package middleware

import (
	"net/http"
	"sync"
	"time"

	"music-server/internal/logging"

	"github.com/labstack/echo/v5"
	"go.uber.org/zap"
)

// RateLimiter implements a simple IP-based rate limiter
type RateLimiter struct {
	visits map[string]*Visit
	mu     sync.Mutex
	limit  int           // requests per window
	window time.Duration // time window
}

type Visit struct {
	count     int
	firstSeen time.Time
}

// NewRateLimiter creates a new rate limiter
func NewRateLimiter(limit int, window time.Duration) *RateLimiter {
	rl := &RateLimiter{
		visits: make(map[string]*Visit),
		limit:  limit,
		window: window,
	}

	// Start cleanup goroutine
	go rl.cleanup()
	return rl
}

// cleanup periodically removes old entries
func (rl *RateLimiter) cleanup() {
	for {
		time.Sleep(rl.window)
		rl.mu.Lock()
		now := time.Now()
		for ip, visit := range rl.visits {
			if now.Sub(visit.firstSeen) > rl.window {
				delete(rl.visits, ip)
			}
		}
		rl.mu.Unlock()
	}
}

// RateLimitMiddleware returns an Echo middleware for rate limiting
func RateLimitMiddleware(rl *RateLimiter) echo.MiddlewareFunc {
	return func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c *echo.Context) error {
			ip := c.RealIP()

			rl.mu.Lock()
			defer rl.mu.Unlock()

			visit, exists := rl.visits[ip]
			now := time.Now()

			if !exists {
				// First visit from this IP
				rl.visits[ip] = &Visit{
					count:     1,
					firstSeen: now,
				}
				return next(c)
			}

			// Check if window has expired
			if now.Sub(visit.firstSeen) > rl.window {
				// Reset for new window
				visit.count = 1
				visit.firstSeen = now
				return next(c)
			}

			// Check if limit exceeded
			if visit.count >= rl.limit {
				logging.GetLogger().Warn("Rate limit exceeded",
					zap.String("ip", ip),
					zap.String("path", c.Request().URL.Path))
				return c.JSON(http.StatusTooManyRequests, map[string]string{
					"error": "Rate limit exceeded. Please try again later.",
				})
			}

			// Increment count
			visit.count++
			return next(c)
		}
	}
}