add(nix): add crate2nix (#1181)

* add(nix): add crate2nix

To have a better experience on ci, due to improved caching
of dependencies. Also organize file hierarchy slightly.

* ci(nix): manually check a default system

Is needed because `nix flake check` accidentally tries to build IFD.

6 files changed, 235 insertions, 128 deletions

diff --git a/.github/workflows/nix.yml b/.github/workflows/nix.yml
index f6ef3e36..c78b831b 100644
--- a/.github/workflows/nix.yml
+++ b/.github/workflows/nix.yml
@@ -9,11 +9,33 @@ on:
       - main
 
 jobs:
-  nix:
+  #check:
+    #runs-on: ubuntu-latest
+    #name: "flake check"
+    #environment: cachix
+    #timeout-minutes: 5
+    #steps:
+      #- uses: actions/checkout@v3
+        #with:
+          ## Nix Flakes doesn't work on shallow clones
+          #fetch-depth: 0
+      #- uses: cachix/install-nix-action@v16
+        #with:
+          #extra_nix_config: |
+            #experimental-features = nix-command flakes
+          #fetch-depth: 0
+      #- uses: cachix/cachix-action@v10
+        #with:
+          #name: zellij
+          ## If you chose API tokens for write access OR if you have a private cache
+          #authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+      #- run: nix flake check --print-build-logs --show-trace
+
+  build:
     runs-on: ubuntu-latest
-    name: nix-build
+    name: "build"
     environment: cachix
-    timeout-minutes: 15
+    timeout-minutes: 25
     steps:
       - uses: actions/checkout@v3
         with:
@@ -29,6 +51,25 @@ jobs:
           name: zellij
           # If you chose API tokens for write access OR if you have a private cache
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-      - run: nix flake check --print-build-logs --show-trace
       - run: nix build
+  develop:
+    runs-on: ubuntu-latest
+    name: develop
+    environment: cachix
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          # Nix Flakes doesn't work on shallow clones
+          fetch-depth: 0
+      - uses: cachix/install-nix-action@v16
+        with:
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+          fetch-depth: 0
+      - uses: cachix/cachix-action@v10
+        with:
+          name: zellij
+          # If you chose API tokens for write access OR if you have a private cache
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
       - run: nix develop --profile devShell
diff --git a/flake.lock b/flake.lock
index 44af65bb..de190c8c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,5 +1,21 @@
 {
   "nodes": {
+    "crate2nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1646322090,
+        "narHash": "sha256-Jtqd5Ory+1LgMMTY0tNJKd/U2mOiPRd/oYnuyTHE08o=",
+        "owner": "kolloch",
+        "repo": "crate2nix",
+        "rev": "c4a479172ebafdd3baf36aa274b2168b4fd42f40",
+        "type": "github"
+      },
+      "original": {
+        "owner": "kolloch",
+        "repo": "crate2nix",
+        "type": "github"
+      }
+    },
     "flake-compat": {
       "flake": false,
       "locked": {
@@ -49,6 +65,7 @@
     },
     "root": {
       "inputs": {
+        "crate2nix": "crate2nix",
         "flake-compat": "flake-compat",
         "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
diff --git a/flake.nix b/flake.nix
index 1650eefd..6e01933d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,130 +10,9 @@
     rust-overlay.inputs.flake-utils.follows = "flake-utils";
     flake-compat.url = "github:edolstra/flake-compat";
     flake-compat.flake = false;
+    crate2nix.url = "github:kolloch/crate2nix";
+    crate2nix.flake = false;
   };
 
-  outputs = { self, rust-overlay, nixpkgs, flake-utils, flake-compat }:
-    flake-utils.lib.eachSystem [
-      "aarch64-linux"
-      "aarch64-darwin"
-      "i686-linux"
-      "x86_64-darwin"
-      "x86_64-linux"
-    ]
-      (system:
-        let
-          overlays = [ (import rust-overlay) ];
-
-          pkgs = import nixpkgs { inherit system overlays; };
-
-          name = "zellij";
-          pname = name;
-          root = toString ./.;
-
-          ignoreSource = [ ".git" "target" "example" ];
-
-          src = pkgs.nix-gitignore.gitignoreSource ignoreSource root;
-
-          rustToolchainToml = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain;
-          cargoLock = {
-              lockFile = (builtins.path { path = ./Cargo.lock; name = "Cargo.lock"; });
-          };
-          cargo = rustToolchainToml;
-          rustc = rustToolchainToml;
-
-          #env
-          RUST_BACKTRACE = 1;
-
-          buildInputs = [
-            rustToolchainToml
-
-            # in order to run tests
-            pkgs.openssl
-          ];
-
-          nativeBuildInputs = [
-            # generates manpages
-            pkgs.mandown
-
-            pkgs.installShellFiles
-            pkgs.copyDesktopItems
-
-            # for openssl/openssl-sys
-            pkgs.pkg-config
-          ];
-
-          devInputs = [
-            pkgs.cargo-make
-            pkgs.rust-analyzer
-            pkgs.nixpkgs-fmt
-
-            # optimizes wasm binaries
-            pkgs.binaryen
-
-            # used for snapshotting the e2e tests
-            pkgs.cargo-insta
-          ];
-
-        in
-        rec {
-
-          packages.zellij =
-            (pkgs.makeRustPlatform { inherit cargo rustc; }).buildRustPackage {
-              inherit src name cargoLock buildInputs nativeBuildInputs;
-
-              preCheck = ''
-                HOME=$TMPDIR
-              '';
-
-              postInstall = ''
-                mandown ./docs/MANPAGE.md > ./zellij.1
-                installManPage ./zellij.1
-
-                # explicit behavior
-                $out/bin/zellij setup --generate-completion bash > ./completions.bash
-                installShellCompletion --bash --name ${pname}.bash ./completions.bash
-                $out/bin/zellij setup --generate-completion fish > ./completions.fish
-                installShellCompletion --fish --name ${pname}.fish ./completions.fish
-                $out/bin/zellij setup --generate-completion zsh > ./completions.zsh
-                installShellCompletion --zsh --name _${pname} ./completions.zsh
-
-                install -Dm644  ./assets/logo.png $out/share/icons/hicolor/scalable/apps/zellij.png
-
-                copyDesktopItems
-              '';
-
-              desktopItems = [
-                (pkgs.makeDesktopItem {
-                  type = "Application";
-                  inherit name;
-                  desktopName = "zellij";
-                  terminal = true;
-                  genericName = "Terminal multiplexer";
-                  comment = "Manage your terminal applications";
-                  exec = "zellij";
-                  icon = "zellij";
-                  categories = [ "ConsoleOnly;System" ];
-                })
-              ];
-
-              meta = with pkgs.lib; {
-                homepage = "https://github.com/zellij-org/zellij/";
-                description = "A terminal workspace with batteries included";
-                license = [ licenses.mit ];
-              };
-            };
-
-          defaultPackage = packages.zellij;
-
-          # nix run
-          apps.zellij = flake-utils.lib.mkApp { drv = packages.zellij; };
-          defaultApp = apps.zellij;
-
-          devShell = pkgs.mkShell {
-            name = "zellij-dev";
-            inherit buildInputs RUST_BACKTRACE;
-            nativeBuildInputs = nativeBuildInputs ++ devInputs;
-          };
-
-        });
+    outputs = { ... } @ args: import ./nix args;
 }
diff --git a/nix/crate2nix.nix b/nix/crate2nix.nix
new file mode 100644
index 00000000..14c1e749
--- /dev/null
+++ b/nix/crate2nix.nix
@@ -0,0 +1,30 @@
+{ pkgs
+, crate2nix
+, name
+, src
+, postInstall
+, desktopItems
+, meta
+}:
+
+let
+  inherit (import "${crate2nix}/tools.nix" { inherit pkgs; })
+    generatedCargoNix;
+
+  project = import
+    (generatedCargoNix {
+        inherit name src;
+    })
+    {
+      inherit pkgs;
+      buildRustCrateForPkgs = pkgs:
+        pkgs.buildRustCrate.override {
+          defaultCrateOverrides = pkgs.defaultCrateOverrides // {
+              inherit postInstall desktopItems meta;
+            # Crate dependency overrides go here
+          };
+        };
+    };
+
+in
+project.workspaceMembers.zellij.build
diff --git a/nix/default.nix b/nix/default.nix
new file mode 100644
index 00000000..a863810a
--- /dev/null
+++ b/nix/default.nix
@@ -0,0 +1,129 @@
+{ self
+, nixpkgs
+, rust-overlay
+, flake-utils
+, flake-compat
+, crate2nix
+}:
+flake-utils.lib.eachSystem [
+  "aarch64-linux"
+  "aarch64-darwin"
+  "i686-linux"
+  "x86_64-darwin"
+  "x86_64-linux"
+]
+  (system:
+    let
+      overlays = [ (import rust-overlay) ];
+
+      pkgs = import nixpkgs { inherit system overlays; };
+
+      name = "zellij";
+      pname = name;
+      root = toString ../.;
+
+      ignoreSource = [ ".git" "target" "example" ];
+
+      src = pkgs.nix-gitignore.gitignoreSource ignoreSource root;
+
+      rustToolchainToml = pkgs.rust-bin.fromRustupToolchainFile ../rust-toolchain;
+      cargoLock = {
+        lockFile = (builtins.path { path = ../Cargo.lock; name = "Cargo.lock"; });
+      };
+      cargo = rustToolchainToml;
+      rustc = rustToolchainToml;
+
+      buildInputs = [
+        rustToolchainToml
+
+        # in order to run tests
+        pkgs.openssl
+      ];
+
+      nativeBuildInputs = [
+        # generates manpages
+        pkgs.mandown
+
+        pkgs.installShellFiles
+        pkgs.copyDesktopItems
+
+        # for openssl/openssl-sys
+        pkgs.pkg-config
+      ];
+
+      devInputs = [
+        pkgs.cargo-make
+        pkgs.rust-analyzer
+        pkgs.nixpkgs-fmt
+
+        # optimizes wasm binaries
+        pkgs.binaryen
+
+        # used for snapshotting the e2e tests
+        pkgs.cargo-insta
+      ];
+
+      postInstall = ''
+        mandown ./docs/MANPAGE.md > ./zellij.1
+        installManPage ./zellij.1
+
+        # explicit behavior
+        $out/bin/zellij setup --generate-completion bash > ./completions.bash
+        installShellCompletion --bash --name ${pname}.bash ./completions.bash
+        $out/bin/zellij setup --generate-completion fish > ./completions.fish
+        installShellCompletion --fish --name ${pname}.fish ./completions.fish
+        $out/bin/zellij setup --generate-completion zsh > ./completions.zsh
+        installShellCompletion --zsh --name _${pname} ./completions.zsh
+
+        install -Dm644  ./assets/logo.png $out/share/icons/hicolor/scalable/apps/zellij.png
+
+        copyDesktopItems
+      '';
+
+      desktopItems = [
+        (pkgs.makeDesktopItem {
+          type = "Application";
+          inherit name;
+          desktopName = "zellij";
+          terminal = true;
+          genericName = "Terminal multiplexer";
+          comment = "Manage your terminal applications";
+          exec = "zellij";
+          icon = "zellij";
+          categories = [ "ConsoleOnly;System" ];
+        })
+      ];
+      meta = with pkgs.lib; {
+        homepage = "https://github.com/zellij-org/zellij/";
+        description = "A terminal workspace with batteries included";
+        license = [ licenses.mit ];
+      };
+    in
+    rec {
+
+      # crate2nix - better incremental builds, but uses ifd
+      packages.zellij = pkgs.callPackage ./crate2nix.nix {
+        inherit crate2nix name src desktopItems postInstall meta;
+      };
+
+      # native nixpkgs support - keep supported
+      packages.zellij-native =
+        (pkgs.makeRustPlatform { inherit cargo rustc; }).buildRustPackage {
+            inherit src name cargoLock
+            buildInputs nativeBuildInputs
+            postInstall desktopItems meta;
+        };
+
+      defaultPackage = packages.zellij;
+
+      # nix run
+      apps.zellij = flake-utils.lib.mkApp { drv = packages.zellij; };
+      defaultApp = apps.zellij;
+
+
+      devShell = pkgs.callPackage ./devShell.nix {
+        inherit buildInputs;
+        nativeBuildInputs = nativeBuildInputs ++ devInputs;
+      };
+
+    })
diff --git a/nix/devShell.nix b/nix/devShell.nix
new file mode 100644
index 00000000..86850e70
--- /dev/null
+++ b/nix/devShell.nix
@@ -0,0 +1,11 @@
+{ mkShell
+, buildInputs
+, nativeBuildInputs
+}:
+
+mkShell {
+  name = "zj-dev-env";
+  inherit buildInputs nativeBuildInputs;
+  ### Environment Variables
+  RUST_BACKTRACE = 1;
+}