#autoload

# Utility function for in-path completion.
# Supported arguments are: `-f', `-/', `-g <patterns>', `-J <group>',
# `-V <group>', `-W paths', `-X explanation', `-P prefix', `-S suffix',
# `-q', `-r remove-chars', `-R remove-func', and `-F <ignore>'. All but 
# the last have the same syntax and meaning as for `compgen' or
# `compadd', respectively. The `-F <ignore>' option may be used to give
# a list of suffixes either by giving the name of an array or
# literally by giving them in a string surrounded by
# parentheses. Files with one of the suffixes thus given are treated
# like files with one of the suffixes in the `fignore' array in normal
# completion.
#
# This function uses the helper functions `_match_test' and `_match_pattern'.

# First see if we should generate matches for the global matcher in use.

_match_test _path_files || return 1

# Yes, so...

local nm prepaths str linepath realpath donepath patstr prepath testpath rest
local tmp1 collect tmp2 suffixes i ignore matchflags opt group sopt pats gopt
local addpfx addsfx expl orig ostr nm=$compstate[nmatches] menu remsfx patlast
local origflags mflags

setopt localoptions nullglob rcexpandparam extendedglob
unsetopt markdirs globsubst shwordsplit nounset

prepaths=('')
ignore=()
group=()
sopt='-'
gopt=''
pats=()
addpfx=()
addsfx=()
remsfx=()
expl=()

# Get the options.

while getopts "P:S:qr:R:W:F:J:V:X:f/g:" opt; do
  case "$opt" in
  P)     addpfx=(-P "$OPTARG")
         ;;
  S)     addsfx=(-S "$OPTARG")
         ;;
  q)     tmp1=yes
         ;;
  [rR])  remsfx=("-$opt" "$OPTARG")
         ;;
  W)     tmp1="$OPTARG"
         if [[ "$tmp1[1]" = '(' ]]; then
           prepaths=( ${^=tmp1[2,-2]}/ )
         else
           prepaths=( ${(P)=${tmp1}} )
           (( ! $#prepaths )) && prepaths=( ${tmp1}/ )
         fi
         (( ! $#prepaths )) && prepaths=( '' )
         ;;
  F)     tmp1="$OPTARG"
         if [[ "$tmp1[1]" = '(' ]]; then
           ignore=( ${^=tmp1[2,-2]}/ )
         else
           ignore=( ${(P)${tmp1}} )
         fi
	 (( $#ignore )) && ignore=(-F "( $ignore )")
         ;;
  [JV])  group=("-$opt" "$OPTARG")
         ;;
  X)     expl=(-X "$OPTARG")
         ;;
  f)     sopt="${sopt}f"
         pats=("$pats[@]" '*')
	 ;;
  /)     sopt="${sopt}/"
         pats=("$pats[@]" '*(-/)')
	 ;;
  g)     gopt='-g'
         pats=("$pats[@]" ${=OPTARG})
	 ;;
  esac
done

[[ -n "$tmp1" && $#addsfx -ne 0 ]] && addsfx[1]=-qS

# If we were given no file selection option, we behave as if we were given
# a `-f'.

if [[ "$sopt" = - ]]; then
  if [[ -z "$gopt" ]]; then
    sopt='-f'
    pats=('*')
  else
    unset sopt
  fi
fi

# str holds the whole string from the command line with a `*' between
# the prefix and the suffix. Then we see if we will do menucompletion.

if [[ $#compstate[pattern_match] -ne 0 ]]; then
  str="${PREFIX}*${SUFFIX}"
else
  str="${PREFIX:q}*${SUFFIX:q}"
  [[ "$str" = \\\~* ]] && str="$str[2,-1]"
fi
orig="${PREFIX}${SUFFIX}"

[[ $compstate[insert] = *menu || -n "$_comp_correct" ||
   ( $#compstate[pattern_match] -ne 0 &&
     "${orig#\~}" != "${${orig#\~}:q}" ) ]] && menu=yes


# We will first try normal completion called with `compgen', but only if we
# weren't given a `-F', `-r', or `-R' option.

if [[ $#ignore -eq 0 && $#remsfx -eq 0 && -z "$_comp_correct" ]]; then
  # First build an array containing the `-W' option, if there is any and we
  # want to use it. We don't want to use it if the string from the command line
  # is a absolute path or relative to the current directory.

  if [[ -z "$tmp1[1]" || "$str[1]" = [~/] || "$str" = (.|..)/* ]]; then
    tmp1=()
  else
    tmp1=(-W "( $prepaths )")
  fi

  # Now call compgen.

  nm=$compstate[nmatches]
  if [[ -z "$gopt" ]]; then
    compgen "$addpfx[@]" "$addsfx[@]" "$group[@]" "$expl[@]" "$tmp1[@]" $sopt
  else
    compgen "$addpfx[@]" "$addsfx[@]" "$group[@]" "$expl[@]" "$tmp1[@]" $sopt -g "$pats"
  fi

  # If this generated any matches, we don't want to do in-path completion.

  [[ compstate[nmatches] -eq nm ]] || return 0
fi

# No `-F' option, so we want to use `fignore'.

(( $#ignore )) || ignore=(-F fignore)

# Now let's have a closer look at the string to complete.

if [[ "$str[1]" = \~ ]]; then
  # It begins with `~', so remember anything before the first slash to be able
  # to report it to the completion code. Also get an expanded version of it
  # (in `realpath'), so that we can generate the matches. Then remove that
  # prefix from the string to complete, set `donepath' to build the correct
  # paths and make sure that the loop below is run only once with an empty
  # prefix path by setting `prepaths'.
  
  linepath="${str%%/*}/"
  eval realpath\=$linepath
  [[ "$realpath" = "$linepath" ]] && return 1
  str="${str#*/}"
  orig="${orig#*/}"
  donepath=''
  prepaths=( '' )
else
  # If the string does not start with a `~' we don't remove a prefix from the
  # string.

  linepath=''
  realpath=''

  if [[ "$str[1]" = / ]]; then
    # If it is a absolut path name, we remove the first slash and put it in
    # `donepath' meaning that we treat it as the path that was already handled.
    # Also, we don't use the paths from `-W'.

    str="$str[2,-1]"
    orig="$orig[2,-1]"
    donepath='/'
    prepaths=( '' )
  else
    # The common case, we just use the string as it is, unless it begins with
    # `./' or `../' in which case we don't use the paths from `-W'.
    
    [[ "$str" = (.|..)/* ]] && prepaths=( '' )
    donepath=''
  fi
fi

# Now build the glob pattern by calling `_match_pattern'.
patstr="$str"
matchflags=""
_match_pattern _path_files patstr matchflags
origflags="$matchflags"
[[ -n "$_comp_correct" ]] && matchflags="$matchflags(#a$_comp_correct)"

# We almost expect the pattern to have changed `..' into `*.*.', `/.' into
# `/*.', and probably to contain two or more consecutive `*'s. Since these
# have special meaning for globbing, we remove them. But before that, we
# add the pattern for matching any characters before a slash.

patstr="$patstr:gs-/-*/-:gs/*.*./../:gs-/*.-/.-:gs/**/*/:gs-.*/-./-"

# We take the last pathname component from the pattern and store it in
# `patlast', replacing `*'s in it with patterns that match any character
# but not slashes. Later we will generate matches using `patstr' with the
# patterns we were given (like `*.c') appended to it, producing all matching
# files. These filenames are then compared to `patlast' and all names not
# matching that will be removed. All this is needed to be able to correctly
# support `completeinword' as otherwise we would have something like `a*x'
# from the line (the `*' was inserted above) and appending the `-g' pattern
# `*.tex' would yield `a*x*.tex' which is not what we want.

if [[ "$patstr" = */* ]]; then
  if [[ -n "$_comp_correct" && "${#orig##*/}" -le _comp_correct ]]; then
    patlast="*/${origflags}${${patstr##*/}//\*/[^/]#}"
  else
    patlast="*/${matchflags}${${patstr##*/}//\*/[^/]#}"
  fi
  patstr="${patstr%/*}/"
else
  if [[ -n "$_comp_correct" && "$#orig" -le _comp_correct ]]; then
    patlast="${origflags}${patstr//\*/[^/]#}"
  else
    patlast="${matchflags}${patstr//\*/[^/]#}"
  fi
  patstr=""
fi

# First we skip over all pathname components in `str' which really exist in
# the file-system, so that `/usr/lib/l<TAB>' doesn't offer you `lib' and
# `lib5'. Pathname components skipped this way are taken from `orig' and added
# to `donepath'.

while [[ "$orig" = */* ]] do
  tmp1=( $realpath$donepath${orig%%/*}/${~matchflags}${~patstr#*/}$^pats )
  tmp1=("${(@M)tmp1:#$~patlast}")
  [[ $#tmp1 -gt 0 && -e "$realpath$donepath${orig%%/*}" ]] || break
  donepath="$donepath${orig%%/*}/"
  orig="${orig#*/}"
  patstr="${patstr#*/}"
done

# Finally, generate the matches. First we loop over all the paths from `-W'.
# Note that in this loop `str' is used as a modifyable version of `patstr'
# and `testpath' is a modifyable version of `donepath'.

for prepath in "$prepaths[@]"; do
  str="$patstr"
  testpath="$donepath"
  ostr="$orig"

  [[ -z "$prepath" || "$prepath[-1]" = / ]] || prepath="${prepath}/"

  # The second loop tests the components of the path in `str' to get the
  # possible matches.

  while [[ "$str" = */* ]] do
    # `rest' is the pathname after the first slash that is left. In `tmp1'
    # we get the globbing matches for the pathname component currently
    # handled.

    if [[ -n "$_comp_correct" && "${#ostr%%/*}" -le _comp_correct ]]; then
      mflags="$origflags"
    else
      mflags="$matchflags"
    fi
    rest="${str#*/}"
    tmp1="${prepath}${realpath}${testpath}${~mflags}${str%%/*}(-/)"
    tmp1=( $~tmp1 )

    if [[ $#tmp1 -eq 0 ]]; then
      # If this didn't produce any matches, we don't need to test this path
      # any further, so continue with the next `-W' path, if any.

      continue 2
    elif [[ $#tmp1 -gt 1 ]]; then
      # If it produced more than one match, we want to remove those which
      # don't have possible following pathname components matching the 
      # rest of the string we are completing. (The case with only one
      # match is handled below.)
      # In `collect' we will collect those of the produced pathnames that
      # have a matching possible path-suffix. In `suffixes' we build an
      # array containing strings build from the rest of the string to 
      # complete and the glob patterns we were given as arguments.

      collect=()
      suffixes=( $rest$^pats )
      suffixes=( "${(@)suffixes:gs.**.*.}" )

      if [[ -n "$_comp_correct" && "${#ostr#*/}" -le _comp_correct ]]; then
        mflags="$origflags"
      else
        mflags="$matchflags"
      fi

      # In the loop the prefixes from the `tmp1' array produced above and
      # the suffixes we just built are used to produce possible matches
      # via globbing.

      for i in "$tmp1[@]" ; do
        tmp2=( ${~i}/${~mflags}${~suffixes} )
        tmp2=("${(@M)tmp2:#$~patlast}")
        [[ $#tmp2 -ne 0 ]] && collect=( $collect $i )
      done

      # If this test showed that none of the matches from the glob in `tmp1'
      # has a possible sub-path matching what's on the line, we add the
      # matches found in `tmp1' and otherwise give up and continue with the
      # next `-W' path.

      if [[ $#collect -eq 0 ]]; then
        continue 2
      elif [[ $#collect -ne 1 ]]; then
        # If we have more than one possible match, this means that the
	# pathname component currently handled is ambiguous, so we give
	# it to the completion code.
	# First we build the full path prefix in `tmp1'.

        tmp1="$prepath$realpath$testpath"

	# Now produce all matching pathnames in `collect'.

        collect=( ${~collect}/${~matchflags}${~suffixes} )
	collect=("${(@M)collect:#$~patlast}")

	# And then remove the common path prefix from all these matches.

        collect=( ${collect#$tmp1} )

	# Finally, we add all these matches with the common (unexpanded)
	# pathprefix (the `-p' option), the path-prefix (the `-W' option)
	# to allow the completion code to test file type, and the path-
	# suffix (the `-s' option). We also tell the completion code that
	# these are file names and that `fignore' should be used as usual
	# (the `-f' and `-F' options).

	if [[ -n "$menu" ]]; then
          compadd -QU "$addpfx[@]" "$addsfx[@]" "$group[@]" "$expl[@]" \
                  -i "$IPREFIX" -p "$linepath${testpath:q}" \
		  -s "/${ostr#*/}" \
		  -W "$tmp1" -f "$ignore[@]" - "${(@)${(@)collect%%/*}:q}"
	else
          for i in $collect; do
            compadd -QU "$addpfx[@]" "$addsfx[@]" "$group[@]" "$expl[@]" \
	            -i "$IPREFIX" -p "$linepath${testpath:q}" -s "/${${i#*/}:q}" \
		    -M 'r:|/=*' -W "$tmp1" -f "$ignore[@]" - "${${i%%/*}:q}"
          done
	fi

	# We have just finished handling all the matches from above, so we
	# can continue with the next `-W' path.

	continue 2
      fi

      # We reach this point if only one of the path prefixes in `tmp1'
      # has a existing path-suffix matching the string from the line.
      # In this case we accept this match and continue with the next
      # path-name component.

      tmp1=( "$collect[1]" )
    elif [[ -n "$_comp_correct" && "$mflags" = "$matchflags" ]]; then

      # If we got only one match with auto-correction and if we get none
      # without correction, stop now.

      tmp2="${prepath}${realpath}${testpath}${~origflags}${str%%/*}(-/)"
      tmp2=( $~tmp2 )

      if [[ $#tmp1 -ne $#tmp2 ]]; then
        compadd -QU "$addpfx[@]" -S '' "$group[@]" "$expl[@]" \
                -i "$IPREFIX" -p "$linepath${testpath:q}" -s "/${ostr#*/}" \
		- "${${tmp1#${prepath}${realpath}${testpath}}:q}"
        continue 2
      fi
    fi
    # This is also reached if the first globbing produced only one match
    # in this case we just continue with the next pathname component, too.

    tmp1="$tmp1[1]"
    testpath="$testpath${tmp1##*/}/"
    str="$rest"
    ostr="${ostr#*/}"
  done

  # We are here if all pathname components except the last one (which is still
  # not tested) are unambiguous. So we add matches with the full path prefix, 
  # no path suffix, the `-W' we are currently handling, all the matches we
  # can produce in this directory, if any.

  if [[ -n "$_comp_correct" && "${#ostr#*/}" -le _comp_correct ]]; then
    mflags="$origflags"
  else
    mflags="$matchflags"
  fi
  tmp1="$prepath$realpath$testpath"
  suffixes=( $str$^pats )
  suffixes=( "${(@)suffixes:gs.**.*.}" )
  tmp2=( ${~tmp1}${~matchflags}${~suffixes} )
  tmp2=("${(@M)tmp2:#$~patlast}")

  if [[ $#tmp2 -eq 0 ]]; then
    # No match, insert the expanded path and add the original tail.

    [[ "$testpath[-1]" = / ]] && testpath="$testpath[1,-2]"
    [[ -z "$testpath" && "$linepath[-1]" = / ]] && linepath="$linepath[1,-2]"
    [[ -n "$ostr" && -n "$linepath$testpath" ]] && ostr="/$ostr"

    # But only if something changed.
    [[ "$linepath$testpath$ostr" = "$PREFIX$SUFFIX" ]] && return 1

    compadd -QU -S '' "$group[@]" "$expl[@]" \
            -i "$IPREFIX" -f - "$linepath${testpath:q}$ostr"
  else
    compadd -QU "$addpfx[@]" "$addsfx[@]" "$remsfx[@]" "$group[@]" "$expl[@]" \
            -i "$IPREFIX" -p "$linepath${testpath:q}" -f "$ignore[@]" \
	    -W "$prepath$realpath$testpath" - "${(@)${(@)tmp2#$tmp1}:q}"
  fi
done

# This sets the return value to indicate that we added matches (or not).

[[ nm -ne compstate[nmatches] ]]