fish-shell/share/functions/__fish_complete_suffix.fish

#
# Find files that complete $argv[1], has the suffix $argv[2], and
# output them as completions with the optional description $argv[3] Both
# $argv[1] and $argv[3] are optional, if only one is specified, it is
# assumed to be the argument to complete.
#

function __fish_complete_suffix -d "Complete using files"

    # Variable declarations

    set -l comp
    set -l suff
    set -l desc
    set -l files

    switch (count $argv)

        case 1
            set comp (commandline -ct)
            set suff $argv
            set desc ""

        case 2
            set comp $argv[1]
            set suff $argv[2]
            set desc ""

        case 3
            set comp $argv[1]
            set suff $argv[2]
            set desc $argv[3]

    end

    # Strip leading ./ as it confuses the detection of base and suffix
    # It is conditionally re-added below.
    set -l base_temp (string replace -r '^\\./' '' -- $comp)

    set base (string replace -r '\\.[^.]*$' '' -- $base_temp | string trim -c '\'"') # " make emacs syntax highlighting happy
    # echo "base: $base" > /dev/tty
    # echo "suffix: $suff" > /dev/tty

    # If $comp is "./ma" and the file is "main.py", we'll catch that case here,
    # but complete.cpp will not consider it a match, so we have to output the
    # correct form.
    if string match -qr '^\\./' -- $comp
        # Also do directory completion, since there might be files
        # with the correct suffix in a subdirectory
        eval "set files ./$base*{$suff,/}"
    else
        # Also do directory completion, since there might be files
        # with the correct suffix in a subdirectory
        eval "set files $base*{$suff,/}"
    end

    # Another problem is that expanded paths are not matched, either.
    # So an expression like $HOME/foo*.zip will expand to /home/rdahl/foo-bar.zip
    # but that no longer matches the expression at the command line.
    if string match -qr '[${}*~]' $comp
        set -l expanded
        eval "set expanded $comp"
        # It's very unfortunate to do all this work in-process and have to shell out here,
        # but unfortunately at this time expressions like "foo{t,te}*" applied against
        # "footer" will result in "footer" being reported twice. Not sure if this can be
        # term a "bug" per-se.
        set files (string replace -- $expanded $comp $files | sort -u)
    end

    if test $files[1]
        printf "%s\t$desc\n" $files
    end

end