package retrieval

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"go.uber.org/zap"

	"github.com/geo-platform/tenant-api/internal/shared/config"
)

var ErrNotConfigured = errors.New("retrieval provider is not configured")

type Provider interface {
	Validate() error
	Embed(ctx context.Context, inputs []string) ([][]float64, error)
	Rerank(ctx context.Context, query string, documents []string, topN int) ([]RerankResult, error)
}

type RerankResult struct {
	Index          int
	RelevanceScore float64
	Text           string
}

func NewProvider(cfg config.RetrievalConfig, logger *zap.Logger) Provider {
	provider := strings.ToLower(strings.TrimSpace(cfg.Provider))
	switch provider {
	case "", "disabled":
		return disabledProvider{reason: "retrieval provider is disabled"}
	case "siliconflow":
		return NewSiliconFlowProvider(cfg, logger)
	default:
		return disabledProvider{reason: fmt.Sprintf("unsupported retrieval provider %q", cfg.Provider)}
	}
}

type disabledProvider struct {
	reason string
}

func (p disabledProvider) Validate() error {
	if p.reason == "" {
		p.reason = "missing retrieval configuration"
	}
	return fmt.Errorf("%w: %s", ErrNotConfigured, p.reason)
}

func (p disabledProvider) Embed(context.Context, []string) ([][]float64, error) {
	return nil, p.Validate()
}

func (p disabledProvider) Rerank(context.Context, string, []string, int) ([]RerankResult, error) {
	return nil, p.Validate()
}