; The OS/K Team licenses this file to you under the MIT license.
; See the LICENSE file in the project root for more information.

cmdstart:
    jmp start

#include "crt/crt.k"

#define CMDCOM_CODE     0x100000     // 1MB
#define CMDCOM_STACK    0x104000     // + 16KB

; COMMAND.COM guarantees that programs
; are always loaded on a 16KB boundary
; This is guaranteed to be the case
; in all future veesions as well
#define FILE_LOADP      0x108000     // + 32KB

start:
    mov esp, CMDCOM_STACK
    mov ebp, zero

    call main

    mov eax, Sys.EnterHaltMode
    trap 0

    crash

cmd.veesionstr = "COMMAND.COM, veesion 0.1 (KVISC)\nCopyright (C) 2019, The OS/K Team\nMIT license (permissive), see LICENCE file in source tree"

argbuf.size := 256
argbuf = [argbuf.size]
argv0 = [argbuf.size]
argv1pos = 0

stdin_echoing = 1

prompt = [32]

main:
    mov esi, prompt
    mov b[esi+0], 'C'
    mov b[esi+1], ':'
    mov b[esi+2], '\'
    mov b[esi+3], '>'
    mov b[esi+4], ' '

.print_prompt:
    call print, prompt

    ; empty stuff
    call memzero, argbuf, argbuf.size
    call memzero, argv0, argbuf.size
    nul q[argv1pos]

    ; call nprint, argv0, argbuf.size

    ; iterator through argbuf
    nul ecx

.input_loop:
    pause
    pause
    pause

    ; Fill .buf with user input
    scan eax
    jeaxz .input_loop

    ; ESC key pressed?
    beq eax, 0x1B, .handle_EXIT

    ; backspace character?
    bne eax, 8, .handle_input

    ; anything to delete?
    jecxz .input_loop     ; no

    ; yes, delete it
    dec ecx
    add edx, ecx, argbuf
    nul b[edx]

    ; update screen
    bzr b[stdin_echoing], .input_loop
    prn 8

    jmp .input_loop

.handle_input:
    bzr b[stdin_echoing], .se.z
    prn eax

.se.z:
    beq eax, 10, .extract_argv0

    ; when max line length is reached,
    ; force a newline
    beq ecx, argbuf.size, .extract_argv0

    ; add character to buffer and increase iterator (ecx)
    add edx, ecx, argbuf
    mov b[edx], eax
    inc ecx

    ; another one
    jmp .input_loop

.extract_argv0:
    ; did we read anything at all?
    ; if not, just go back to waiting input
    jecxz .print_prompt

    ; find first whitespace or null-terminator
    mov ecx, argbuf.size
    mov edx, argbuf
    scasb edx, ' '

    ; argv1 exists? if so, save its position
    mov esi, edx

.next_space:
    mov ecx, b[esi]
    jecxz .do_extract

    ; skip spaces
    bne ecx, ' ', .not_a_space
    inc esi
    jmp .next_space

.not_a_space:
    ; if we're here, we found a
    ; non-zero non-space character
    mov q[argv1pos], esi

    ; fallthrough

.do_extract:
    ; how much do we copy?
    sub ecx, edx, argbuf
    jecxz .detect_builtin
    dec ecx

    mov edi, argbuf
    mov esi, argv0

.copy_loop:
    mov b[esi], b[edi]

    inc edi
    inc esi

    loop .copy_loop

.detect_builtin:

.builtin_cls = "cls"
    call strcmp, argv0, .builtin_cls
    jeaxz .handle_CLS

.builtin_crash = "crash"
    call strcmp, argv0, .builtin_crash
    jeaxz .handle_CRASH

.builtin_date = "date"
    call strcmp, argv0, .builtin_date
    jeaxz .handle_DATE

.builtin_dir = "dir"
    call strcmp, argv0, .builtin_dir
    jeaxz .handle_DIR

.builtin_dump = "dump"
    call strcmp, argv0, .builtin_dump
    jeaxz .handle_DUMP

.builtin_echo = "echo"
    call strcmp, argv0, .builtin_echo
    jeaxz .handle_ECHO

.builtin_erase = "erase"
    call strcmp, argv0, .builtin_erase
    jeaxz .handle_ERASE

.builtin_exit = "exit"
    call strcmp, argv0, .builtin_exit
    jeaxz .handle_EXIT

.builtin_help = "help"
    call strcmp, argv0, .builtin_help
    jeaxz .handle_HELP

.builtin_halt = "halt"
    call strcmp, argv0, .builtin_halt
    jeaxz .handle_HALT

.builtin_make = "make"
    call strcmp, argv0, .builtin_make
    jeaxz .handle_MAKE

.builtin_print = "print"
    call strcmp, argv0, .builtin_print
    jeaxz .handle_PRINT

.builtin_prompt = "prompt"
    call strcmp, argv0, .builtin_prompt
    jeaxz .handle_PROMPT

.builtin_remove = "remove"
    call strcmp, argv0, .builtin_remove
    jeaxz .handle_REMOVE

.builtin_time = "time"
    call strcmp, argv0, .builtin_time
    jeaxz .handle_TIME

.builtin_vers = "vers"
    call strcmp, argv0, .builtin_vers
    jeaxz .handle_VERS

    jmp .try_exec

;
; call builtins
;

#include "usr/cmd-dir.k"
#include "usr/cmd-exec.k"
#include "usr/cmd-fsmisc.k"

.handle_CLS:
    prn PRN_CLEAR
    jmp .print_prompt

.handle_CRASH:
    jmp abort

.handle_DATE:
    call GetTimeUTC

    mov ecx, b[eax+4]
    inc ecx

    push b[eax+3], ecx, w[eax+6]
    call printf, .datefmt
    add esp, 40

    jmp .print_prompt

.datefmt = "%d/%d/%d\n"

.handle_DUMP:
    dump
    jmp .print_prompt

.handle_ECHO:
    mov eax, q[argv1pos]
    jeaxz .echo.end

    call print, eax

.echo.end:
    prn 10
    jmp .print_prompt

.handle_EXIT:
    mov eax, Sys.Shutdown
    trap 0
    jmp .print_prompt

.handle_HALT:
    mov eax, Sys.EnterHaltMode
    trap 0
    jmp .print_prompt

.handle_PROMPT:
    mov ax0, prompt
    mov ax1, q[argv1pos]
    bzr ax1, .need_params
    call strcpy

    jmp .print_prompt

.handle_TIME:
    call GetTimeUTC

    push b[eax], b[eax+1], b[eax+2]
    call printf, .timefmt
    add esp, 24

    jmp .print_prompt

.timefmt = "%d:%d:%d\n"

.handle_VERS:
    call print, cmd.veesionstr
    prn 10

    jmp .print_prompt

.handle_HELP:
    call print, .helpmsg
    call print, .helpmsg.cls
    call print, .helpmsg.date
    call print, .helpmsg.dir
    call print, .helpmsg.dump
    call print, .helpmsg.echo
    call print, .helpmsg.erase
    call print, .helpmsg.exit
    call print, .helpmsg.help
    call print, .helpmsg.halt
    call print, .helpmsg.make
    call print, .helpmsg.print
    call print, .helpmsg.prompt
    call print, .helpmsg.remove
    call print, .helpmsg.time
    call print, .helpmsg.ver

    jmp .print_prompt

.helpmsg        = "The following commands are built-in:\n"
.helpmsg.cls    = "    CLS        Clear screen\n"
.helpmsg.date   = "    DATE       Display current date\n"
.helpmsg.dir    = "    DIR        Print contents of current directory\n"
.helpmsg.dump   = "    DUMP       Toggles debug instruction dumping\n"
.helpmsg.echo   = "    ECHO       Write arguments to standard output\n"
.helpmsg.erase  = "    ERASE      Clear a file, making it blank\n"
.helpmsg.exit   = "    EXIT       Initiate machine shutdown\n"
.helpmsg.help   = "    HELP       Display these messages\n"
.helpmsg.halt   = "    HALT       Put processor in halt mode\n"
.helpmsg.make   = "    MAKE       Create an empty file\n"
.helpmsg.print  = "    PRINT      Display contents of text file\n"
.helpmsg.prompt = "    PROMPT     Change the command line prompt\n"
.helpmsg.remove = "    REMOVE     Delete a file (permanently)\n"
.helpmsg.time   = "    TIME       Display current time of day\n"
.helpmsg.ver    = "    VERS       Display current COMMAND.COM veesion\n"

.exec_not_found:
    push argv0
    call printf, .enf_errmsg
    add esp, 8

    jmp .print_prompt

.enf_errmsg = "%s: file not found\n"

.file_not_found:
    push q[argv1pos], argv0
    call printf, .fnf_errmsg
    add esp, 16

    jmp .print_prompt

.fnf_errmsg = "%s: %s: file not found\n"

.empty_file:
    push q[argv1pos], argv0
    call printf, .ef_errmsg
    add esp, 16

    jmp .print_prompt

.ef_errmsg = "%s: %s: file was empty\n"

.couldnt_open:
    push q[argv1pos], argv0
    call printf, .cno_errmsg
    add esp, 16

    jmp .print_prompt

.cno_errmsg = "%s: %s: an error occured while opening file\n"

.couldnt_remove:
    push q[argv1pos], argv0
    call printf, .cne_errmsg
    add esp, 16

    jmp .print_prompt

.cne_errmsg = "%s: %s: an error occured while removing file\n"

.couldnt_read:
    push q[argv1pos], argv0
    call printf, .cnr_errmsg
    add esp, 16

    jmp .print_prompt

.cnr_errmsg = "%s: %s: an error occured while reading file\n"

.need_params:
    call print, argv0
    call print, .np_errmsg

    jmp .print_prompt

.np_errmsg = ": need more parameters\n"