/*
 * Copyright 2007-2008, Christof Lutteroth, lutteroth@cs.auckland.ac.nz
 * Copyright 2007-2008, James Kim, jkim202@ec.auckland.ac.nz
 * Copyright 2010, Clemens Zeidler <haiku@clemens-zeidler.de>
 * Distributed under the terms of the MIT License.
 */


#include "LinearSpec.h"

#include <new>

#include "ActiveSetSolver.h"


using namespace LinearProgramming;


// #define DEBUG_LINEAR_SPECIFICATIONS

#ifdef DEBUG_LINEAR_SPECIFICATIONS
#include <stdio.h>
#define TRACE(x...) printf(x)
#else
#define TRACE(x...) /* nothing */
#endif


SolverInterface::SolverInterface(LinearSpec* linSpec)
        :
        fLinearSpec(linSpec)
{

}


SolverInterface::~SolverInterface()
{       
}


bool
SolverInterface::AddConstraint(Constraint* constraint, bool notifyListener)
{
        return fLinearSpec->AddConstraint(constraint, notifyListener);
}


bool
SolverInterface::RemoveConstraint(Constraint* constraint, bool deleteConstraint,
        bool notifyListener)
{
        return fLinearSpec->RemoveConstraint(constraint, deleteConstraint,
                notifyListener);
}

        
SpecificationListener::~SpecificationListener()
{
}


void
SpecificationListener::VariableAdded(Variable* variable)
{       
}


void
SpecificationListener::VariableRemoved(Variable* variable)
{
}


void
SpecificationListener::ConstraintAdded(Constraint* constraint)
{
}


void
SpecificationListener::ConstraintRemoved(Constraint* constraint)
{
}


/**
 * Constructor.
 * Creates a new specification for a linear programming problem.
 */
LinearSpec::LinearSpec()
        :
        fResult(kError),
        fSolvingTime(0)
{
        fSolver = new ActiveSetSolver(this);
}


/**
 * Destructor.
 * Removes the specification and deletes all constraints,
 * objective function summands and variables.
 */
LinearSpec::~LinearSpec()
{
        for (int32 i = 0; i < fConstraints.CountItems(); i++)
                delete (Constraint*)fConstraints.ItemAt(i);
        while (fVariables.CountItems() > 0)
                RemoveVariable(fVariables.ItemAt(0));

        delete fSolver;
}


bool
LinearSpec::AddListener(SpecificationListener* listener)
{
        return fListeners.AddItem(listener);    
}


bool
LinearSpec::RemoveListener(SpecificationListener* listener)
{
        return fListeners.RemoveItem(listener);
}


/**
 * Adds a new variable to the specification.
 *
 * @return the new variable
 */
Variable*
LinearSpec::AddVariable()
{
        Variable* variable = new(std::nothrow) Variable(this);
        if (!variable)
                return NULL;
        if (!AddVariable(variable)) {
                delete variable;
                return NULL;
        }

        return variable;
}


bool
LinearSpec::AddVariable(Variable* variable)
{
        if (variable->IsValid())
                return false;

        if (!fVariables.AddItem(variable))
                return false;

        if (variable->fLS == NULL)
                variable->fLS = this;

        if (!fSolver->VariableAdded(variable)) {
                fVariables.RemoveItem(variable);
                return false;
        }
        variable->fIsValid = true;

        if (!UpdateRange(variable)) {
                RemoveVariable(variable, false);
                return false;
        }

        for (int32 i = 0; i < fListeners.CountItems(); i++)
                fListeners.ItemAt(i)->VariableAdded(variable);

        return true;
}


bool
LinearSpec::RemoveVariable(Variable* variable, bool deleteVariable)
{
        // must be called first otherwise the index is invalid
        if (fSolver->VariableRemoved(variable) == false)
                return false;

        // do we know the variable?
        if (fVariables.RemoveItem(variable) == false)
                return false;
        fUsedVariables.RemoveItem(variable);
        variable->fIsValid = false;

        // invalidate all constraints that use this variable
        ConstraintList markedForInvalidation;
        const ConstraintList& constraints = Constraints();
        for (int i = 0; i < constraints.CountItems(); i++) {
                Constraint* constraint = constraints.ItemAt(i);

                SummandList* summands = constraint->LeftSide();
                for (int j = 0; j < summands->CountItems(); j++) {
                        Summand* summand = summands->ItemAt(j);
                        if (summand->Var() == variable) {
                                markedForInvalidation.AddItem(constraint);
                                break;
                        }
                }
        }
        for (int i = 0; i < markedForInvalidation.CountItems(); i++)
                RemoveConstraint(markedForInvalidation.ItemAt(i));

        if (deleteVariable)
                delete variable;

        for (int32 i = 0; i < fListeners.CountItems(); i++)
                fListeners.ItemAt(i)->VariableRemoved(variable);

        return true;
}


int32
LinearSpec::IndexOf(const Variable* variable) const
{
        return fUsedVariables.IndexOf(variable);
}


int32
LinearSpec::GlobalIndexOf(const Variable* variable) const
{
        return fVariables.IndexOf(variable);
}


bool
LinearSpec::UpdateRange(Variable* variable)
{
        if (!fSolver->VariableRangeChanged(variable))
                return false;
        return true;
}


bool
LinearSpec::AddConstraint(Constraint* constraint)
{
        return AddConstraint(constraint, true);
}


bool
LinearSpec::RemoveConstraint(Constraint* constraint, bool deleteConstraint)
{
        return RemoveConstraint(constraint, deleteConstraint, true);
}


bool
LinearSpec::AddConstraint(Constraint* constraint, bool notifyListener)
{
        if (!fConstraints.AddItem(constraint))
                return false;

        // ref count the used variables
        SummandList* leftSide = constraint->LeftSide();
        for (int i = 0; i < leftSide->CountItems(); i++) {
                Variable* var = leftSide->ItemAt(i)->Var();
                _AddConstraintRef(var);
        }

        if (!fSolver->ConstraintAdded(constraint)) {
                RemoveConstraint(constraint, false);
                return false;
        }

        constraint->fLS = this;

        if (notifyListener) {
                for (int32 i = 0; i < fListeners.CountItems(); i++)
                        fListeners.ItemAt(i)->ConstraintAdded(constraint);
        }

        return true;
}


bool
LinearSpec::RemoveConstraint(Constraint* constraint, bool deleteConstraint,
        bool notifyListener)
{
        if (constraint == NULL)
                return false;
        fSolver->ConstraintRemoved(constraint);
        if (!fConstraints.RemoveItem(constraint))
                return false;

        SummandList* leftSide = constraint->LeftSide();
        for (int32 i = 0; i < leftSide->CountItems(); i++) {
                Variable* var = leftSide->ItemAt(i)->Var();
                _RemoveConstraintRef(var);
        }

        if (notifyListener) {
                for (int32 i = 0; i < fListeners.CountItems(); i++)
                        fListeners.ItemAt(i)->ConstraintRemoved(constraint);
        }

        constraint->fLS = NULL;
        if (deleteConstraint)
                delete constraint;

        return true;
}


void
LinearSpec::_AddConstraintRef(Variable* var)
{
        if (var->AddReference() == 1)
                fUsedVariables.AddItem(var);
}


void
LinearSpec::_RemoveConstraintRef(Variable* var)
{
        if (var->RemoveReference() == 0)
                fUsedVariables.RemoveItem(var);
}


bool
LinearSpec::UpdateLeftSide(Constraint* constraint,
        const SummandList* oldSummands)
{
        SummandList* leftSide = constraint->LeftSide();
        if (leftSide != NULL) {
                for (int32 i = 0; i < leftSide->CountItems(); i++) {
                        Variable* var = leftSide->ItemAt(i)->Var();
                        _AddConstraintRef(var);                 
                }
        }
        if (oldSummands != NULL) {
                // the summands have changed, update the var ref count
                for (int32 i = 0; i < oldSummands->CountItems(); i++) {
                        Variable* var = oldSummands->ItemAt(i)->Var();
                        _RemoveConstraintRef(var);                      
                }
        }

        if (!fSolver->LeftSideChanged(constraint))
                return false;
        return true;
}


bool
LinearSpec::UpdateRightSide(Constraint* constraint)
{
        if (!fSolver->RightSideChanged(constraint))
                return false;
        return true;
}


bool
LinearSpec::UpdateOperator(Constraint* constraint)
{
        if (!fSolver->OperatorChanged(constraint))
                return false;
        return true;
}


bool
LinearSpec::UpdatePenalties(Constraint* constraint)
{
        if (!fSolver->PenaltiesChanged(constraint))
                return false;
        return true;
}


/**
 * Adds a new soft linear constraint to the specification.
 * i.e. a constraint that does not always have to be satisfied.
 *
 * @param coeffs                the constraint's coefficients
 * @param vars                  the constraint's variables
 * @param op                    the constraint's operand
 * @param rightSide             the constant value on the constraint's right side
 * @param penaltyNeg    the coefficient penalizing negative deviations from the exact solution
 * @param penaltyPos    the coefficient penalizing positive deviations from the exact solution
 */
Constraint*
LinearSpec::AddConstraint(SummandList* summands, OperatorType op,
                double rightSide, double penaltyNeg, double penaltyPos)
{
        return _AddConstraint(summands, op, rightSide, penaltyNeg, penaltyPos);
}


/**
 * Adds a new soft linear constraint to the specification with a single summand.
 *
 * @param coeff1                the constraint's first coefficient
 * @param var1                  the constraint's first variable
 * @param op                    the constraint's operand
 * @param rightSide             the constant value on the constraint's right side
 * @param penaltyNeg    the coefficient penalizing negative deviations from the exact solution
 * @param penaltyPos    the coefficient penalizing positive deviations from the exact solution
 */
Constraint*
LinearSpec::AddConstraint(double coeff1, Variable* var1,
                OperatorType op, double rightSide, double penaltyNeg, double penaltyPos)
{
        SummandList* summands = new(std::nothrow) SummandList(1);
        if (!summands)
                return NULL;
        summands->AddItem(new(std::nothrow) Summand(coeff1, var1));
        if (!_CheckSummandList(summands))
                return NULL;
        return _AddConstraint(summands, op, rightSide, penaltyNeg, penaltyPos);
}


/**
 * Adds a new soft linear constraint to the specification with two summands.
 *
 * @param coeff1                the constraint's first coefficient
 * @param var1                  the constraint's first variable
 * @param coeff2                the constraint's second coefficient
 * @param var2                  the constraint's second variable
 * @param op                    the constraint's operand
 * @param rightSide             the constant value on the constraint's right side
 * @param penaltyNeg    the coefficient penalizing negative deviations from the exact solution
 * @param penaltyPos    the coefficient penalizing positive deviations from the exact solution
 */
Constraint*
LinearSpec::AddConstraint(double coeff1, Variable* var1,
        double coeff2, Variable* var2, OperatorType op, double rightSide,
        double penaltyNeg, double penaltyPos)
{
        SummandList* summands = new(std::nothrow) SummandList(2);
        if (!summands)
                return NULL;
        summands->AddItem(new(std::nothrow) Summand(coeff1, var1));
        summands->AddItem(new(std::nothrow) Summand(coeff2, var2));
        if (!_CheckSummandList(summands))
                return NULL;
        return _AddConstraint(summands, op, rightSide, penaltyNeg, penaltyPos);
}


/**
 * Adds a new soft linear constraint to the specification with three summands.
 *
 * @param coeff1                the constraint's first coefficient
 * @param var1                  the constraint's first variable
 * @param coeff2                the constraint's second coefficient
 * @param var2                  the constraint's second variable
 * @param coeff3                the constraint's third coefficient
 * @param var3                  the constraint's third variable
 * @param op                    the constraint's operand
 * @param rightSide             the constant value on the constraint's right side
 * @param penaltyNeg    the coefficient penalizing negative deviations from the exact solution
 * @param penaltyPos    the coefficient penalizing positive deviations from the exact solution
 */
Constraint*
LinearSpec::AddConstraint(double coeff1, Variable* var1,
        double coeff2, Variable* var2, double coeff3, Variable* var3,
        OperatorType op, double rightSide, double penaltyNeg, double penaltyPos)
{
        SummandList* summands = new(std::nothrow) SummandList(2);
        if (!summands)
                return NULL;
        summands->AddItem(new(std::nothrow) Summand(coeff1, var1));
        summands->AddItem(new(std::nothrow) Summand(coeff2, var2));
        summands->AddItem(new(std::nothrow) Summand(coeff3, var3));
        if (!_CheckSummandList(summands))
                return NULL;
        return _AddConstraint(summands, op, rightSide, penaltyNeg, penaltyPos);
}


/**
 * Adds a new soft linear constraint to the specification with four summands.
 *
 * @param coeff1                the constraint's first coefficient
 * @param var1                  the constraint's first variable
 * @param coeff2                the constraint's second coefficient
 * @param var2                  the constraint's second variable
 * @param coeff3                the constraint's third coefficient
 * @param var3                  the constraint's third variable
 * @param coeff4                the constraint's fourth coefficient
 * @param var4                  the constraint's fourth variable
 * @param op                    the constraint's operand
 * @param rightSide             the constant value on the constraint's right side
 * @param penaltyNeg    the coefficient penalizing negative deviations from the exact solution
 * @param penaltyPos    the coefficient penalizing positive deviations from the exact solution
 */
Constraint*
LinearSpec::AddConstraint(double coeff1, Variable* var1,
        double coeff2, Variable* var2, double coeff3, Variable* var3,
        double coeff4, Variable* var4, OperatorType op, double rightSide,
        double penaltyNeg, double penaltyPos)
{
        SummandList* summands = new(std::nothrow) SummandList(2);
        if (!summands)
                return NULL;
        summands->AddItem(new(std::nothrow) Summand(coeff1, var1));
        summands->AddItem(new(std::nothrow) Summand(coeff2, var2));
        summands->AddItem(new(std::nothrow) Summand(coeff3, var3));
        summands->AddItem(new(std::nothrow) Summand(coeff4, var4));
        if (!_CheckSummandList(summands))
                return NULL;
        return _AddConstraint(summands, op, rightSide, penaltyNeg, penaltyPos);
}


ResultType
LinearSpec::FindMins(const VariableList* variables)
{
        fResult = fSolver->FindMins(variables);
        return fResult;
}


ResultType
LinearSpec::FindMaxs(const VariableList* variables)
{
        fResult = fSolver->FindMaxs(variables);
        return fResult;
}


bool
LinearSpec::_CheckSummandList(SummandList* list)
{
        bool ok = true;
        for (int i = 0; i < list->CountItems(); i++) {
                if (list->ItemAt(i) == NULL) {
                        ok = false;
                        break;
                }
        }
        if (ok)
                return true;

        delete list;
        return false;
}


Constraint*
LinearSpec::_AddConstraint(SummandList* leftSide, OperatorType op,
        double rightSide, double penaltyNeg, double penaltyPos)
{
        Constraint* constraint = new(std::nothrow) Constraint(this, leftSide,
                op, rightSide, penaltyNeg, penaltyPos);
        if (constraint == NULL)
                return NULL;
        if (!AddConstraint(constraint)) {
                delete constraint;
                return NULL;
        }
        return constraint;
}


#ifdef DEBUG_LINEAR_SPECIFICATIONS
static bigtime_t sAverageSolvingTime = 0;
static int32 sSolvedCount = 0;
#endif


ResultType
LinearSpec::Solve()
{
        bigtime_t startTime = system_time();

        fResult = fSolver->Solve();

        fSolvingTime = system_time() - startTime;

#ifdef DEBUG_LINEAR_SPECIFICATIONS
        sAverageSolvingTime += fSolvingTime;
        sSolvedCount++;
        TRACE("Solving time %i average %i [micro s]\n", (int)fSolvingTime,
                int(sAverageSolvingTime / sSolvedCount));
#endif

        return fResult;
}


/**
 * Writes the specification into a text file.
 * The file will be overwritten if it exists.
 *
 * @param fname the file name
 */
bool
LinearSpec::Save(const char* fileName)
{
        return fSolver->SaveModel(fileName) == B_OK;
}


/**
 * Gets the constraints generated by calls to Variable::SetRange()
 *
 */
void
LinearSpec::GetRangeConstraints(const Variable* var, const Constraint** _min,
        const Constraint** _max) const
{
        fSolver->GetRangeConstraints(var, _min, _max);
}


/**
 * Gets the constraints.
 *
 * @return the constraints
 */
const ConstraintList&
LinearSpec::Constraints() const
{
        return fConstraints;
}


const VariableList&
LinearSpec::UsedVariables() const
{
        return fUsedVariables;
}


const VariableList&
LinearSpec::AllVariables() const
{
        return fVariables;
}


/**
 * Gets the result type.
 *
 * @return the result type
 */
ResultType
LinearSpec::Result() const
{
        return fResult;
}


/**
 * Gets the solving time.
 *
 * @return the solving time
 */
bigtime_t
LinearSpec::SolvingTime() const
{
        return fSolvingTime;
}


BString
LinearSpec::ToString() const
{
        BString string;
        string << "LinearSpec " << (addr_t)this << ":\n";
        for (int i = 0; i < fVariables.CountItems(); i++) {
                Variable* variable = fVariables.ItemAt(i);
                string += variable->ToString();
                string << "=" << (float)variable->Value() << " ";
        }
        string << "\n";
        for (int i = 0; i < fConstraints.CountItems(); i++) {
                Constraint* c = fConstraints.ItemAt(i);
                string << i << ": ";
                string += c->ToString();
                string << "\n";
        }
        string << "Result=";
        if (fResult == kError)
                string << "kError";
        else if (fResult == kOptimal)
                string << "kOptimal";
        else if (fResult == kSuboptimal)
                string << "kSuboptimal";
        else if (fResult == kInfeasible)
                string << "kInfeasible";
        else if (fResult == kUnbounded)
                string << "kUnbounded";
        else if (fResult == kDegenerate)
                string << "kDegenerate";
        else if (fResult == kNumFailure)
                string << "kNumFailure";
        else
                string << fResult;
        string << " SolvingTime=" << fSolvingTime << "micro s";
        return string;
}