From 49436bdbb77f32ffec2035e836add04f98be49e3 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 29 May 2019 22:17:08 +0200
Subject: nix flake info --json: List the "provides"

It also lists the contents of "checks" and "packages".

For example:

  $ nix flake info --json | jq
  {
    "branch": "HEAD",
    "description": "The purely functional package manager",
    "epoch": 2019,
    "id": "nix",
    "lastModified": 1559161142,
    "path": "/nix/store/2w2qla8735dbxah8gai8r1nsbf5x4f5d-source",
    "provides": {
      "checks": {
        "binaryTarball": {},
        "nix-copy-closure": {},
        "perlBindings": {},
        "remoteBuilds": {},
        "setuid": {}
      },
      "defaultPackage": {},
      "devShell": {},
      "hydraJobs": {},
      "packages": {
        "nix": {},
        "nix-perl-bindings": {}
      }
    },
    "revCount": 6955,
    "revision": "8cb24e04e8b6cc60e2504733afe78e0eadafcd98",
    "uri": "/home/eelco/Dev/nix"
  }

Fixes #2820.
---
 src/nix/flake.cc | 56 +++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 41 insertions(+), 15 deletions(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 0be003da2..872ec2849 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -199,6 +199,19 @@ struct CmdFlakeUpdate : FlakeCommand
     }
 };
 
+static void enumerateProvides(EvalState & state, Value & vFlake,
+    std::function<void(const std::string & name, Value & vProvide)> callback)
+{
+    state.forceAttrs(vFlake);
+
+    auto vProvides = (*vFlake.attrs->get(state.symbols.create("provides")))->value;
+
+    state.forceAttrs(*vProvides);
+
+    for (auto & attr : *vProvides->attrs)
+        callback(attr.name, *attr.value);
+}
+
 struct CmdFlakeInfo : FlakeCommand, MixJSON
 {
     std::string name() override
@@ -215,25 +228,38 @@ struct CmdFlakeInfo : FlakeCommand, MixJSON
     {
         auto flake = getFlake();
         stopProgressBar();
-        if (json)
-            std::cout << flakeToJson(flake).dump() << std::endl;
-        else
-            printFlakeInfo(flake);
-    }
-};
 
-static void enumerateProvides(EvalState & state, Value & vFlake,
-    std::function<void(const std::string & name, Value & vProvide)> callback)
-{
-    state.forceAttrs(vFlake);
+        if (json) {
+            auto json = flakeToJson(flake);
 
-    auto vProvides = (*vFlake.attrs->get(state.symbols.create("provides")))->value;
+            auto state = getEvalState();
 
-    state.forceAttrs(*vProvides);
+            auto vFlake = state->allocValue();
+            flake::callFlake(*state, flake, *vFlake);
 
-    for (auto & attr : *vProvides->attrs)
-        callback(attr.name, *attr.value);
-}
+            auto provides = nlohmann::json::object();
+
+            enumerateProvides(*state,
+                *vFlake,
+                [&](const std::string & name, Value & vProvide) {
+                    auto provide = nlohmann::json::object();
+
+                    if (name == "checks" || name == "packages") {
+                        state->forceAttrs(vProvide);
+                        for (auto & aCheck : *vProvide.attrs)
+                            provide[aCheck.name] = nlohmann::json::object();
+                    }
+
+                    provides[name] = provide;
+                });
+
+            json["provides"] = std::move(provides);
+
+            std::cout << json.dump() << std::endl;
+        } else
+            printFlakeInfo(flake);
+    }
+};
 
 struct CmdFlakeCheck : FlakeCommand, MixJSON
 {
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