package router

import (
	"fmt"
	"sync"

	"github.com/edgeai/gateway/internal/config"
)

// LogicalModelMapping maps logical model names to actual model configurations.
type LogicalModelMapping struct {
	mu     sync.RWMutex
	mapping map[string]*ModelTarget
}

// ModelTarget represents the resolved target for a logical model.
type ModelTarget struct {
	LogicalModel  string
	ActualModel   string
	Provider      string
	Endpoint      string
	ContextWindow int
	MaxOutputTokens int
	MaxConcurrency  int
	CancelSupported bool
}

// NewLogicalModelMapping creates a mapping from config.
func NewLogicalModelMapping(cfg *config.Config) *LogicalModelMapping {
	m := &LogicalModelMapping{mapping: make(map[string]*ModelTarget)}
	for logical, mc := range cfg.Models {
		m.mapping[logical] = &ModelTarget{
			LogicalModel:    logical,
			ActualModel:      mc.ActualModel,
			Provider:        mc.Provider,
			Endpoint:        mc.Endpoint,
			ContextWindow:   mc.ContextWindow,
			MaxOutputTokens: mc.MaxOutputTokens,
			MaxConcurrency:  mc.MaxConcurrency,
			CancelSupported: mc.CancelSupported,
		}
	}
	return m
}

// Resolve returns the ModelTarget for a logical model name.
func (m *LogicalModelMapping) Resolve(logicalModel string) (*ModelTarget, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()

	target, ok := m.mapping[logicalModel]
	if !ok {
		return nil, fmt.Errorf("logical model not found: %s", logicalModel)
	}
	return target, nil
}

// List returns all logical model names.
func (m *LogicalModelMapping) List() []string {
	m.mu.RLock()
	defer m.mu.RUnlock()

	names := make([]string, 0, len(m.mapping))
	for n := range m.mapping {
		names = append(names, n)
	}
	return names
}

// Update updates the mapping (for config hot-reload).
func (m *LogicalModelMapping) Update(cfg *config.Config) {
	m.mu.Lock()
	defer m.mu.Unlock()

	m.mapping = make(map[string]*ModelTarget)
	for logical, mc := range cfg.Models {
		m.mapping[logical] = &ModelTarget{
			LogicalModel:    logical,
			ActualModel:     mc.ActualModel,
			Provider:        mc.Provider,
			Endpoint:       mc.Endpoint,
			ContextWindow:   mc.ContextWindow,
			MaxOutputTokens: mc.MaxOutputTokens,
			MaxConcurrency:  mc.MaxConcurrency,
			CancelSupported: mc.CancelSupported,
		}
	}
}