#!/bin/bash
# PostgreSQL 自動修復腳本
# 功能：檢測資料庫問題，自動 VACUUM、重建索引、恢復連線

set -e

NAMESPACE="momo"
DB_HOST="momo-postgres"
DB_NAME="momo_analytics"
DB_USER="momo"
TELEGRAM_BOT="<TELEGRAM_BOT_TOKEN>"
TELEGRAM_CHAT="5619078117"
LOG_FILE="/var/log/postgres_repair.log"
BACKUP_DIR="/home/wooo/backups/postgres"

log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a "$LOG_FILE"
}

send_telegram() {
    curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT}/sendMessage" \
        -d "chat_id=${TELEGRAM_CHAT}" \
        -d "parse_mode=HTML" \
        -d "text=$1" > /dev/null
}

# 在 Pod 內執行 SQL
exec_sql() {
    kubectl exec -n "$NAMESPACE" momo-postgres-0 -- \
        psql -U "$DB_USER" -d "$DB_NAME" -t -c "$1" 2>/dev/null
}

# 檢查資料庫連線
check_connection() {
    if exec_sql "SELECT 1" | grep -q "1"; then
        return 0
    else
        return 1
    fi
}

# 檢查死鎖
check_deadlocks() {
    local deadlocks=$(exec_sql "SELECT count(*) FROM pg_stat_activity WHERE wait_event_type = 'Lock'")
    echo "$deadlocks" | tr -d ' '
}

# 檢查 Dead Tuples (需要 VACUUM)
check_dead_tuples() {
    local dead_tuples=$(exec_sql "SELECT sum(n_dead_tup) FROM pg_stat_user_tables")
    echo "$dead_tuples" | tr -d ' '
}

# 檢查膨脹比例
check_bloat() {
    local bloat=$(exec_sql "
        SELECT round(100 * sum(n_dead_tup)::numeric / NULLIF(sum(n_live_tup + n_dead_tup), 0), 2)
        FROM pg_stat_user_tables
    ")
    echo "$bloat" | tr -d ' '
}

# 執行 VACUUM ANALYZE
do_vacuum() {
    log "執行 VACUUM ANALYZE..."
    kubectl exec -n "$NAMESPACE" momo-postgres-0 -- \
        psql -U "$DB_USER" -d "$DB_NAME" -c "VACUUM ANALYZE" 2>/dev/null
    log "VACUUM ANALYZE 完成"
}

# 終止長時間查詢
kill_long_queries() {
    local threshold_minutes=30
    log "終止超過 ${threshold_minutes} 分鐘的查詢..."

    local killed=$(exec_sql "
        SELECT pg_terminate_backend(pid)
        FROM pg_stat_activity
        WHERE state = 'active'
        AND query_start < now() - interval '${threshold_minutes} minutes'
        AND pid <> pg_backend_pid()
    " | grep -c "t" || echo "0")

    log "已終止 $killed 個長時間查詢"
    echo "$killed"
}

# 重建索引 (針對特定表)
reindex_table() {
    local table=$1
    log "重建索引: $table"
    exec_sql "REINDEX TABLE $table"
}

# 備份資料庫
backup_database() {
    local backup_file="${BACKUP_DIR}/momo_$(date +%Y%m%d_%H%M%S).sql.gz"
    mkdir -p "$BACKUP_DIR"

    log "備份資料庫到 $backup_file"
    kubectl exec -n "$NAMESPACE" momo-postgres-0 -- \
        pg_dump -U "$DB_USER" "$DB_NAME" | gzip > "$backup_file"

    # 保留最近 7 個備份
    ls -t "${BACKUP_DIR}"/*.sql.gz 2>/dev/null | tail -n +8 | xargs rm -f 2>/dev/null || true

    log "備份完成: $backup_file"
    echo "$backup_file"
}

# 重啟 PostgreSQL Pod
restart_postgres() {
    log "重啟 PostgreSQL Pod..."
    kubectl rollout restart statefulset/momo-postgres -n "$NAMESPACE"
    kubectl rollout status statefulset/momo-postgres -n "$NAMESPACE" --timeout=180s
    log "PostgreSQL 重啟完成"
}

# 主修復邏輯
main() {
    log "===== 開始 PostgreSQL 健康檢查 ====="

    local issues_found=0
    local actions_taken=""

    # 1. 檢查連線
    if ! check_connection; then
        log "錯誤：無法連線到資料庫"

        # 嘗試重啟
        restart_postgres
        sleep 30

        if check_connection; then
            actions_taken="${actions_taken}• 重啟 PostgreSQL Pod\n"
            issues_found=1
        else
            send_telegram "🔴 <b>PostgreSQL 連線失敗</b>

❌ 自動重啟後仍無法連線
📋 需要人工檢查

🔗 SSH: <code>ssh wooo@192.168.0.110</code>
⏰ 時間: $(date '+%Y-%m-%d %H:%M:%S')"
            exit 1
        fi
    fi

    # 2. 檢查死鎖
    deadlocks=$(check_deadlocks)
    if [ "$deadlocks" -gt 0 ]; then
        log "發現 $deadlocks 個死鎖"
        killed=$(kill_long_queries)
        actions_taken="${actions_taken}• 終止 $killed 個死鎖查詢\n"
        issues_found=1
    fi

    # 3. 檢查 Dead Tuples
    dead_tuples=$(check_dead_tuples)
    if [ "${dead_tuples:-0}" -gt 100000 ]; then
        log "Dead tuples 過多: $dead_tuples"
        do_vacuum
        actions_taken="${actions_taken}• 執行 VACUUM ANALYZE\n"
        issues_found=1
    fi

    # 4. 檢查膨脹比例
    bloat=$(check_bloat)
    if [ "$(echo "$bloat > 30" | bc -l 2>/dev/null || echo 0)" -eq 1 ]; then
        log "表膨脹過高: ${bloat}%"
        do_vacuum
        actions_taken="${actions_taken}• 表膨脹 ${bloat}%，已執行 VACUUM\n"
        issues_found=1
    fi

    # 5. 每週自動備份 (週日)
    if [ "$(date +%u)" -eq 7 ] && [ "$(date +%H)" -eq 2 ]; then
        backup_file=$(backup_database)
        log "週備份完成: $backup_file"
    fi

    # 發送通知 (如有問題)
    if [ $issues_found -gt 0 ]; then
        send_telegram "🔧 <b>PostgreSQL 自動維護完成</b>

📋 <b>執行動作:</b>
${actions_taken}
📊 目前狀態:
• Dead Tuples: ${dead_tuples:-0}
• 死鎖數: ${deadlocks:-0}
• 膨脹比例: ${bloat:-0}%

✅ 資料庫已恢復正常

⏰ 時間: $(date '+%Y-%m-%d %H:%M:%S')
🏷️ <i>MOMO Pro 自動修復系統</i>"
    fi

    log "===== PostgreSQL 健康檢查完成 ====="
}

main "$@"