package org.embulk.config;

import java.util.List;
import java.util.Map;
import java.util.Iterator;
import com.google.common.collect.ImmutableList;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;

public class DataSourceImpl
        implements ConfigSource, TaskSource, CommitReport, ConfigDiff
{
    protected final ObjectNode data;
    protected final ModelManager model;

    public DataSourceImpl(ModelManager model)
    {
        this(model, new ObjectNode(JsonNodeFactory.instance));
    }

    // visible for DataSourceSerDe, ConfigSourceLoader and TaskInvocationHandler.dump
    public DataSourceImpl(ModelManager model, ObjectNode data)
    {
        this.data = data;
        this.model = model;
    }

    protected DataSourceImpl newInstance(ModelManager model, ObjectNode data)
    {
        return new DataSourceImpl(model, (ObjectNode) data);
    }

    // visible for DataSourceSerDe.DataSourceSerializer
    @Override
    public ObjectNode getObjectNode()
    {
        return data;
    }

    @Override
    public List<String> getAttributeNames()
    {
        return ImmutableList.copyOf(data.fieldNames());
    }

    @Override
    public Iterable<Map.Entry<String, JsonNode>> getAttributes()
    {
        return new Iterable<Map.Entry<String,JsonNode>>() {
            public Iterator<Map.Entry<String, JsonNode>> iterator()
            {
                return data.fields();
            }
        };
    }

    @Override
    public boolean isEmpty()
    {
        return !data.fieldNames().hasNext();
    }

    @Override
    public <E> E get(Class<E> type, String attrName)
    {
        JsonNode json = data.get(attrName);
        if (json == null) {
            throw new ConfigException("Attribute "+attrName+" is required but not set");
        }
        return model.readObject(type, json.traverse());
    }

    @Override
    public <E> E get(Class<E> type, String attrName, E defaultValue)
    {
        JsonNode json = data.get(attrName);
        if (json == null) {
            return defaultValue;
        }
        return model.readObject(type, json.traverse());
    }

    @Override
    public DataSourceImpl getNested(String attrName)
    {
        JsonNode json = data.get(attrName);
        if (json == null) {
            throw new ConfigException("Attribute "+attrName+" is required but not set");
        }
        if (!json.isObject()) {
            throw new ConfigException("Attribute "+attrName+" must be an object");
        }
        return newInstance(model, (ObjectNode) json);
    }

    @Override
    public DataSourceImpl getNestedOrSetEmpty(String attrName)
    {
        JsonNode json = data.get(attrName);
        if (json == null) {
            json = data.objectNode();
            data.set(attrName, json);
        } else if (!json.isObject()) {
            throw new ConfigException("Attribute "+attrName+" must be an object");
        }
        return newInstance(model, (ObjectNode) json);
    }

    @Override
    public DataSourceImpl set(String attrName, Object v)
    {
        if (v == null) {
            remove(attrName);
        } else {
            data.put(attrName, model.writeObjectAsJsonNode(v));
        }
        return this;
    }

    @Override
    public DataSourceImpl setNested(String attrName, DataSource v)
    {
        data.put(attrName, v.getObjectNode());
        return this;
    }

    @Override
    public DataSourceImpl setAll(DataSource other)
    {
        for (Map.Entry<String, JsonNode> field : other.getAttributes()) {
            data.put(field.getKey(), field.getValue());
        }
        return this;
    }

    @Override
    public DataSourceImpl remove(String attrName)
    {
        data.remove(attrName);
        return this;
    }

    @Override
    public DataSourceImpl deepCopy()
    {
        return newInstance(model, data.deepCopy());
    }

    @Override
    public DataSourceImpl merge(DataSource other)
    {
        mergeJsonObject(data, other.deepCopy().getObjectNode());
        return this;
    }

    private static void mergeJsonObject(ObjectNode src, ObjectNode other)
    {
        Iterator<Map.Entry<String, JsonNode>> ite = other.fields();
        while (ite.hasNext()) {
            Map.Entry<String, JsonNode> pair = ite.next();
            JsonNode s = src.get(pair.getKey());
            JsonNode v = pair.getValue();
            if (v.isObject() && s != null && s.isObject()) {
                mergeJsonObject((ObjectNode) s, (ObjectNode) v);
            } else if (v.isArray() && s != null && s.isArray()) {
                mergeJsonArray((ArrayNode) s, (ArrayNode) v);
            } else {
                src.replace(pair.getKey(), v);
            }
        }
    }

    private static void mergeJsonArray(ArrayNode src, ArrayNode other)
    {
        for (int i=0; i < other.size(); i++) {
            JsonNode s = src.get(i);
            JsonNode v = other.get(i);
            if (s == null) {
                src.add(v);
            } else if (v.isObject() && s.isObject()) {
                mergeJsonObject((ObjectNode) s, (ObjectNode) v);
            } else if (v.isArray() && s.isArray()) {
                mergeJsonArray((ArrayNode) s, (ArrayNode) v);
            } else {
                src.remove(i);
                src.insert(i, v);
            }
        }
    }

    @Override
    public <T> T loadTask(Class<T> taskType)
    {
        return model.readObject(taskType, data.traverse());
    }

    @Override
    public <T> T loadConfig(Class<T> taskType)
    {
        return model.readObjectWithConfigSerDe(taskType, data.traverse());
    }

    @Override
    public String toString()
    {
        return data.toString();
    }

    @Override
    public boolean equals(Object other)
    {
        if (!(other instanceof DataSource)) {
            return false;
        }
        return data.equals(((DataSource) other).getObjectNode());
    }

    @Override
    public int hashCode()
    {
        return data.hashCode();
    }
}