// SPDX-License-Identifier: AGPLv3
pragma solidity >= 0.8.0;

import { ISuperAgreement } from "../superfluid/ISuperAgreement.sol";
import { ISuperfluidToken } from "../superfluid/ISuperfluidToken.sol";


/**
 * @title Instant Distribution Agreement interface
 * @author Superfluid
 *
 * Notes:
 *   - A publisher can create as many as indices as possibly identifiable with `indexId`.
 *     - `indexId` is deliberately limited to 32 bits, to avoid the chance for sha-3 collision.
 *       Despite knowing sha-3 collision is only theoretical.
 *   - A publisher can create a subscription to an index for any subscriber.
 *   - A subscription consists of:
 *     - The index it subscribes to.
 *     - Number of units subscribed.
 *   - An index consists of:
 *     - Current value as `uint128 indexValue`.
 *     - Total units of the approved subscriptions as `uint128 totalUnitsApproved`.
 *     - Total units of the non approved subscription as `uint128 totalUnitsPending`.
 *   - A publisher can update an index with a new value that doesn't decrease.
 *   - A publisher can update a subscription with any number of units.
 *   - A publisher or a subscriber can delete a subscription and reset its units to zero.
 *   - A subscriber must approve the index in order to receive distributions from the publisher
 *     each time the index is updated.
 *     - The amount distributed is $$\Delta{index} * units$$
 *   - Distributions to a non approved subscription stays in the publisher's deposit until:
 *     - the subscriber approves the subscription (side effect),
 *     - the publisher updates the subscription (side effect),
 *     - the subscriber deletes the subscription even if it is never approved (side effect),
 *     - or the subscriber can explicitly claim them.
 */
abstract contract IInstantDistributionAgreementV1 is ISuperAgreement {

    /// @dev ISuperAgreement.agreementType implementation
    function agreementType() external override pure returns (bytes32) {
        return keccak256("org.superfluid-finance.agreements.InstantDistributionAgreement.v1");
    }

    /**************************************************************************
     * Index operations
     *************************************************************************/

    /**
     * @dev Create a new index for the publisher
     * @param token Super token address
     * @param indexId Id of the index
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * # App callbacks
     *
     * None
     */
    function createIndex(
        ISuperfluidToken token,
        uint32 indexId,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);
    /**
    * @dev Index created event
    * @param token Super token address
    * @param publisher Index creator and publisher
    * @param indexId The specified indexId of the newly created index
    * @param userData The user provided data
    */
    event IndexCreated(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        bytes userData);

    /**
     * @dev Query the data of a index
     * @param token Super token address
     * @param publisher The publisher of the index
     * @param indexId Id of the index
     * @return exist Does the index exist
     * @return indexValue Value of the current index
     * @return totalUnitsApproved Total units approved for the index
     * @return totalUnitsPending Total units pending approval for the index
     */
    function getIndex(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId)
            external
            view
            virtual
            returns(
                bool exist,
                uint128 indexValue,
                uint128 totalUnitsApproved,
                uint128 totalUnitsPending);

    /**
     * @dev Calculate actual distribution amount
     * @param token Super token address
     * @param publisher The publisher of the index
     * @param indexId Id of the index
     * @param amount The amount of tokens desired to be distributed
     * @return actualAmount The amount to be distributed after ensuring no rounding errors
     * @return newIndexValue The index value given the desired amount of tokens to be distributed
     */
    function calculateDistribution(
       ISuperfluidToken token,
       address publisher,
       uint32 indexId,
       uint256 amount)
           external view
           virtual
           returns(
               uint256 actualAmount,
               uint128 newIndexValue);

    /**
     * @dev Update index value of an index
     * @param token Super token address
     * @param indexId Id of the index
     * @param indexValue Value of the index
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * # App callbacks
     *
     * None
     */
    function updateIndex(
        ISuperfluidToken token,
        uint32 indexId,
        uint128 indexValue,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);
    /**
      * @dev Index updated event
      * @param token Super token address
      * @param publisher Index updater and publisher
      * @param indexId The specified indexId of the updated index
      * @param oldIndexValue The previous index value
      * @param newIndexValue The updated index value
      * @param totalUnitsPending The total units pending when the indexValue was updated
      * @param totalUnitsApproved The total units approved when the indexValue was updated
      * @param userData The user provided data
      */
    event IndexUpdated(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        uint128 oldIndexValue,
        uint128 newIndexValue,
        uint128 totalUnitsPending,
        uint128 totalUnitsApproved,
        bytes userData);

    /**
     * @dev Distribute tokens through the index
     * @param token Super token address
     * @param indexId Id of the index
     * @param amount The amount of tokens desired to be distributed
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * NOTE:
     * - This is a convenient version of updateIndex. It adds to the index
     *   a delta that equals to `amount / totalUnits`
     * - The actual amount distributed could be obtained via
     *   `calculateDistribution`. This is due to precision error with index
     *   value and units data range
     *
     * # App callbacks
     *
     * None
     */
    function distribute(
        ISuperfluidToken token,
        uint32 indexId,
        uint256 amount,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);


    /**************************************************************************
     * Subscription operations
     *************************************************************************/

    /**
     * @dev Approve the subscription of an index
     * @param token Super token address
     * @param publisher The publisher of the index
     * @param indexId Id of the index
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * # App callbacks
     *
     * - if subscription exist
     *   - AgreementCreated callback to the publisher:
     *      - agreementId is for the subscription
     * - if subscription does not exist
     *   - AgreementUpdated callback to the publisher:
     *      - agreementId is for the subscription
     */
    function approveSubscription(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);
    /**
      * @dev Index subscribed event
      * @param token Super token address
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param subscriber The approved subscriber
      * @param userData The user provided data
      */
    event IndexSubscribed(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        address subscriber,
        bytes userData);

    /**
      * @dev Subscription approved event
      * @param token Super token address
      * @param subscriber The approved subscriber
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param userData The user provided data
      */
    event SubscriptionApproved(
        ISuperfluidToken indexed token,
        address indexed subscriber,
        address publisher,
        uint32 indexId,
        bytes userData);

    /**
    * @notice Revoke the subscription of an index
    * @dev "Unapproves" the subscription and moves approved units to pending
    * @param token Super token address
    * @param publisher The publisher of the index
    * @param indexId Id of the index
    * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
    *
    * # App callbacks
    * - AgreementUpdated callback to the publisher:
    *    - agreementId is for the subscription
    */
    function revokeSubscription(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId,
        bytes calldata ctx)
         external
         virtual
         returns(bytes memory newCtx);
    /**
      * @dev Index unsubscribed event
      * @param token Super token address
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param subscriber The unsubscribed subscriber
      * @param userData The user provided data
      */
    event IndexUnsubscribed(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        address subscriber,
        bytes userData);
    
    /**
      * @dev Subscription approved event
      * @param token Super token address
      * @param subscriber The approved subscriber
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param userData The user provided data
      */
    event SubscriptionRevoked(
        ISuperfluidToken indexed token,
        address indexed subscriber,
        address publisher,
        uint32 indexId,
        bytes userData);

    /**
     * @dev Update the nuber of units of a subscription
     * @param token Super token address
     * @param indexId Id of the index
     * @param subscriber The subscriber of the index
     * @param units Number of units of the subscription
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * # App callbacks
     *
     * - if subscription exist
     *   - AgreementCreated callback to the subscriber:
     *      - agreementId is for the subscription
     * - if subscription does not exist
     *   - AgreementUpdated callback to the subscriber:
     *      - agreementId is for the subscription
     */
    function updateSubscription(
        ISuperfluidToken token,
        uint32 indexId,
        address subscriber,
        uint128 units,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);

    /**
      * @dev Index units updated event
      * @param token Super token address
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param subscriber The subscriber units updated
      * @param units The new units amount
      * @param userData The user provided data
      */
    event IndexUnitsUpdated(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        address subscriber,
        uint128 units,
        bytes userData);
    
    /**
      * @dev Subscription units updated event
      * @param token Super token address
      * @param subscriber The subscriber units updated
      * @param indexId The specified indexId
      * @param publisher Index publisher
      * @param units The new units amount
      * @param userData The user provided data
      */
    event SubscriptionUnitsUpdated(
        ISuperfluidToken indexed token,
        address indexed subscriber,
        address publisher,
        uint32 indexId,
        uint128 units,
        bytes userData);

    /**
     * @dev Get data of a subscription
     * @param token Super token address
     * @param publisher The publisher of the index
     * @param indexId Id of the index
     * @param subscriber The subscriber of the index
     * @return exist Does the subscription exist?
     * @return approved Is the subscription approved?
     * @return units Units of the suscription
     * @return pendingDistribution Pending amount of tokens to be distributed for unapproved subscription
     */
    function getSubscription(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId,
        address subscriber)
            external
            view
            virtual
            returns(
                bool exist,
                bool approved,
                uint128 units,
                uint256 pendingDistribution
            );

    /**
     * @notice Get data of a subscription by agreement ID
     * @dev indexId (agreementId) is the keccak256 hash of encodePacked("publisher", publisher, indexId)
     * @param token Super token address
     * @param agreementId The agreement ID
     * @return publisher The publisher of the index
     * @return indexId Id of the index
     * @return approved Is the subscription approved?
     * @return units Units of the suscription
     * @return pendingDistribution Pending amount of tokens to be distributed for unapproved subscription
     */
    function getSubscriptionByID(
        ISuperfluidToken token,
        bytes32 agreementId)
            external
            view
            virtual
            returns(
                address publisher,
                uint32 indexId,
                bool approved,
                uint128 units,
                uint256 pendingDistribution
            );

    /**
     * @dev List subscriptions of an user
     * @param token Super token address
     * @param subscriber The subscriber's address
     * @return publishers Publishers of the subcriptions
     * @return indexIds Indexes of the subscriptions
     * @return unitsList Units of the subscriptions
     */
    function listSubscriptions(
        ISuperfluidToken token,
        address subscriber)
            external
            view
            virtual
            returns(
                address[] memory publishers,
                uint32[] memory indexIds,
                uint128[] memory unitsList);

    /**
     * @dev Delete the subscription of an user
     * @param token Super token address
     * @param publisher The publisher of the index
     * @param indexId Id of the index
     * @param subscriber The subscriber's address
     * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
     *
     * # App callbacks
     *
     * - if the subscriber called it
     *   - AgreementTerminated callback to the publsiher:
     *      - agreementId is for the subscription
     * - if the publisher called it
     *   - AgreementTerminated callback to the subscriber:
     *      - agreementId is for the subscription
     */
    function deleteSubscription(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId,
        address subscriber,
        bytes calldata ctx)
            external
            virtual
            returns(bytes memory newCtx);

    /**
    * @dev Claim pending distributions
    * @param token Super token address
    * @param publisher The publisher of the index
    * @param indexId Id of the index
    * @param subscriber The subscriber's address
    * @param ctx Context bytes (see ISuperfluid.sol for Context struct)
    *
    * The subscription should not be approved yet
    *
    * # App callbacks
    *
    * - AgreementUpdated callback to the publisher:
    *    - agreementId is for the subscription
    */
    function claim(
        ISuperfluidToken token,
        address publisher,
        uint32 indexId,
        address subscriber,
        bytes calldata ctx)
        external
        virtual
        returns(bytes memory newCtx);
    
    /**
      * @dev Index distribution claimed event
      * @param token Super token address
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param subscriber The subscriber units updated
      * @param amount The pending amount claimed
      */
    event IndexDistributionClaimed(
        ISuperfluidToken indexed token,
        address indexed publisher,
        uint32 indexed indexId,
        address subscriber,
        uint256 amount);
    
    /**
      * @dev Subscription distribution claimed event
      * @param token Super token address
      * @param subscriber The subscriber units updated
      * @param publisher Index publisher
      * @param indexId The specified indexId
      * @param amount The pending amount claimed
      */
    event SubscriptionDistributionClaimed(
        ISuperfluidToken indexed token,
        address indexed subscriber,
        address publisher,
        uint32 indexId,
        uint256 amount);

}