// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.9.0;

/**
 * @title IChainStorageContainer
 */
interface IChainStorageContainer {
    /********************
     * Public Functions *
     ********************/

    /**
     * Sets the container's global metadata field. We're using `bytes27` here because we use five
     * bytes to maintain the length of the underlying data structure, meaning we have an extra
     * 27 bytes to store arbitrary data.
     * @param _globalMetadata New global metadata to set.
     */
    function setGlobalMetadata(bytes27 _globalMetadata) external;

    /**
     * Retrieves the container's global metadata field.
     * @return Container global metadata field.
     */
    function getGlobalMetadata() external view returns (bytes27);

    /**
     * Retrieves the number of objects stored in the container.
     * @return Number of objects in the container.
     */
    function length() external view returns (uint256);

    /**
     * Pushes an object into the container.
     * @param _object A 32 byte value to insert into the container.
     */
    function push(bytes32 _object) external;

    /**
     * Pushes an object into the container. Function allows setting the global metadata since
     * we'll need to touch the "length" storage slot anyway, which also contains the global
     * metadata (it's an optimization).
     * @param _object A 32 byte value to insert into the container.
     * @param _globalMetadata New global metadata for the container.
     */
    function push(bytes32 _object, bytes27 _globalMetadata) external;

    /**
     * Retrieves an object from the container.
     * @param _index Index of the particular object to access.
     * @return 32 byte object value.
     */
    function get(uint256 _index) external view returns (bytes32);

    /**
     * Removes all objects after and including a given index.
     * @param _index Object index to delete from.
     */
    function deleteElementsAfterInclusive(uint256 _index) external;

    /**
     * Removes all objects after and including a given index. Also allows setting the global
     * metadata field.
     * @param _index Object index to delete from.
     * @param _globalMetadata New global metadata for the container.
     */
    function deleteElementsAfterInclusive(uint256 _index, bytes27 _globalMetadata) external;
}