buildAndWatch

#!/usr/bin/env bash
set -eou pipefail

function buildAndWatchWithNix() {
    if [[ -n "${IN_NIX_SHELL+x}" ]]; then
        echo "buildAndWatch does not work inside of a nix shell. Please exit the nix-shell and retry."
        exit 1
    fi

    if [[ ! -x $(type -P "nix-build") ]]; then
        echo "nix-build is not available. Please install nix from https://nixos.org/download.html"
        exit 1
    fi

    export LC_ALL=C.UTF-8       # fix locale error with Hakyll (see #29)
    nix-build -A builder && \
        ./result/bin/haskell-org-site clean && \
        ./result/bin/haskell-org-site build && \
        ./result/bin/haskell-org-site watch
    exit 0
}

function buildAndWatchWithoutNix() {
    if [[ ! -x $(type -P "cabal") ]]; then
        echo "Please download and install a haskell environment. See: https://www.haskell.org/downloads/"
        exit 1
    fi

    pushd builder
    cabal v2-build
    builder=$(cabal v2-exec -- which haskell-org-site)
    popd

    if [[ ! -x "${builder}" ]]; then
        cat <<EOF
After building 'haskell-org-site' I was unable to find the path to a
runnable executable. This may be because of a bug in this script. You
may want to try to build and run the builder manually, ask for help,
or submit a bug report.
EOF
        exit 1
    fi

    "${builder}" clean
    "${builder}" build
    "${builder}" watch
    exit 0
}

function buildAndWatchAuto() {
    if [[ -x $(type -P "nix-build") ]]; then
        if [[ -n "${IN_NIX_SHELL+x}" ]]; then
            cat <<EOF
I found a 'nix' installation, but we're currently inside of a nix
shell. I will try to build using cabal. If building with cabal fails,
you should try to re-run this script when you are not inside of a nix
shell.
EOF
            buildAndWatchWithoutNix
        else
            buildAndWatchWithNix
        fi
    else
        buildAndWatchWithoutNix
    fi
}

function showHelp() {
    cat <<EOF
Usage: buildAndWatch [buildMode]

Build the haskell.org site builder, compile the site, and start a
local server on port 8000 to preview changes.

buildAndWatch takes a single optional argument, 'buildMode'. If it's
omitted, buildAndWatch will attempt to select the best method for
building the site based on your current environment. If you provide an
argument, it may be one of the following:

  auto (default)      Automatically select between 'nix' or 'cabal' based on the
                        current environment.
  nix                 Use nix to build the site
  cabal               Use cabal to build the site. If you are in a nix shell,
                        it will use your nix environment. Otherwise, it will use
                        your system-wide cabal installation.
  help                Show this help message and exit
EOF
}


function buildAndWatchWithArgs() {
    case ${1} in
        "auto")
            buildAndWatchAuto
            ;;
        "nix")
            buildAndWatchWithNix
            ;;
        "cabal")
            buildAndWatchWithoutNix
            ;;
        "help")
            showHelp
            ;;
        *)
            echo "Unrecognized or missing arguments"
            showHelp
            exit 1
    esac
}

if [[ $# -gt 0 ]]; then
    buildAndWatchWithArgs "${1}"
else
    buildAndWatchWithArgs "auto"
fi