package handlers

import (
	"fmt"
	"runtime"
	"time"

	"github.com/gofiber/fiber/v3"
)

func ErrorHandler(c fiber.Ctx, err error) error {
	code := fiber.StatusInternalServerError
	message := "Internal Server Error"

	if e, ok := err.(*fiber.Error); ok {
		code = e.Code
		message = e.Message
	}

	return c.Status(code).JSON(fiber.Map{
		"error":     message,
		"timestamp": time.Now().UTC(),
		"path":      c.Path(),
		"method":    c.Method(),
		"request_id": c.Get("X-Request-ID", ""),
	})
}

func HealthCheck(c fiber.Ctx) error {
	uptime := time.Since(startTime)
	
	return c.JSON(fiber.Map{
		"status":    "ok",
		"timestamp": time.Now().UTC(),
		"uptime":    uptime.String(),
		"service":   "gateway",
		"version":   "1.0.0",
		"checks": fiber.Map{
			"database": "ok",
			"cache":    "ok",
		},
	})
}

func Metrics(c fiber.Ctx) error {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	
	return c.JSON(fiber.Map{
		"system": fiber.Map{
			"memory": fiber.Map{
				"allocated":     formatBytes(m.Alloc),
				"total_allocated": formatBytes(m.TotalAlloc),
				"system":        formatBytes(m.Sys),
				"gc_runs":       m.NumGC,
			},
			"goroutines": runtime.NumGoroutine(),
			"cpu_count":  runtime.NumCPU(),
		},
		"service": fiber.Map{
			"uptime":    time.Since(startTime).String(),
			"version":   "1.0.0",
			"timestamp": time.Now().UTC(),
		},
	})
}

var startTime = time.Now()

func formatBytes(b uint64) string {
	const unit = 1024
	if b < unit {
		return fmt.Sprintf("%d B", b)
	}
	div, exp := uint64(unit), 0
	for n := b / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "KMGTPE"[exp])
}