rewrite zsh completion generation

devscripts/zsh-completion.in

@@ -3,26 +3,8 @@
 __youtube_dl() {
     local curcontext="$curcontext" fileopts diropts cur prev
     typeset -A opt_args
-    fileopts="{{fileopts}}"
-    diropts="{{diropts}}"
-    cur=$words[CURRENT]
-    case $cur in
-        :)
-            _arguments '*: :(::ytfavorites ::ytrecommended ::ytsubscriptions ::ytwatchlater ::ythistory)'
-        ;;
-        *)
-            prev=$words[CURRENT-1]
-            if [[ ${prev} =~ ${fileopts} ]]; then
-                _path_files
-            elif [[ ${prev} =~ ${diropts} ]]; then
-                _path_files -/
-            elif [[ ${prev} == "--recode-video" ]]; then
-                _arguments '*: :(mp4 flv ogg webm mkv)'
-            else
-                _arguments '*: :({{flags}})'
-            fi
-        ;;
-    esac
+    _arguments {{args}} \
+      '*: :(::ytfavorites ::ytrecommended ::ytsubscriptions ::ytwatchlater ::ythistory)'
 }
 
-__youtube_dl
+__youtube_dl

devscripts/zsh-completion.py

@@ -4,6 +4,7 @@ from __future__ import unicode_literals
 import os
 from os.path import dirname as dirn
 import sys
+import optparse
 
 sys.path.insert(0, dirn(dirn((os.path.abspath(__file__)))))
 import youtube_dl
@@ -15,31 +16,45 @@ ZSH_COMPLETION_TEMPLATE = "devscripts/zsh-completion.in"
 def build_completion(opt_parser):
     opts = [opt for group in opt_parser.option_groups
             for opt in group.option_list]
-    opts_file = [opt for opt in opts if opt.metavar == "FILE"]
-    opts_dir = [opt for opt in opts if opt.metavar == "DIR"]
 
-    fileopts = []
-    for opt in opts_file:
+    # escaping is hard:
+    #  - help may contain colons
+    #  - metavar must have colons : escaped
+    #  - single quotes must be removed
+    #  - help must have square brackets [] escaped
+    def metaparse(opt):
+        if "--recode-video" == opt.get_opt_string():
+            return ":{}:(mp4 flv ogg webm mkv)".format(opt.metavar)
+        if opt.metavar is None:
+            return ""
+        if opt.metavar == "FILE":
+            return ":FILE:_files"
+        if opt.metavar == "DIR":
+            return ":DIR:_directories"
+        else:
+            return ":{}:".format(opt.metavar.replace(":", "\\:"))
+
+    def helpescape(opthelp):
+        if opthelp == optparse.SUPPRESS_HELP:
+            return ""
+        return "[{}]".format(opthelp.replace("'", "\"").replace("]", "\\]").replace("[", "\\["))
+
+    def optionexclude(opt):
+        # When an argument has a long and short version, the arguments entry shall be
+        # _arguments \
+        #   "(-t --thing)"{-t,--thing}"[do things]:WHAT_THING:"
+        # i.e. in parentheses with space the explanation of redundancy and in curly braces
+        # regular shell expansion to create two mostly identical entries.
         if opt._short_opts:
-            fileopts.extend(opt._short_opts)
-        if opt._long_opts:
-            fileopts.extend(opt._long_opts)
+            return "({0} {1})'{{{0},{1}}}'".format(opt._short_opts[0], opt.get_opt_string())
+        return "{}".format(opt.get_opt_string())
 
-    diropts = []
-    for opt in opts_dir:
-        if opt._short_opts:
-            diropts.extend(opt._short_opts)
-        if opt._long_opts:
-            diropts.extend(opt._long_opts)
-
-    flags = [opt.get_opt_string() for opt in opts]
+    mytest = ["'{}{}{}'".format(optionexclude(opt), helpescape(opt.help), metaparse(opt)) for opt in opts]
 
     with open(ZSH_COMPLETION_TEMPLATE) as f:
         template = f.read()
 
-    template = template.replace("{{fileopts}}", "|".join(fileopts))
-    template = template.replace("{{diropts}}", "|".join(diropts))
-    template = template.replace("{{flags}}", " ".join(flags))
+    template = template.replace("{{args}}", " \\\n      ".join(mytest))
 
     with open(ZSH_COMPLETION_FILE, "w") as f:
         f.write(template)