build-document.nix

# Build a reproducible latex document with latexmk, based on:
# https://flyx.org/nix-flakes-latex/

{ pkgs
# Document source
, src ? ./.

# Name of the final pdf file
, name ? "document.pdf"

# Use -shell-escape
, shellEscape ? false

# Use minted (requires shellEscape)
, minted ? false

# Additional flags for latexmk
, extraFlags ? []

# Do not use the default latexmk flags. Usefull if you have a .latexmkrc or you
# don't want to use lualatex
, dontUseDefaultFlags ? false

# texlive packages needed to build the document
# you can also include other packages as a list.
, texlive ? pkgs.texlive.combined.scheme-full

# Pygments package to use (needed for minted)
, pygments ? pkgs.python39Packages.pygments

# Add system fonts
# you can specify one font directly with: pkgs.fira-code
# of join multiple fonts using symlinJoin:
#   pkgs.symlinkJoin { name = "fonts"; paths = with pkgs; [ fira-code souce-code-pro ]; }
, fonts ? null

# Date for the document in unix time. You can change it
# to "$(date -r . +%s)" , "$(date -d "2022/02/22" +%s)", toString
# self.lastModified
, SOURCE_DATE_EPOCH ? "$(git log -1 --pretty=%ct)"
}:

let 
  lib = pkgs.lib;
  defaultFlags = [
    "-interaction=nonstopmode"
    "-pdf"
    "-lualatex"
    "-pretex='\\pdfvariable suppressoptionalinfo 512\\relax'"
    "-usepretex"
  ];
  flags = lib.concatLists [
    (lib.optional (!dontUseDefaultFlags) defaultFlags)
    extraFlags
    (lib.optional shellEscape ["-shell-escape" ])
  ];
in

assert minted -> shellEscape;

pkgs.stdenvNoCC.mkDerivation rec {
  inherit src name;

  buildInputs = [ texlive pkgs.git ] ++
    lib.optional minted [ pkgs.which pygments ];

  TEXMFHOME = "./cache";
  TEXMFVAR = "./cache/var";

  OSFONTDIR = lib.optionalString (fonts != null) "${fonts}/share/fonts";

  buildPhase = ''
  runHook preBuild

  SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH}" latexmk ${toString flags}

  runHook postBuild
  '';

  installPhase = ''
  runHook preInstall

  install -m644 -D *.pdf $out/${name}

  runHook postInstall
  '';
}