contract BondingManager is ManagerProxyTarget, IBondingManager {
    using SafeMath for uint256;
    using SortedDoublyLL for SortedDoublyLL.Data;
    using EarningsPool for EarningsPool.Data;

    // Time between unbonding and possible withdrawl in rounds
    uint64 public unbondingPeriod;
    // Number of active transcoders
    uint256 public numActiveTranscoders;
    // Max number of rounds that a caller can claim earnings for at once
    uint256 public maxEarningsClaimsRounds;

    // Represents a transcoder's current state
    struct Transcoder {
        uint256 lastRewardRound;                             // Last round that the transcoder called reward
        uint256 rewardCut;                                   // % of reward paid to transcoder by a delegator
        uint256 feeShare;                                    // % of fees paid to delegators by transcoder
        uint256 pricePerSegment;                             // Price per segment (denominated in LPT units) for a stream
        uint256 pendingRewardCut;                            // Pending reward cut for next round if the transcoder is active
        uint256 pendingFeeShare;                             // Pending fee share for next round if the transcoder is active
        uint256 pendingPricePerSegment;                      // Pending price per segment for next round if the transcoder is active
        mapping (uint256 => EarningsPool.Data) earningsPoolPerRound;  // Mapping of round => earnings pool for the round
    }

    // The various states a transcoder can be in
    enum TranscoderStatus { NotRegistered, Registered }

    // Represents a delegator's current state
    struct Delegator {
        uint256 bondedAmount;                    // The amount of bonded tokens
        uint256 fees;                            // The amount of fees collected
        address delegateAddress;                 // The address delegated to
        uint256 delegatedAmount;                 // The amount of tokens delegated to the delegator
        uint256 startRound;                      // The round the delegator transitions to bonded phase and is delegated to someone
        uint256 withdrawRoundDEPRECATED;         // DEPRECATED - DO NOT USE
        uint256 lastClaimRound;                  // The last round during which the delegator claimed its earnings
        uint256 nextUnbondingLockId;             // ID for the next unbonding lock created
        mapping (uint256 => UnbondingLock) unbondingLocks; // Mapping of unbonding lock ID => unbonding lock
    }

    // The various states a delegator can be in
    enum DelegatorStatus { Pending, Bonded, Unbonded }

    // Represents an amount of tokens that are being unbonded
    struct UnbondingLock {
        uint256 amount;              // Amount of tokens being unbonded
        uint256 withdrawRound;       // Round at which unbonding period is over and tokens can be withdrawn
    }

    // Keep track of the known transcoders and delegators
    mapping (address => Delegator) private delegators;
    mapping (address => Transcoder) private transcoders;

    // DEPRECATED - DO NOT USE
    // The function getTotalBonded() no longer uses this variable
    // and instead calculates the total bonded value separately
    uint256 private totalBondedDEPRECATED;

    // Candidate and reserve transcoders
    SortedDoublyLL.Data private transcoderPool;

    // Represents the active transcoder set
    struct ActiveTranscoderSet {
        address[] transcoders;
        mapping (address => bool) isActive;
        uint256 totalStake;
    }

    // Keep track of active transcoder set for each round
    mapping (uint256 => ActiveTranscoderSet) public activeTranscoderSet;

    // Check if sender is JobsManager
    modifier onlyJobsManager() {
        require(msg.sender == controller.getContract(keccak256("JobsManager")));
        _;
    }

    // Check if sender is RoundsManager
    modifier onlyRoundsManager() {
        require(msg.sender == controller.getContract(keccak256("RoundsManager")));
        _;
    }

    // Check if current round is initialized
    modifier currentRoundInitialized() {
        require(roundsManager().currentRoundInitialized());
        _;
    }

    // Automatically claim earnings from lastClaimRound through the current round
    modifier autoClaimEarnings() {
        updateDelegatorWithEarnings(msg.sender, roundsManager().currentRound());
        _;
    }

    /**
     * @dev BondingManager constructor. Only invokes constructor of base Manager contract with provided Controller address
     * @param _controller Address of Controller that this contract will be registered with
     */
    function BondingManager(address _controller) public Manager(_controller) {}

    /**
     * @dev Set unbonding period. Only callable by Controller owner
     * @param _unbondingPeriod Rounds between unbonding and possible withdrawal
     */
    function setUnbondingPeriod(uint64 _unbondingPeriod) external onlyControllerOwner {
        unbondingPeriod = _unbondingPeriod;

        ParameterUpdate("unbondingPeriod");
    }

    /**
     * @dev Set max number of registered transcoders. Only callable by Controller owner
     * @param _numTranscoders Max number of registered transcoders
     */
    function setNumTranscoders(uint256 _numTranscoders) external onlyControllerOwner {
        // Max number of transcoders must be greater than or equal to number of active transcoders
        require(_numTranscoders >= numActiveTranscoders);

        transcoderPool.setMaxSize(_numTranscoders);

        ParameterUpdate("numTranscoders");
    }

    /**
     * @dev Set number of active transcoders. Only callable by Controller owner
     * @param _numActiveTranscoders Number of active transcoders
     */
    function setNumActiveTranscoders(uint256 _numActiveTranscoders) external onlyControllerOwner {
        // Number of active transcoders cannot exceed max number of transcoders
        require(_numActiveTranscoders <= transcoderPool.getMaxSize());

        numActiveTranscoders = _numActiveTranscoders;

        ParameterUpdate("numActiveTranscoders");
    }

    /**
     * @dev Set max number of rounds a caller can claim earnings for at once. Only callable by Controller owner
     * @param _maxEarningsClaimsRounds Max number of rounds a caller can claim earnings for at once
     */
    function setMaxEarningsClaimsRounds(uint256 _maxEarningsClaimsRounds) external onlyControllerOwner {
        maxEarningsClaimsRounds = _maxEarningsClaimsRounds;

        ParameterUpdate("maxEarningsClaimsRounds");
    }

    /**
     * @dev The sender is declaring themselves as a candidate for active transcoding.
     * @param _rewardCut % of reward paid to transcoder by a delegator
     * @param _feeShare % of fees paid to delegators by a transcoder
     * @param _pricePerSegment Price per segment (denominated in Wei) for a stream
     */
    function transcoder(uint256 _rewardCut, uint256 _feeShare, uint256 _pricePerSegment)
        external
        whenSystemNotPaused
        currentRoundInitialized
    {
        Transcoder storage t = transcoders[msg.sender];
        Delegator storage del = delegators[msg.sender];

        if (roundsManager().currentRoundLocked()) {
            // If it is the lock period of the current round
            // the lowest price previously set by any transcoder
            // becomes the price floor and the caller can lower its
            // own price to a point greater than or equal to the price floor

            // Caller must already be a registered transcoder
            require(transcoderStatus(msg.sender) == TranscoderStatus.Registered);
            // Provided rewardCut value must equal the current pendingRewardCut value
            // This value cannot change during the lock period
            require(_rewardCut == t.pendingRewardCut);
            // Provided feeShare value must equal the current pendingFeeShare value
            // This value cannot change during the lock period
            require(_feeShare == t.pendingFeeShare);

            // Iterate through the transcoder pool to find the price floor
            // Since the caller must be a registered transcoder, the transcoder pool size will always at least be 1
            // Thus, we can safely set the initial price floor to be the pendingPricePerSegment of the first
            // transcoder in the pool
            address currentTranscoder = transcoderPool.getFirst();
            uint256 priceFloor = transcoders[currentTranscoder].pendingPricePerSegment;
            for (uint256 i = 0; i < transcoderPool.getSize(); i++) {
                if (transcoders[currentTranscoder].pendingPricePerSegment < priceFloor) {
                    priceFloor = transcoders[currentTranscoder].pendingPricePerSegment;
                }

                currentTranscoder = transcoderPool.getNext(currentTranscoder);
            }

            // Provided pricePerSegment must be greater than or equal to the price floor and
            // less than or equal to the previously set pricePerSegment by the caller
            require(_pricePerSegment >= priceFloor && _pricePerSegment <= t.pendingPricePerSegment);

            t.pendingPricePerSegment = _pricePerSegment;

            TranscoderUpdate(msg.sender, t.pendingRewardCut, t.pendingFeeShare, _pricePerSegment, true);
        } else {
            // It is not the lock period of the current round
            // Caller is free to change rewardCut, feeShare, pricePerSegment as it pleases
            // If caller is not a registered transcoder, it can also register and join the transcoder pool
            // if it has sufficient delegated stake
            // If caller is not a registered transcoder and does not have sufficient delegated stake
            // to join the transcoder pool, it can change rewardCut, feeShare, pricePerSegment
            // as information signals to delegators in an effort to camapaign and accumulate
            // more delegated stake

            // Reward cut must be a valid percentage
            require(MathUtils.validPerc(_rewardCut));
            // Fee share must be a valid percentage
            require(MathUtils.validPerc(_feeShare));

            // Must have a non-zero amount bonded to self
            require(del.delegateAddress == msg.sender && del.bondedAmount > 0);

            t.pendingRewardCut = _rewardCut;
            t.pendingFeeShare = _feeShare;
            t.pendingPricePerSegment = _pricePerSegment;

            uint256 delegatedAmount = del.delegatedAmount;

            // Check if transcoder is not already registered
            if (transcoderStatus(msg.sender) == TranscoderStatus.NotRegistered) {
                if (!transcoderPool.isFull()) {
                    // If pool is not full add new transcoder
                    transcoderPool.insert(msg.sender, delegatedAmount, address(0), address(0));
                } else {
                    address lastTranscoder = transcoderPool.getLast();

                    if (delegatedAmount > transcoderTotalStake(lastTranscoder)) {
                        // If pool is full and caller has more delegated stake than the transcoder in the pool with the least delegated stake:
                        // - Evict transcoder in pool with least delegated stake
                        // - Add caller to pool
                        transcoderPool.remove(lastTranscoder);
                        transcoderPool.insert(msg.sender, delegatedAmount, address(0), address(0));

                        TranscoderEvicted(lastTranscoder);
                    }
                }
            }

            TranscoderUpdate(msg.sender, _rewardCut, _feeShare, _pricePerSegment, transcoderPool.contains(msg.sender));
        }
    }

    /**
     * @dev Delegate stake towards a specific address.
     * @param _amount The amount of LPT to stake.
     * @param _to The address of the transcoder to stake towards.
     */
    function bond(
        uint256 _amount,
        address _to
    )
        external
        whenSystemNotPaused
        currentRoundInitialized
        autoClaimEarnings
    {
        Delegator storage del = delegators[msg.sender];

        uint256 currentRound = roundsManager().currentRound();
        // Amount to delegate
        uint256 delegationAmount = _amount;
        // Current delegate
        address currentDelegate = del.delegateAddress;

        if (delegatorStatus(msg.sender) == DelegatorStatus.Unbonded) {
            // New delegate
            // Set start round
            // Don't set start round if delegator is in pending state because the start round would not change
            del.startRound = currentRound.add(1);
            // Unbonded state = no existing delegate and no bonded stake
            // Thus, delegation amount = provided amount
        } else if (del.delegateAddress != address(0) && _to != del.delegateAddress) {
            // A registered transcoder cannot delegate its bonded stake toward another address
            // because it can only be delegated toward itself
            // In the future, if delegation towards another registered transcoder as an already
            // registered transcoder becomes useful (i.e. for transitive delegation), this restriction
            // could be removed
            require(transcoderStatus(msg.sender) == TranscoderStatus.NotRegistered);
            // Changing delegate
            // Set start round
            del.startRound = currentRound.add(1);
            // Update amount to delegate with previous delegation amount
            delegationAmount = delegationAmount.add(del.bondedAmount);
            // Decrease old delegate's delegated amount
            delegators[currentDelegate].delegatedAmount = delegators[currentDelegate].delegatedAmount.sub(del.bondedAmount);

            if (transcoderStatus(currentDelegate) == TranscoderStatus.Registered) {
                // Previously delegated to a transcoder
                // Decrease old transcoder's total stake
                transcoderPool.updateKey(currentDelegate, transcoderTotalStake(currentDelegate).sub(del.bondedAmount), address(0), address(0));
            }
        }

        // Delegation amount must be > 0 - cannot delegate to someone without having bonded stake
        require(delegationAmount > 0);
        // Update delegate
        del.delegateAddress = _to;
        // Update current delegate's delegated amount with delegation amount
        delegators[_to].delegatedAmount = delegators[_to].delegatedAmount.add(delegationAmount);

        if (transcoderStatus(_to) == TranscoderStatus.Registered) {
            // Delegated to a transcoder
            // Increase transcoder's total stake
            transcoderPool.updateKey(_to, transcoderTotalStake(del.delegateAddress).add(delegationAmount), address(0), address(0));
        }

        if (_amount > 0) {
            // Update bonded amount
            del.bondedAmount = del.bondedAmount.add(_amount);
            // Transfer the LPT to the Minter
            livepeerToken().transferFrom(msg.sender, minter(), _amount);
        }

        Bond(_to, currentDelegate, msg.sender, _amount, del.bondedAmount);
    }

    /**
     * @dev Unbond an amount of the delegator's bonded stake
     * @param _amount Amount of tokens to unbond
     */
    function unbond(uint256 _amount)
        external
        whenSystemNotPaused
        currentRoundInitialized
        autoClaimEarnings
    {
        // Caller must be in bonded state
        require(delegatorStatus(msg.sender) == DelegatorStatus.Bonded);

        Delegator storage del = delegators[msg.sender];

        // Amount must be greater than 0
        require(_amount > 0);
        // Amount to unbond must be less than or equal to current bonded amount 
        require(_amount <= del.bondedAmount);

        address currentDelegate = del.delegateAddress;
        uint256 currentRound = roundsManager().currentRound();
        uint256 withdrawRound = currentRound.add(unbondingPeriod);
        uint256 unbondingLockId = del.nextUnbondingLockId;

        // Create new unbonding lock
        del.unbondingLocks[unbondingLockId] = UnbondingLock({
            amount: _amount,
            withdrawRound: withdrawRound
        });
        // Increment ID for next unbonding lock
        del.nextUnbondingLockId = unbondingLockId.add(1);
        // Decrease delegator's bonded amount
        del.bondedAmount = del.bondedAmount.sub(_amount);
        // Decrease delegate's delegated amount
        delegators[del.delegateAddress].delegatedAmount = delegators[del.delegateAddress].delegatedAmount.sub(_amount);

        if (transcoderStatus(del.delegateAddress) == TranscoderStatus.Registered && (del.delegateAddress != msg.sender || del.bondedAmount > 0)) {
            // A transcoder's delegated stake within the registered pool needs to be decreased if:
            // - The caller's delegate is a registered transcoder
            // - Caller is not delegated to self OR caller is delegated to self and has a non-zero bonded amount
            // If the caller is delegated to self and has a zero bonded amount, it will be removed from the 
            // transcoder pool so its delegated stake within the pool does not need to be decreased
            transcoderPool.updateKey(del.delegateAddress, transcoderTotalStake(del.delegateAddress).sub(_amount), address(0), address(0));
        }

        // Check if delegator has a zero bonded amount
        // If so, update its delegation status
        if (del.bondedAmount == 0) {
            // Delegator no longer delegated to anyone if it does not have a bonded amount
            del.delegateAddress = address(0);
            // Delegator does not have a start round if it is no longer delegated to anyone
            del.startRound = 0;

            if (transcoderStatus(msg.sender) == TranscoderStatus.Registered) {
                // If caller is a registered transcoder and is no longer bonded, resign
                resignTranscoder(msg.sender);
            }
        } 

        Unbond(currentDelegate, msg.sender, unbondingLockId, _amount, withdrawRound);
    }

    /**
     * @dev Rebond tokens for an unbonding lock to a delegator's current delegate while a delegator
     * is in the Bonded or Pending states
     * @param _unbondingLockId ID of unbonding lock to rebond with
     */
    function rebond(
        uint256 _unbondingLockId
    ) 
        external
        whenSystemNotPaused
        currentRoundInitialized 
        autoClaimEarnings
    {
        // Caller must not be an unbonded delegator
        require(delegatorStatus(msg.sender) != DelegatorStatus.Unbonded);

        // Process rebond using unbonding lock
        processRebond(msg.sender, _unbondingLockId);
    }

    /**
     * @dev Rebond tokens for an unbonding lock to a delegate while a delegator
     * is in the Unbonded state
     * @param _to Address of delegate
     * @param _unbondingLockId ID of unbonding lock to rebond with
     */
    function rebondFromUnbonded(
        address _to,
        uint256 _unbondingLockId
    )
        external
        whenSystemNotPaused
        currentRoundInitialized
        autoClaimEarnings
    {
        // Caller must be an unbonded delegator
        require(delegatorStatus(msg.sender) == DelegatorStatus.Unbonded);

        // Set delegator's start round and transition into Pending state
        delegators[msg.sender].startRound = roundsManager().currentRound().add(1);
        // Set delegator's delegate
        delegators[msg.sender].delegateAddress = _to;
        // Process rebond using unbonding lock
        processRebond(msg.sender, _unbondingLockId);
    }

    /**
     * @dev Withdraws tokens for an unbonding lock that has existed through an unbonding period
     * @param _unbondingLockId ID of unbonding lock to withdraw with
     */
    function withdrawStake(uint256 _unbondingLockId)
        external
        whenSystemNotPaused
        currentRoundInitialized
    {
        Delegator storage del = delegators[msg.sender];
        UnbondingLock storage lock = del.unbondingLocks[_unbondingLockId];

        // Unbonding lock must be valid
        require(isValidUnbondingLock(msg.sender, _unbondingLockId));
        // Withdrawal must be valid for the unbonding lock i.e. the withdraw round is now or in the past
        require(lock.withdrawRound <= roundsManager().currentRound());

        uint256 amount = lock.amount;
        uint256 withdrawRound = lock.withdrawRound;
        // Delete unbonding lock
        delete del.unbondingLocks[_unbondingLockId];

        // Tell Minter to transfer stake (LPT) to the delegator
        minter().trustedTransferTokens(msg.sender, amount);

        WithdrawStake(msg.sender, _unbondingLockId, amount, withdrawRound);
    }

    /**
     * @dev Withdraws fees to the caller
     */
    function withdrawFees()
        external
        whenSystemNotPaused
        currentRoundInitialized
        autoClaimEarnings
    {
        // Delegator must have fees
        require(delegators[msg.sender].fees > 0);

        uint256 amount = delegators[msg.sender].fees;
        delegators[msg.sender].fees = 0;

        // Tell Minter to transfer fees (ETH) to the delegator
        minter().trustedWithdrawETH(msg.sender, amount);

        WithdrawFees(msg.sender);
    }

    /**
     * @dev Set active transcoder set for the current round
     */
    function setActiveTranscoders() external whenSystemNotPaused onlyRoundsManager {
        uint256 currentRound = roundsManager().currentRound();
        uint256 activeSetSize = Math.min256(numActiveTranscoders, transcoderPool.getSize());

        uint256 totalStake = 0;
        address currentTranscoder = transcoderPool.getFirst();

        for (uint256 i = 0; i < activeSetSize; i++) {
            activeTranscoderSet[currentRound].transcoders.push(currentTranscoder);
            activeTranscoderSet[currentRound].isActive[currentTranscoder] = true;

            uint256 stake = transcoderTotalStake(currentTranscoder);
            uint256 rewardCut = transcoders[currentTranscoder].pendingRewardCut;
            uint256 feeShare = transcoders[currentTranscoder].pendingFeeShare;
            uint256 pricePerSegment = transcoders[currentTranscoder].pendingPricePerSegment;

            Transcoder storage t = transcoders[currentTranscoder];
            // Set pending rates as current rates
            t.rewardCut = rewardCut;
            t.feeShare = feeShare;
            t.pricePerSegment = pricePerSegment;
            // Initialize token pool
            t.earningsPoolPerRound[currentRound].init(stake, rewardCut, feeShare);

            totalStake = totalStake.add(stake);

            // Get next transcoder in the pool
            currentTranscoder = transcoderPool.getNext(currentTranscoder);
        }

        // Update total stake of all active transcoders
        activeTranscoderSet[currentRound].totalStake = totalStake;
    }

    /**
     * @dev Distribute the token rewards to transcoder and delegates.
     * Active transcoders call this once per cycle when it is their turn.
     */
    function reward() external whenSystemNotPaused currentRoundInitialized {
        uint256 currentRound = roundsManager().currentRound();

        // Sender must be an active transcoder
        require(activeTranscoderSet[currentRound].isActive[msg.sender]);

        // Transcoder must not have called reward for this round already
        require(transcoders[msg.sender].lastRewardRound != currentRound);
        // Set last round that transcoder called reward
        transcoders[msg.sender].lastRewardRound = currentRound;

        // Create reward based on active transcoder's stake relative to the total active stake
        // rewardTokens = (current mintable tokens for the round * active transcoder stake) / total active stake
        uint256 rewardTokens = minter().createReward(activeTranscoderTotalStake(msg.sender, currentRound), activeTranscoderSet[currentRound].totalStake);

        updateTranscoderWithRewards(msg.sender, rewardTokens, currentRound);

        Reward(msg.sender, rewardTokens);
    }

    /**
     * @dev Update transcoder's fee pool
     * @param _transcoder Transcoder address
     * @param _fees Fees from verified job claims
     */
    function updateTranscoderWithFees(
        address _transcoder,
        uint256 _fees,
        uint256 _round
    )
        external
        whenSystemNotPaused
        onlyJobsManager
    {
        // Transcoder must be registered
        require(transcoderStatus(_transcoder) == TranscoderStatus.Registered);

        Transcoder storage t = transcoders[_transcoder];

        EarningsPool.Data storage earningsPool = t.earningsPoolPerRound[_round];
        // Add fees to fee pool
        earningsPool.addToFeePool(_fees);
    }

    /**
     * @dev Slash a transcoder. Slashing can be invoked by the protocol or a finder.
     * @param _transcoder Transcoder address
     * @param _finder Finder that proved a transcoder violated a slashing condition. Null address if there is no finder
     * @param _slashAmount Percentage of transcoder bond to be slashed
     * @param _finderFee Percentage of penalty awarded to finder. Zero if there is no finder
     */
    function slashTranscoder(
        address _transcoder,
        address _finder,
        uint256 _slashAmount,
        uint256 _finderFee
    )
        external
        whenSystemNotPaused
        onlyJobsManager
    {
        Delegator storage del = delegators[_transcoder];

        if (del.bondedAmount > 0) {
            uint256 penalty = MathUtils.percOf(delegators[_transcoder].bondedAmount, _slashAmount);

            // Decrease bonded stake
            del.bondedAmount = del.bondedAmount.sub(penalty);

            // If still bonded
            // - Decrease delegate's delegated amount
            // - Decrease total bonded tokens
            if (delegatorStatus(_transcoder) == DelegatorStatus.Bonded) {
                delegators[del.delegateAddress].delegatedAmount = delegators[del.delegateAddress].delegatedAmount.sub(penalty);
            }

            // If registered transcoder, resign it
            if (transcoderStatus(_transcoder) == TranscoderStatus.Registered) {
                resignTranscoder(_transcoder);
            }

            // Account for penalty
            uint256 burnAmount = penalty;

            // Award finder fee if there is a finder address
            if (_finder != address(0)) {
                uint256 finderAmount = MathUtils.percOf(penalty, _finderFee);
                minter().trustedTransferTokens(_finder, finderAmount);

                // Minter burns the slashed funds - finder reward
                minter().trustedBurnTokens(burnAmount.sub(finderAmount));

                TranscoderSlashed(_transcoder, _finder, penalty, finderAmount);
            } else {
                // Minter burns the slashed funds
                minter().trustedBurnTokens(burnAmount);

                TranscoderSlashed(_transcoder, address(0), penalty, 0);
            }
        } else {
            TranscoderSlashed(_transcoder, _finder, 0, 0);
        }
    }

    /**
     * @dev Pseudorandomly elect a currently active transcoder that charges a price per segment less than or equal to the max price per segment for a job
     * Returns address of elected active transcoder and its price per segment
     * @param _maxPricePerSegment Max price (in LPT base units) per segment of a stream
     * @param _blockHash Job creation block hash used as a pseudorandom seed for assigning an active transcoder
     * @param _round Job creation round
     */
    function electActiveTranscoder(uint256 _maxPricePerSegment, bytes32 _blockHash, uint256 _round) external view returns (address) {
        uint256 activeSetSize = activeTranscoderSet[_round].transcoders.length;
        // Create array to store available transcoders charging an acceptable price per segment
        address[] memory availableTranscoders = new address[](activeSetSize);
        // Keep track of the actual number of available transcoders
        uint256 numAvailableTranscoders = 0;
        // Keep track of total stake of available transcoders
        uint256 totalAvailableTranscoderStake = 0;

        for (uint256 i = 0; i < activeSetSize; i++) {
            address activeTranscoder = activeTranscoderSet[_round].transcoders[i];
            // If a transcoder is active and charges an acceptable price per segment add it to the array of available transcoders
            if (activeTranscoderSet[_round].isActive[activeTranscoder] && transcoders[activeTranscoder].pricePerSegment <= _maxPricePerSegment) {
                availableTranscoders[numAvailableTranscoders] = activeTranscoder;
                numAvailableTranscoders++;
                totalAvailableTranscoderStake = totalAvailableTranscoderStake.add(activeTranscoderTotalStake(activeTranscoder, _round));
            }
        }

        if (numAvailableTranscoders == 0) {
            // There is no currently available transcoder that charges a price per segment less than or equal to the max price per segment for a job
            return address(0);
        } else {
            // Pseudorandomly pick an available transcoder weighted by its stake relative to the total stake of all available transcoders
            uint256 r = uint256(_blockHash) % totalAvailableTranscoderStake;
            uint256 s = 0;
            uint256 j = 0;

            while (s <= r && j < numAvailableTranscoders) {
                s = s.add(activeTranscoderTotalStake(availableTranscoders[j], _round));
                j++;
            }

            return availableTranscoders[j - 1];
        }
    }

    /**
     * @dev Claim token pools shares for a delegator from its lastClaimRound through the end round
     * @param _endRound The last round for which to claim token pools shares for a delegator
     */
    function claimEarnings(uint256 _endRound) external whenSystemNotPaused currentRoundInitialized {
        // End round must be after the last claim round
        require(delegators[msg.sender].lastClaimRound < _endRound);
        // End round must not be after the current round
        require(_endRound <= roundsManager().currentRound());

        updateDelegatorWithEarnings(msg.sender, _endRound);
    }

    /**
     * @dev Returns pending bonded stake for a delegator from its lastClaimRound through an end round
     * @param _delegator Address of delegator
     * @param _endRound The last round to compute pending stake from
     */
    function pendingStake(address _delegator, uint256 _endRound) public view returns (uint256) {
        uint256 currentRound = roundsManager().currentRound();
        Delegator storage del = delegators[_delegator];
        // End round must be before or equal to current round and after lastClaimRound
        require(_endRound <= currentRound && _endRound > del.lastClaimRound);

        uint256 currentBondedAmount = del.bondedAmount;

        for (uint256 i = del.lastClaimRound + 1; i <= _endRound; i++) {
            EarningsPool.Data storage earningsPool = transcoders[del.delegateAddress].earningsPoolPerRound[i];

            bool isTranscoder = _delegator == del.delegateAddress;
            if (earningsPool.hasClaimableShares()) {
                // Calculate and add reward pool share from this round
                currentBondedAmount = currentBondedAmount.add(earningsPool.rewardPoolShare(currentBondedAmount, isTranscoder));
            }
        }

        return currentBondedAmount;
    }

    /**
     * @dev Returns pending fees for a delegator from its lastClaimRound through an end round
     * @param _delegator Address of delegator
     * @param _endRound The last round to compute pending fees from
     */
    function pendingFees(address _delegator, uint256 _endRound) public view returns (uint256) {
        uint256 currentRound = roundsManager().currentRound();
        Delegator storage del = delegators[_delegator];
        // End round must be before or equal to current round and after lastClaimRound
        require(_endRound <= currentRound && _endRound > del.lastClaimRound);

        uint256 currentFees = del.fees;
        uint256 currentBondedAmount = del.bondedAmount;

        for (uint256 i = del.lastClaimRound + 1; i <= _endRound; i++) {
            EarningsPool.Data storage earningsPool = transcoders[del.delegateAddress].earningsPoolPerRound[i];

            if (earningsPool.hasClaimableShares()) {
                bool isTranscoder = _delegator == del.delegateAddress;
                // Calculate and add fee pool share from this round
                currentFees = currentFees.add(earningsPool.feePoolShare(currentBondedAmount, isTranscoder));
                // Calculate new bonded amount with rewards from this round. Updated bonded amount used
                // to calculate fee pool share in next round
                currentBondedAmount = currentBondedAmount.add(earningsPool.rewardPoolShare(currentBondedAmount, isTranscoder));
            }
        }

        return currentFees;
    }

    /**
     * @dev Returns total bonded stake for an active transcoder
     * @param _transcoder Address of a transcoder
     */
    function activeTranscoderTotalStake(address _transcoder, uint256 _round) public view returns (uint256) {
        // Must be active transcoder
        require(activeTranscoderSet[_round].isActive[_transcoder]);

        return transcoders[_transcoder].earningsPoolPerRound[_round].totalStake;
    }

    /**
     * @dev Returns total bonded stake for a transcoder
     * @param _transcoder Address of transcoder
     */
    function transcoderTotalStake(address _transcoder) public view returns (uint256) {
        return transcoderPool.getKey(_transcoder);
    }

    /*
     * @dev Computes transcoder status
     * @param _transcoder Address of transcoder
     */
    function transcoderStatus(address _transcoder) public view returns (TranscoderStatus) {
        if (transcoderPool.contains(_transcoder)) {
            return TranscoderStatus.Registered;
        } else {
            return TranscoderStatus.NotRegistered;
        }
    }

    /**
     * @dev Computes delegator status
     * @param _delegator Address of delegator
     */
    function delegatorStatus(address _delegator) public view returns (DelegatorStatus) {
        Delegator storage del = delegators[_delegator];

        if (del.bondedAmount == 0) {
            // Delegator unbonded all its tokens
            return DelegatorStatus.Unbonded;
        } else if (del.startRound > roundsManager().currentRound()) {
            // Delegator round start is in the future
            return DelegatorStatus.Pending;
        } else if (del.startRound > 0 && del.startRound <= roundsManager().currentRound()) {
            // Delegator round start is now or in the past
            return DelegatorStatus.Bonded;
        } else {
            // Default to unbonded
            return DelegatorStatus.Unbonded;
        }
    }

    /**
     * @dev Return transcoder information
     * @param _transcoder Address of transcoder
     */
    function getTranscoder(
        address _transcoder
    )
        public
        view
        returns (uint256 lastRewardRound, uint256 rewardCut, uint256 feeShare, uint256 pricePerSegment, uint256 pendingRewardCut, uint256 pendingFeeShare, uint256 pendingPricePerSegment)
    {
        Transcoder storage t = transcoders[_transcoder];

        lastRewardRound = t.lastRewardRound;
        rewardCut = t.rewardCut;
        feeShare = t.feeShare;
        pricePerSegment = t.pricePerSegment;
        pendingRewardCut = t.pendingRewardCut;
        pendingFeeShare = t.pendingFeeShare;
        pendingPricePerSegment = t.pendingPricePerSegment;
    }

    /**
     * @dev Return transcoder's token pools for a given round
     * @param _transcoder Address of transcoder
     * @param _round Round number
     */
    function getTranscoderEarningsPoolForRound(
        address _transcoder,
        uint256 _round
    )
        public
        view
        returns (uint256 rewardPool, uint256 feePool, uint256 totalStake, uint256 claimableStake, uint256 transcoderRewardCut, uint256 transcoderFeeShare, uint256 transcoderRewardPool, uint256 transcoderFeePool, bool hasTranscoderRewardFeePool)
    {
        EarningsPool.Data storage earningsPool = transcoders[_transcoder].earningsPoolPerRound[_round];

        rewardPool = earningsPool.rewardPool;
        feePool = earningsPool.feePool;
        totalStake = earningsPool.totalStake;
        claimableStake = earningsPool.claimableStake;
        transcoderRewardCut = earningsPool.transcoderRewardCut;
        transcoderFeeShare = earningsPool.transcoderFeeShare;
        transcoderRewardPool = earningsPool.transcoderRewardPool;
        transcoderFeePool = earningsPool.transcoderFeePool;
        hasTranscoderRewardFeePool = earningsPool.hasTranscoderRewardFeePool;
    }

    /**
     * @dev Return delegator info
     * @param _delegator Address of delegator
     */
    function getDelegator(
        address _delegator
    )
        public
        view
        returns (uint256 bondedAmount, uint256 fees, address delegateAddress, uint256 delegatedAmount, uint256 startRound, uint256 lastClaimRound, uint256 nextUnbondingLockId)
    {
        Delegator storage del = delegators[_delegator];

        bondedAmount = del.bondedAmount;
        fees = del.fees;
        delegateAddress = del.delegateAddress;
        delegatedAmount = del.delegatedAmount;
        startRound = del.startRound;
        lastClaimRound = del.lastClaimRound;
        nextUnbondingLockId = del.nextUnbondingLockId;
    }

    /**
     * @dev Return delegator's unbonding lock info
     * @param _delegator Address of delegator
     * @param _unbondingLockId ID of unbonding lock
     */
    function getDelegatorUnbondingLock(
        address _delegator,
        uint256 _unbondingLockId
    ) 
        public
        view
        returns (uint256 amount, uint256 withdrawRound) 
    {
        UnbondingLock storage lock = delegators[_delegator].unbondingLocks[_unbondingLockId];

        return (lock.amount, lock.withdrawRound);
    }

    /**
     * @dev Returns max size of transcoder pool
     */
    function getTranscoderPoolMaxSize() public view returns (uint256) {
        return transcoderPool.getMaxSize();
    }

    /**
     * @dev Returns size of transcoder pool
     */
    function getTranscoderPoolSize() public view returns (uint256) {
        return transcoderPool.getSize();
    }

    /**
     * @dev Returns transcoder with most stake in pool
     */
    function getFirstTranscoderInPool() public view returns (address) {
        return transcoderPool.getFirst();
    }

    /**
     * @dev Returns next transcoder in pool for a given transcoder
     * @param _transcoder Address of a transcoder in the pool
     */
    function getNextTranscoderInPool(address _transcoder) public view returns (address) {
        return transcoderPool.getNext(_transcoder);
    }

    /**
     * @dev Return total bonded tokens
     */
    function getTotalBonded() public view returns (uint256) {
        uint256 totalBonded = 0;
        uint256 totalTranscoders = transcoderPool.getSize();
        address currentTranscoder = transcoderPool.getFirst();

        for (uint256 i = 0; i < totalTranscoders; i++) {
            // Add current transcoder's total delegated stake to total bonded counter
            totalBonded = totalBonded.add(transcoderTotalStake(currentTranscoder));
            // Get next transcoder in the pool
            currentTranscoder = transcoderPool.getNext(currentTranscoder);
        }

        return totalBonded;
    }

    /**
     * @dev Return total active stake for a round
     * @param _round Round number
     */
    function getTotalActiveStake(uint256 _round) public view returns (uint256) {
        return activeTranscoderSet[_round].totalStake;
    }

    /**
     * @dev Return whether a transcoder was active during a round
     * @param _transcoder Transcoder address
     * @param _round Round number
     */
    function isActiveTranscoder(address _transcoder, uint256 _round) public view returns (bool) {
        return activeTranscoderSet[_round].isActive[_transcoder];
    }

    /**
     * @dev Return whether a transcoder is registered
     * @param _transcoder Transcoder address
     */
    function isRegisteredTranscoder(address _transcoder) public view returns (bool) {
        return transcoderStatus(_transcoder) == TranscoderStatus.Registered;
    }

    /**
     * @dev Return whether an unbonding lock for a delegator is valid
     * @param _delegator Address of delegator
     * @param _unbondingLockId ID of unbonding lock
     */
    function isValidUnbondingLock(address _delegator, uint256 _unbondingLockId) public view returns (bool) {
        // A unbonding lock is only valid if it has a non-zero withdraw round (the default value is zero)
        return delegators[_delegator].unbondingLocks[_unbondingLockId].withdrawRound > 0;
    }

    /**
     * @dev Remove transcoder
     */
    function resignTranscoder(address _transcoder) internal {
        uint256 currentRound = roundsManager().currentRound();
        if (activeTranscoderSet[currentRound].isActive[_transcoder]) {
            // Decrease total active stake for the round
            activeTranscoderSet[currentRound].totalStake = activeTranscoderSet[currentRound].totalStake.sub(activeTranscoderTotalStake(_transcoder, currentRound));
            // Set transcoder as inactive
            activeTranscoderSet[currentRound].isActive[_transcoder] = false;
        }

        // Remove transcoder from pools
        transcoderPool.remove(_transcoder);

        TranscoderResigned(_transcoder);
    }

    /**
     * @dev Update a transcoder with rewards
     * @param _transcoder Address of transcoder
     * @param _rewards Amount of rewards
     * @param _round Round that transcoder is updated
     */
    function updateTranscoderWithRewards(address _transcoder, uint256 _rewards, uint256 _round) internal {
        Transcoder storage t = transcoders[_transcoder];
        Delegator storage del = delegators[_transcoder];

        EarningsPool.Data storage earningsPool = t.earningsPoolPerRound[_round];
        // Add rewards to reward pool
        earningsPool.addToRewardPool(_rewards);
        // Update transcoder's delegated amount with rewards
        del.delegatedAmount = del.delegatedAmount.add(_rewards);
        // Update transcoder's total stake with rewards
        uint256 newStake = transcoderTotalStake(_transcoder).add(_rewards);
        transcoderPool.updateKey(_transcoder, newStake, address(0), address(0));
    }

    /**
     * @dev Update a delegator with token pools shares from its lastClaimRound through a given round
     * @param _delegator Delegator address
     * @param _endRound The last round for which to update a delegator's stake with token pools shares
     */
    function updateDelegatorWithEarnings(address _delegator, uint256 _endRound) internal {
        Delegator storage del = delegators[_delegator];

        // Only will have earnings to claim if you have a delegate
        // If not delegated, skip the earnings claim process
        if (del.delegateAddress != address(0)) {
            // Cannot claim earnings for more than maxEarningsClaimsRounds
            // This is a number to cause transactions to fail early if
            // we know they will require too much gas to loop through all the necessary rounds to claim earnings
            // The user should instead manually invoke `claimEarnings` to split up the claiming process
            // across multiple transactions
            require(_endRound.sub(del.lastClaimRound) <= maxEarningsClaimsRounds);

            uint256 currentBondedAmount = del.bondedAmount;
            uint256 currentFees = del.fees;

            for (uint256 i = del.lastClaimRound + 1; i <= _endRound; i++) {
                EarningsPool.Data storage earningsPool = transcoders[del.delegateAddress].earningsPoolPerRound[i];

                if (earningsPool.hasClaimableShares()) {
                    bool isTranscoder = _delegator == del.delegateAddress;

                    var (fees, rewards) = earningsPool.claimShare(currentBondedAmount, isTranscoder);

                    currentFees = currentFees.add(fees);
                    currentBondedAmount = currentBondedAmount.add(rewards);
                }
            }

            // Rewards are bonded by default
            del.bondedAmount = currentBondedAmount;
            del.fees = currentFees;
        }

        del.lastClaimRound = _endRound;
    }

    /**
     * @dev Update the state of a delegator and its delegate by processing a rebond using an unbonding lock
     * @param _delegator Address of delegator
     * @param _unbondingLockId ID of unbonding lock to rebond with
     */
    function processRebond(address _delegator, uint256 _unbondingLockId) internal {
        Delegator storage del = delegators[_delegator];
        UnbondingLock storage lock = del.unbondingLocks[_unbondingLockId];

        // Unbonding lock must be valid
        require(isValidUnbondingLock(_delegator, _unbondingLockId));

        uint256 amount = lock.amount;
        // Increase delegator's bonded amount
        del.bondedAmount = del.bondedAmount.add(amount);
        // Increase delegate's delegated amount
        delegators[del.delegateAddress].delegatedAmount = delegators[del.delegateAddress].delegatedAmount.add(amount);

        if (transcoderStatus(del.delegateAddress) == TranscoderStatus.Registered) {
            // If delegate is a registered transcoder increase its delegated stake in registered pool
            transcoderPool.updateKey(del.delegateAddress, transcoderTotalStake(del.delegateAddress).add(amount), address(0), address(0));
        }

        // Delete lock
        delete del.unbondingLocks[_unbondingLockId];

        Rebond(del.delegateAddress, _delegator, _unbondingLockId, amount);
    }

    /**
     * @dev Return LivepeerToken interface
     */
    function livepeerToken() internal view returns (ILivepeerToken) {
        return ILivepeerToken(controller.getContract(keccak256("LivepeerToken")));
    }

    /**
     * @dev Return Minter interface
     */
    function minter() internal view returns (IMinter) {
        return IMinter(controller.getContract(keccak256("Minter")));
    }

    /**
     * @dev Return RoundsManager interface
     */
    function roundsManager() internal view returns (IRoundsManager) {
        return IRoundsManager(controller.getContract(keccak256("RoundsManager")));
    }
}
/**
 * @title BondingManager
 * @dev Manages bonding, transcoder and rewards/fee accounting related operations of the Livepeer protocol
 */
function withdrawFees()
    external
    whenSystemNotPaused
    currentRoundInitialized
    autoClaimEarnings
{
    // Delegator must have fees
    require(delegators[msg.sender].fees > 0);

    uint256 amount = delegators[msg.sender].fees;
    delegators[msg.sender].fees = 0;

    // Tell Minter to transfer fees (ETH) to the delegator
    minter().trustedWithdrawETH(msg.sender, amount);

    WithdrawFees(msg.sender);
}

/**
 * @dev Withdraws fees to the caller
 */