;**
;**		BRIEF -- Basic Reconfigurable Interactive Editing Facility
;**
;**		Written by Dave Nanian and Michael Strickman.
;**
;**		Revision history:
;**		-----------------
;**

;**
;**		wp.m:
;**
;**		This file contains a set of macros that can help with very simple word
;**	processing applications.  The functions supported are word_wrap, centering,
;**	and paragraph reformatting, with a flexible right margin.  By default,
;**	word_wrap is turned on when this package is loaded.  The other functions
;**	can be invoked as they are needed, or can be assigned to any keys you
;**	choose.
;**
;**		These functions are NOT intended to replace a full-featured word processor.
;**	They are useful for letters and other short documents, and as a supplement
;**	to a text formatter.
;**

#define	ADD_CHAR_MACRO		0
#define	NEW_FILE_MACRO		1
#define	DEFAULT_MARGIN		70

;**
;**	_init:
;**
;**		This macro starts the package by setting up word_wrap and initializing
;**	the margin.
;**

(macro _init
	(
		(int		margin_val
					default_margin
		)
		(global	margin_val
					default_margin
		)
		(= margin_val (= default_margin DEFAULT_MARGIN))
	)
)

(macro wp
	(error "You must set BPACKAGES to turn on WP.")
)

;**
;**		_wp_on, _wp_off:
;**
;**		These macros are called to turn word processing on and off for specific
;**	files.  Note that an optional margin can be specified in the BPACKAGES
;**	line; the previous margin is restored when the current file is changed.
;**

(macro _wp_on
	(
		(if (! (get_parm 0 margin_val))
			(= margin_val default_margin)
		)
		(register_macro ADD_CHAR_MACRO "_word_wrap")
		(return "_wp_off")
	)
)

(macro _wp_off
	(unregister_macro ADD_CHAR_MACRO "_word_wrap")
)

;**
;**		center:
;**
;**		Centers the current line in the work area (the area between column 1
;**	and the current margin).
;**

(macro center
	(
		(string	text)

		(search_back "<[ \\t]@\\c[~ \\t]")
		(= text (read))
		(= text (substr text 1 (- (strlen text) 1)))
		(beginning_of_line)
		(delete_to_eol)
		(move_rel 0 (/ (- margin_val (strlen text)) 2))
		(insert text)
	)
)

;**
;**		word_wrap:
;**
;**		This macro is automatically invoked after each time that a character
;**	is typed.  It moves the cursor to the next line when it is past the 
;**	margin, taking the current word with it if necessary.
;**
;**		Automatic invocation is done via the standard BPACKAGES interface.
;**

(macro _word_wrap
	(
		(int		col)

		(inq_position NULL col)

		(if (> col margin_val)
			(
				(prev_char)
			
				(if (! (index " \t" (read 1)))
					(
						(int	new_col
								space_between_words
						)
						(= space_between_words 1)

						(search_back "<|[ \\t][~ \\t]")
						(inq_position NULL new_col)

						(if (== (read 1) "\t")
							(= space_between_words (distance_to_tab))
						)

						(if (== new_col 1)
							(end_of_line)
						)
						(insert "\n")

						(if (!= new_col 1)
							(
								(delete_char)
								(move_rel 0 (- (- col new_col) space_between_words))
							)
						)
					)
				;else
					(next_char)
				)
			)
		)
	)
)
				
;**
;**		margin:
;**
;**		Resets the current margin, prompting the user if necessary.
;**

(macro margin
	(
		(get_parm 0 default_margin "Enter margin: ")
		(= margin_val default_margin)
	)
)		

;**
;**		reform:
;**
;**		Reformats the currently marked area a line at a time.  The main
;**	loop goes through each line, adjusting it to the margin as necessary.
;**	If the line is too long, it splits it at the last space before the
;**	margin; it it's too short, it keeps joining the following lines to it,
;**	or parts of them if they are too long, until the line fits the margin.
;**

(macro reform
	(
		(string		last_char
						tab_reply
		)
		(int			old_buffer
						temp_buffer
						start_line
						start_col
						end_line
						end_col
						curr_line
						curr_col
						prev_line
						prev_col
						not_done
						tab_stop
		)
		(= tab_reply (use_tab_char "n"))

		(message "Reformatting paragraph...")

		;** If no paragraph marked, find ends of it at blank or indented lines.

		(if (! (inq_marked))
			(
				(end_of_line)
				(move_rel 0 -1)
				(if (! (search_back "{<[ \t]+[~ \t\n]}|{\n @\n\\c}"))
					(top_of_buffer)
				)
				(drop_anchor)
				(next_char)
				(if (! (search_fwd "{\\c\n[ \t]+[~ \t]}|{\\c\n[ \t]@\n}"))
					(end_of_buffer)
				)
			)
		)

		;** Transfer marked area into a fresh buffer, then delete it.

		(inq_marked start_line start_col end_line end_col)

		(save_position)
		(beginning_of_line)
		(= tab_stop (distance_to_tab))
		(restore_position)

		(= old_buffer (inq_buffer))
		(set_buffer (= temp_buffer (create_buffer "Word Process" NULL 1)))
		(tabs tab_stop)
		(transfer old_buffer start_line start_col end_line end_col)
		(set_buffer old_buffer)
		(delete_block)
		(move_abs start_line start_col)
		(set_buffer temp_buffer)
		(top_of_buffer)

		;** Loop through buffer a line at a time, shrinking or expanding
		;** each line as necessary.

		(while (! (inq_position))
			(
				(end_of_line)
				(inq_position NULL curr_col)

				;** If line is too long, split it.

				(if (> curr_col margin_val)
					(
						(move_abs 0 (+ margin_val 1))
						(search_back "[ \t]")
						(insert "\n")

						(while (== " " (read 1))
							(delete_char)
						)
						(up)
					)
				;else line might need to be merged with following lines.
					(
						(= not_done 1)

						(while not_done
							(
								(left)
								(= last_char (read 1))

								;** Skip current character and leave two spaces after 
								;** .:!?

								(+= curr_col (!= last_char " "))
								(+= curr_col (> (index ".:!?" last_char) 0))

								;** Stop if we don't need any more after punc.

								(if (>= curr_col margin_val)
									(= not_done 0)
								;else try to fill more of line
									(
										(down)
										(end_of_line)
										(inq_position prev_line prev_col)

										;** If we need the entire next line, prepare for join.

										(if (<= (-- prev_col) (- margin_val curr_col))
											(
												(beginning_of_line)

												(if (== (read) "\n")
													(= not_done 0)
												)
												(up)
											)
										;else if we need just a chunk of it
											(
												;** Find the maximum amt. we can take.

												(move_abs 0 (+ 1 (- margin_val curr_col)))
												(search_back "[ \t][~ \t]")
												(inq_position curr_line)

												;** If the first word on the next line is
												;** too long, we're done with the line.

												(if (!= curr_line prev_line)
													(= not_done 0)
												;else
													(
														;** Split off line and clean up start of next.

														(insert "\n")
														(delete_char)
			
														;** Go back up and prepare to join.
			
														(move_rel -2 0)
													)
												)	;Endif first word is too long
											)
										) ;Endif (now have old line + chunk)

										;** Now join the lines together if needed.

										(if not_done
											(
												(move_abs 0 curr_col)
												(delete_char)
											)
										)

										;** Prepare to loop again.

										(end_of_line)
										(inq_position NULL curr_col)
									)
								) ;Endif line needs to be extended
							)
						) ;Endwhile line isn't full
					)
				) ;Endif (Line is now ready to insert)

				;** Read line into string and insert in other buffer.

				(beginning_of_line)
				(= last_char (read))
				(set_buffer old_buffer)

				(if (!= last_char "\n")
					(insert last_char)
				)
				(refresh)
				(set_buffer temp_buffer)
				(delete_line)

				(if (== (read) "\n")
					(delete_line)
				)
			)
		) ;Endwhile there are lines to insert.

		;** Get rid of the scrap buffer and insert the remaining text.

		(set_buffer old_buffer)
		(delete_buffer temp_buffer)
		(message "Reformatting complete.")
		(use_tab_char tab_reply)
	)
)