package handler

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

	"carrotskin/pkg/redis"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

// NewHealthCheck 构造健康检查 handler，依赖通过参数注入。
func NewHealthCheck(db *gorm.DB, redisClient *redis.Client) gin.HandlerFunc {
	return func(c *gin.Context) {
		ctx, cancel := context.WithTimeout(c.Request.Context(), 5*time.Second)
		defer cancel()

		checks := make(map[string]string)
		status := "ok"

		// 检查数据库
		if err := checkDatabase(ctx, db); err != nil {
			checks["database"] = "unhealthy: " + err.Error()
			status = "degraded"
		} else {
			checks["database"] = "healthy"
		}

		// 检查Redis
		if err := checkRedis(ctx, redisClient); err != nil {
			checks["redis"] = "unhealthy: " + err.Error()
			status = "degraded"
		} else {
			checks["redis"] = "healthy"
		}

		// 根据状态返回相应的HTTP状态码
		httpStatus := http.StatusOK
		if status == "degraded" {
			httpStatus = http.StatusServiceUnavailable
		}

		c.JSON(httpStatus, gin.H{
			"status":    status,
			"message":   "CarrotSkin API health check",
			"checks":    checks,
			"timestamp": time.Now().Unix(),
		})
	}
}

// checkDatabase 检查数据库连接
func checkDatabase(ctx context.Context, db *gorm.DB) error {
	if db == nil {
		return errors.New("数据库未初始化")
	}
	sqlDB, err := db.DB()
	if err != nil {
		return err
	}

	// 使用Ping检查连接
	if err := sqlDB.PingContext(ctx); err != nil {
		return err
	}

	// 执行简单查询验证
	var result int
	if err := db.WithContext(ctx).Raw("SELECT 1").Scan(&result).Error; err != nil {
		return err
	}

	return nil
}

// checkRedis 检查Redis连接
func checkRedis(ctx context.Context, client *redis.Client) error {
	if client == nil {
		return errors.New("Redis客户端未初始化")
	}

	// 使用Ping检查连接（封装后的方法直接返回error）
	if err := client.Ping(ctx); err != nil {
		return err
	}

	return nil
}