#!/bin/bash
# backfill-proofs.sh - Generate/upgrade OpenTimestamp proofs for all commits
# Usage: backfill-proofs.sh [repository-path]

set -e

REPO_PATH="${1:-.}"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

cd "$REPO_PATH"

# Verify we're in a git repository
if ! git rev-parse --git-dir > /dev/null 2>&1; then
    echo "Error: not a git repository" >&2
    exit 1
fi

# Find the generate-proof.sh script
GENERATE_SCRIPT=""

# Check if generate-proof.sh is in the same directory as this script
if [ -f "$SCRIPT_DIR/generate-proof.sh" ]; then
    GENERATE_SCRIPT="$SCRIPT_DIR/generate-proof.sh"
# Check in repository root
elif [ -f "generate-proof.sh" ]; then
    GENERATE_SCRIPT="./generate-proof.sh"
# Check if skill is installed globally
elif [ -f "$HOME/.openclaw/workspace/skills/git-ots-hook/scripts/generate-proof.sh" ]; then
    GENERATE_SCRIPT="$HOME/.openclaw/workspace/skills/git-ots-hook/scripts/generate-proof.sh"
else
    echo "Error: generate-proof.sh not found" >&2
    exit 1
fi

chmod +x "$GENERATE_SCRIPT"

# Ensure .ots directory exists
mkdir -p .ots

# Cache file for attestation status (avoids repeated ots info calls)
STATUS_CACHE=".ots/.attestation-cache"
if [ ! -f "$STATUS_CACHE" ]; then
    echo "# Attestation status cache" > "$STATUS_CACHE"
    echo "# Format: commit-hash:status:timestamp" >> "$STATUS_CACHE"
fi

# Function to check cached status
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)
        local age=$((now - timestamp))
        # Cache valid for 1 hour (3600 seconds)
        if [ "$age" -lt 3600 ]; then
            echo "$status"
            return 0
        fi
    fi
    return 1
}

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

echo "[ots-backfill] Scanning commit history..."

# Get all commit hashes (oldest to newest)
COMMITS=$(git rev-list --reverse HEAD)
TOTAL=$(echo "$COMMITS" | wc -l)
CURRENT=0

# Track if any proofs were updated
UPDATED=0

for COMMIT in $COMMITS; do
    CURRENT=$((CURRENT + 1))
    echo "[ots-backfill] Processing commit $CURRENT/$TOTAL: ${COMMIT:0:8}"
    
    # Check if proof exists for this commit
    PROOF_FILE=".ots/${COMMIT}.ots"
    
    if [ -f "$PROOF_FILE" ]; then
        # Check cached status first
        CACHED_STATUS=$(get_cached_status "$COMMIT" || echo "")
        
        if [ "$CACHED_STATUS" = "attested" ]; then
            echo "  ✓ Already attested (cached, skipping)"
            continue
        fi
        
        # Check if already fully attested (only if not cached or cache expired)
        PENDING_COUNT=$(ots info "$PROOF_FILE" 2>&1 | grep -c "PendingAttestation" || echo "0")
        
        if [ "$PENDING_COUNT" -eq 0 ]; then
            echo "  ✓ Already attested"
            cache_status "$COMMIT" "attested"
            continue
        fi
        
        # Cache as pending
        cache_status "$COMMIT" "pending"
        
        # Try to upgrade existing proof (only contacts calendars if pending)
        echo "  Upgrading pending proof..."
        if ots upgrade "$PROOF_FILE" 2>/dev/null; then
            echo "  ✓ Upgraded to attested"
            cache_status "$COMMIT" "attested"
            UPDATED=$((UPDATED + 1))
        else
            echo "  - Still pending (no upgrade available yet)"
        fi
    else
        # Generate new proof for this commit
        echo "  Generating new proof..."
        "$GENERATE_SCRIPT" "$COMMIT" "$PROOF_FILE" >/dev/null 2>&1
        echo "  ✓ Generated proof"
        cache_status "$COMMIT" "pending"
        UPDATED=$((UPDATED + 1))
    fi
done

# Create/update latest proof symlink
LATEST_COMMIT=$(git rev-parse HEAD)
if [ -f ".ots/${LATEST_COMMIT}.ots" ]; then
    cp ".ots/${LATEST_COMMIT}.ots" ".ots/proof.ots"
    echo "[ots-backfill] Updated .ots/proof.ots for latest commit"
fi

# Save previous commit chain info
echo "[ots-backfill] Saving commit chain..."
git rev-list HEAD | while read COMMIT; do
    PREV=$(git rev-parse ${COMMIT}^1 2>/dev/null || echo "")
    if [ -n "$PREV" ]; then
        echo "$COMMIT:$PREV" >> ".ots/commit-chain.txt"
    fi
done

echo ""
echo "[ots-backfill] Complete! Processed $TOTAL commits, updated $UPDATED proofs"
echo ""
echo "Proofs stored in: .ots/"
echo "  - Individual proofs: .ots/<commit-hash>.ots"
echo "  - Latest proof: .ots/proof.ots"
echo "  - Commit chain: .ots/commit-chain.txt"