#!/usr/bin/env bash
# Proof-of-concept program to verify provenance attestations for direct module dependencies

set -o errexit -o nounset -o pipefail

# Minimum required version: https://github.com/cli/cli/releases/tag/v2.49.0
REQUIRED_GH_VERSION="2.49.0"

# Check if gh is available
if ! command -v gh &> /dev/null; then
    echo "Error: GitHub CLI (gh) is not installed or not in your PATH."
    exit 1
fi

# Get installed gh version (strip 'gh version ' prefix)
INSTALLED_VERSION=$(gh --version | head -n 1 | awk '{print $3}')

# Function to compare versions
version_ge() {
    # returns 0 if $1 >= $2
    [[ "$(printf '%s\n' "$1" "$2" | sort -V | head -n 1)" == "$2" ]]
}

# Compare versions
if ! version_ge "$INSTALLED_VERSION" "$REQUIRED_GH_VERSION"; then
    echo "Error: gh version $REQUIRED_GH_VERSION or higher is required for the 'attestation' subcommand. Found version: $INSTALLED_VERSION"
    exit 1
fi

yellow='\033[0;33m'
bold_blue='\033[1;34m'
reset='\033[0m'

# List direct dependency module names
bazel mod deps --depth 1 '<root>' --output json | jq '.dependencies[] | .name' --raw-output | while IFS= read -r module; do
    echo "┌────────────────────────────────────────────"

    # Find the module's source URL
    source_url=$(bazel mod show_repo "$module" | grep 'urls = \[' | sed -E 's/.*urls = \[(.*)\],/\1/' | tr -d '"' | tr -d ' ')
    org=$(echo "$source_url" | sed -E 's|https://github.com/([^/]+)/.*|\1|')
    echo -e "| ${bold_blue}Verifying ${org}/${module} ${reset}[fetched from $source_url] ..."

    # Download the file
    release_artifact=$(mktemp)
    curl --fail --silent --show-error --location "$source_url" --output "$release_artifact"

    # Are there attestations for it?
    # This is a clumsy way to detect, by attempting a download. Perhaps it can be improved by calling the GH API manually.
    if ! 2>&1 >/dev/null gh attestation download "$release_artifact" --owner "${org}"; then
        echo -e "| ⚠️  ${yellow}Warning: no attestations found for this module, skipping.${reset}"
        echo "└────────────────────────────────────────────"
        continue
    fi
    # cleanup the file that was downloaded
    rm sha256:*.jsonl

    # Perform the verification
    gh attestation verify "$release_artifact" --owner "${org}" --signer-repo bazel-contrib/.github
    echo "└────────────────────────────────────────────"
done