1 files changed, 111 insertions, 0 deletions
diff --git a/modules/by-name/ni/nix-index/command_not_found.fish b/modules/by-name/ni/nix-index/command_not_found.fish
new file mode 100644
index 00000000..bbdb2230
--- /dev/null
+++ b/modules/by-name/ni/nix-index/command_not_found.fish
@@ -0,0 +1,111 @@
+#!/usr/bin/env fish
+
+# nixos-config - My current NixOS configuration
+#
+# Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of my nixos-config.
+#
+# You should have received a copy of the License along with this program.
+# If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
+
+# This was taken from the
+# `${pkgs.nix-index}/etc/profile.d/command-not-found.sh` file on 2024-02-28
+
+function _log
+    printf $argv >&2
+end
+
+function _bail
+    __fish_default_command_not_found_handler $argv
+    return "$status"
+end
+
+function _common_prefix
+    set --function prefix
+
+    for str in $argv
+        set position 1
+        for c in (string split '' "$str")
+            if test -z $prefix[$position]
+                set prefix[$position] "$c"
+            else if test $prefix[$position] != "$c"
+                if test $position = 1
+                    # The first letter of the prefix mis-matched.
+                    # As such there is no shared prefix, and we can simple bail early.
+                    echo ""
+                    return
+                else
+                    set prefix $prefix[1..(math $position - 1)]
+                end
+                break
+            end
+
+            set position (math $position + 1)
+        end
+    end
+
+    echo "$(string join "" $prefix)"
+end
+
+function fish_command_not_found
+    # Only run if it's an interactive shell
+    if not status is-interactive
+        return (_bail $argv)
+    end
+
+    # The nixpkgs flake should always be available on NixOS
+    set --local toplevel nixpkgs
+    set --local cmd "$argv[1]"
+
+    set --local attrs "$(nix-locate --minimal --no-group --type x --type s --whole-name --at-root "/bin/$cmd")"
+
+    if test -n "$attrs"
+        set --function len "$(echo "$attrs" | count)"
+    else
+        set --function len 0
+    end
+
+    switch "$len"
+    case 0
+    case 1 or '*'
+        _log "The program '%s' is currently not installed.\n" "$cmd"
+    end
+
+    switch "$len"
+    case 0
+        return (_bail $argv)
+    case 1
+        # If only one package provides this, then we can invoke it
+        # without asking the user.
+
+        # These will not return 127 if they worked correctly.
+
+        _log "A shell will be opened with it.\n"
+
+        if nix build "$toplevel#$attrs" --no-link
+            nix shell "$toplevel#$attrs"
+            return "$status"
+        else
+            _log "Failed to build: '%s#%s'\n" "$toplevel" "$attrs"
+            return (_bail $argv)
+        end
+    case '*'
+        _log "It is provided by several packages. You can run it load it with:\n"
+
+        set --local counter 0
+        set --local attrs $(echo $attrs)
+        for attr in $attrs
+            _log "%3s)" "$counter"
+            _log " nix shell %s#%s\n" "$toplevel" "$attr";
+
+            set counter "$(math "$counter" + 1)"
+        end
+
+        commandline "nix shell $toplevel#$(_common_prefix $attrs)"
+    end
+
+    # command not found should always exit with 127
+    return 127
+end