package provider

import (
	"fmt"
	"sort"

	"llm-gateway/internal/config"
)

// Route maps a model to a specific provider with pricing.
type Route struct {
	Provider      Provider
	ProviderModel string
	Priority      int
	InputPrice    float64 // per 1M tokens
	OutputPrice   float64 // per 1M tokens
}

// Registry maps model names to provider routes.
type Registry struct {
	routes map[string][]Route
	order  []string // preserves config order
}

func NewRegistry(cfg *config.Config) (*Registry, error) {
	// Build providers
	providers := make(map[string]Provider)
	for _, pc := range cfg.Providers {
		providers[pc.Name] = NewOpenAIProvider(pc.Name, pc.BaseURL, pc.APIKey, pc.Timeout)
	}

	// Build routes (preserving config order)
	routes := make(map[string][]Route)
	order := make([]string, 0, len(cfg.Models))
	for _, mc := range cfg.Models {
		var modelRoutes []Route
		for _, rc := range mc.Routes {
			p, ok := providers[rc.Provider]
			if !ok {
				return nil, fmt.Errorf("model %s: unknown provider %s", mc.Name, rc.Provider)
			}
			pc := cfg.ProviderByName(rc.Provider)
			priority := pc.Priority
			modelRoutes = append(modelRoutes, Route{
				Provider:      p,
				ProviderModel: rc.Model,
				Priority:      priority,
				InputPrice:    rc.Pricing.Input,
				OutputPrice:   rc.Pricing.Output,
			})
		}
		// Sort by priority (lower = higher priority)
		sort.Slice(modelRoutes, func(i, j int) bool {
			return modelRoutes[i].Priority < modelRoutes[j].Priority
		})
		routes[mc.Name] = modelRoutes
		order = append(order, mc.Name)
	}

	return &Registry{routes: routes, order: order}, nil
}

// Lookup returns the routes for a model name.
func (r *Registry) Lookup(model string) ([]Route, bool) {
	routes, ok := r.routes[model]
	return routes, ok
}

// ModelNames returns all registered model names in config order.
func (r *Registry) ModelNames() []string {
	return r.order
}