package pipeline

import (
	"fmt"
	"log/slog"

	"textmachine/backend/internal/config"
	"textmachine/backend/internal/llm"
)

// clients.go builds LLMClients from models.yaml. One client per model name
// (a model carries its ExtraBody), lazily cached by the runner.

// BuildClient constructs the adapter for one configured model.
func BuildClient(models *config.Models, modelName string, logger *slog.Logger) (llm.LLMClient, error) {
	mod, ok := models.Models[modelName]
	if !ok {
		return nil, fmt.Errorf("pipeline: model %q is not defined in models.yaml", modelName)
	}
	prov := models.Providers[mod.Provider] // существование проверено fail-fast валидацией

	switch prov.Kind {
	case "openai":
		return llm.NewOpenAICompatClient(llm.OpenAICompatConfig{
			Name:      mod.Provider,
			BaseURL:   prov.BaseURL,
			APIKey:    prov.APIKey(),
			Profile:   prov.Timeouts.Profile(),
			Reasoning: llm.ReasoningSemantics(prov.Reasoning),
			ExtraBody: mod.ExtraBody,
		}, logger), nil
	case "anthropic":
		return llm.NewAnthropicClient(llm.AnthropicConfig{
			BaseURL:  prov.BaseURL,
			APIKey:   prov.APIKey(),
			Profile:  prov.Timeouts.Profile(),
			CacheTTL: prov.CacheTTL,
		}, logger), nil
	case "local":
		return llm.NewLocalClient(llm.LocalConfig{
			BaseURL:   prov.BaseURL,
			APIKey:    prov.APIKey(),
			Model:     prov.Model,
			MaxTokens: prov.MaxTokens,
			Profile:   prov.Timeouts.Profile(),
		}, logger), nil
	default:
		return nil, fmt.Errorf("pipeline: provider %q has unknown kind %q", mod.Provider, prov.Kind)
	}
}