package api

import (
	"context"
	"net/http"
	"sync"
	"time"

	hub "git.ipao.vip/rogee/creator-hub/internal/environment"
	"github.com/sirupsen/logrus"
)

// gatewayHealthProbeTimeout 是单次 /healthz 探活的超时；测试可临时替换。
var gatewayHealthProbeTimeout = 5 * time.Second

// gatewayHealthStore 是网关健康检查所需的存储能力；生产实现为 *hub.Store，测试使用内存桩。
type gatewayHealthStore interface {
	ListGateways(ctx context.Context) ([]hub.Gateway, error)
	RecordGatewayCheck(ctx context.Context, name, status, reason string) (hub.Gateway, error)
}

// classifyGatewayHealth 将一次 /healthz 探活结果归一为持久化状态与原因。
// 连接失败或 5xx 判为 unhealthy；其余（含 401 令牌不匹配）说明进程可达，判为 healthy
// 并把异常状态写进 reason 供排查。
func classifyGatewayHealth(status int, callErr error) (string, string) {
	if callErr != nil {
		reason := callErr.Error()
		if len(reason) > 300 {
			reason = reason[:300]
		}
		return "unhealthy", reason
	}
	if status >= 500 {
		return "unhealthy", "gateway returned status " + http.StatusText(status)
	}
	if status >= 400 {
		return "healthy", "gateway responded with status " + http.StatusText(status)
	}
	return "healthy", ""
}

// RecordGatewayHealthChecks 执行一轮网关健康探活并落库；供 workers 定时任务与测试调用。
func RecordGatewayHealthChecks(ctx context.Context, store *hub.Store) error {
	return recordGatewayHealthChecks(ctx, store)
}

// recordGatewayHealthChecks 对全部注册网关并发探活一次，每个网关只覆盖写入最近一次结果。
func recordGatewayHealthChecks(ctx context.Context, store gatewayHealthStore) error {
	gateways, err := store.ListGateways(ctx)
	if err != nil {
		return err
	}
	var wg sync.WaitGroup
	for _, gateway := range gateways {
		wg.Add(1)
		go func() {
			defer wg.Done()
			probeAndRecordGateway(ctx, store, gateway)
		}()
	}
	wg.Wait()
	return nil
}

// probeAndRecordGateway 对单个网关探活一次并覆盖写入最近一次结果；落库失败不阻断其余网关，仅记日志。
func probeAndRecordGateway(ctx context.Context, store gatewayHealthStore, gateway hub.Gateway) {
	status, _, callErr := gatewayCall(ctx, gateway, http.MethodGet, "/healthz", nil, gatewayHealthProbeTimeout)
	healthStatus, reason := classifyGatewayHealth(status, callErr)
	if _, recordErr := store.RecordGatewayCheck(ctx, gateway.Name, healthStatus, reason); recordErr != nil {
		logrus.WithFields(logrus.Fields{
			"service":    "control-plane",
			"event_type": "gateway_health_check",
			"gateway":    gateway.Name,
			"probed":     healthStatus,
		}).WithError(recordErr).Warn("gateway health check result was not persisted")
	}
}

// probeGatewayAsync 在后台对单个网关立即探活一次并落库，不阻塞当前请求；
// 用 WithoutCancel 脱离请求生命周期，请求结束后探活与落库仍会完成。
func probeGatewayAsync(ctx context.Context, store gatewayHealthStore, gateway hub.Gateway) {
	go probeAndRecordGateway(context.WithoutCancel(ctx), store, gateway)
}