From 6997988d1bdcbb0558d6239d1b83294d9472f53a Mon Sep 17 00:00:00 2001
From: Arthur Noel <arthur@ischium.net>
Date: Thu, 23 Nov 2023 20:37:03 +0000
Subject: [PATCH] drop nix_direnv_watch_file - instead parse DIRENV_WATCHES

fixes #408
---
 README.md   |  8 ++++----
 default.nix |  6 ++++--
 direnvrc    | 45 ++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index 113b7e9..a9149e9 100644
--- a/README.md
+++ b/README.md
@@ -314,23 +314,23 @@ when deciding to update its cache.
     * `flake.lock`
     * `devshell.toml` if it exists
 
-To add more files to be checked use `nix_direnv_watch_file` like this
+To add more files to be checked use `watch_file` like this
 
 ```shell
-nix_direnv_watch_file your-file.nix
+watch_file your-file.nix
 use nix # or use flake
 ```
 
 Or - if you don't mind the overhead (runtime and conceptual) of watching all nix-files:
 
 ```shell
-nix_direnv_watch_file $(find . -name "*.nix" -printf '"%p" ')
+watch_file $(find . -name "*.nix" -printf '"%p" ')
 ```
 
 Note that this will re-execute direnv for any nix change,
 regardless of whether that change is meaningful for the devShell in use.
 
-`nix_direnv_watch_file` must be invoked before either `use flake` or `use nix` to take effect.
+`watch_file` must be invoked before either `use flake` or `use nix` to take effect.
 
 ## General direnv tips
 
diff --git a/default.nix b/default.nix
index b287a36..fffb0eb 100644
--- a/default.nix
+++ b/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, nix, gnugrep, lib }:
+{ stdenv, nix, gnugrep, gzip, jq, lib }:
 
 stdenv.mkDerivation {
   name = "nix-direnv";
@@ -8,7 +8,9 @@ stdenv.mkDerivation {
   postPatch = ''
     sed -i "2iNIX_BIN_PREFIX=${nix}/bin/" direnvrc
     substituteInPlace direnvrc \
-      --replace "grep" "${gnugrep}/bin/grep"
+      --replace "grep" "${gnugrep}/bin/grep" \
+      --replace gzip "${gzip}/bin/gzip" \
+      --replace JQ= "JQ=${jq}/bin/jq"
   '';
 
   installPhase = ''
diff --git a/direnvrc b/direnvrc
index 6e622ea..02485f9 100644
--- a/direnvrc
+++ b/direnvrc
@@ -197,8 +197,39 @@ _nix_argsum_suffix() {
 }
 
 nix_direnv_watch_file() {
+  # shellcheck disable=2016
+  log_error '`nix_direnv_watch_file` is deprecated - use `watch_file`'
   watch_file "$@"
-  nix_watches+=("$@")
+}
+
+# set by nix build - see ./default.nix
+JQ=
+
+_jq() {
+  if [[ -n $JQ ]]
+  then
+    $JQ "$@"
+  elif has jq
+  then
+    jq "$@"
+  else
+    nix-shell --packages jq --run "$(join_args jq "$@")"
+  fi
+}
+
+_nix_direnv_watches() {
+  local -n _watches=$1
+  # DIRENV_WATCHES is json | gzip (without header and trailer) | base64url
+  # allow files under $XDG_DATA_HOME/direenv/allow are filtered out as not relevant
+  # gzip header: https://datatracker.ietf.org/doc/html/rfc1952#page-6
+  mapfile -td "" _watches < <(
+    # shellcheck disable=2016
+    tr -- "-_" "+/" <<< "$DIRENV_WATCHES" \
+      | base64 --decode \
+      | (echo -ne "\x1f\x8b\x08\x00\x00\x00\x00\x00"; cat /dev/stdin) \
+      | (gzip --decompress 2>/dev/null || true) \
+      | _jq --join-output '.[] | select(.Exists ) | .Path | select(. | test($ENV.XDG_DATA_HOME + "/direnv/allow") | not) | (. + "\u0000")'
+  )
 }
 
 _nix_direnv_manual_reload=0
@@ -229,7 +260,7 @@ use_flake() {
     files_to_watch+=("$flake_dir/flake.nix" "$flake_dir/flake.lock" "$flake_dir/devshell.toml")
   fi
 
-  nix_direnv_watch_file "${files_to_watch[@]}"
+  watch_file "${files_to_watch[@]}"
 
   local layout_dir profile
   layout_dir=$(direnv_layout_dir)
@@ -238,8 +269,10 @@ use_flake() {
   local flake_inputs="${layout_dir}/flake-inputs/"
 
   local need_update=0
+  local watches
+  _nix_direnv_watches watches
   local file=
-  for file in "${nix_watches[@]}"; do
+  for file in "${watches[@]}"; do
     if [[ "$file" -nt "$profile_rc" ]]; then
       need_update=1
       break
@@ -388,11 +421,13 @@ use_nix() {
     esac
   done
 
-  nix_direnv_watch_file "$HOME/.direnvrc" "$HOME/.config/direnv/direnvrc" ".envrc" "shell.nix" "default.nix"
+  watch_file "$HOME/.direnvrc" "$HOME/.config/direnv/direnvrc" ".envrc" "shell.nix" "default.nix"
 
   local need_update=0
+  local watches
+  _nix_direnv_watches watches
   local file=
-  for file in "${nix_watches[@]}"; do
+  for file in "${watches[@]}"; do
     if [[ "$file" -nt "$profile_rc" ]]; then
       need_update=1
       break