start

#!/bin/sh

MIN_BAZEL_MAJOR=0
MIN_BAZEL_MINOR=20

set -e

actual_raw=$(bazel version | egrep '^Build label:' | egrep -o '[0-9.]+')

IFS=. read actual_major actual_minor actual_patch <<EOF
$actual_raw
EOF

expected=$MIN_BAZEL_MAJOR.$MIN_BAZEL_MINOR.0
cmp=$expected'\n'$actual

if ! ( [ "$actual_major" -gt "$MIN_BAZEL_MAJOR" ] || (
           [ "$actual_major" -eq "$MIN_BAZEL_MAJOR" ] &&
               [ "$actual_minor" -ge "$MIN_BAZEL_MINOR" ] ) )
then
    echo Need at least Bazel v${expected}. v${actual_raw} detected. >/dev/stderr
    exit 1
fi

if [ -e WORKSPACE ] || [ -e BUILD ]
then
    echo Current directory already has WORKSPACE and/or BUILD files. >/dev/stderr
    exit 1
fi

cat > WORKSPACE <<EOF
workspace(name = "YOUR_PROJECT_NAME_HERE")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
  name = "io_tweag_rules_haskell",
  strip_prefix = "rules_haskell-0.6",
  urls = ["https://github.com/tweag/rules_haskell/archive/v0.6.tar.gz"]
)

load("@io_tweag_rules_haskell//haskell:repositories.bzl", "haskell_repositories")
haskell_repositories()

http_archive(
  name = "io_tweag_rules_nixpkgs",
  strip_prefix = "rules_nixpkgs-0.4.0",
  urls = ["https://github.com/tweag/rules_nixpkgs/archive/v0.4.0.tar.gz"],
)

load(
    "@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl",
    "nixpkgs_package",
    "nixpkgs_git_repository",
    "nixpkgs_cc_configure",
)

nixpkgs_git_repository(
    name = "nixpkgs",
    remote = "https://github.com/NixOS/nixpkgs",
    revision = "18.09",
    sha256 = "6451af4083485e13daa427f745cbf859bc23cb8b70454c017887c006a13bd65e",
)

nixpkgs_package(
  name = "ghc",
  attribute_path = "haskell.compiler.ghc843",
  repository = "@nixpkgs",
)

nixpkgs_cc_configure(repository = "@nixpkgs")
register_toolchains("//:ghc")
EOF

cat > BUILD <<EOF
package(default_visibility = ["//visibility:public"])

load(
  "@io_tweag_rules_haskell//haskell:haskell.bzl",
  "haskell_library",
  "haskell_toolchain",
  "haskell_import",
)

haskell_toolchain(
  name = "ghc",
  version = "8.4.3",
  tools = "@ghc//:bin",
)

haskell_import(
  name = "base_pkg",
  package = "base",
)

haskell_library(
  name = "MY_LIBRARY_NAME",
  src_strip_prefix = "src",
  srcs = glob(['src/**/*.hs']),
  deps = [
    "base_pkg"
  ],
)
EOF

cat <<EOF
WORKSPACE and initial BUILD files created. To run Bazel:

    $ bazel build //...
EOF