require "language/haskell"

class Agda < Formula
  include Language::Haskell::Cabal

  desc "Dependently typed functional programming language"
  homepage "http://wiki.portal.chalmers.se/agda/"

  stable do
    url "https://hackage.haskell.org/package/Agda-2.5.4/Agda-2.5.4.tar.gz"
    sha256 "b40971e3312461771e36a11aaf4002424178301cf315b21a679f527b79c09e09"

    resource "stdlib" do
      url "https://github.com/agda/agda-stdlib.git",
          :revision => "209626953d56294e9bd3d8892eda43b844b0edf9"
    end
  end

  bottle do
    sha256 "414ea2394732564d1460ffe14e0fedd0a6a9e32df9b73085bedf9405b2a16962" => :high_sierra
    sha256 "dc42fc5d6a0c317ca4c3ede6eb8c6449b04aa5c288e9ee4e9fa0f8c78641842f" => :sierra
    sha256 "d71ecb0480c3494219b14a0f99774b3c194d02efc4b46432016314051fe5736c" => :el_capitan
  end

  head do
    url "https://github.com/agda/agda.git"

    resource "stdlib" do
      url "https://github.com/agda/agda-stdlib.git"
    end
  end

  deprecated_option "without-ghc@8.2" => "without-ghc"
  deprecated_option "without-malonzo" => "without-ghc"

  option "without-stdlib", "Don't install the Agda standard library"
  option "without-ghc", "Disable the GHC backend"

  depends_on "ghc" => :recommended
  if build.with? "ghc"
    depends_on "cabal-install" => [:build, :test]
  else
    depends_on "cabal-install" => :build
    depends_on "ghc" => :build
  end

  depends_on "emacs" => :recommended

  def install
    # install Agda core
    install_cabal_package :using => ["alex", "happy", "cpphs"]

    if build.with? "stdlib"
      resource("stdlib").stage lib/"agda"

      # generate the standard library's bytecode
      cd lib/"agda" do
        cabal_sandbox :home => buildpath, :keep_lib => true do
          cabal_install "--only-dependencies"
          cabal_install
          system "GenerateEverything"
        end
      end

      # generate the standard library's documentation and vim highlighting files
      cd lib/"agda" do
        system bin/"agda", "-i", ".", "-i", "src", "--html", "--vim", "README.agda"
      end
    end

    # compile the included Emacs mode
    if build.with? "emacs"
      system bin/"agda-mode", "compile"
      elisp.install_symlink Dir["#{share}/*/Agda-#{version}/emacs-mode/*"]
    end
  end

  def caveats
    s = ""

    if build.with? "stdlib"
      s += <<~EOS
        To use the Agda standard library by default:
          mkdir -p ~/.agda
          echo #{HOMEBREW_PREFIX}/lib/agda/standard-library.agda-lib >>~/.agda/libraries
          echo standard-library >>~/.agda/defaults
      EOS
    end

    s
  end

  test do
    simpletest = testpath/"SimpleTest.agda"
    simpletest.write <<~EOS
      module SimpleTest where

      data ℕ : Set where
        zero : ℕ
        suc  : ℕ → ℕ

      infixl 6 _+_
      _+_ : ℕ → ℕ → ℕ
      zero  + n = n
      suc m + n = suc (m + n)

      infix 4 _≡_
      data _≡_ {A : Set} (x : A) : A → Set where
        refl : x ≡ x

      cong : ∀ {A B : Set} (f : A → B) {x y} → x ≡ y → f x ≡ f y
      cong f refl = refl

      +-assoc : ∀ m n o → (m + n) + o ≡ m + (n + o)
      +-assoc zero    _ _ = refl
      +-assoc (suc m) n o = cong suc (+-assoc m n o)
    EOS

    stdlibtest = testpath/"StdlibTest.agda"
    stdlibtest.write <<~EOS
      module StdlibTest where

      open import Data.Nat
      open import Relation.Binary.PropositionalEquality

      +-assoc : ∀ m n o → (m + n) + o ≡ m + (n + o)
      +-assoc zero    _ _ = refl
      +-assoc (suc m) n o = cong suc (+-assoc m n o)
    EOS

    iotest = testpath/"IOTest.agda"
    iotest.write <<~EOS
      module IOTest where

      open import Agda.Builtin.IO
      open import Agda.Builtin.Unit

      postulate
        return : ∀ {A : Set} → A → IO A

      {-# COMPILED return (\\_ -> return) #-}

      main : _
      main = return tt
    EOS

    stdlibiotest = testpath/"StdlibIOTest.agda"
    stdlibiotest.write <<~EOS
      module StdlibIOTest where

      open import IO

      main : _
      main = run (putStr "Hello, world!")
    EOS

    # typecheck a simple module
    system bin/"agda", simpletest

    # typecheck a module that uses the standard library
    if build.with? "stdlib"
      system bin/"agda", "-i", lib/"agda"/"src", stdlibtest
    end

    # compile a simple module using the JS backend
    system bin/"agda", "--js", simpletest

    # test the GHC backend
    if build.with? "ghc"
      cabal_sandbox do
        cabal_install "text", "ieee754"
        dbpath = Dir["#{testpath}/.cabal-sandbox/*-packages.conf.d"].first
        dbopt = "--ghc-flag=-package-db=#{dbpath}"

        # compile and run a simple program
        system bin/"agda", "-c", dbopt, iotest
        assert_equal "", shell_output(testpath/"IOTest")

        # compile and run a program that uses the standard library
        if build.with? "stdlib"
          system bin/"agda", "-c", "-i", lib/"agda"/"src", dbopt, stdlibiotest
          assert_equal "Hello, world!", shell_output(testpath/"StdlibIOTest")
        end
      end
    end
  end
end