dh, 21
        mov dl, 3
        mov ah, 13h
        mov bp, offset string_menu
        int 10h

  ret

  createMenuBox endp

;*****************************************************************
; createFormulaBox -
; descricao: creates a box where the user will input operations
; input -
; output -
; destroi -
;*****************************************************************

    createFormulaBox proc ;Provavelmente vamos ter de alterar o
                          ;tamanho da caixa da formula

        mov ax, 80 ; formula lenght
        mov cx, 20
        mov dx, 124
        mov bx, 02h
        call hLine

        mov ax, 17 ; formula height + 1
        mov cx, 20
        mov dx, 124
        mov bx, 01h
        call vLine

        mov ax, 17 ; formula height + 1
        mov cx, 100
        mov dx, 124
        mov bx, 01h
        call vLine

    ret

    createFormulaBox endp


;*****************************************************************
; createResultBox -
; descricao: creates a box to output the result
; input -
; output -
; destroi -
;*****************************************************************

    createResultBox proc

        mov ax, 80 ;cell lenght
        mov cx, 140
        mov dx, 124
        mov bx, 02h
        call hLine

        mov ax, 17 ; formula height + 1
        mov cx, 140
        mov dx, 124
        mov bx, 01h
        call vLine

        mov ax, 17 ; formula height + 1
        mov cx, 220
        mov dx, 124
        mov bx, 01h
        call vLine

    ret

    createResultBox endp

;*****************************************************************
; showLetter -
; descricao: prints a letter for each matrix collumn,
;            also prints "Formula" and "Result"
; input -
; output -
; destroi -
;*****************************************************************

    showLetters proc

        xor bh, bh
        mov bl, 0Fh
        mov cx, 1
        mov dl, 04
        mov al, 'A'

        new_letter:
            ;set cursor position
            mov dh, 02h
            mov ah, 02h
            int 10h

            ;write char at cursor position
            mov ah, 09h
            int 10h

            inc al
            add dl, 5
            cmp al, 'E'
            jnz new_letter

        ;writes "Formula" above the big cell
        mov al, 1
        mov bl, 0Fh
        mov cx, 7    ;string lenght
        mov dh, 14
        mov dl, 3
        mov ah, 13h
        mov bp, offset string_formula
        int 10h

        ;writes "Result" aove the small cell
        mov dl, 18
        mov cx, 6   ;string lenght deve ser 6
        mov bp, offset string_result
        int 10h

    ret

    showLetters endp

;*****************************************************************
; showNumbers -
; descricao: prints a number for each matrix row
; input -
; output -
; destroi -
;*****************************************************************

    showNumbers proc

        xor bh, bh
        mov bl, 0Fh
        mov cx, 1
        mov dh, 04h
        mov al, '1'

        new_number:
        ;set cursor position
        mov dl, 01h
        mov ah, 02h
        int 10h

        ;write char at cursor position
        mov ah, 09h
        int 10h

        inc al
        add dh, 2
        cmp al, '5'
        jnz new_number

    ret

    showNumbers endp

;*****************************************************************
; matrixCellClicked -
; descricao: edit clicked cell
; input -
; output -
; destroi -
;*****************************************************************

    matrixCellClicked proc

        xor bx, bx

        ;meter o cursor no sitio certo
        push cx
        push dx

        mov al, 5   ;multiplo necessario
        mul dl     ;multiplicar a celula pelo multiplo de posicao
        add al, 3  ;somar a constante de deslocamento incial
        mov dh, al ;adquirir a posicao em x do cursor

        mov al, 2   ;a mesma coisa mas para o
        mul cl     ;eixo do y
        add al, 4
        mov dl, al

        mov ah, 02h
        int 10h

        mov al, 'a'
        mov bl, 0Fh
        mov cx, 4
        mov ah, 09h
        int 10h

        pop dx
        pop cx


    ret
    matrixCellClicked endp



;*****************************************************************
; checkCell -
; descricao: checks and eveluates what to do with the cell clicked by the user
; input -
; output -
; destroi -
;*****************************************************************

    cANDeCell proc

        xor bx, bx ;nao sei se isto e preciso, tem a ver com um racicionio que ja nao me lembro

        ;check if user clicked on the margin

        cmp cx, 20
        jb done_checking
        cmp dx, 28
        jb done_checking

        mov ax, cx
        sub ax, 20

        mov bx, 40
        div bl
        xor ah, ah ;sabemos agora a celula das letras
        mov cx, ax ;o resultado esta em cx

        mov ax, dx
        sub ax, 28

        mov bx, 16
        div bl
        xor ah, ah
        mov dx, ax ;coordonates are now stored in cx(x) and dx(y)

        ;check if user clicked on a matrix cell

        cmp cx, 3
        ja not_matrix
        cmp dx, 3
        ja not_matrix
        call matrixCellClicked    ;a celula clicada foi uma da matriz descrita por cx e dx
        jmp done_checking

        ;check if user clicked on the formula or result cell
        not_matrix:
        cmp dx, 6
        jnz not_fORr
        cmp cx, 1
        ja not_formula
        ;a celula clicada e a celula da formula
        jmp done_checking

        not_formula:
        cmp cx, 3
        jnz not_fORr
        cmp cx, 4
        jnz not_fORr
        ;a celula clicada e a celula do resultado
        jmp done_checking

        not_fORr:
        ;check if used clicked on MENU
        cmp dx, 8 ;esta na linha do menu
        jnz done_checking
        cmp cx, 0
        jnz done_checking
        xor bx, bx
        done_checking:

    ret
    cANDeCell endp

;*****************************************************************
; fopen -
; descricao: abre um ficheiro em modo read(al==0), write(al==1) ou append(al==2)
; input - dx=offset nome ficheiro
; output - ax=file_handle
; destroi -
;*****************************************************************

    fopen proc
        mov ah, 3Dh
        mov al, 02h
        mov cx, 00h
        int 21h

        ret
    fopen endp

;*****************************************************************
; fclose -
; descricao:
; input - bx= file handle
; output -
; destroi -
;*****************************************************************

    fclose proc
        mov ah, 3Eh
        int 21h

        ret
    fclose endp

;*****************************************************************
; fcreate -
; descricao: cria um ficheiro
; input - dx=offset nome ficheiro
; output - ax=file_handle
; destroi -
;*****************************************************************

    fcreate proc
        mov ah, 3Ch
        mov cx, 00h
        int 21h

        ret
    fcreate endp

;*****************************************************************
; save_contents -
; descricao: saves contents.bin or creates it
; input -
; output -
; destroi -
;*****************************************************************

    save_contents proc
        ;tries to open file
        mov dx, offset name_contents
        call fopen
        jnc save

        ;in case it doesn't exist, creates it
        call fcreate

        save:
        mov bx, ax ;move handle

        mov cx, 16 ;number of bytes
        mov dx, offset cell ;offset to write to
        mov ah, 40h
        int 21h

        ;closes file
        call fclose

        ret
    save_contents endp

;*****************************************************************
; open_contents -
; descricao: opens contents.bin if it exists
; input -
; output -
; destroi - tudo
;*****************************************************************

    open_contents proc
        ;tries to open file
        mov dx, offset name_contents
        call fopen
        jc end_open_cont ;in case it doesn't exist yet

        mov bx, ax

        mov cx, 16 ;number of bytes
        mov dx, offset cell ;offset to write to
        mov ah, 3Fh
        int 21h

        call fclose
        end_open_cont:
        ret
    open_contents endp

ends

end start ; set entry point and stop the assembler.