package io.gitlab.jfronny.resclone.util.config;

import com.google.gson.reflect.TypeToken;
import io.gitlab.jfronny.commons.serialize.gson.api.v1.GsonHolders;
import io.gitlab.jfronny.gson.JsonParseException;
import io.gitlab.jfronny.gson.TypeAdapter;
import io.gitlab.jfronny.gson.stream.*;
import io.gitlab.jfronny.resclone.data.PackMetaUnloaded;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.Set;

public class RescloneConfigTypeAdapter extends TypeAdapter<RescloneConfig> {
    private static final String PACKS = "packs";
    private static final String PRUNE_UNUSED = "pruneUnused";
    private static final Type META_SET = new TypeToken<Set<PackMetaUnloaded>>(){}.getType();

    @Override
    public RescloneConfig read(JsonReader jsonReader) throws IOException {
        if (jsonReader.peek() == JsonToken.BEGIN_ARRAY) {
            // Legacy format compatibility
            return new RescloneConfig(GsonHolders.CONFIG.getGson().fromJson(jsonReader, META_SET), false, true);
        } else if (jsonReader.peek() == JsonToken.BEGIN_OBJECT) {
            // New format
            jsonReader.beginObject();
            Set<PackMetaUnloaded> packs = null;
            Boolean pruneUnused = null;
            boolean updateRequired = false;
            while (jsonReader.peek() != JsonToken.END_OBJECT) {
                final String name = jsonReader.nextName();
                switch (name) {
                    case PACKS -> {
                        if (packs != null) throw new JsonParseException("Unexpected duplicate \"" + PACKS + "\" in Resclone config");
                        packs = GsonHolders.CONFIG.getGson().fromJson(jsonReader, META_SET);
                    }
                    case PRUNE_UNUSED -> {
                        if (pruneUnused != null) throw new JsonParseException("Unexpected duplicate \"" + PRUNE_UNUSED + "\" in Resclone config");
                        pruneUnused = jsonReader.nextBoolean();
                    }
                    default -> throw new JsonParseException("Unexpected element: \"" + name + "\" in Resclone config");
                }
            }
            jsonReader.endObject();
            if (packs == null) throw new JsonParseException("Expected Resclone config object to contain packs");
            if (pruneUnused == null) {
                pruneUnused = true;
                updateRequired = true;
            }
            return new RescloneConfig(packs, pruneUnused, updateRequired);
        } else throw new JsonParseException("Expected Resclone config to be an object or array");
    }

    @Override
    public void write(JsonWriter jsonWriter, RescloneConfig rescloneConfig) throws IOException {
        jsonWriter.beginObject()
                .comment("The packs to be loaded by resclone")
                .name(PACKS);
        GsonHolders.CONFIG.getGson().toJson(rescloneConfig.packs(), META_SET, jsonWriter);
        jsonWriter.comment("Whether to prune unused packs from the cache")
                .name(PRUNE_UNUSED)
                .value(rescloneConfig.pruneUnused())
                .endObject();
    }
}