to format :from :to
openread :from
openwrite :to
setread :from
setwrite :to
init.vars
loop
setread []
setwrite []
close :from
close :to
end

to init.vars
make "pageheight 66
make "topmar 6
make "lines 54
make "leftmar 7
make "width 65
make "filltab 5
make "nofilltab 0
make "parskip 1
make "spacing 1
make "started "false
make "filling "true
make "printed 0
make "inline []
end

to loop
forever [if process nextword [stop]]
end

;; Add a word to the output file, starting a new line if necessary

to process :word
if listp :word [output "true]
if not :started [start]
if (:linecount+1+count :word) > :width [putline]
addword :word
output "false
end

to addword :word
if not emptyp :line [make "linecount :linecount+1]
make "line lput :word :line
make "linecount :linecount+count :word
end

to putline
repeat :leftmar+:indent [type "| |]
putwords :line ((count :line)-1) (:width-:linecount)
newline
skip :spacing
end

to putwords :line :spaces :filler
local "perword
if emptyp :line [stop]
type first :line
make "perword ifelse :spaces > 0 [int ((:filler+:spaces-1)/:spaces)] [0]
if :filler > 0 [repeat :perword [type "| |]]
type "| |
putwords (butfirst :line) (:spaces-1) (:filler-:perword)
end

;; Get the next input word, reading a new line if necessary

to nextword
if not emptyp :inline [output extract.word]
if not :filling [break]
make "inline readword
if listp :inline [break output []]
if emptyp :inline [break output nextword]
if equalp first :inline "|*| ~
   [run butfirst :inline
    make "inline "]
make "inline skipspaces :inline
output nextword
end

to extract.word
local "result
make "result firstword :inline
make "inline skipfirst :inline
output :result
end

to firstword :word
if emptyp :word [output "]
if equalp first :word "| | [output "]
output word (first :word) (firstword butfirst :word)
end

to skipfirst :word
if emptyp :word [output "]
if equalp first :word "| | [output skipspaces :word]
output skipfirst butfirst :word
end

to skipspaces :word
if emptyp :word [output "]
if equalp first :word "| | [output skipspaces butfirst :word]
output :word
end

;; Formatting helpers

to start
make "started "true
repeat :topmar [print []]
newindent
end

to newindent
newline
make "indent ifelse :filling [:filltab] [:nofilltab]
make "linecount :indent
end

to newline
make "line []
make "indent 0
make "linecount 0
end

to break
if emptyp :line [stop]
make "linecount :width
putline
newindent
if :filling [skip :parskip]
end

;; Formatting commands to be invoked by the user

to skip :howmany
break
repeat :howmany [print []]
make "printed :printed+:howmany
if :printed < :lines [stop]
repeat :pageheight-:printed [print []]
make "printed 0
end

to nofill
break
make "filling "false
newindent
end

to yesfill
break
if not :filling [skip :parskip]
make "filling "true
newindent
end