package handler

import (
	"net/http"
	"runtime"
	"time"

	"github.com/enterprise-ai-platform/server/internal/response"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/redis/go-redis/v9"
)

type HealthHandler struct {
	pool *pgxpool.Pool
	rdb  *redis.Client
}

func NewHealthHandler(pool *pgxpool.Pool, rdb *redis.Client) *HealthHandler {
	return &HealthHandler{pool: pool, rdb: rdb}
}

func (h *HealthHandler) HealthCheck(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	type dep struct {
		Name   string `json:"name"`
		Status string `json:"status"`
		Error  string `json:"error,omitempty"`
	}
	deps := []dep{}

	// PostgreSQL
	if h.pool != nil {
		if err := h.pool.Ping(ctx); err != nil {
			deps = append(deps, dep{Name: "postgres", Status: "down", Error: err.Error()})
		} else {
			deps = append(deps, dep{Name: "postgres", Status: "up"})
		}
	} else {
		deps = append(deps, dep{Name: "postgres", Status: "not_configured"})
	}

	// Redis
	if h.rdb != nil {
		if err := h.rdb.Ping(ctx).Err(); err != nil {
			deps = append(deps, dep{Name: "redis", Status: "down", Error: err.Error()})
		} else {
			deps = append(deps, dep{Name: "redis", Status: "up"})
		}
	} else {
		deps = append(deps, dep{Name: "redis", Status: "not_configured"})
	}

	// Overall status
	status := "ok"
	httpStatus := http.StatusOK
	for _, d := range deps {
		if d.Status == "down" {
			status = "degraded"
			httpStatus = http.StatusServiceUnavailable
			break
		}
	}

	// Runtime stats
	var m runtime.MemStats
	runtime.ReadMemStats(&m)

	response.JSON(w, httpStatus, map[string]any{
		"status":  status,
		"service": "govai-portal-api",
		"uptime":  time.Since(startTime).String(),
		"go":      runtime.Version(),
		"memory": map[string]any{
			" Alloc":   m.Alloc / 1024 / 1024,
			"Sys":     m.Sys / 1024 / 1024,
			"NumGC":   m.NumGC,
			"Goroutine": runtime.NumGoroutine(),
		},
		"dependencies": deps,
	})
}

// startTime is shared with the original health.go init block.
var startTime = time.Now()