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package com.vladsch.flexmark.util.data;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * NOTE: Constructors have changed in a breaking way from 0.50.x and prior implementations
 * 
 * Previously you could provide:
 * 

 * 1. [T] defaultValue
 * 2. DataValueFactory[T]
 * 3. DataKey[T]
 * 

 * Options 1. and 2. are not available separately and both have to be provided to the constructor
 * to eliminate the need for handling null for DataHolder in the data value factory.
 * 

 * Now you have the following choices:
 * 

 * 1. [T] defaultValue AND DataNotNullValueFactory
 * 2. NotNullValueSupplier[T]
 * 3. DataKey[T] from which default value will be taken on construction, and values will be retrieved if no value is set for this key
 * 

 * Additional changes include separating NullableDataKey out so that DataKey values cannot be null. If you need
 * a key with null result value then use NullableDataKey which is identical to DataKey but allows nulls to be used for values.
 *
 * @param  type of data held by the key
 */
public class DataKey extends DataKeyBase {
    /**
     * Creates a DataKey with non-null data value and factory
     * 

     * Use this constructor to ensure that factory is never called with null data holder value
     *
     * @param name         See {@link #getName()}.
     * @param defaultValue default to use when data holder is null
     * @param factory      data value factory for creating a new default value for the key for a non-null data holder
     */
    public DataKey(@NotNull String name, @NotNull T defaultValue, @NotNull DataNotNullValueFactory factory) {
        super(name, defaultValue, factory);
    }

    /**
     * Creates a DataKey with non-null data value and factory
     * 

     * Use this constructor to ensure that factory is never called with null data holder value
     *
     * @param name     See {@link #getName()}.
     * @param supplier data value factory for creating a new default value for the key not dependent on dataHolder
     */
    public DataKey(@NotNull String name, @NotNull NotNullValueSupplier supplier) {
        super(name, supplier.get(), (holder) -> supplier.get());
    }

    /**
     * Creates a DataKey with a dynamic default value taken from a value of another key
     * 
     * does not cache the returned default value but will always delegate to another key until this key
     * gets its own value set.
     *
     * @param name       See {@link #getName()}.
     * @param defaultKey The NullableDataKey to take the default value from at time of construction.
     */
    public DataKey(@NotNull String name, @NotNull DataKey defaultKey) {
        this(name, defaultKey.getDefaultValue(), defaultKey::get);
    }

    public DataKey(@NotNull String name, @NotNull T defaultValue) {
        this(name, defaultValue, options -> defaultValue);
    }

    @NotNull
    public DataNotNullValueFactory getFactory() {
        return (DataNotNullValueFactory) super.getFactory();
    }

    @NotNull
    public T getDefaultValue() {
        return super.getDefaultValue();
    }

    @NotNull
    public T getDefaultValue(@NotNull DataHolder holder) {
        return super.getDefaultValue(holder);
    }

    @NotNull
    public T get(@Nullable DataHolder holder) {
        return super.get(holder);
    }

    @Override
    public @NotNull MutableDataHolder set(@NotNull MutableDataHolder dataHolder, @NotNull T value) {
        return dataHolder.set(this, value);
    }

    @Override
    public String toString() {
        // factory applied to null in constructor, no sense doing it again here
        T defaultValue = getDefaultValue();
        return "DataKey<" + defaultValue.getClass().getSimpleName() + "> " + getName();
    }
}