completion: exif (#8246)

Adds completion support for the exif command line tool (upstream:
https://github.com/libexif/exif).

CHANGELOG.rst

@@ -87,6 +87,7 @@ Completions
 - Added completions for:
 
   - ``black`` (:issue:`8123`)
+  - ``exif`` (:issue:`8246`)
   - ``gping`` (:issue:`8181`)
   - Angular's ``ng`` (:issue:`8111`)
   - ``zef`` (:issue:`8114`)

share/completions/exif.fish

@@ -0,0 +1,60 @@
+function __fish_exif_target_file_tags
+    for target in (string match -v -- '-*' (commandline -po)[2..])
+        string replace -f '*' '' (exif --list-tags "$target" 2> /dev/null)[2..] | string replace -r '(\s+-){4}' '' | string split -m1 ' ' | string trim
+    end
+end
+
+function __fish_exif_potential_targets
+    set -l token (commandline -t)
+    set -l matching_files (complete -C "__fish_command_without_completions $token")
+    for file in $matching_files
+        if eval "test -d \"$file\""
+            echo $file
+        else if eval "exif \"$file\"" &>/dev/null
+            echo $file
+        else if not eval "test -e \"$file\""
+            # Handle filenames containing $.
+            if exif $file &>/dev/null
+                echo $file
+            end
+        end
+    end
+end
+
+function __fish_exif_token_begins_with_arg
+    not string match -- '-*' (commandline -t)
+end
+
+complete -c exif -f -a "(__fish_exif_potential_targets)" -n __fish_exif_token_begins_with_arg
+
+for line in (exif --help)
+    set -l short
+    set -l long
+    set -l description
+    if set -l matches (string match -r '^\s+-([\w?]),\s--([\w=-]+)\s+(.*)$' "$line")
+        set short $matches[2]
+        set long $matches[3]
+        set description $matches[4]
+    else if set -l matches (string match -r '^\s+--([\w=-]+)\s+(.*)$' "$line")
+        set long $matches[2]
+        set description $matches[3]
+    else
+        continue
+    end
+
+    if set -l sub_parts (string split -n --max 1 '=' $long)
+        set long "$sub_parts[1]"
+        switch (string lower "$sub_parts[2]")
+            case tag
+                complete -c exif -s$short -l $long -d "$description" -x -a "(__fish_exif_target_file_tags)"
+            case ifd
+                complete -c exif -s$short -l $long -d "$description" -x -a "0 1 EXIF GPS Interoperability"
+            case file
+                complete -c exif -s$short -l $long -d "$description" -F
+            case "*"
+                complete -c exif -s$short -l $long -d "$description" -x
+        end
+    else
+        complete -c exif -s$short -l $long -d "$description"
+    end
+end