// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6 <0.9;

interface IVPContractEvents {
    /**
     * Event triggered when an account delegates or undelegates another account.
     * Definition: `votePowerFromTo(from, to)` is `changed` from `priorVotePower` to `newVotePower`.
     * For undelegation, `newVotePower` is 0.
     *
     * Note: the event is always emitted from VPToken's `writeVotePowerContract`.
     */
    event Delegate(
        address indexed from,
        address indexed to,
        uint256 priorVotePower,
        uint256 newVotePower
    );

    /**
     * Event triggered only when account `delegator` revokes delegation to `delegatee`
     * for a single block in the past (typically the current vote block).
     *
     * Note: the event is always emitted from VPToken's `writeVotePowerContract` and/or `readVotePowerContract`.
     */
    event Revoke(
        address indexed delegator,
        address indexed delegatee,
        uint256 votePower,
        uint256 blockNumber
    );
}