#!/usr/bin/ruby
# vim: et sw=2

VER="(d4e2ac8)"
ME="blppr: "

$lpp=0
$fl=0

class Block
  attr_reader :la, :lc
  Line=Struct.new :l, :st, :b, :c

  def initialize(h,s)
    @hdr=h
    @hst=s
    @hdr2=nil
    @hst2=nil
    @fld=nil
    @sep=nil
    @la=[]
    @lc=2
    @b=nil
    @c=nil
  end

  def hdr2(h,s)
    @hdr2=h
    @hst2=s
    @lc+=1
  end

  def fld(f,s)
    @fld=f
    @sep=s
    @lc+=2
  end

  def add(l,s)
    t=Line.new(l,s,nil,nil)
    if l.start_with?("\t") or l.start_with?(" "*8)
      t.c=@c
    elsif l.start_with?("  ")
      t.b=@b
      @c=t
    else
      @b=@c=t
    end
    @la<<t
    @lc+=1
  end

  def header
    res=[]
    if ($fl&2)!=0
      res<<@hst+@hdr
      res<<@hst2+@hdr2 if @hdr2
      res<<" "+@fld
      res<<" "+@sep
      return res
    end
    res<<@hdr
    res<<@fld
    res<<@sep
  end

  def sep
    if ($fl&2)!=0
      return " "+@sep
    end
    return @sep
  end
end

def spc(s)
  tmp=s.split(/\t+/)
  tmp2=s.scan(/[^\t]*\t*/)
  res=""
  tmp.length.times do |i|
    t=tmp2[i].count("\t")*8-(tmp[i].length%8)
    if t>0
      res+=tmp[i]+" "*t
    else
      res+=tmp[i]
    end
  end
  return res
end

def fmt(l)
  if ($fl&2)!=0
    return l.st+l.l
  end
  return l.l
end

def usage
  me=ME.delete(":")
  puts "Usage: "+me+"[-d] [-w] [-l <num>] [<file>]"
  puts "  -l <num>  - num of lines per page"
  puts "  -w        - fix whitespaces (tabs to spaces)"
  puts "  -d        - parse bldiff output"
  puts "  -c        - continuous output (no pages)"
  exit
end

i=0
while i<ARGV.length
  if ARGV[i]=="--"
    i+=1
    break
  end
  break if ARGV[i]=="-"
  break if not ARGV[i].start_with?("-")
  usage if ARGV[i]=="--help"
  if ARGV[i]=="--version"
    me=ME.delete(":")
    puts me+VER+" by Borg."
    exit
  end

  if ARGV[i]=="-l"
    i+=1
    if !ARGV[i]
      $stderr.puts ME+"Need argument for '-l' option"
      exit
    end
    $lpp=ARGV[i].to_i
    i+=1
    next
  end
  if ARGV[i]=="-w"
    i+=1
    $fl|=1
    next
  end
  if ARGV[i]=="-d"
    i+=1
    $fl|=3
    next
  end
  if ARGV[i]=="-c"
    i+=1
    $fl|=4
    next
  end
  $stderr.puts ME+"Unknown option: "+ARGV[i]
  exit
end

if ($fl&4)==0
  $lpp=ENV["BLPP"].to_i if $lpp==0
  if $lpp<20
    $stderr.puts ME+"lines per page too small"
    exit
  end
else
  $lpp=-1
end

if i<ARGV.length
  fn=ARGV[i]
  begin
    f=File.open(fn)
  rescue
    $stderr.puts ME+"unable to open file: "+fn
    exit
  end
else
  f=$stdin
end

blocks=[]
bl=fld=nil
inbl=false
for l in f
  l.chop!
  next if l.empty?
  st=" "
  if ($fl&2)!=0
    st=l.slice!(0,1)
  end
  if ($fl&1)!=0
    l=spc(l)
  end
  if inbl
    if l.start_with?("-----")
      blocks<<bl
      bl=fld=nil
      inbl=false
      next
    end
    bl.add(l,st)
    next
  end
  if l.start_with?("#")
    if bl
      bl.hdr2(l,st)
      next
    end
    bl=Block.new(l,st)
    next
  end
  if bl
    if not l.start_with?("-----")
      fld=l
      next
    end
    if !fld
      bl=nil
      next
    end
    bl.fld(fld,l)
    inbl=true
    next
  end
end
f.close if f!=$stdin

buf=[]
tmp=[]
lc=0
for bl in blocks
  lc=0 if lc==$lpp
  c=lc+bl.lc
  n=$lpp-lc
  if $lpp>0 and c>$lpp and (bl.lc<$lpp/2 or n<10)
    ($lpp-lc).times { buf<<"" }
    lc=0
  end
  if lc>0
    buf<<""
    lc+=1
  end
  arr=bl.header
  buf+=arr
  lc+=arr.length
  for l in bl.la
    if tmp.empty? or l.c
      tmp<<l
      next
    end
    z=tmp.last
    if l.b and (!z.b and !z.c)
      tmp<<l
      next
    end
    if $lpp<0 or lc+tmp.length<$lpp
      buf+=tmp.collect { |t| fmt(t) }
      lc+=tmp.length
      tmp.clear
      redo
    end
    if tmp.length>$lpp/2 or tmp.first.c
      while lc<$lpp-1
        buf<<fmt(tmp.shift)
        lc+=1
      end
    end
    buf<<bl.sep
    lc+=1
    if lc<$lpp
      ($lpp-lc).times { buf<<"" }
    end
    arr=bl.header
    buf+=arr
    lc=arr.length
    z=tmp.first
    if b=z.c
      if t=b.b
        buf<<fmt(t)
        lc+=1
      end
      buf<<fmt(b)
      lc+=1
    elsif b=z.b
      buf<<fmt(b)
      lc+=1
    end
    buf+=tmp.collect { |t| fmt(t) }
    lc+=tmp.length
    tmp.clear
    redo
  end
  while not tmp.empty?
    if $lpp<0 or lc+tmp.length<$lpp
      buf+=tmp.collect { |t| fmt(t) }
      lc+=tmp.length
      tmp.clear
      break
    end
    if tmp.length>$lpp/2 or tmp.first.c
      while lc<$lpp-1
        buf<<fmt(tmp.shift)
        lc+=1
      end
    end
    buf<<bl.sep
    lc+=1
    if lc<$lpp
      ($lpp-lc).times { buf<<"" }
    end
    arr=bl.header
    buf+=arr
    lc=arr.length
    z=tmp.first
    if b=z.c
      if t=b.b
        buf<<fmt(t)
        lc+=1
      end
      buf<<fmt(b)
      lc+=1
    elsif b=z.b
      buf<<fmt(b)
      lc+=1
    end
  end
  buf<<bl.sep
  lc+=1
end

fn="/tmp/blppr.%d" % Process.pid
begin
  f=File.open(fn,"w")
rescue
  $stderr.puts ME+"unable to open file: "+fn
end
buf.each { |l| f.puts l }
f.close
wn=`cygpath -m #{fn}`.chop
fork do
  system("/win/notepad2 "+wn)
  File.unlink(fn)
end