#!/usr/bin/env bash
export LC_ALL=C
set -e -o pipefail

# shellcheck source=contrib/shell/realpath.bash
source contrib/shell/realpath.bash

# shellcheck source=contrib/shell/git-utils.bash
source contrib/shell/git-utils.bash

################
# Required non-builtin commands should be invocable
################

check_tools() {
    for cmd in "$@"; do
        if ! command -v "$cmd" > /dev/null 2>&1; then
            echo "ERR: This script requires that '$cmd' is installed and available in your \$PATH"
            exit 1
        fi
    done
}

################
# SOURCE_DATE_EPOCH should not unintentionally be set
################

check_source_date_epoch() {
    if [ -n "$SOURCE_DATE_EPOCH" ] && [ -z "$FORCE_SOURCE_DATE_EPOCH" ]; then
        cat << EOF
ERR: Environment variable SOURCE_DATE_EPOCH is set which may break reproducibility.

     Aborting...

Hint: You may want to:
      1. Unset this variable: \`unset SOURCE_DATE_EPOCH\` before rebuilding
      2. Set the 'FORCE_SOURCE_DATE_EPOCH' environment variable if you insist on
         using your own epoch
EOF
        exit 1
    fi
}

check_tools cat env readlink dirname basename git

################
# We should be at the top directory of the repository
################

same_dir() {
    local resolved1 resolved2
    resolved1="$(bash_realpath "${1}")"
    resolved2="$(bash_realpath "${2}")"
    [ "$resolved1" = "$resolved2" ]
}

if ! same_dir "${PWD}" "$(git_root)"; then
cat << EOF
ERR: This script must be invoked from the top level of the git repository

Hint: This may look something like:
    env FOO=BAR ./contrib/guix/guix-<blah>

EOF
exit 1
fi

################
# Execute "$@" in a pinned, possibly older version of Guix, for reproducibility
# across time.
time-machine() {
    # shellcheck disable=SC2086
    guix time-machine --url=https://codeberg.org/guix/guix.git \
                      --commit=53396a22afc04536ddf75d8f82ad2eafa5082725 \
                      --cores="$JOBS" \
                      --keep-failed \
                      --fallback \
                      ${SUBSTITUTE_URLS:+--substitute-urls="$SUBSTITUTE_URLS"} \
                      ${ADDITIONAL_GUIX_COMMON_FLAGS} ${ADDITIONAL_GUIX_TIMEMACHINE_FLAGS} \
                      -- "$@"
}

################
guix_prefetch_temp=
trap 'test -n "$guix_prefetch_temp" && rm -rf -- "$guix_prefetch_temp"' EXIT

guix-prefetch() {
    local hash="$1" uri="$2"
    test -n "$guix_prefetch_temp" || guix_prefetch_temp="$(mktemp)"
    cat > "$guix_prefetch_temp" << EOF
(use-modules (guix packages)
             (guix download)
             (guix build-system trivial)
             (guix licenses))

(define-public dummy
  (package
    (name "dummy")
    (version "0")
    (source (origin
              (method url-fetch)
              (uri "${uri}")
              (sha256 (base32 "${hash}"))))
    (build-system trivial-build-system)
    (synopsis "")
    (description "")
    (home-page "")
    (license gpl3+)))

dummy
EOF
    guix build -f "$guix_prefetch_temp" --source
}

################
# Set common variables
################

VERSION="${FORCE_VERSION:-$(git_head_version)}"
DISTNAME="${DISTNAME:-limenka-${VERSION}}"

version_base_prefix="${PWD}/guix-build-"
VERSION_BASE="${version_base_prefix}${VERSION}"  # TOP

DISTSRC_BASE="${DISTSRC_BASE:-${VERSION_BASE}}"

OUTDIR_BASE="${OUTDIR_BASE:-${VERSION_BASE}/output}"

var_base_basename="var"
VAR_BASE="${VAR_BASE:-${VERSION_BASE}/${var_base_basename}}"

profiles_base_basename="profiles"
PROFILES_BASE="${PROFILES_BASE:-${VAR_BASE}/${profiles_base_basename}}"