package agent

import "os"

// defaultCompactionModels maps backend names to cheap models suitable for compaction.
var defaultCompactionModels = map[string]string{
	"anthropic":  "claude-3-5-haiku-latest",
	"openai":     "gpt-4o-mini",
	"openrouter": "deepseek-v4-flash",
	"gemini":     "gemini-2.0-flash",
}

// backendNamer is the subset of backend.Backend needed for compaction model resolution.
type backendNamer interface {
	Name() string
}

// resolveCompactionModel returns the model to use for compaction.
// Priority: agent config > OLLIE_COMPACTION_MODEL env > per-backend default.
// Returns "" if no override is configured (use the session's current model).
func resolveCompactionModel(cfgModel string, b backendNamer) string {
	if cfgModel != "" {
		return cfgModel
	}
	if env := os.Getenv("OLLIE_COMPACTION_MODEL"); env != "" {
		return env
	}
	if b != nil {
		return defaultCompactionModels[b.Name()]
	}
	return ""
}