From dca60104d2f0d935530a882f0e793b5c85d68d0f Mon Sep 17 00:00:00 2001
From: Timothy DeHerrera <tim@nrdxp.dev>
Date: Wed, 11 Jan 2023 13:53:42 -0700
Subject: [PATCH] path-info: inplement --query-substitutes

Fixes #3946
---
 src/nix/path-info.cc | 43 +++++++++++++++++++++++++++++++++++++++++--
 src/nix/path-info.md |  9 +++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 613c5b1918dc..0dd191a8ac45 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -16,6 +16,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
     bool showClosureSize = false;
     bool humanReadable = false;
     bool showSigs = false;
+    bool showSubStatus = false;
 
     CmdPathInfo()
     {
@@ -45,6 +46,13 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             .description = "Show signatures.",
             .handler = {&showSigs, true},
         });
+
+        addFlag({
+            .longName = "--query-substitutes",
+            .shortName = 'U',
+            .description = "Query path availability in the configured substituters, printing only those that are not; with `--json` adds a `substitutable` boolean to the output.",
+            .handler = {&showSubStatus, true},
+        });
     }
 
     std::string description() override
@@ -87,13 +95,44 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             pathLen = std::max(pathLen, store->printStorePath(storePath).size());
 
         if (json) {
-            std::cout << store->pathInfoToJSON(
+            auto json = store->pathInfoToJSON(
                 // FIXME: preserve order?
                 StorePathSet(storePaths.begin(), storePaths.end()),
-                true, showClosureSize, SRI, AllowInvalid).dump();
+                true, showClosureSize, SRI, AllowInvalid);
+
+            if (showSubStatus) {
+                StorePathSet inputPaths = StorePathSet(storePaths.begin(), storePaths.end());
+                auto substitutablePaths = store->querySubstitutablePaths(inputPaths);
+
+                auto jsonNew = nlohmann::json::array();
+
+                for (auto v : json) {
+                    std::string const storePathS = v["path"];
+                    substitutablePaths.find(store->followLinksToStorePath(storePathS)) ==
+                            substitutablePaths.end()
+                        ? v["substitutable"] = false
+                        : v["substitutable"] = true;
+                    jsonNew.emplace_back(std::move(v));
+                }
+                std::cout << jsonNew.dump();
+            }
+            else std::cout << json.dump();
         }
 
         else {
+            StorePaths missingPaths;
+
+            if (showSubStatus) {
+                StorePathSet inputPaths = StorePathSet(storePaths.begin(), storePaths.end());
+                auto substitutablePaths = store->querySubstitutablePaths(inputPaths);
+
+                for (auto & path : storePaths) {
+                    if (substitutablePaths.find(path) == substitutablePaths.end())
+                      missingPaths.emplace_back(std::move(path));
+                }
+
+                storePaths = missingPaths;
+            }
 
             for (auto & storePath : storePaths) {
                 auto info = store->queryPathInfo(storePath);
diff --git a/src/nix/path-info.md b/src/nix/path-info.md
index b30898ac0f03..eb29700fd238 100644
--- a/src/nix/path-info.md
+++ b/src/nix/path-info.md
@@ -39,6 +39,15 @@ R""(
 
   ```
 
+* Print all dependant paths which do not exist in any configured binary cache:
+
+  ```console
+  # nix path-info -rU /nix/store/blzxgyvrk32ki6xga10phr4sby2xf25q-geeqie-1.5.1
+  /nix/store/blzxgyvrk32ki6xga10phr4sby2xf25q-geeqie-1.5.1
+  /nix/store/w2vgpk3rdl6smqz7ixxywqapgagsarjf-fbida-2.14
+  ...
+  ```
+
 * Print the 10 most recently added paths (using --json and the jq(1)
   command):