package ym

import (
	"fmt"
	"net/http"
	"sipro-mps/internal/redis"
	"time"

	"github.com/redis/rueidis"
)

// RateLimit defines a rate limit configuration
type RateLimit struct {
	Count     int           // Number of requests allowed
	TimeDelta time.Duration // Time window
}

// Path rate limits for Yandex Market API
var PathLimits = map[string]RateLimit{
	"/tariffs/calculate": {Count: 100, TimeDelta: time.Minute},
	"/campaigns":         {Count: 300, TimeDelta: time.Minute},
	"/orders":            {Count: 1000, TimeDelta: time.Minute},
}

var rateLimitScript = rueidis.NewLuaScript(`
local key = KEYS[1]
local now = tonumber(ARGV[1])
local window = tonumber(ARGV[2])
local limit = tonumber(ARGV[3])

-- Remove old entries outside the time window
redis.call('ZREMRANGEBYSCORE', key, '-inf', now - window)
local count = redis.call('ZCARD', key)

if count < limit then
	-- Add new request timestamp and set TTL
	redis.call('ZADD', key, now, now)
	redis.call('EXPIRE', key, math.ceil(window / 1000))
	return 0
else
	-- Find oldest request timestamp
	local oldest = redis.call('ZRANGE', key, 0, 0, 'WITHSCORES')[2]
	-- Return wait time until oldest request expires
	return (tonumber(oldest) + window) - now
end
`)

type RateLimitTransport struct {
	http.RoundTripper
}

func (t *RateLimitTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	ctx := req.Context()

	// Extract API key from headers
	apiKey := req.Header.Get("Api-Key")
	if apiKey == "" {
		return nil, fmt.Errorf("Api-Key header is required for rate limiting")
	}

	// Get path from header or URL
	var path string
	path = req.URL.Path

	// Get rate limit for this path
	rateLimit, exists := PathLimits[path]
	if !exists {
		rateLimit = RateLimit{Count: 100, TimeDelta: time.Minute} // default limit
	}

	// Create unique key based on API key and path
	rateLimitKey := fmt.Sprintf("ym:ratelimit:%s:%s", apiKey, path)

	now := time.Now().UnixMilli()
	windowMillis := int64(rateLimit.TimeDelta / time.Millisecond)

	client := *redis.Client

	waitTime, err := rateLimitScript.Exec(ctx, client, []string{rateLimitKey}, []string{
		fmt.Sprintf("%d", now),
		fmt.Sprintf("%d", windowMillis),
		fmt.Sprintf("%d", rateLimit.Count),
	}).ToInt64()

	if err != nil {
		return nil, fmt.Errorf("rate limit script error: %w", err)
	}

	if waitTime > 0 {
		select {
		case <-time.After(time.Duration(waitTime) * time.Millisecond):
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}

	return t.RoundTripper.RoundTrip(req)
}

// NewRateLimitTransport creates a new rate limiting transport
func NewRateLimitTransport() *RateLimitTransport {
	return &RateLimitTransport{
		RoundTripper: http.DefaultTransport,
	}
}

// SetPathLimit sets a custom rate limit for a specific path
func SetPathLimit(path string, timeDelta time.Duration, count int) {
	PathLimits[path] = RateLimit{
		Count:     count,
		TimeDelta: timeDelta,
	}
}