#!/bin/sh
# entrypoint.sh — Persist SQLite across HF Spaces rebuilds
#
# Uses huggingface-cli to upload/download the DB to a private Dataset repo.
# HF_TOKEN must be set as a Space secret.
# HF_BACKUP_REPO is the dataset repo (e.g. FordAI/hss-pos-backup).

LOCAL_DB="/app/data/restaurant.db"
BACKUP_REPO="${HF_BACKUP_REPO:-FordAI/hss-pos-backup}"
BACKUP_FILE="restaurant.db"
SERVER_PORT="${PORT:-7860}"

mkdir -p /app/data

# ── Helper: get file size portably (works on BusyBox & GNU) ──
file_size() {
    if [ -f "$1" ]; then
        wc -c < "$1" | tr -d ' '
    else
        echo 0
    fi
}

# ── Restore DB from HF Dataset repo on startup ──
if [ -n "$HF_TOKEN" ]; then
    echo "[PERSIST] Downloading database from $BACKUP_REPO..."
    if hf download "$BACKUP_REPO" "$BACKUP_FILE" \
        --repo-type dataset \
        --local-dir /app/data \
        --token "$HF_TOKEN" 2>&1; then
        DB_SIZE=$(file_size "$LOCAL_DB")
        echo "[PERSIST] Download finished — DB size: $DB_SIZE bytes"
        if [ "$DB_SIZE" -gt 8192 ]; then
            echo "[PERSIST] Database restored successfully"
            # Remove stale WAL/SHM from any previous run
            rm -f "${LOCAL_DB}-wal" "${LOCAL_DB}-shm"
        else
            echo "[PERSIST] Downloaded file too small or empty — starting fresh"
            rm -f "$LOCAL_DB"
        fi
    else
        echo "[PERSIST] Download failed (expected on first run) — starting fresh"
        rm -f "$LOCAL_DB"
    fi
else
    echo "[PERSIST] HF_TOKEN not set — persistence disabled"
fi

# ── Wait for Go server to be ready ──
wait_for_server() {
    echo "[PERSIST] Waiting for server on port $SERVER_PORT..."
    TRIES=0
    while [ "$TRIES" -lt 60 ]; do
        if wget -q -O /dev/null "http://127.0.0.1:${SERVER_PORT}/health" 2>/dev/null; then
            echo "[PERSIST] Server is ready"
            return 0
        fi
        TRIES=$((TRIES + 1))
        sleep 1
    done
    echo "[PERSIST] WARNING: Server not ready after 60s"
    return 1
}

# ── Flush WAL to main DB file before backup ──
wal_checkpoint() {
    echo "[PERSIST] Requesting WAL checkpoint..."
    RESP=$(wget -q -O - "http://127.0.0.1:${SERVER_PORT}/api/v1/internal/checkpoint" 2>&1) || true
    echo "[PERSIST] Checkpoint response: $RESP"
}

# ── Upload DB to HF Dataset repo ──
do_backup() {
    if [ -z "$HF_TOKEN" ]; then
        echo "[PERSIST] Skipping backup: HF_TOKEN not set"
        return
    fi
    if [ ! -f "$LOCAL_DB" ]; then
        echo "[PERSIST] Skipping backup: DB file not found"
        return
    fi

    # Checkpoint WAL so all data is in the main .db file
    wal_checkpoint

    DB_SIZE=$(file_size "$LOCAL_DB")
    echo "[PERSIST] DB size after checkpoint: $DB_SIZE bytes"
    if [ "$DB_SIZE" -le 8192 ]; then
        echo "[PERSIST] Skipping backup: DB too small ($DB_SIZE bytes)"
        return
    fi

    echo "[PERSIST] Uploading $DB_SIZE bytes to $BACKUP_REPO..."
    if hf upload "$BACKUP_REPO" "$LOCAL_DB" "$BACKUP_FILE" \
        --repo-type dataset \
        --token "$HF_TOKEN" 2>&1; then
        echo "[PERSIST] Backup complete ($DB_SIZE bytes)"
    else
        echo "[PERSIST] Backup FAILED (exit code $?)"
    fi
}

# ── Start the Go server ──
echo "[STARTUP] Launching Go server..."
./server &
SERVER_PID=$!

# ── Periodic backup (waits for server first) ──
backup_loop() {
    wait_for_server
    echo "[PERSIST] First backup in 10s..."
    sleep 10
    do_backup
    while true; do
        sleep 300
        do_backup
    done
}
backup_loop &
BACKUP_PID=$!

# ── Graceful shutdown: final backup ──
cleanup() {
    echo "[PERSIST] Shutdown — running final backup..."
    do_backup
    kill "$BACKUP_PID" 2>/dev/null || true
    exit 0
}
trap cleanup TERM INT

wait $SERVER_PID