#!/bin/bash

#  or

#!/usr/bin/env bash

#

# compact_comments.sh

# Copyright 2008 Ryan Barrett

#

# Compacts PyBlosxom comment files generated by comments.py into a single file,

# per entry. This makes rendering more efficient, particularly for entries with

# many comments, since fewer distinct files need to be statted and read from disk.

#

# For entry XXX, the all comment file will be named XXX-all.cmt.

#

# Operates on comment files in the current directory. Renames compacted

# comment files from *.cmt to *.cmt.compacted, but does not delete them.

#

# Currently, the .txt entry file suffix and .cmt comment file suffix are hard

# coded. If there's demand, they could easily be parameterized.

#

#

# Requires:

#

# - rename(1) that takes a perl expression, as opposed to fixed before and after

#   patterns.

#

# - xargs(1) that supports the -0 option.

#

# - find(1) that supports the -print0 option.

#

# - sed(1), head(1), tail(1), wc(1), expr(1)

echo 'Compacting all comments...'

for file in *.txt; do

  # filenames and patterns for the comment files for this entry

  all_cmt_file=`sed 's/.txt$/-all.cmt/' <<<"$file"`

  new_all_cmt_file="${all_cmt_file}.new"

  cmt_glob=`sed 's/.txt$/-????*.cmt/' <<<"$file"`

  # enumerate the comment files ahead of time, so that there's no race condition

  # in the globbing for copying their contents and for deleting them.

  cmt_files=`find . -maxdepth 1 -name "$cmt_glob"`

  if [ ! "$cmt_files" ]; then

    # no comment files for this entry to compact. skip it.

    continue

  fi

  # we know we're going to compact this entry's comments now.

  echo "$cmt_files"

  # write all of the comment files, including any existing -all.cmt file, to an

  # -all.cmt.new file.

  cat > "$new_all_cmt_file" <<-EOF

	<?xml version="1.0" encoding="utf-8"?>

	<items>

	EOF

  if [ -f "$all_cmt_file" ]; then

    # strip the leading <xml ...> and <items> and trailing </items> lines

    lines=`cat "$all_cmt_file" | wc -l`

    head -n `expr $lines - 1` "$all_cmt_file" \

      | tail -n `expr $lines - 3` \

      >> "$new_all_cmt_file"

  fi

  echo "$cmt_files" | while read cmt_file; do

    # strip the leading <xml ...> line

    lines=`cat "$cmt_file" | wc -l`

    tail -n `expr $lines - 1` "$cmt_file" >> "$new_all_cmt_file" 

  done

  cat >> "$new_all_cmt_file" <<-EOF

	</items>

	EOF

  # rename the existing *.cmt files to *.cmt.compacted.

  echo "$cmt_files" | while read cmt_file; do

    mv "$cmt_file" "${cmt_file}.compacted"

  done

  if [ -f "$all_cmt_file" ]; then

    mv "$all_cmt_file" "${all_cmt_file}.compacted"

  fi

  # finally, rename the -all.cmt.new file to -all.cmt.

  mv "${new_all_cmt_file}" "${all_cmt_file}"

done

echo '...done! Consider archiving or deleting *.compacted.'