package modelvalidator

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	"gitea.nik4nao.com/nik/home-services/discord-bot/internal/core/ports/driven"
)

// Validator caches the model list briefly and normalizes friendly names.
type Validator struct {
	client driven.AIGateway
	ttl    time.Duration

	mu       sync.Mutex
	cache    []string
	cachedAt time.Time
}

// New constructs a model validator with a TTL cache.
func New(client driven.AIGateway, ttl time.Duration) *Validator {
	return &Validator{client: client, ttl: ttl}
}

// Known returns the cached model list, refreshing when stale.
func (v *Validator) Known(ctx context.Context) ([]string, error) {
	v.mu.Lock()
	defer v.mu.Unlock()
	if len(v.cache) > 0 && time.Since(v.cachedAt) < v.ttl {
		return append([]string(nil), v.cache...), nil
	}
	models, err := v.client.ListModels(ctx)
	if err != nil {
		return nil, err
	}
	v.cache = append([]string(nil), models...)
	v.cachedAt = time.Now()
	return append([]string(nil), v.cache...), nil
}

// Normalize resolves a user-provided name to a canonical installed model name.
func (v *Validator) Normalize(ctx context.Context, name string) (string, error) {
	models, err := v.Known(ctx)
	if err != nil {
		return "", err
	}
	for _, model := range models {
		if model == name {
			return model, nil
		}
	}
	latest := name + ":latest"
	for _, model := range models {
		if model == latest {
			return model, nil
		}
	}

	lower := strings.ToLower(name)
	for _, model := range models {
		if strings.ToLower(model) == lower {
			return model, nil
		}
	}
	lowerLatest := strings.ToLower(latest)
	for _, model := range models {
		if strings.ToLower(model) == lowerLatest {
			return model, nil
		}
	}

	matches := make([]string, 0, 2)
	prefix := lower + ":"
	for _, model := range models {
		if strings.HasPrefix(strings.ToLower(model), prefix) {
			matches = append(matches, model)
		}
	}
	if len(matches) > 1 {
		return "", fmt.Errorf("ambiguous model name")
	}
	return "", fmt.Errorf("unknown model")
}