Model Picker — Java source

// model-picker — Java port: filter + rank the AI model catalog.
import java.util.Comparator;
import java.util.List;
import java.util.Map;

/** Filter + rank the AI model catalog, ported from the canonical TS lib. */
public final class ModelPicker {

    /** Pricing projection of the TS AiModel record — null fields play the
     *  role of TS null (unpriced model / unknown release date). */
    public record Model(String id, String tier, long contextWindow,
                        Double inputPerM, Double outputPerM, String released) {}

    /** Projection of the TS ModelFilter — the three constraints the presets use. */
    public record ModelFilter(String tier, Long minContext, Double maxInputPerM) {
        public static final ModelFilter NONE = new ModelFilter(null, null, null);
    }

    /** Curated entry points: a filter + the sort that makes that filter useful. */
    public static final Map<String, ModelFilter> PRESET_FILTERS = Map.of(
            "long-context", new ModelFilter(null, 500_000L, null),
            "cheap-bulk", new ModelFilter(null, null, 1d),
            "flagship", new ModelFilter("flagship", null, null));

    /** id ascending — the shared stable tie-break for every sort. */
    static final Comparator<Model> BY_ID = Comparator.comparing(Model::id);

    /** Output tokens per USD: 1e6 / outputPerM, or null when unpriced. */
    static Double tokensPerDollar(Model m) {
        return m.outputPerM() == null ? null : 1e6 / m.outputPerM();
    }

    /** Sort comparator per key: value order first, null last, id asc on ties. */
    static final Map<String, Comparator<Model>> COMPARATORS = Map.of(
            "price", Comparator.comparing(Model::inputPerM,
                            Comparator.nullsLast(Comparator.naturalOrder())).thenComparing(BY_ID),
            "context", Comparator.comparingLong(Model::contextWindow).reversed().thenComparing(BY_ID),
            "tokensPerDollar", Comparator.comparing(ModelPicker::tokensPerDollar,
                            Comparator.nullsLast(Comparator.reverseOrder())).thenComparing(BY_ID),
            "released", Comparator.comparing(Model::released,
                            Comparator.nullsLast(Comparator.reverseOrder())).thenComparing(BY_ID));

    /** Filter step, inlined from listModels in src/lib/ai/models.ts (the
     *  pricing snapshot accessor): null prices never satisfy maxInputPerM. */
    static List<Model> listModels(List<Model> models, ModelFilter f) {
        return models.stream().filter(m ->
                (f.tier() == null || m.tier().equals(f.tier())) &&
                (f.minContext() == null || m.contextWindow() >= f.minContext()) &&
                (f.maxInputPerM() == null ||
                        (m.inputPerM() != null && m.inputPerM() <= f.maxInputPerM())))
                .toList();
    }

    /** Filter the model list, then sort it. See COMPARATORS for the exact order. */
    static List<Model> pickModels(List<Model> models, ModelFilter f, String sort) {
        return listModels(models, f).stream().sorted(COMPARATORS.get(sort)).toList();
    }

    public static void main(String[] args) {
        List<Model> models = List.of(
                new Model("atlas-flagship", "flagship", 1_000_000, 3.0, 15.0, "2025-03-01"),
                new Model("atlas-mini", "fast", 200_000, 0.5, 2.0, "2025-01-15"),
                new Model("nova-open", "balanced", 1_000_000, null, null, null), // unpriced
                new Model("zeta-budget", "budget", 128_000, 0.5, 1.0, "2024-12-01"));

        System.out.println("long-context (minContext >= 500000, sort context):");
        for (Model m : pickModels(models, PRESET_FILTERS.get("long-context"), "context"))
            System.out.printf("  %-14s ctx %d%n", m.id(), m.contextWindow());

        System.out.println("price sort (all models, unpriced last, ties by id):");
        for (Model m : pickModels(models, ModelFilter.NONE, "price")) {
            if (m.inputPerM() != null)
                System.out.printf("  %-14s $%.2f/M in%n", m.id(), m.inputPerM());
            else
                System.out.printf("  %-14s unpriced%n", m.id());
        }
    }
}