init

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1748026106,
+        "narHash": "sha256-6m1Y3/4pVw1RWTsrkAK2VMYSzG4MMIj7sqUy7o8th1o=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "063f43f2dbdef86376cc29ad646c45c46e93234c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,16 @@
+{
+  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+  outputs = { nixpkgs, ... }: let
+    supportedArchitectures = [
+      "aarch64-darwin"
+      "aarch64-linux"
+      "x86_64-darwin"
+      "x86_64-linux"
+    ];
+  in {
+    packages = nixpkgs.lib.genAttrs supportedArchitectures (system: {
+      nix_templater = nixpkgs.legacyPackages.${system}.callPackage ./pkgs/nix_templater {};
+    });
+    legacyPackages = nixpkgs.lib.genAttrs supportedArchitectures (system: import ./lib.nix { pkgs = nixpkgs.legacyPackages.${system}; });
+  };
+}

lib.nix

@@ -0,0 +1,29 @@
+{ pkgs, text_templater }:
+rec {
+  fileContents = file: {
+   outPath = "<${builtins.placeholder "nix_template"}${toString file}${builtins.placeholder "nix_template"}>";
+   file = file;
+  };
+
+  template_text = { name, text, outPath }:
+    pkgs.runCommand name {
+      textBeforeTemplate = text;
+      script = ''
+        ${text_templater}/bin/text_templater ${builtins.placeholder "out"}/template ${builtins.placeholder "nix_template"} "${outPath}"
+      '';
+      passAsFile = [ "script" "textBeforeTemplate" ];
+    } ''
+      mkdir -p $out/bin
+      cp $textBeforeTemplatePath $out/template
+      cp $scriptPath $out/bin/${name}
+      chmod +x $out/bin/${name}
+    '';
+
+  test = template_text {
+    name = "test";
+    text = ''
+      blablabla ${fileContents (pkgs.writeText "lol" "lol")}
+    '';
+    outPath = "./test";
+  };
+}

pkgs/nix_templater/default.nix

@@ -0,0 +1,10 @@
+{ writeShellApplication, python3 }:
+writeShellApplication {
+  name = "text_templater";
+  runtimeInputs = [
+    python3
+  ];
+  text = ''
+    python ${./replace.py} "$@"
+    '';
+}

pkgs/nix_templater/replace.py

@@ -0,0 +1,31 @@
+import sys
+from pathlib import Path
+
+tempalte_file = sys.argv[1]
+magic_string = sys.argv[2]
+outfile = sys.argv[3]
+
+if Path(outfile).exists():
+    print(f"{outfile} already exists, aborting")
+    sys.exit(1)
+
+template_bytes = Path(tempalte_file).read_bytes()
+loc = 0
+output = b""
+
+
+while True:
+    magic_start = template_bytes[loc:].find(f"<{magic_string}".encode())
+    if magic_start == -1:
+        output += template_bytes[loc:]
+        break
+    magic_end = template_bytes[loc + magic_start :].find(f"{magic_string}>".encode())
+    magic_file = template_bytes[
+        (loc + magic_start + len(magic_string) + 1) : loc + magic_start + magic_end
+    ]
+    output += template_bytes[loc : loc + magic_start]
+    # TODO handle errors better here
+    output += Path(magic_file.decode()).read_bytes()
+    loc = loc + magic_start + magic_end + len(magic_string) + 1
+
+Path(outfile).write_bytes(output)