class Camlp5TransitionalModeRequirement < Requirement
  fatal true

  satisfy(:build_env => false) { !Tab.for_name("camlp5").with?("strict") }

  def message; <<~EOS
    camlp5 must be compiled in transitional mode (instead of --strict mode):
      brew install camlp5
    EOS
  end
end

class Coq < Formula
  desc "Proof assistant for higher-order logic"
  homepage "https://coq.inria.fr/"
  url "https://github.com/coq/coq/archive/V8.7.0.tar.gz"
  sha256 "f376207ed051b3fd27c519f44b25eb25f8dddbce22715f68c3cedfd2e4b39297"
  head "https://github.com/coq/coq.git"

  bottle do
    sha256 "9fb0fc75bd4e70ded62131e90ab69f864eea83f8e36af4c796bdd9fab9b6a188" => :high_sierra
    sha256 "b338308d66bb15c1869d4d2fd2866c60c123aa0d64468e8ddc8f6877a9bcf016" => :sierra
    sha256 "1436182a25030ea3e118f696a3df0606957734bb000d782fef8ab021b8c0b687" => :el_capitan
  end

  depends_on "opam" => :build
  depends_on Camlp5TransitionalModeRequirement
  depends_on "camlp5"
  depends_on "ocaml"

  def install
    ENV["OPAMYES"] = "1"
    opamroot = buildpath/"../opamroot"
    opamroot.mkpath
    ENV["OPAMROOT"] = opamroot
    system "opam", "init", "--no-setup"
    system "opam", "install", "ocamlfind"

    system "opam", "config", "exec", "--",
           "./configure", "-prefix", prefix,
                          "-mandir", man,
                          "-emacslib", elisp,
                          "-coqdocdir", "#{pkgshare}/latex",
                          "-coqide", "no",
                          "-with-doc", "no"
    system "make", "world"
    ENV.deparallelize { system "make", "install" }
  end

  test do
    (testpath/"testing.v").write <<~EOS
      Require Coq.omega.Omega.
      Require Coq.ZArith.ZArith.

      Inductive nat : Set :=
      | O : nat
      | S : nat -> nat.
      Fixpoint add (n m: nat) : nat :=
        match n with
        | O => m
        | S n' => S (add n' m)
        end.
      Lemma add_O_r : forall (n: nat), add n O = n.
      Proof.
      intros n; induction n; simpl; auto; rewrite IHn; auto.
      Qed.

      Import Coq.omega.Omega.
      Import Coq.ZArith.ZArith.
      Open Scope Z.
      Lemma add_O_r_Z : forall (n: Z), n + 0 = n.
      Proof.
      intros; omega.
      Qed.
    EOS
    system("#{bin}/coqc", "#{testpath}/testing.v")
  end
end