package handlers

import (
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

// HealthHandler provides a health check endpoint that verifies database connectivity.
type HealthHandler struct {
	dbPool *pgxpool.Pool
}

// NewHealthHandler creates a new HealthHandler with the given database pool.
func NewHealthHandler(dbPool *pgxpool.Pool) *HealthHandler {
	return &HealthHandler{dbPool: dbPool}
}

// ServeHTTP handles GET /health requests.
func (h *HealthHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	dbConnected := false
	if h.dbPool != nil {
		if err := h.dbPool.Ping(ctx); err == nil {
			dbConnected = true
		} else {
			slog.Warn("health check db ping failed", "error", err)
		}
	}

	resp := map[string]any{
		"status":       "ok",
		"timestamp":    time.Now().UTC().Format(time.RFC3339),
		"db_connected": dbConnected,
	}

	w.Header().Set("Content-Type", "application/json")
	if !dbConnected {
		w.WriteHeader(http.StatusServiceUnavailable)
	}
	if err := json.NewEncoder(w).Encode(resp); err != nil {
		slog.Error("failed to encode health response", "error", err)
	}
}