#!/usr/bin/env bash
# SPDX-License-Identifier: AGPL-3.0-or-later
# BENCH-AUTO-401-019: Online DSSE + Rekor verification script

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "${SCRIPT_DIR}/../.." && pwd)"

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

log_pass() { echo -e "${GREEN}✓${NC} $*"; }
log_fail() { echo -e "${RED}✗${NC} $*"; }
log_warn() { echo -e "${YELLOW}!${NC} $*"; }

usage() {
    echo "Usage: $0 <dsse-file> [--catalog PATH] [--rekor-url URL]"
    echo ""
    echo "Verify a VEX proof bundle with DSSE signature and Rekor inclusion."
    echo ""
    echo "Options:"
    echo "  --catalog PATH    Path to justification catalog (default: docs/benchmarks/vex-justifications.catalog.json)"
    echo "  --rekor-url URL   Rekor URL (default: https://rekor.sigstore.dev)"
    echo "  --offline         Skip Rekor verification"
    echo "  --help, -h        Show this help"
    exit 1
}

DSSE_FILE=""
CATALOG="${REPO_ROOT}/docs/benchmarks/vex-justifications.catalog.json"
REKOR_URL="https://rekor.sigstore.dev"
OFFLINE=false

while [[ $# -gt 0 ]]; do
    case $1 in
        --catalog)
            CATALOG="$2"
            shift 2
            ;;
        --rekor-url)
            REKOR_URL="$2"
            shift 2
            ;;
        --offline)
            OFFLINE=true
            shift
            ;;
        --help|-h)
            usage
            ;;
        *)
            if [[ -z "$DSSE_FILE" ]]; then
                DSSE_FILE="$1"
            else
                echo "Unknown option: $1"
                usage
            fi
            shift
            ;;
    esac
done

if [[ -z "$DSSE_FILE" ]]; then
    echo "Error: DSSE file required"
    usage
fi

if [[ ! -f "$DSSE_FILE" ]]; then
    echo "Error: DSSE file not found: $DSSE_FILE"
    exit 1
fi

echo "Verifying: $DSSE_FILE"
echo ""

# Step 1: Validate JSON structure
if ! python3 -c "import json; json.load(open('$DSSE_FILE'))" 2>/dev/null; then
    log_fail "Invalid JSON"
    exit 1
fi
log_pass "Valid JSON structure"

# Step 2: Check DSSE envelope structure
PAYLOAD_TYPE=$(python3 -c "import json; print(json.load(open('$DSSE_FILE')).get('payloadType', ''))")
if [[ -z "$PAYLOAD_TYPE" ]]; then
    log_fail "Missing payloadType"
    exit 1
fi
log_pass "DSSE payloadType: $PAYLOAD_TYPE"

# Step 3: Decode and validate payload
PAYLOAD_B64=$(python3 -c "import json; print(json.load(open('$DSSE_FILE')).get('payload', ''))")
if [[ -z "$PAYLOAD_B64" ]]; then
    log_fail "Missing payload"
    exit 1
fi

# Decode payload
PAYLOAD_JSON=$(echo "$PAYLOAD_B64" | base64 -d 2>/dev/null || echo "")
if [[ -z "$PAYLOAD_JSON" ]]; then
    log_fail "Failed to decode payload"
    exit 1
fi
log_pass "Payload decoded successfully"

# Step 4: Validate OpenVEX structure (if applicable)
if [[ "$PAYLOAD_TYPE" == *"openvex"* ]]; then
    STATEMENTS_COUNT=$(echo "$PAYLOAD_JSON" | python3 -c "import json,sys; d=json.load(sys.stdin); print(len(d.get('statements', [])))")
    if [[ "$STATEMENTS_COUNT" -eq 0 ]]; then
        log_warn "OpenVEX has no statements"
    else
        log_pass "OpenVEX contains $STATEMENTS_COUNT statement(s)"
    fi
fi

# Step 5: Check signature presence
SIG_COUNT=$(python3 -c "import json; print(len(json.load(open('$DSSE_FILE')).get('signatures', [])))")
if [[ "$SIG_COUNT" -eq 0 ]]; then
    log_fail "No signatures found"
    exit 1
fi
log_pass "Found $SIG_COUNT signature(s)"

# Step 6: Check for placeholder signatures
SIG_VALUE=$(python3 -c "import json; sigs=json.load(open('$DSSE_FILE')).get('signatures', []); print(sigs[0].get('sig', '') if sigs else '')")
if [[ "$SIG_VALUE" == "PLACEHOLDER"* ]]; then
    log_warn "Signature is a placeholder (not yet signed)"
else
    log_pass "Signature present (verification requires public key)"
fi

# Step 7: Rekor verification (if online)
if [[ "$OFFLINE" == false ]]; then
    # Check for rekor.txt in same directory
    DSSE_DIR=$(dirname "$DSSE_FILE")
    REKOR_FILE="${DSSE_DIR}/rekor.txt"

    if [[ -f "$REKOR_FILE" ]]; then
        LOG_INDEX=$(grep -E "^log_index:" "$REKOR_FILE" | cut -d: -f2 | tr -d ' ')
        if [[ "$LOG_INDEX" != "PENDING" && -n "$LOG_INDEX" ]]; then
            log_pass "Rekor log index: $LOG_INDEX"

            # Verify with Rekor API
            if command -v curl &>/dev/null; then
                REKOR_RESP=$(curl -s "${REKOR_URL}/api/v1/log/entries?logIndex=${LOG_INDEX}" 2>/dev/null || echo "")
                if [[ -n "$REKOR_RESP" && "$REKOR_RESP" != "null" ]]; then
                    log_pass "Rekor inclusion verified"
                else
                    log_warn "Could not verify Rekor inclusion (may be offline or index invalid)"
                fi
            else
                log_warn "curl not available for Rekor verification"
            fi
        else
            log_warn "Rekor entry pending submission"
        fi
    else
        log_warn "No rekor.txt found - Rekor verification skipped"
    fi
else
    log_warn "Offline mode - Rekor verification skipped"
fi

# Step 8: Check justification catalog membership
if [[ -f "$CATALOG" ]]; then
    # Extract justification from payload if present
    JUSTIFICATION=$(echo "$PAYLOAD_JSON" | python3 -c "
import json, sys
d = json.load(sys.stdin)
stmts = d.get('statements', [])
if stmts:
    print(stmts[0].get('justification', ''))
" 2>/dev/null || echo "")

    if [[ -n "$JUSTIFICATION" ]]; then
        CATALOG_MATCH=$(python3 -c "
import json
catalog = json.load(open('$CATALOG'))
entries = catalog if isinstance(catalog, list) else catalog.get('entries', [])
ids = [e.get('id', '') for e in entries]
print('yes' if '$JUSTIFICATION' in ids else 'no')
" 2>/dev/null || echo "no")

        if [[ "$CATALOG_MATCH" == "yes" ]]; then
            log_pass "Justification '$JUSTIFICATION' found in catalog"
        else
            log_warn "Justification '$JUSTIFICATION' not in catalog"
        fi
    fi
else
    log_warn "Justification catalog not found at $CATALOG"
fi

echo ""
echo "Verification complete."