#!/bin/bash
# Git OpenTimestamp Post-Commit Hook (ots CLI version)
# Requires: opentimestamps-client (pipx install opentimestamps-client)

set -e

OUTPUT_DIR=".ots"
OUTPUT_FILE="$OUTPUT_DIR/proof.ots"

mkdir -p "$OUTPUT_DIR"

COMMIT_HASH=$(git rev-parse HEAD)

# Generate proof using ots CLI
temp_file=$(mktemp)
temp_ots="${temp_file}.ots"

python3 -c "import sys; sys.stdout.buffer.write(bytes.fromhex('$COMMIT_HASH'))" > "$temp_file"
ots stamp "$temp_file" 2>/dev/null

if [ -f "$temp_ots" ]; then
    mv "$temp_ots" "$OUTPUT_FILE"
    rm -f "$temp_file"
    echo "[ots] Generated proof: ${COMMIT_HASH:0:8}"
else
    rm -f "$temp_file"
    echo "[ots] Warning: Failed to generate proof" >&2
    exit 0
fi

# Save previous commit for chaining
PREV_COMMIT=$(git rev-parse HEAD^1 2>/dev/null || echo "")
if [ -n "$PREV_COMMIT" ]; then
    echo "$PREV_COMMIT" > "$OUTPUT_DIR/prev-commit.txt"
fi

# Create individual proof file
INDIVIDUAL_PROOF="$OUTPUT_DIR/${COMMIT_HASH}.ots"
cp "$OUTPUT_FILE" "$INDIVIDUAL_PROOF"

echo "[ots] Proof generated successfully"