From c934073436f1b19289634ad1abda6d40d26afb14 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Wed, 8 Dec 2021 01:05:35 +0100
Subject: import tex2nix bits

From https://github.com/Mic92/tex2nix commit 9379d49
---
 README.md           |  68 +++++++++++++++++++++++++++++++++
 tex2nix/__init__.py | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 176 insertions(+)
 create mode 100644 README.md
 create mode 100644 tex2nix/__init__.py

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1072dcf
--- /dev/null
+++ b/README.md
@@ -0,0 +1,68 @@
+# tex2nix
+
+Generate Texlive environment containing all dependencies for your document
+rather than downloading gigabytes of texlive packages.
+
+## Installation
+
+With stable nix you can do:
+
+``` console
+nix-build && ./result/bin/tex2nix
+```
+
+If you use flakes put the following in your inputs
+
+```nix
+{
+  inputs.tex2nix.url = "github:Mic92/tex2nix";
+  inputs.tex2nix.inputs.utils.follows = "nixpkgs";
+}
+```
+
+or just do:
+
+```console
+$ nix run github:Mic92/tex2nix
+```
+
+
+## USAGE
+
+```console
+$ tex2nix main.tex
+wrote tex-env.nix
+$ cat tex-env.nix
+# Generated with tex2nix 0.0.0
+{ texlive }:
+(texlive.combine {
+    inherit (texlive) scheme-small;
+    "varwidth" = texlive."varwidth";
+    "tabu" = texlive."tabu";
+
+})
+```
+
+tex2nix does not follow `\input` or `\include`. However you can specify multiple
+texfiles as input
+
+```console
+$ tex2nix *.tex
+```
+
+The resulting expression can be imported like this to in your document directory:
+
+```nix
+# shell.nix
+with import <nixpkgs> {};
+mkShell {
+  buildInputs = [ (pkgs.callPackage ./tex-env.nix {}) ];
+}
+```
+
+``` console
+$ nix-shell shell.nix
+nix-shell> pdflatex --version
+pdfTeX 3.14159265-2.6-1.40.21 (TeX Live 2020/NixOS.org)
+...
+```
diff --git a/tex2nix/__init__.py b/tex2nix/__init__.py
new file mode 100644
index 0000000..252895a
--- /dev/null
+++ b/tex2nix/__init__.py
@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+
+import re
+import fileinput
+import subprocess
+import json
+import os
+
+from typing import Set, Iterable
+
+
+def get_nix_packages() -> Set[str]:
+    res = subprocess.run(
+        [
+            "nix",
+            "--experimental-features",
+            "nix-command",
+            "eval",
+            "--json",
+            "-f",
+            "<nixpkgs>",
+            "texlive",
+            "--apply",
+            "builtins.attrNames",
+        ],
+        check=True,
+        text=True,
+        stdout=subprocess.PIPE,
+    )
+    return set(json.loads(res.stdout))
+
+
+def get_packages(line: str) -> Set[str]:
+    match = re.match(r"\\(?:usepackage|RequirePackage).*{([^}]+)}", line)
+    if not match:
+        return set()
+    args = match.group(1)
+    packages = set()
+    for arg in args.split(","):
+        packages.add(arg.strip())
+    return packages
+
+
+def _collect_deps(
+    working_set: Set[str], done: Set[str], all_packages: Set[str]
+) -> None:
+    package = working_set.pop()
+    done.add(package)
+    cmd = ["nix-build", "--no-out-link", "<nixpkgs>", "-A", f"texlive.{package}.pkgs"]
+    paths = subprocess.run(cmd, check=True, text=True, stdout=subprocess.PIPE)
+    for dir in paths.stdout.split("\n"):
+        path = os.path.join(dir, "tex")
+        for root, _, files in os.walk(path):
+            for fname in files:
+                path = os.path.join(root, fname)
+                with open(path, "rb") as f:
+                    for line in f:
+                        packages = get_packages(line.decode("utf-8", errors="ignore"))
+                        working_set |= all_packages & (packages - done)
+
+
+def collect_deps(packages: Set[str], all_packages: Set[str]) -> Set[str]:
+    working_set: Set[str] = set(packages)
+    done: Set[str] = set()
+    while working_set:
+        _collect_deps(working_set, done, all_packages)
+
+    return done
+
+
+def write_tex_env(dir: str, packages: Set[str]) -> str:
+    name = os.path.join(dir, "tex-env.nix")
+    with open(name, "w") as f:
+        f.write(
+            """# Generated with tex2nix 0.0.0
+{ texlive, extraTexPackages ? {} }:
+(texlive.combine ({
+    inherit (texlive) scheme-small;
+"""
+        )
+        for package in packages:
+            f.write(f'    "{package}" = texlive."{package}";\n')
+        f.write(
+            """
+} // extraTexPackages))
+"""
+        )
+    print("wrote tex-env.nix...")
+    return name
+
+
+def extract_dependencies(lines: Iterable[str]) -> Set[str]:
+    packages = set()
+    for line in lines:
+        packages |= get_packages(line)
+
+    all_packages = get_nix_packages()
+    nix_packages = packages & all_packages
+    return collect_deps(nix_packages, all_packages)
+
+
+def main() -> None:
+    packages = extract_dependencies(fileinput.input())
+    write_tex_env(os.getcwd(), packages)
+
+
+if __name__ == "__main__":
+    main()
-- 
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