Move to a profile-based configuration where common

This patch makes it so common configuration is now located in shared/
and each host basically just becomes a bunch of import statements.

The exception here is host-specific configuration like the `*.linus.onl`
that live inside `hosts/ahmed/`.

Specifically I have:

- moved common configuration `shared/{nixos,home-manager,nix-darwin}`.
- moved `hosts/common.nix` to `shared/nixos/common-{nix,shell}-settings.nix`.
- split `hosts/muhammed/{dev-utils,neovim}` into per-language
  configuration.

This patch was done in preparation for the arrival of a new host, which
will need to share a lot of configuration with Muhammed.

3 files changed, 111 insertions, 0 deletions

diff --git a/shared/home-manager/git/aliases.nix b/shared/home-manager/git/aliases.nix
new file mode 100644
index 0000000..03e586c
--- /dev/null
+++ b/shared/home-manager/git/aliases.nix
@@ -0,0 +1,25 @@
+# This module defines my personal git aliases. Some of these are
+# pseudo-subcommands which are easier to remember while others simply save me
+# some keystrokes.
+{...}: {
+  programs.git.aliases = {
+    unstage = "restore --staged"; # remove file from staging area
+    undo = "reset --soft HEAD~"; # undo last commit
+  };
+
+  home.shellAliases = {
+    gs = "git status";
+    gd = "git diff --";
+    gl = "git log --oneline HEAD~10..HEAD --";
+
+    gc = "git commit";
+    gcp = "git commit --patch";
+    gf = "git commit --amend --no-edit --";
+    gfp = "git commit --amend --no-edit --patch --";
+
+    ga = "git add --";
+    gan = "git add -N";
+    gap = "git add --patch";
+    gu = "git unstage";
+  };
+}
diff --git a/shared/home-manager/git/default.nix b/shared/home-manager/git/default.nix
new file mode 100644
index 0000000..748025d
--- /dev/null
+++ b/shared/home-manager/git/default.nix
@@ -0,0 +1,49 @@
+{
+  pkgs,
+  lib,
+  ...
+}: let
+  inherit (lib) optional;
+  inherit (pkgs.stdenv.hostPlatform) isDarwin;
+in {
+  imports = [
+    ./ignore.nix
+    ./aliases.nix
+  ];
+
+  programs.git = {
+    enable = true;
+
+    # Set privacy-respecting user information.
+    userName = "Linnnus";
+    userEmail = "[email protected]";
+
+    extraConfig = {
+      init.defaultBranch = "master";
+
+      help.autoCorrect = "prompt";
+
+      # Make sure we don't accidentally update submodules with changes that are only available locally.
+      # See: https://git-scm.com/book/en/v2/Git-Tools-Submodules
+      push.recurseSubmodules = "check";
+
+      # It seems like a de facto standard to have a file with this name in the
+      # project root containing all the commits that should be ignored when
+      # running `git blame`.
+      blame.ignoreRevsFile = ".git-blame-ignore-revs";
+
+      credential = {
+        "https://github.com/" = {
+          username = "linnnus";
+          helper = "${pkgs.gh}/bin/gh auth git-credential";
+        };
+        helper = (optional isDarwin "osxkeychain") ++ ["cache"];
+      };
+    };
+  };
+
+  home.packages = with pkgs; [
+    # Add the GitHub CLI for authentication.
+    gh
+  ];
+}
diff --git a/shared/home-manager/git/ignore.nix b/shared/home-manager/git/ignore.nix
new file mode 100644
index 0000000..8d1da2f
--- /dev/null
+++ b/shared/home-manager/git/ignore.nix
@@ -0,0 +1,37 @@
+# This module defines the contents of `~/.config/git/ignore`. It fetches the
+# templates for different gitignores and compiles them into one.
+{
+  pkgs,
+  lib,
+  ...
+}: let
+  gitignore = ignores:
+    pkgs.stdenv.mkDerivation {
+      name = (lib.concatStringsSep "+" ignores) + ".gitignore";
+
+      src = pkgs.fetchFromGitHub {
+        owner = "toptal";
+        repo = "gitignore";
+        rev = "7e72ecd8af69b39c25aedc645117f0dc261cedfd";
+        hash = "sha256-Ln3w6wx+pX4UFLY2gGJGax2/nxgp/Svrn0uctSIRdEc=";
+      };
+
+      inherit ignores;
+      buildPhase = ''
+        for i in $ignores; do
+          cat ./templates/$i.gitignore >>$out
+        done
+      '';
+    };
+
+  targets =
+    [
+      "Node"
+      "Deno"
+      "C"
+    ]
+    ++ (lib.optional pkgs.stdenv.isDarwin "MacOS")
+    ++ (lib.optional pkgs.stdenv.isLinux "Linux");
+in {
+  xdg.configFile."git/ignore".source = gitignore targets;
+}