# EpochController.sol

The `EpochController` contract is a critical component for managing and tracking epochs in a blockchain-based system. Epochs are defined as fixed intervals of blocks and are used for various time-based operations, such as staking, reward distribution, and lock periods. This contract provides administrators the ability to configure epoch parameters and query epoch-related information in a decentralized manner.

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## Key Features

1. **Epoch Management**:
   * Tracks the current epoch and calculates the start of the next epoch.
   * Allows modification of epoch-related parameters like length, lock periods, and reward delays.
2. **Admin-Restricted Modifications**:
   * All configuration changes can only be performed by accounts with the `DEFAULT_ADMIN_ROLE`.
3. **Parameter Validations**:
   * Ensures epoch parameters fall within specified minimum and maximum bounds to maintain system stability.
4. **Event Emission**:
   * Emits events whenever epoch parameters are updated, enabling off-chain monitoring and integration.

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## Key Parameters

### Public Constants

* **`MIN_EPOCH_LENGTH` / `MAX_EPOCH_LENGTH`**: Minimum and maximum allowed blocks per epoch.
* **`MIN_EPOCH_LOCK` / `MAX_EPOCH_LOCK`**: Bounds for the minimum number of epochs tokens can be locked.
* **`MIN_REWARD_DELAY` / `MAX_REWARD_DELAY`**: Bounds for the delay in epochs before rewards can be claimed.

### State Variables

* **`epochLength`**: The number of blocks in an epoch.
* **`firstEpochBlock`**: The block number of the first epoch.
* **`minEpochsLocked`**: Minimum number of epochs tokens are locked.
* **`epochRewardDelay`**: Number of epochs before rewards are claimable.
* **`epochCheckpoint`**: The current epoch checkpoint number.
* **`epochCheckpointBlock`**: Block number when the last checkpoint was updated.

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## Key Functions

### Constructor

Sets the initial values for the epoch parameters and validates them against the defined bounds.

#### Parameters:

* **`_epochLength`**: Number of blocks in an epoch.
* **`_firstEpochBlock`**: Block number of the first epoch. If zero, it defaults to the next epoch block.
* **`_minEpochsLocked`**: Minimum number of epochs tokens are locked.
* **`_epochRewardDelay`**: Number of epochs before rewards are claimable.

#### Emits:

* `EpochRewardDelayUpdated`
* `MinEpochsLockedUpdated`
* `EpochLengthUpdated`

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### Epoch Parameter Setters

#### `setEpochLength(uint256 _epochLength)`

* Updates the number of blocks per epoch.
* Reverts if the new epoch length is outside the allowed range or if reducing the epoch length in the current epoch.

#### Emits:

* `EpochLengthUpdated`

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#### `setMinEpochsLocked(uint256 _minEpochsLocked)`

* Updates the minimum number of epochs tokens are locked.
* Reverts if the new value is outside the allowed range.

#### Emits:

* `MinEpochsLockedUpdated`

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#### `setEpochRewardDelay(uint256 _epochRewardDelay)`

* Updates the reward delay in epochs.
* Reverts if the new value is outside the allowed range.

#### Emits:

* `EpochRewardDelayUpdated`

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### Epoch Queries

#### `nextEpochBlock()`

* Returns the block number of the next epoch based on the current block and configured parameters.

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#### `epochNumber()`

* Returns the current epoch number based on the current block, `epochLength`, and `epochCheckpoint`.

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## Access Control

The contract uses OpenZeppelin's `AccessControl` for role-based access management.

### Roles:

* **`DEFAULT_ADMIN_ROLE`**:
  * Has the authority to update epoch parameters.
  * Assigned to the deploying account during contract initialization.

***

## Events

* **`EpochLengthUpdated(uint256 epochLength)`**\
  Emitted when the epoch length is updated.
* **`MinEpochsLockedUpdated(uint256 minEpochsLocked)`**\
  Emitted when the minimum epochs lock parameter is updated.
* **`EpochRewardDelayUpdated(uint256 epochRewardDelay)`**\
  Emitted when the epoch reward delay parameter is updated.

## Usage Examples

### Initialization

```solidity
EpochController epochController = new EpochController(
    100,        // epochLength (blocks)
    1000000,    // firstEpochBlock
    10,         // minEpochsLocked
    5           // epochRewardDelay
);
```

### Querying Epoch Information

```solidity
uint256 currentEpoch = epochController.epochNumber();
uint256 nextEpochStartBlock = epochController.nextEpochBlock();
```

This contract is designed to be a robust and flexible controller for epoch-based systems, enabling precise control over time-sensitive operations in decentralized environments.