zsh: improve reuse completion

.config/zsh/completions/_reuse

@@ -7,10 +7,19 @@
 local curcontext=${curcontext} state state_descr line ret=1
 
 function _reuse_licenses() {
-    local licenses=(
-        $(reuse supported-licenses 2>&- | cut -d' ' -f1)
-    )
-    _values 'license' ${licenses}
+    local -a licenses
+    OLDIFS=${IFS}
+    IFS=$'\n'
+    for line in $(reuse supported-licenses 2>&-); do
+        # remove everything before and including the first whitespace and
+        # everything after and including the first http
+        desc=${${line#*[[:blank:]]}%[[:blank:]]http*}
+        # trim whitespace
+        [[ ${desc} =~ '^\s*(\S.*\S)\s*$' ]] && desc=$match[1] || desc=''
+        licenses+=(${line%% *}:${desc})
+    done
+    IFS=${OLDIFS}
+    _describe -t licenses license licenses && ret=0
 }
 
 function _reuse_styles() {
@@ -71,10 +80,8 @@ case ${state} in
             init:'initialize REUSE project'
             lint:'list all non-compliant files'
             spdx:"print the project's bill of materials in SPDX format"
-            supported-licenses:'list all supported SPDX licenses'
-            supported-licences:'list all supported SPDX licences'
+            {supported-licenses,supported-licences}:'list all supported SPDX licenses'
         )
-
         _describe -t subcommands subcommand subcommands && ret=0
         ;;
     (subcommand)
@@ -87,7 +94,7 @@ case ${state} in
                     {'(--license)-l','(-l)--license'}'[SPDX Identifier, repeatable]':license:_reuse_licenses \
                     {'(--year)-y','(-y)--year'}'[year of copyright statement, optional]':year \
                     {'(--style)-s','(-s)--style'}'[comment style to use, optional]':style:_reuse_styles \
-                    --copyright-style'[copyright style to use, optional]':copyright\ style:_reuse_copyright_styles \
+                    --copyright-style'[copyright style to use, optional]':'copyright style':_reuse_copyright_styles \
                     {'(--template)-t','(-t)--template'}'[name of template to use, optional]':template \
                     --exclude-year'[do not include year in statement]' \
                     --merge-copyrights'[merge copyright lines if copyright statements are identical]' \
@@ -97,6 +104,7 @@ case ${state} in
                     {'(--recursive)-r','(-r)--recursive'}'[add headers to all files under specified directories recursively]' \
                     --skip-unrecognised'[skip files with unrecognised comment styles]' \
                     --skip-existing'[skip files that already contain SPDX information]' \
+                    1:path:'_files' \
                     && ret=0
                 ;;
             (download)