# =============================================================================
# CONSOLE (FRAMEWORK FILE)                                   VERSION 2026-04-19
# =============================================================================
# The console system prints text strings, scrolls the screen, and blinks
# the cursor.  Each letter is a tile that is rendered using tile_layer_a.
# If your program doesn't need to display text, you could delete this file.

# -----------------------------------------------------------------------------
module console
  var _input_queue_index: byte

  var _row: byte
  var _col: byte
  var _pos: pair

  var _color_addend: pair  # (0..9) << 10
  var _blink_save: pair
  var _blink: bool

  var cursor_visible: bool

  var scroll_off: bool
  var reverse: bool
  var matte: bool

  var ctrl_key: bool

  # ---------------------------------------------------------------------------
  func init(io_tilemap: io_tilemap)
    # Clear the input queue
    console::_input_queue_index <- io::input_queue_end_index

    # Start with white because the background is black
    console::_color_addend <- 1024

    console::_print_char('{cls}')

    # Initialize the console tilemap
    io_tilemap.col_count <- 64
    io_tilemap.row_count <- 32
    io_tilemap.tile_codes_address <- to_address(kernel::console_grid)
  end func

  # ---------------------------------------------------------------------------
  func _blink_off()
    if console::_blink then
      console::_blink <- false
      kernel::console_grid[console::_pos] <- console::_blink_save
    end if
  end func

  # ---------------------------------------------------------------------------
  # *Assuming* _blink is false, this blinks on unless the cursor is not visible
  func _blink_restore()
    if console::cursor_visible then
      console::_blink <- true
      var c: pair
      c <- kernel::console_grid[console::_pos]
      console::_blink_save <- c

      c <- to_pair(math::bit_and(c, $3ff))      # remove the old color
      c <- to_pair(c + console::_color_addend)  # add the new color
      c <- to_pair(math::bit_xor(c, $4000))     # reverse
      kernel::console_grid[console::_pos] <- c
    end if
  end func

  # ---------------------------------------------------------------------------
  # Specifies the color (Palix system theme) to be used when printing text.
  func set_color(color: int)
    console::_blink_off()

    if color < 0 or color > 15
    do kernel::fail_code(20) # function was called with an invalid argument

    console::_color_addend <- to_pair(color * 1024)

    console::_blink_restore()
  end func

  # ---------------------------------------------------------------------------
  func print(s: string)
    console::_print(s, s.size)
  end func

  # ---------------------------------------------------------------------------
  func print_text(text: text)
    console::_print(text._chars, text.length)
  end func

  # ---------------------------------------------------------------------------
  func _print(text: char[], size: int)
    console::_blink_off()

    var i: int
    i <- 0

    loop
      if i >= size
      do drop

      var c: pair
      c <- text[i]

      console::_print_char(c)

      i <- i + 1
    end loop

    console::_blink_restore()
  end func

  # ---------------------------------------------------------------------------
  # Print a number
  func print_int(n: int)
    console::_blink_off()

    var c: int
    c <- n

    # To handle MIN_INT properly, the trick is to use negative math
    if n < 0 then
      console::print_char('-')
    else
      c <- -c
    end if

    # Extract digits from right-to-left, putting them into scratch_bytes[]
    var i: int, digit: int
    i <- 0
    loop
      digit <- -(c % 10)
      unsafe(kernel::scratch_bytes)[i] <- to_byte(48 + digit)

      c <- c / 10
      if c = 0
      do drop

      i <- i + 1
    end loop

    # Now read scratch_bytes[] in reverse, so digits are left-to-right
    loop
      console::_print_char(kernel::scratch_bytes[i])

      i <- i - 1
      if i < 0
      do drop
    end loop

    console::_blink_restore()
  end func

  # ---------------------------------------------------------------------------
  # Print one character that is specified using its HASCII code.
  func print_char(c: pair)
    console::_blink_off()

    console::_print_char(c)

    console::_blink_restore()
  end func

  # ---------------------------------------------------------------------------
  func _print_char(c: pair)
    var col: byte
    var row: byte
    var pos: pair

    col <- console::_col
    row <- console::_row
    pos <- console::_pos

    if c < 0
    do c <- to_pair(c + 256)

    if c < 32 then
      # Control codes

      if c = '{reset}' then
        console::scroll_off <- false
        console::reverse <- false
        console::matte <- false
      elsif c = '{soff}' then
        # scroll off
        console::scroll_off <- true
      elsif c = '{sup}' then
        # scroll up
        console::_scroll_up()
      elsif c = '{sdown}' then
        # scroll down

        # Offsets are double because they are pairs
        kernel::copy_memory_bytes(
        | to_address(kernel::console_grid) + 128,
        | to_address(kernel::console_grid),
        | 3456) # 64 * 27 * 2

        kernel::set_memory_pairs(
        | to_address(kernel::console_grid),  # 64 * 27 * 2
        | 32, # space
        | 40)
      elsif c = '{cls}' then
        # clear screen
        kernel::set_memory_pairs(
        | to_address(kernel::console_grid),
        | ' ',
        | 1792) # 64 * 28

        pos <- 0
        col <- 0
        row <- 0
      elsif c = '{cll}' then
        # clear line
        pos <- to_pair(pos - col)
        col <- 0

        kernel::set_memory_pairs(
        | to_address(kernel::console_grid) + pos * 2,
        | ' ',
        | 40)
      elsif c = '{tab}' then
        var tab_amount: int
        tab_amount <- 8 - to_byte(math::bit_and(col, 7)) # TODO: improve this
        col <- to_byte(col + tab_amount)
        pos <- to_pair(pos + tab_amount)

        if col >= 40 then
          pos <- to_pair(pos - col + 64)
          col <- 0
          row <- to_byte(row + 1)
        end if
      elsif c = '{n}' then
        # newline (lf)
        pos <- to_pair(pos - col + 64)
        col <- 0
        row <- to_byte(row + 1)
      elsif c = '{home}' then
        pos <- 0
        col <- 0
        row <- 0
      elsif c = '{end}' then
        pos <- 1728 # 27 * 64
        col <- 0
        row <- 27
      elsif c = '{cr}' then
        # carriage return
        pos <- to_pair(pos - col)
        col <- 0
      elsif c = '{rev}' then
        console::reverse <- true
      elsif c = 15 then
        # {mat}
        console::matte <- true
      elsif c >= 16 and c <= 25 then
        # color codes
        console::_color_addend <- to_pair((c - 16) * 1024)
      elsif c = '{u}' then
        # up
        if row > 0 then
          pos <- to_pair(pos - 64)
          row <- to_byte(row - 1)
        end if
      elsif c = '{d}' then
        # down
        pos <- to_pair(pos + 64)
        row <- to_byte(row + 1)
      elsif c = '{l}' then
        # left
        if col > 0 then
          pos <- to_pair(pos - 1)
          col <- to_byte(col - 1)
        else
          if row > 0 then
            pos <- to_pair(pos - col - (64 - 39))
            col <- 39
            row <- to_byte(row - 1)
          end if
        end if
      elsif c = '{r}' then
        # right
        if col < 39 then
          pos <- to_pair(pos + 1)
          col <- to_byte(col + 1)
        else
          pos <- to_pair(pos - col + 64)
          col <- 0
          row <- to_byte(row + 1)
        end if
      end if
    else
      # Add in the color bits
      var p: pair
      p <- to_pair(c + console::_color_addend)
      if console::reverse then
        p <- to_pair(math::bit_or(p, $4000))
      end if

      if console::matte then
        p <- to_pair(math::bit_or(p, $8000))
      end if

      kernel::console_grid[pos] <- p

      if col < 39 then
        pos <- to_pair(pos + 1)
        col <- to_byte(col + 1)
      else
        pos <- to_pair(pos - col + 64)
        col <- 0
        row <- to_byte(row + 1)
      end if
    end if

    if row >= 28 then
      row <- to_byte(row - 1)
      pos <- to_pair(pos - 64)

      if not console::scroll_off then
        console::_scroll_up()
      end if
    end if

    console::_col <- col
    console::_row <- row
    console::_pos <- pos
  end func

  # ---------------------------------------------------------------------------
  func _scroll_up()
    # Offsets are double because they are pairs
    kernel::copy_memory_bytes(
    | to_address(kernel::console_grid),
    | to_address(kernel::console_grid) + 128,
    | 3456) # 64 * 27 * 2

    kernel::set_memory_pairs(
    | to_address(kernel::console_grid) + 3456,  # 64 * 27 * 2
    | ' ',
    | 40)
  end func

  # ---------------------------------------------------------------------------
  # Extracts the next key from the keyboard buffer, returning its HASCII code.
  # If no key was pressed, then 0 is returned.
  func read_key(): byte
    var index: byte, end_index: byte
    var result: byte

    end_index <- io::input_queue_end_index

    index <- console::_input_queue_index
    result <- 0

    loop
      if index = end_index
      do drop

      # Read at index
      var event: ^io_input_event
      event <- io::input_queue[index]

      index <- to_byte(index + 1)
      if index >= 16
      do index <- 0

      var event_kind: byte, event_keyid: byte
      event_kind <- event.kind
      event_keyid <- event.keyid

      if event_kind = 0 or event_kind = 1 then  # key down or key repeat
        if event_keyid = 18 or event_keyid = 19 then # left/right ctrl
          console::ctrl_key <- true
        elsif event.hascii > 0 and event.hascii < 256 then
          result <- to_byte(event.hascii)
          drop
        end if
      else
        if event_keyid = 18 or event_keyid = 19 then # left/right ctrl
          console::ctrl_key <- false
        end if
      end if
    end loop

    console::_input_queue_index <- index

    return result
  end func

  # ---------------------------------------------------------------------------
  # Saves the current location of the cursor for use with goto_bookmark().
  func get_bookmark(): pair
    return console::_pos
  end func

  # ---------------------------------------------------------------------------
  # Move the cursor to a bookmark that was made using get_bookmark()
  func goto_bookmark(bookmark: pair)
    if bookmark >= 1792 # 64 * 28
    do kernel::fail_code(20) # function was called with an invalid argument

    console::_blink_off()

    # divide by 64
    console::_row <- to_byte(math::shift_right_unsigned(bookmark, 6))
    # remainder
    console::_col <- to_byte(math::bit_and(bookmark, 63))
    console::_pos <- bookmark

    console::_blink_restore()
  end func

  # ---------------------------------------------------------------------------
  # The main loop should call this to blink the cursor.
  func think()
    var blink_counter: int

    blink_counter <- math::bit_and(io::frame_counter, 31)

    if not console::cursor_visible or blink_counter >= 16 then
      console::_blink_off()
    else
      if not console::_blink then
        console::_blink <- true
        console::_blink_restore()
      end if
    end if
  end func
end module