#!/bin/bash
# Copyright (c) StellaOps. All rights reserved.
# Licensed under the BUSL-1.1 license.
#
# generate-slsa-provenance.sh
# Generates SLSA v1.0 provenance statements for release artifacts
#
# Usage: ./generate-slsa-provenance.sh --version <version> --commit <sha> --output <dir>

set -euo pipefail

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Default values
VERSION=""
COMMIT=""
OUTPUT_DIR="provenance"
ARTIFACTS_DIR="artifacts"
BUILDER_ID="${BUILDER_ID:-https://ci.stella-ops.org/builder/v1}"
BUILD_TYPE="${BUILD_TYPE:-https://stella-ops.io/ReleaseBuilder/v1}"
REPOSITORY_URI="${REPOSITORY_URI:-git+https://git.stella-ops.org/stella-ops.org/git.stella-ops.org}"

# Parse arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        --version)
            VERSION="$2"
            shift 2
            ;;
        --commit)
            COMMIT="$2"
            shift 2
            ;;
        --output)
            OUTPUT_DIR="$2"
            shift 2
            ;;
        --artifacts)
            ARTIFACTS_DIR="$2"
            shift 2
            ;;
        --builder-id)
            BUILDER_ID="$2"
            shift 2
            ;;
        --build-type)
            BUILD_TYPE="$2"
            shift 2
            ;;
        --help)
            echo "Usage: $0 --version <version> --commit <sha> --output <dir>"
            echo ""
            echo "Options:"
            echo "  --version     Release version (required)"
            echo "  --commit      Git commit SHA (required)"
            echo "  --output      Output directory for provenance files (default: provenance)"
            echo "  --artifacts   Directory containing release artifacts (default: artifacts)"
            echo "  --builder-id  Builder ID URI (default: https://ci.stella-ops.org/builder/v1)"
            echo "  --build-type  Build type URI (default: https://stella-ops.io/ReleaseBuilder/v1)"
            exit 0
            ;;
        *)
            echo -e "${RED}Unknown option: $1${NC}"
            exit 1
            ;;
    esac
done

# Validate required arguments
if [[ -z "$VERSION" ]]; then
    echo -e "${RED}Error: --version is required${NC}"
    exit 1
fi

if [[ -z "$COMMIT" ]]; then
    echo -e "${RED}Error: --commit is required${NC}"
    exit 1
fi

# Create output directory
mkdir -p "$OUTPUT_DIR"

# Get timestamps
STARTED_ON="${BUILD_STARTED_ON:-$(date -u +%Y-%m-%dT%H:%M:%SZ)}"
FINISHED_ON="$(date -u +%Y-%m-%dT%H:%M:%SZ)"

# Get invocation ID from CI environment
INVOCATION_ID="${CI_JOB_ID:-${GITHUB_RUN_ID:-$(uuidgen || cat /proc/sys/kernel/random/uuid 2>/dev/null || echo "local-build")}}"

echo -e "${GREEN}Generating SLSA v1.0 provenance for version ${VERSION}${NC}"
echo "  Commit: ${COMMIT}"
echo "  Builder: ${BUILDER_ID}"
echo "  Output: ${OUTPUT_DIR}"

# Function to generate provenance for a single artifact
generate_provenance() {
    local artifact_path="$1"
    local artifact_name
    artifact_name=$(basename "$artifact_path")

    # Compute SHA-256 digest
    local sha256
    sha256=$(sha256sum "$artifact_path" | cut -d' ' -f1)

    # Determine component name from artifact
    local component_name
    component_name=$(echo "$artifact_name" | sed -E 's/stella-([^-]+).*/\1/')

    local output_file="${OUTPUT_DIR}/${component_name}.slsa.intoto.jsonl"

    echo "  Generating provenance for: ${artifact_name}"

    # Generate SLSA v1.0 provenance statement
    cat > "$output_file" << EOF
{
  "_type": "https://in-toto.io/Statement/v1",
  "subject": [
    {
      "name": "${artifact_name}",
      "digest": {
        "sha256": "${sha256}"
      }
    }
  ],
  "predicateType": "https://slsa.dev/provenance/v1",
  "predicate": {
    "buildDefinition": {
      "buildType": "${BUILD_TYPE}",
      "externalParameters": {
        "version": "${VERSION}",
        "repository": "${REPOSITORY_URI}",
        "ref": "refs/tags/v${VERSION}"
      },
      "internalParameters": {},
      "resolvedDependencies": [
        {
          "uri": "${REPOSITORY_URI}@refs/tags/v${VERSION}",
          "digest": {
            "gitCommit": "${COMMIT}"
          }
        }
      ]
    },
    "runDetails": {
      "builder": {
        "id": "${BUILDER_ID}",
        "version": {
          "stellaOps": "${VERSION}"
        }
      },
      "metadata": {
        "invocationId": "${INVOCATION_ID}",
        "startedOn": "${STARTED_ON}",
        "finishedOn": "${FINISHED_ON}"
      },
      "byproducts": []
    }
  }
}
EOF

    echo -e "    ${GREEN}Created: ${output_file}${NC}"
}

# Find and process artifacts
artifact_count=0
for artifact in "${ARTIFACTS_DIR}"/stella-*.tar.gz "${ARTIFACTS_DIR}"/stella-*.zip; do
    if [[ -f "$artifact" ]]; then
        generate_provenance "$artifact"
        ((artifact_count++))
    fi
done

if [[ $artifact_count -eq 0 ]]; then
    echo -e "${YELLOW}Warning: No artifacts found in ${ARTIFACTS_DIR}${NC}"
    exit 0
fi

echo ""
echo -e "${GREEN}Generated ${artifact_count} provenance statement(s)${NC}"
echo "Files written to: ${OUTPUT_DIR}/"