#!/bin/bash
# 自動回滾腳本
# 功能：檢測應用異常（高錯誤率、健康檢查失敗），自動回滾到上一個版本

set -e

NAMESPACE="momo"
DEPLOYMENT="momo-app"
HEALTH_URL="https://mo.wooo.work/health"
ERROR_THRESHOLD=5  # 連續失敗次數閾值
TELEGRAM_BOT="<TELEGRAM_BOT_TOKEN>"
TELEGRAM_CHAT="5619078117"
LOG_FILE="/var/log/auto_rollback.log"
STATE_FILE="/tmp/rollback_state.json"

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
}

# 讀取/更新狀態
get_state() {
    local key=$1
    if [ -f "$STATE_FILE" ]; then
        python3 -c "import json; d=json.load(open('$STATE_FILE')); print(d.get('$key', ''))" 2>/dev/null || echo ""
    fi
}

set_state() {
    local key=$1
    local value=$2
    if [ -f "$STATE_FILE" ]; then
        python3 -c "import json; d=json.load(open('$STATE_FILE')); d['$key']='$value'; json.dump(d, open('$STATE_FILE','w'))"
    else
        echo "{\"$key\": \"$value\"}" > "$STATE_FILE"
    fi
}

# 健康檢查
check_health() {
    local status=$(curl -s -o /dev/null -w '%{http_code}' -m 10 "$HEALTH_URL" 2>/dev/null)
    if [ "$status" = "200" ]; then
        return 0
    else
        return 1
    fi
}

# 檢查 Pod 狀態
check_pod_status() {
    local ready=$(kubectl get deployment "$DEPLOYMENT" -n "$NAMESPACE" -o jsonpath='{.status.readyReplicas}' 2>/dev/null || echo "0")
    local desired=$(kubectl get deployment "$DEPLOYMENT" -n "$NAMESPACE" -o jsonpath='{.spec.replicas}' 2>/dev/null || echo "1")

    if [ "${ready:-0}" -ge "${desired:-1}" ]; then
        return 0
    else
        return 1
    fi
}

# 檢查 5xx 錯誤率 (需要 Prometheus)
check_error_rate() {
    # 簡化版：使用最近 10 次請求的失敗比例
    local fail_count=0
    for i in $(seq 1 5); do
        if ! check_health; then
            ((fail_count++))
        fi
        sleep 1
    done

    if [ $fail_count -ge 3 ]; then
        return 1  # 超過 60% 失敗率
    fi
    return 0
}

# 取得當前版本
get_current_revision() {
    kubectl rollout history deployment/"$DEPLOYMENT" -n "$NAMESPACE" 2>/dev/null | \
        grep -E '^[0-9]+' | tail -1 | awk '{print $1}'
}

# 取得上一個版本
get_previous_revision() {
    kubectl rollout history deployment/"$DEPLOYMENT" -n "$NAMESPACE" 2>/dev/null | \
        grep -E '^[0-9]+' | tail -2 | head -1 | awk '{print $1}'
}

# 執行回滾
do_rollback() {
    local current_rev=$(get_current_revision)
    local previous_rev=$(get_previous_revision)

    if [ -z "$previous_rev" ] || [ "$previous_rev" = "$current_rev" ]; then
        log "沒有可回滾的版本"
        return 1
    fi

    log "執行回滾: $current_rev -> $previous_rev"

    # 記錄回滾時間（防止頻繁回滾）
    local last_rollback=$(get_state "last_rollback")
    local now=$(date +%s)

    if [ -n "$last_rollback" ]; then
        local elapsed=$((now - last_rollback))
        if [ $elapsed -lt 3600 ]; then  # 1 小時內不重複回滾
            log "最近 1 小時內已回滾過，跳過"
            return 1
        fi
    fi

    # 執行回滾
    kubectl rollout undo deployment/"$DEPLOYMENT" -n "$NAMESPACE"
    kubectl rollout status deployment/"$DEPLOYMENT" -n "$NAMESPACE" --timeout=120s

    set_state "last_rollback" "$now"
    set_state "rollback_from" "$current_rev"
    set_state "rollback_to" "$previous_rev"

    log "回滾完成"
    return 0
}

# 驗證回滾成功
verify_rollback() {
    sleep 30  # 等待服務穩定

    if check_health && check_pod_status; then
        return 0
    else
        return 1
    fi
}

# 主邏輯
main() {
    log "===== 開始異常檢測 ====="

    local fail_count=$(get_state "fail_count")
    fail_count=${fail_count:-0}

    # 檢查健康狀態
    if check_health && check_pod_status; then
        # 服務正常，重置計數
        if [ "$fail_count" -gt 0 ]; then
            log "服務已恢復正常，重置失敗計數"
            set_state "fail_count" "0"
        fi
        log "服務狀態正常"
        return 0
    fi

    # 服務異常
    ((fail_count++))
    set_state "fail_count" "$fail_count"
    log "檢測到異常，連續失敗次數: $fail_count"

    if [ $fail_count -ge $ERROR_THRESHOLD ]; then
        log "達到回滾閾值 ($ERROR_THRESHOLD)，開始自動回滾"

        current_rev=$(get_current_revision)

        if do_rollback; then
            # 等待並驗證
            if verify_rollback; then
                send_telegram "🔄 <b>自動回滾成功</b>

📦 Deployment: <code>$DEPLOYMENT</code>
📊 版本回滾: $current_rev → $(get_current_revision)
🔍 原因: 連續 $ERROR_THRESHOLD 次健康檢查失敗

✅ 服務已恢復正常

⚠️ <b>請檢查最新部署的程式碼問題</b>

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

                set_state "fail_count" "0"
                log "回滾驗證成功"
            else
                send_telegram "🔴 <b>自動回滾失敗</b>

📦 Deployment: <code>$DEPLOYMENT</code>
❌ 回滾後服務仍然異常
📋 需要人工介入

🔗 SSH: <code>ssh wooo@192.168.0.110</code>
🔗 查看日誌: <code>kubectl logs -f deployment/$DEPLOYMENT -n $NAMESPACE</code>

⏰ 時間: $(date '+%Y-%m-%d %H:%M:%S')"
            fi
        fi
    else
        log "異常次數 $fail_count 未達閾值 $ERROR_THRESHOLD"
    fi

    log "===== 異常檢測完成 ====="
}

main "$@"