Add cheat.sh script

home/packages/cli/scripts/default.nix

@@ -7,5 +7,6 @@
 in {
     home.packages = with scriptPkgs; [
       bitcoin
+      cheatsh
     ];
 }

home/packages/cli/scripts/packages/cheatsh/cheat.sh

@@ -0,0 +1,112 @@
+#!/bin/sh
+
+# 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 "%s" "$string" | tail -c 1)"
+  if [ "$last_char" = "/" ]; then
+    rm_trailing_slashes "${string%?}"
+  else
+    echo "$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 $url"
+      exit 1
+    fi
+  # Select the option with fzf, optionally allow other matches if must_match isn't set.
+  else
+    if [ "$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%s" "$selectable" |
+          fzf --bind=alt-enter:print-query \
+            --print-query \
+            --prompt="cheat.sh/$query query>" \
+            --header="$header"
+      )"
+    else
+      selected=$(printf "%s" "$selectable" | fzf --prompt="cheat.sh/$query category>")
+      # shellcheck disable=SC2181
+      if [ $? -ne 0 ]; then
+        echo "Invalid selection: '$selected'"
+        echo "For all selections, query $url"
+        exit 1
+      fi
+    fi
+    selected=$(printf "%s" "$selected" | tail -1)
+  fi
+
+  # Replace spaces with '+' (cheat.sh resolves those as spaces)
+  selected="$(echo "$selected" | tr ' ' '+')"
+
+  # Prepend the original query, if we have one
+  # Print the selected category, or subcategory with the category
+  if [ -n "$query" ]; then
+    result="$query/$selected"
+  else
+    result="$selected"
+  fi
+
+  # Recurse, if specified and the result ended with /
+  if [ "$recurse" -eq 1 ]; then
+    if [ "$(printf "%s" "$selected" | tail -c 1)" = "/" ]; then
+      result="$(pick_category "$must_match" "$result" "$argument" 1)"
+    fi
+  fi
+
+  # Print the result
+  printf "%s" "$result"
+}
+
+# Select the cheatsheat category (language/core-util/...)
+query=$(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"

home/packages/cli/scripts/packages/cheatsh/default.nix

@@ -0,0 +1,8 @@
+{pkgs, ...}:
+(pkgs.writeShellApplication {
+  name = "cheat.sh";
+  runtimeInputs = with pkgs; [coreutils curl jq gnugrep fzf];
+  text = ''
+    ${builtins.readFile ./cheat.sh}
+  '';
+})

home/packages/cli/scripts/packages/default.nix

@@ -4,6 +4,7 @@
 }: let
   packages = {
     bitcoin = pkgs.callPackage ./bitcoin.nix {};
+    cheatsh = pkgs.callPackage ./cheatsh {};
   };
 in
   packages