pragma solidity ^0.4.18;

/*
    Copyright 2017, Jordi Baylina
    Contributors: Adrià Massanet <adria@codecontext.io>, RJ Ewing, Griff
    Green, Arthur Lunn

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import "./LiquidPledgingStorage.sol";
import "./PledgeAdmins.sol";
import "./Pledges.sol";
import "@aragon/os/contracts/apps/AragonApp.sol";

/// @dev `LiquidPledgingBase` is the base level contract used to carry out
///  liquidPledging's most basic functions, mostly handling and searching the
///  data structures
contract LiquidPledgingBase is AragonApp, LiquidPledgingStorage, PledgeAdmins, Pledges {

    event Transfer(uint indexed from, uint indexed to, uint amount);
    event CancelProject(uint indexed idProject);

/////////////
// Modifiers
/////////////

    /// @dev The `vault`is the only addresses that can call a function with this
    ///  modifier
    modifier onlyVault() {
        require(msg.sender == address(vault));
        _;
    }

///////////////
// Constructor
///////////////

    /// @param _vault The vault where the ETH backing the pledges is stored
    function initialize(address _vault) onlyInit public {
        require(_vault != 0x0);
        initialized();

        vault = ILPVault(_vault);

        admins.length = 1; // we reserve the 0 admin
        pledges.length = 1; // we reserve the 0 pledge
    }


/////////////////////////////
// Public constant functions
/////////////////////////////

    /// @notice Getter to find Delegate w/ the Pledge ID & the Delegate index
    /// @param idPledge The id number representing the pledge being queried
    /// @param idxDelegate The index number for the delegate in this Pledge 
    function getPledgeDelegate(uint64 idPledge, uint64 idxDelegate) external view returns(
        uint64 idDelegate,
        address addr,
        string name
    ) {
        Pledge storage p = _findPledge(idPledge);
        idDelegate = p.delegationChain[idxDelegate - 1];
        PledgeAdmin storage delegate = _findAdmin(idDelegate);
        addr = delegate.addr;
        name = delegate.name;
    }

///////////////////
// Public functions
///////////////////

    /// @notice Only affects pledges with the Pledged PledgeState for 2 things:
    ///   #1: Checks if the pledge should be committed. This means that
    ///       if the pledge has an intendedProject and it is past the
    ///       commitTime, it changes the owner to be the proposed project
    ///       (The UI will have to read the commit time and manually do what
    ///       this function does to the pledge for the end user
    ///       at the expiration of the commitTime)
    ///
    ///   #2: Checks to make sure that if there has been a cancellation in the
    ///       chain of projects, the pledge's owner has been changed
    ///       appropriately.
    ///
    /// This function can be called by anybody at anytime on any pledge.
    ///  In general it can be called to force the calls of the affected 
    ///  plugins, which also need to be predicted by the UI
    /// @param idPledge This is the id of the pledge that will be normalized
    /// @return The normalized Pledge!
    function normalizePledge(uint64 idPledge) public returns(uint64) {
        Pledge storage p = _findPledge(idPledge);

        // Check to make sure this pledge hasn't already been used 
        // or is in the process of being used
        if (p.pledgeState != PledgeState.Pledged) {
            return idPledge;
        }

        // First send to a project if it's proposed and committed
        if ((p.intendedProject > 0) && ( _getTime() > p.commitTime)) {
            uint64 oldPledge = _findOrCreatePledge(
                p.owner,
                p.delegationChain,
                0,
                0,
                p.oldPledge,
                p.token,
                PledgeState.Pledged
            );
            uint64 toPledge = _findOrCreatePledge(
                p.intendedProject,
                new uint64[](0),
                0,
                0,
                oldPledge,
                p.token,
                PledgeState.Pledged
            );
            _doTransfer(idPledge, toPledge, p.amount);
            idPledge = toPledge;
            p = _findPledge(idPledge);
        }

        toPledge = _getOldestPledgeNotCanceled(idPledge);
        if (toPledge != idPledge) {
            _doTransfer(idPledge, toPledge, p.amount);
        }

        return toPledge;
    }

////////////////////
// Internal methods
////////////////////

    /// @notice A check to see if the msg.sender is the owner or the
    ///  plugin contract for a specific Admin
    /// @param idAdmin The id of the admin being checked
    function _checkAdminOwner(uint64 idAdmin) internal view {
        PledgeAdmin storage a = _findAdmin(idAdmin);
        require(msg.sender == address(a.plugin) || msg.sender == a.addr);
    }

    function _transfer( 
        uint64 idSender,
        uint64 idPledge,
        uint amount,
        uint64 idReceiver
    ) internal
    {
        require(idReceiver > 0); // prevent burning value
        idPledge = normalizePledge(idPledge);

        Pledge storage p = _findPledge(idPledge);
        PledgeAdmin storage receiver = _findAdmin(idReceiver);

        require(p.pledgeState == PledgeState.Pledged);

        // If the sender is the owner of the Pledge
        if (p.owner == idSender) {

            if (receiver.adminType == PledgeAdminType.Giver) {
                _transferOwnershipToGiver(idPledge, amount, idReceiver);
                return;
            } else if (receiver.adminType == PledgeAdminType.Project) {
                _transferOwnershipToProject(idPledge, amount, idReceiver);
                return;
            } else if (receiver.adminType == PledgeAdminType.Delegate) {

                uint recieverDIdx = _getDelegateIdx(p, idReceiver);
                if (p.intendedProject > 0 && recieverDIdx != NOTFOUND) {
                    // if there is an intendedProject and the receiver is in the delegationChain,
                    // then we want to preserve the delegationChain as this is a veto of the
                    // intendedProject by the owner

                    if (recieverDIdx == p.delegationChain.length - 1) {
                        uint64 toPledge = _findOrCreatePledge(
                            p.owner,
                            p.delegationChain,
                            0,
                            0,
                            p.oldPledge,
                            p.token,
                            PledgeState.Pledged);
                        _doTransfer(idPledge, toPledge, amount);
                        return;
                    }

                    _undelegate(idPledge, amount, p.delegationChain.length - receiverDIdx - 1);
                    return;
                }
                // owner is not vetoing an intendedProject and is transferring the pledge to a delegate,
                // so we want to reset the delegationChain
                idPledge = _undelegate(
                    idPledge,
                    amount,
                    p.delegationChain.length
                );
                _appendDelegate(idPledge, amount, idReceiver);
                return;
            }

            // This should never be reached as the receiver.adminType
            // should always be either a Giver, Project, or Delegate
            assert(false);
        }

        // If the sender is a Delegate
        uint senderDIdx = _getDelegateIdx(p, idSender);
        if (senderDIdx != NOTFOUND) {

            // And the receiver is another Giver
            if (receiver.adminType == PledgeAdminType.Giver) {
                // Only transfer to the Giver who owns the pledge
                assert(p.owner == idReceiver);
                _undelegate(idPledge, amount, p.delegationChain.length);
                return;
            }

            // And the receiver is another Delegate
            if (receiver.adminType == PledgeAdminType.Delegate) {
                uint receiverDIdx = _getDelegateIdx(p, idReceiver);

                // And not in the delegationChain or part of the delegationChain
                // is after the sender, then all of the other delegates after 
                // the sender are removed and the receiver is appended at the 
                // end of the delegationChain
                if (receiverDIdx == NOTFOUND || receiverDIdx > senderDIdx) {
                    idPledge = _undelegate(
                        idPledge,
                        amount,
                        p.delegationChain.length - senderDIdx - 1
                    );
                    _appendDelegate(idPledge, amount, idReceiver);
                    return;
                }

                // And is already part of the delegate chain but is before the
                //  sender, then the sender and all of the other delegates after
                //  the RECEIVER are removed from the delegationChain
                _undelegate(
                    idPledge,
                    amount,
                    p.delegationChain.length - receiverDIdx - 1
                );
                return;
            }

            // And the receiver is a Project, all the delegates after the sender
            //  are removed and the amount is pre-committed to the project
            if (receiver.adminType == PledgeAdminType.Project) {
                idPledge = _undelegate(
                    idPledge,
                    amount,
                    p.delegationChain.length - senderDIdx - 1
                );
                _proposeAssignProject(idPledge, amount, idReceiver);
                return;
            }
        }
        assert(false);  // When the sender is not an owner or a delegate
    }

    /// @notice `transferOwnershipToProject` allows for the transfer of
    ///  ownership to the project, but it can also be called by a project
    ///  to un-delegate everyone by setting one's own id for the idReceiver
    /// @param idPledge the id of the pledge to be transfered.
    /// @param amount Quantity of value that's being transfered
    /// @param idReceiver The new owner of the project (or self to un-delegate)
    function _transferOwnershipToProject(
        uint64 idPledge,
        uint amount,
        uint64 idReceiver
    ) internal 
    {
        Pledge storage p = _findPledge(idPledge);

        // Ensure that the pledge is not already at max pledge depth
        // and the project has not been canceled
        require(_getPledgeLevel(p) < MAX_INTERPROJECT_LEVEL);
        require(!isProjectCanceled(idReceiver));

        uint64 oldPledge = _findOrCreatePledge(
            p.owner,
            p.delegationChain,
            0,
            0,
            p.oldPledge,
            p.token,
            PledgeState.Pledged
        );
        uint64 toPledge = _findOrCreatePledge(
            idReceiver,                     // Set the new owner
            new uint64[](0),                // clear the delegation chain
            0,
            0,
            oldPledge,
            p.token,
            PledgeState.Pledged
        );
        _doTransfer(idPledge, toPledge, amount);
    }   


    /// @notice `transferOwnershipToGiver` allows for the transfer of
    ///  value back to the Giver, value is placed in a pledged state
    ///  without being attached to a project, delegation chain, or time line.
    /// @param idPledge the id of the pledge to be transferred.
    /// @param amount Quantity of value that's being transferred
    /// @param idReceiver The new owner of the pledge
    function _transferOwnershipToGiver(
        uint64 idPledge,
        uint amount,
        uint64 idReceiver
    ) internal 
    {
        Pledge storage p = _findPledge(idPledge);

        uint64 toPledge = _findOrCreatePledge(
            idReceiver,
            new uint64[](0),
            0,
            0,
            0,
            p.token,
            PledgeState.Pledged
        );
        _doTransfer(idPledge, toPledge, amount);
    }

    /// @notice `appendDelegate` allows for a delegate to be added onto the
    ///  end of the delegate chain for a given Pledge.
    /// @param idPledge the id of the pledge thats delegate chain will be modified.
    /// @param amount Quantity of value that's being chained.
    /// @param idReceiver The delegate to be added at the end of the chain
    function _appendDelegate(
        uint64 idPledge,
        uint amount,
        uint64 idReceiver
    ) internal 
    {
        Pledge storage p = _findPledge(idPledge);

        require(p.delegationChain.length < MAX_DELEGATES);
        uint64[] memory newDelegationChain = new uint64[](
            p.delegationChain.length + 1
        );
        for (uint i = 0; i < p.delegationChain.length; i++) {
            newDelegationChain[i] = p.delegationChain[i];
        }

        // Make the last item in the array the idReceiver
        newDelegationChain[p.delegationChain.length] = idReceiver;

        uint64 toPledge = _findOrCreatePledge(
            p.owner,
            newDelegationChain,
            0,
            0,
            p.oldPledge,
            p.token,
            PledgeState.Pledged
        );
        _doTransfer(idPledge, toPledge, amount);
    }

    /// @notice `appendDelegate` allows for a delegate to be added onto the
    ///  end of the delegate chain for a given Pledge.
    /// @param idPledge the id of the pledge thats delegate chain will be modified.
    /// @param amount Quantity of value that's shifted from delegates.
    /// @param q Number (or depth) of delegates to remove
    /// @return toPledge The id for the pledge being adjusted or created
    function _undelegate(
        uint64 idPledge,
        uint amount,
        uint q
    ) internal returns (uint64 toPledge)
    {
        Pledge storage p = _findPledge(idPledge);
        uint64[] memory newDelegationChain = new uint64[](
            p.delegationChain.length - q
        );

        for (uint i = 0; i < p.delegationChain.length - q; i++) {
            newDelegationChain[i] = p.delegationChain[i];
        }
        toPledge = _findOrCreatePledge(
            p.owner,
            newDelegationChain,
            0,
            0,
            p.oldPledge,
            p.token,
            PledgeState.Pledged
        );
        _doTransfer(idPledge, toPledge, amount);
    }

    /// @notice `proposeAssignProject` proposes the assignment of a pledge
    ///  to a specific project.
    /// @dev This function should potentially be named more specifically.
    /// @param idPledge the id of the pledge that will be assigned.
    /// @param amount Quantity of value this pledge leader would be assigned.
    /// @param idReceiver The project this pledge will potentially 
    ///  be assigned to.
    function _proposeAssignProject(
        uint64 idPledge,
        uint amount,
        uint64 idReceiver
    ) internal 
    {
        Pledge storage p = _findPledge(idPledge);

        require(_getPledgeLevel(p) < MAX_INTERPROJECT_LEVEL);
        require(!isProjectCanceled(idReceiver));

        uint64 toPledge = _findOrCreatePledge(
            p.owner,
            p.delegationChain,
            idReceiver,
            uint64(_getTime() + _maxCommitTime(p)),
            p.oldPledge,
            p.token,
            PledgeState.Pledged
        );
        _doTransfer(idPledge, toPledge, amount);
    }

    /// @notice `doTransfer` is designed to allow for pledge amounts to be 
    ///  shifted around internally.
    /// @param from This is the id of the pledge from which value will be transferred.
    /// @param to This is the id of the pledge that value will be transferred to.
    /// @param _amount The amount of value that will be transferred.
    function _doTransfer(uint64 from, uint64 to, uint _amount) internal {
        uint amount = _callPlugins(true, from, to, _amount);
        if (from == to) {
            return;
        }
        if (amount == 0) {
            return;
        }

        Pledge storage pFrom = _findPledge(from);
        Pledge storage pTo = _findPledge(to);

        require(pFrom.amount >= amount);
        pFrom.amount -= amount;
        pTo.amount += amount;
        require(pTo.amount >= amount);

        Transfer(from, to, amount);
        _callPlugins(false, from, to, amount);
    }

    /// @notice A getter to find the longest commitTime out of the owner and all
    ///  the delegates for a specified pledge
    /// @param p The Pledge being queried
    /// @return The maximum commitTime out of the owner and all the delegates
    function _maxCommitTime(Pledge p) internal view returns(uint64 commitTime) {
        PledgeAdmin storage a = _findAdmin(p.owner);
        commitTime = a.commitTime; // start with the owner's commitTime

        for (uint i = 0; i < p.delegationChain.length; i++) {
            a = _findAdmin(p.delegationChain[i]);

            // If a delegate's commitTime is longer, make it the new commitTime
            if (a.commitTime > commitTime) {
                commitTime = a.commitTime;
            }
        }
    }

    /// @notice A getter to find the oldest pledge that hasn't been canceled
    /// @param idPledge The starting place to lookup the pledges
    /// @return The oldest idPledge that hasn't been canceled (DUH!)
    function _getOldestPledgeNotCanceled(
        uint64 idPledge
    ) internal view returns(uint64)
    {
        if (idPledge == 0) {
            return 0;
        }

        Pledge storage p = _findPledge(idPledge);
        PledgeAdmin storage admin = _findAdmin(p.owner);
        
        if (admin.adminType == PledgeAdminType.Giver) {
            return idPledge;
        }

        assert(admin.adminType == PledgeAdminType.Project);
        if (!isProjectCanceled(p.owner)) {
            return idPledge;
        }

        return _getOldestPledgeNotCanceled(p.oldPledge);
    }

    /// @notice `callPlugin` is used to trigger the general functions in the
    ///  plugin for any actions needed before and after a transfer happens.
    ///  Specifically what this does in relation to the plugin is something
    ///  that largely depends on the functions of that plugin. This function
    ///  is generally called in pairs, once before, and once after a transfer.
    /// @param before This toggle determines whether the plugin call is occurring
    ///  before or after a transfer.
    /// @param adminId This should be the Id of the *trusted* individual
    ///  who has control over this plugin.
    /// @param fromPledge This is the Id from which value is being transfered.
    /// @param toPledge This is the Id that value is being transfered to.
    /// @param context The situation that is triggering the plugin. See plugin
    ///  for a full description of contexts.
    /// @param amount The amount of value that is being transfered.
    function _callPlugin(
        bool before,
        uint64 adminId,
        uint64 fromPledge,
        uint64 toPledge,
        uint64 context,
        address token,
        uint amount
    ) internal returns (uint allowedAmount) 
    {
        uint newAmount;
        allowedAmount = amount;
        PledgeAdmin storage admin = _findAdmin(adminId);

        // Checks admin has a plugin assigned and a non-zero amount is requested
        if (address(admin.plugin) != 0 && allowedAmount > 0) {
            // There are two separate functions called in the plugin.
            // One is called before the transfer and one after
            if (before) {
                newAmount = admin.plugin.beforeTransfer(
                    adminId,
                    fromPledge,
                    toPledge,
                    context,
                    token,
                    amount
                );
                require(newAmount <= allowedAmount);
                allowedAmount = newAmount;
            } else {
                admin.plugin.afterTransfer(
                    adminId,
                    fromPledge,
                    toPledge,
                    context,
                    token,
                    amount
                );
            }
        }
    }

    /// @notice `callPluginsPledge` is used to apply plugin calls to
    ///  the delegate chain and the intended project if there is one.
    ///  It does so in either a transferring or receiving context based
    ///  on the `p` and  `fromPledge` parameters.
    /// @param before This toggle determines whether the plugin call is occuring
    ///  before or after a transfer.
    /// @param idPledge This is the id of the pledge on which this plugin
    ///  is being called.
    /// @param fromPledge This is the Id from which value is being transfered.
    /// @param toPledge This is the Id that value is being transfered to.
    /// @param amount The amount of value that is being transfered.
    function _callPluginsPledge(
        bool before,
        uint64 idPledge,
        uint64 fromPledge,
        uint64 toPledge,
        uint amount
    ) internal returns (uint allowedAmount) 
    {
        // Determine if callPlugin is being applied in a receiving
        // or transferring context
        uint64 offset = idPledge == fromPledge ? 0 : 256;
        allowedAmount = amount;
        Pledge storage p = _findPledge(idPledge);

        // Always call the plugin on the owner
        allowedAmount = _callPlugin(
            before,
            p.owner,
            fromPledge,
            toPledge,
            offset,
            p.token,
            allowedAmount
        );

        // Apply call plugin to all delegates
        for (uint64 i = 0; i < p.delegationChain.length; i++) {
            allowedAmount = _callPlugin(
                before,
                p.delegationChain[i],
                fromPledge,
                toPledge,
                offset + i + 1,
                p.token,
                allowedAmount
            );
        }

        // If there is an intended project also call the plugin in
        // either a transferring or receiving context based on offset
        // on the intended project
        if (p.intendedProject > 0) {
            allowedAmount = _callPlugin(
                before,
                p.intendedProject,
                fromPledge,
                toPledge,
                offset + 255,
                p.token,
                allowedAmount
            );
        }
    }

    /// @notice `callPlugins` calls `callPluginsPledge` once for the transfer
    ///  context and once for the receiving context. The aggregated 
    ///  allowed amount is then returned.
    /// @param before This toggle determines whether the plugin call is occurring
    ///  before or after a transfer.
    /// @param fromPledge This is the Id from which value is being transferred.
    /// @param toPledge This is the Id that value is being transferred to.
    /// @param amount The amount of value that is being transferred.
    function _callPlugins(
        bool before,
        uint64 fromPledge,
        uint64 toPledge,
        uint amount
    ) internal returns (uint allowedAmount) 
    {
        allowedAmount = amount;

        // Call the plugins in the transfer context
        allowedAmount = _callPluginsPledge(
            before,
            fromPledge,
            fromPledge,
            toPledge,
            allowedAmount
        );

        // Call the plugins in the receive context
        allowedAmount = _callPluginsPledge(
            before,
            toPledge,
            fromPledge,
            toPledge,
            allowedAmount
        );
    }

/////////////
// Test functions
/////////////

    /// @notice Basic helper function to return the current time
    function _getTime() internal view returns (uint) {
        return now;
    }
}