package handler

import (
	"context"
	"database/sql"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/redis/go-redis/v9"
)

// Healthz 健康检查 + /metrics 端点
type Healthz struct {
	db    *sql.DB
	redis *redis.Client
}

// NewHealthz 构造 healthz handler
func NewHealthz(db *sql.DB, rdb *redis.Client) *Healthz {
	return &Healthz{db: db, redis: rdb}
}

// Register 在 gin engine 上注册 /healthz 和 /metrics 路由
func (h *Healthz) Register(r *gin.Engine) {
	r.GET("/healthz", h.handleHealthz)
	r.GET("/metrics", gin.WrapH(promhttp.Handler()))
}

func (h *Healthz) handleHealthz(c *gin.Context) {
	ctx, cancel := context.WithTimeout(c.Request.Context(), 1*time.Second)
	defer cancel()

	status := gin.H{"status": "ok"}

	if err := h.db.PingContext(ctx); err != nil {
		status["db"] = "down"
		status["db_error"] = err.Error()
	} else {
		status["db"] = "up"
	}

	if err := h.redis.Ping(ctx).Err(); err != nil {
		status["redis"] = "down"
		status["redis_error"] = err.Error()
	} else {
		status["redis"] = "up"
	}

	code := http.StatusOK
	if status["db"] == "down" || status["redis"] == "down" {
		code = http.StatusServiceUnavailable
	}
	c.JSON(code, status)
}