Rewrite cheat.sh fzf helper script

home/.local/bin/scripts/cheat.sh

@@ -1,47 +1,111 @@
 #!/bin/sh
 
-# Select the cheatsheat
-SELECTABLE="$(curl -s "cheat.sh/:list")"
-if [ -n "$1" ]; then
-    if echo "$SELECTABLE" | grep -qe "\b$1\b"; then
-        selected="$1"
+# rm_trailing_slashes(string)
+#
+# Prints a string without any trailing slashes.
+# This is used because cheat.sh doesn't play nicely with multiple slashes in
+# URLs.
+rm_trailing_slashes() {
+    string="$1"
+    last_char="$(printf "$string" | tail -c 1)"
+    if [ "$last_char" = "/" ]; then
+        echo "$(rm_trailing_slashes "${string%?}")"
     else
-        echo "Invalid selection. For all selections, query cheat.sh/:list"
+        echo "$string"
+    fi
+}
+
+# pick_category(must_match, query, argument, recurse)
+#
+# Pick cheat.sh category.
+# if must_match is 1, only allow listed options to be picked.
+# if query is specified, pick sub-category of it, else pick global categories.
+# if argument is specified, optionally perform must_match check and print it.
+# if recurse is 1, if the selected option ends with /, run the function again.
+#
+# Prints the chosen category
+pick_category() {
+    must_match="$1"
+    query="$(rm_trailing_slashes "$2")"
+    argument="$3"
+    recurse="$4"
+
+    # Query all possible options
+    if [ -n "$query" ]; then
+        url="cheat.sh/$query/:list"
+    else
+        url="cheat.sh/:list"
+    fi
+    selectable="$(curl -s "$url")"
+
+    # If argument is specified, print it, optionally perform must_match check.
+    if [ -n "$argument" ]; then
+        if [ "$must_match" -ne 1 ] || echo "$selectable" | grep -qe "\b$1\b"; then
+            selected="$argument"
+        else
+            echo "Invalid selection: '$argument'"
+            echo "For all selections, query $url"
             exit 1
         fi
+    # Select the option with fzf, optionally allow other matches if must_match isn't set.
     else
-    selected=$(printf "$SELECTABLE" | fzf)
+        if [ "$must_match" -ne 1 ]; then
+            if [ -z "$selectable" ]; then
+                header="No selections found, you can use empty query to show category help, or type a custom query."
+            else
+                header="Use alt-enter to enter non-listed query. You can use empty queries to show category help."
+            fi
+            selected="$(printf "\n$selectable" | \
+                fzf --bind=alt-enter:print-query \
+                --print-query \
+                --prompt="cheat.sh/$query query>" \
+                --header="$header"\
+                )"
+        else
+            selected=$(printf "$selectable" | fzf --prompt="cheat.sh/$query category>")
             if [ $? -ne 0 ]; then
                 echo "Invalid selection: '$selected'"
+                echo "For all selections, query $url"
                 exit 1
             fi
+        fi
         selected=$(printf "$selected" | tail -1)
     fi
 
-# If the cheatsheet doesn't already include a query, select a query
-if echo "$selected" | grep -qe "[/:]"; then
-    query=""
-elif [ -n "$2" ]; then
-    query="$2"
-else
-    options=$(curl -s "cheat.sh/$selected/:list")
-    query="$(printf "\n$options" | \
-        fzf --bind=alt-enter:print-query \
-        --print-query \
-        --prompt="cheat.sh query>" \
-        --header="Use alt-enter to enter non-listed query. Empty queries are allowed."\
-        )"
-    query=$(echo "$query" | tail -1)
-fi
-query="$(echo "$query" | tr ' ' '+')"
 
-# cheat.sh doesn't play nicely with trailing / in URLs
+    # Replace spaces with '+' (cheat.sh resolves those as spaces)
+    selected="$(echo "$selected" | tr ' ' '+')"
+
+    # Prepend the original query, if we have one
+    # Print the selected category, or subcategory with the category
     if [ -n "$query" ]; then
-    url="cheat.sh/$selected/$query"
+        result="$query/$selected"
     else
-    url="cheat.sh/$selected"
+        result="$selected"
     fi
 
-# Print the URL and make the request
+    # Recurse, if specified and the result ended with /
+    if [ "$recurse" -eq 1 ]; then
+        if [ "$(printf "$selected" | tail -c 1)" = "/" ]; then
+            result="$(pick_category "$must_match" "$result" "$argument" 1)"
+        fi
+    fi
+
+    # Print the result
+    printf "$result"
+}
+
+# Select the cheatsheat category (language/core-util/...)
+query=$(pick_category 1 "" "$1" 0)
+
+# If the query isn't already complete, select a sub-category
+if ! echo "$query" | grep -qe ":"; then
+    query="$(pick_category 0 "$query" "$2" 1)"
+fi
+
+# Construct the URL from given query and print it
+url="cheat.sh/$query"
 echo "$url"
+
+# Show the output of cheat.sh request
 curl -s "$url"