package design.persistence;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.SimpleModule;
import design.model.Course;
import design.model.Golfer;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class JSONPersonalDatabase implements PersonalDatabase {

    private final Map<String, Golfer> cache;
    private final ObjectMapper mapper;
    private final File file;

    public JSONPersonalDatabase(String filename) {
        this.file = new File(filename);
        this.cache = new HashMap<>();
        this.mapper = new ObjectMapper();

        SimpleModule module = new SimpleModule();
        module.addDeserializer(Course.class, new CourseIdDeserializer());
        module.addSerializer(Course.class, new CourseIdSerializer());
        mapper.registerModule(module);
        mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
        mapper.writerWithDefaultPrettyPrinter();

        try {
            load();
        } catch (IOException ex) {
            throw new RuntimeException(ex);
        }
    }

    private void load() throws IOException {
        Golfer[] data = mapper.readValue(file, Golfer[].class);
        cache.clear();
        for (Golfer i : data) {
            cache.put(i.getUsername(), i);
        }
    }

    private void save() throws IOException {
        Golfer[] data = cache.values().toArray(Golfer[]::new);
        mapper.writeValue(file, data);
    }

    @Override
    public Golfer[] getGolfers() {
        return new Golfer[0];
    }

    @Override
    public Golfer getGolfer(String username) {
        return cache.get(username);
    }

    @Override
    public void addGolfer(Golfer golfer) throws IOException {
        cache.put(golfer.getUsername(), golfer);
        save();
    }

    @Override
    public void removeGolfer(Golfer golfer) throws IOException {
        cache.remove(golfer.getUsername());
        save();
    }

    @Override
    public void updateGolfer(Golfer golfer) throws IOException {
        cache.put(golfer.getUsername(), golfer);
        save();
    }

    private static class CourseIdSerializer extends JsonSerializer<Course> {
        @Override
        public void serialize(Course course, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeNumber(course.getId());
        }
    }

    private static class CourseIdDeserializer extends JsonDeserializer<Course> {
        MasterDatabase masterDB = MasterDatabase.INSTANCE;

        @Override
        public Course deserialize(JsonParser p, DeserializationContext context) throws IOException {
            int id = p.getValueAsInt();
            return masterDB.getCourse(id);
        }
    }
}