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

# Source the common prelude, which:
#   1. Checks if we're at the top directory of the Bitcoin Core repository
#   2. Defines a few common functions and variables
#
# shellcheck source=libexec/prelude.bash
source "$(dirname "${BASH_SOURCE[0]}")/libexec/prelude.bash"


###################
## Sanity Checks ##
###################

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

check_tools cat env basename mkdir xargs find gpg

################
# Required env vars should be non-empty
################

cmd_usage() {
cat <<EOF
Synopsis:

    env GUIX_SIGS_REPO=<path/to/guix.sigs> \\
        SIGNER=GPG_KEY_NAME[=SIGNER_NAME] \\
      ./contrib/guix/guix-attest

Example w/o overriding signing name:

    env GUIX_SIGS_REPO=/home/achow101/guix.sigs \\
        SIGNER=achow101 \\
      ./contrib/guix/guix-attest

Example overriding signing name:

    env GUIX_SIGS_REPO=/home/dongcarl/guix.sigs \\
        SIGNER=0x96AB007F1A7ED999=dongcarl \\
      ./contrib/guix/guix-attest

EOF
}

if [ -z "$GUIX_SIGS_REPO" ] || [ -z "$SIGNER" ]; then
    cmd_usage
    exit 1
fi

################
# GUIX_SIGS_REPO should exist as a directory
################

if [ ! -d "$GUIX_SIGS_REPO" ]; then
cat << EOF
ERR: The specified GUIX_SIGS_REPO is not an existent directory:

    '$GUIX_SIGS_REPO'

Hint: Please clone the guix.sigs repository and point to it with the
      GUIX_SIGS_REPO environment variable.

EOF
cmd_usage
exit 1
fi

################
# The key specified in SIGNER should be usable
################

IFS='=' read -r gpg_key_name signer_name <<< "$SIGNER"
if [ -z "${signer_name}" ]; then
    signer_name="$gpg_key_name"
fi

if ! gpg --dry-run --list-secret-keys "${gpg_key_name}" >/dev/null 2>&1; then
    echo "ERR: GPG can't seem to find any key named '${gpg_key_name}'"
    exit 1
fi

################
# We should be able to find at least one output
################

echo "Looking for build output directories in ${OUTDIR_BASE}"

shopt -s nullglob
OUTDIRS=( "${OUTDIR_BASE}"/* ) # This expands to an array of directories...
shopt -u nullglob

if (( ${#OUTDIRS[@]} )); then
    echo "Found build output directories:"
    for outdir in "${OUTDIRS[@]}"; do
        echo "    '$outdir'"
    done
    echo
else
    echo "ERR: Could not find any build output directories in ${OUTDIR_BASE}"
    exit 1
fi


##############
##  Attest  ##
##############

# Usage: out_name $outdir
#
#   HOST: The output directory being attested
#
out_name() {
    basename "$1"
}

# Usage: out_sig_dir $outdir
#
#   outdir: The output directory being attested
#
out_sig_dir() {
    echo "$GUIX_SIGS_REPO/$VERSION/$(out_name "$1")/$signer_name"
}

# Accumulate a list of signature directories that already exist...
outdirs_already_attested_to=()

echo "Attesting to build outputs for version: '${VERSION}'"
echo ""

# MAIN LOGIC: Loop through each output for VERSION and attest to output in
#             GUIX_SIGS_REPO as SIGNER, if attestation does not exist
for outdir in "${OUTDIRS[@]}"; do
    outname="$(out_name "$outdir")"
    outsigdir="$(out_sig_dir "$outdir")"
    if [ -e "$outsigdir" ]; then
        echo "${outname}: SKIPPING: Signature directory already exists in the specified guix.sigs repository"
        outdirs_already_attested_to+=("$outdir")
    else
        mkdir -p "$outsigdir"
        echo "${outname}: Hashing build outputs to produce SHA256SUMS"
        (
            cd "$outdir"
            find . -type f -printf '%P\0' | env LC_ALL=C sort -z | xargs -r0 sha256sum >> "$outsigdir"/SHA256SUMS
        )
        echo "${outname}: Signing SHA256SUMS to produce SHA256SUMS.asc"
        gpg --detach-sign --local-user "$gpg_key_name" --output "$outsigdir"/SHA256SUMS.asc "$outsigdir"/SHA256SUMS
        echo ""
    fi
done

if (( ${#outdirs_already_attested_to[@]} )); then
# ...so that we can print them out nicely in a warning message
cat << EOF

WARN: Signature directories from '$signer_name' already exist in the specified
      guix.sigs repository for the following output directories and were
      skipped:

EOF
for outdir in "${outdirs_already_attested_to[@]}"; do
    echo "    '${outdir}'"
    echo "    Corresponds to: '$(out_sig_dir "$outdir")'"
    echo ""
done
fi