#!/bin/bash
# Git OpenTimestamp Pre-Commit Backfill Hook (Node.js version)
# Requires: @opentimestamps/ots (npm install)
# Note: Node version only generates local proofs, no calendar submission

set -e

OUTPUT_DIR=".ots"
STATUS_CACHE="$OUTPUT_DIR/.attestation-cache"

mkdir -p "$OUTPUT_DIR"

# Initialize cache
if [ ! -f "$STATUS_CACHE" ]; then
    echo "# Format: commit-hash:status:timestamp" > "$STATUS_CACHE"
fi

get_cached_status() {
    local commit="$1"
    local cache_line=$(grep "^$commit:" "$STATUS_CACHE" 2>/dev/null | tail -1)
    if [ -n "$cache_line" ]; then
        local status=$(echo "$cache_line" | cut -d: -f2)
        local timestamp=$(echo "$cache_line" | cut -d: -f3)
        local now=$(date +%s)
        if [ "$((now - timestamp))" -lt 3600 ]; then
            echo "$status"
            return 0
        fi
    fi
    return 1
}

cache_status() {
    local commit="$1"
    local status="$2"
    echo "$commit:$status:$(date +%s)" >> "$STATUS_CACHE"
}

generate_proof_node() {
    local hash="$1"
    local output="$2"
    
    node -e "
const ots = require('@opentimestamps/ots');
const fs = require('fs');
const hash = '$hash';
const output = '$output';
const hashBuffer = Buffer.from(hash, 'hex');

ots.Timestamp.hash(hashBuffer).then(timestamp => {
    const proof = { hash: hash, timestamp: new Date().toISOString(), status: 'pending' };
    fs.writeFileSync(output, JSON.stringify(proof, null, 2));
}).catch(err => { console.error('Error:', err); process.exit(1); });
"
}

echo "[ots-node] Backfilling proofs (local only, no calendar)..."

COMMITS=$(git rev-list --reverse HEAD)
TOTAL=$(echo "$COMMITS" | wc -l)
CURRENT=0
UPDATED=0

for COMMIT in $COMMITS; do
    CURRENT=$((CURRENT + 1))
    PROOF_FILE="$OUTPUT_DIR/${COMMIT}.ots"
    
    if [ $CURRENT -le 3 ] || [ $CURRENT -eq $TOTAL ]; then
        echo "[ots-node] Processing $CURRENT/$TOTAL: ${COMMIT:0:8}"
    elif [ $CURRENT -eq 4 ]; then
        echo "[ots-node] ... processing remaining ..."
    fi
    
    if [ -f "$PROOF_FILE" ]; then
        # Node version doesn't support upgrade, just check cache
        CACHED_STATUS=$(get_cached_status "$COMMIT" || echo "")
        [ "$CACHED_STATUS" = "attested" ] && continue
        
        # Mark as pending (node can't attest)
        cache_status "$COMMIT" "pending"
    else
        if generate_proof_node "$COMMIT" "$PROOF_FILE"; then
            cache_status "$COMMIT" "pending"
            UPDATED=$((UPDATED + 1))
        fi
    fi
done

# Update latest proof
LATEST_COMMIT=$(git rev-parse HEAD)
[ -f "$OUTPUT_DIR/${LATEST_COMMIT}.ots" ] && cp "$OUTPUT_DIR/${LATEST_COMMIT}.ots" "$OUTPUT_DIR/proof.ots"

# Save commit chain
rm -f "$OUTPUT_DIR/commit-chain.txt"
git rev-list HEAD | while read COMMIT; do
    PREV=$(git rev-parse ${COMMIT}^1 2>/dev/null || echo "")
    [ -n "$PREV" ] && echo "$COMMIT:$PREV" >> "$OUTPUT_DIR/commit-chain.txt"
done

echo "[ots-node] Backfill complete: $UPDATED generated (local proofs only)"