package keyselectors

import (
	"math/rand"

	"github.com/maximhq/bifrost/core/schemas"
)

func WeightedRandom(ctx *schemas.BifrostContext, keys []schemas.Key, providerKey schemas.ModelProvider, model string) (schemas.Key, error) {
	// Use a weighted random selection based on key weights
	totalWeight := 0
	for _, key := range keys {
		totalWeight += int(key.Weight * 100) // Convert float to int for better performance
	}

	// If all keys have zero weight, fall back to uniform random selection
	if totalWeight == 0 {
		return keys[rand.Intn(len(keys))], nil
	}

	// Use global thread-safe random (Go 1.20+) - no allocation, no syscall
	randomValue := rand.Intn(totalWeight)

	// Select key based on weight
	currentWeight := 0
	for _, key := range keys {
		currentWeight += int(key.Weight * 100)
		if randomValue < currentWeight {
			return key, nil
		}
	}

	// Fallback to first key if something goes wrong
	return keys[0], nil
}