#! /usr/bin/env python
'''Library for motion prediction methods'''

import moving
import math
import random

class PredictedTrajectory:
    '''Class for predicted trajectories with lazy evaluation
    if the predicted position has not been already computed, compute it

    it should also have a probability'''

    def __init__(self):
        self.probability = 0.
        self.predictedPositions = {}
        self.predictedSpeedOrientations = {}
        #self.collisionPoints = {}
        #self.crossingZones = {}

    def predictPosition(self, nTimeSteps):
        if nTimeSteps > 0 and not nTimeSteps in self.predictedPositions.keys():
            self.predictPosition(nTimeSteps-1)
            self.predictedPositions[nTimeSteps], self.predictedSpeedOrientations[nTimeSteps] = moving.predictPosition(self.predictedPositions[nTimeSteps-1], self.predictedSpeedOrientations[nTimeSteps-1], self.getControl(), self.maxSpeed)
        return self.predictedPositions[nTimeSteps]

    def getPredictedTrajectory(self):
        return moving.Trajectory.fromPointList(self.predictedPositions.values())

    def getPredictedSpeeds(self):
        return [so.norm for so in self.predictedSpeedOrientations.values()]

    def draw(self, options = '', withOrigin = False, timeStep = 1, **kwargs):
        self.getPredictedTrajectory().draw(options, withOrigin, timeStep, **kwargs)

class PredictedTrajectoryConstant(PredictedTrajectory):
    '''Predicted trajectory at constant speed or acceleration
    TODO generalize by passing a series of velocities/accelerations'''

    def __init__(self, initialPosition, initialVelocity, control = moving.NormAngle(0,0), probability = 1., maxSpeed = None):
        self.control = control
        self.maxSpeed = maxSpeed
        self.probability = probability
        self.predictedPositions = {0: initialPosition}
        self.predictedSpeedOrientations = {0: moving.NormAngle.fromPoint(initialVelocity)}

    def getControl(self):
        return self.control

class PredictedTrajectoryNormalAdaptation(PredictedTrajectory):
    '''Random small adaptation of vehicle control '''
    def __init__(self, initialPosition, initialVelocity, accelerationDistribution, steeringDistribution, probability = 1., maxSpeed = None):
        '''Constructor
        accelerationDistribution and steeringDistribution are distributions 
        that return random numbers drawn from them'''
        self.accelerationDistribution = accelerationDistribution
        self.steeringDistribution = steeringDistribution
        self.maxSpeed = maxSpeed
        self.probability = probability
        self.predictedPositions = {0: initialPosition}
        self.predictedSpeedOrientations = {0: moving.NormAngle.fromPoint(initialVelocity)}

    def getControl(self):
        return moving.NormAngle(self.accelerationDistribution(),self.steeringDistribution())

class SafetyPoint(moving.Point):
    '''Can represent a collision point or crossing zone 
    with respective safety indicator, TTC or pPET'''
    def __init__(self, p, probability = 1., indicator = -1):
        self.x = p.x
        self.y = p.y
        self.probability = probability
        self.indicator = indicator

    def __str__(self):
        return '{0} {1} {2} {3}'.format(self.x, self.y, self.probability, self.indicator)

    @staticmethod
    def save(out, points, predictionInstant, objNum1, objNum2):
        for p in points:
            out.write('{0} {1} {2} {3}\n'.format(objNum1, objNum2, predictionInstant, p))

    @staticmethod
    def computeExpectedIndicator(points):
        from numpy import sum
        return sum([p.indicator*p.probability for p in points])/sum([p.probability for p in points])

def computeCollisionTime(predictedTrajectory1, predictedTrajectory2, collisionDistanceThreshold, timeHorizon):
    '''Computes the first instant at which two predicted trajectories are within some distance threshold'''
    t = 1
    p1 = predictedTrajectory1.predictPosition(t)
    p2 = predictedTrajectory2.predictPosition(t)
    while t <= timeHorizon and (p1-p2).norm2() > collisionDistanceThreshold:
        p1 = predictedTrajectory1.predictPosition(t)
        p2 = predictedTrajectory2.predictPosition(t)
        t += 1
    return t, p1, p2

class PredictionParameters:
    def __init__(self, name, maxSpeed):
        self.name = name
        self.maxSpeed = maxSpeed

    def __str__(self):
        return '{0} {1}'.format(self.name, self.maxSpeed)

    def generatePredictedTrajectories(self, obj, instant):
        return []

    def computeCrossingsCollisionsAtInstant(self, currentInstant, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ = False, debug = False):
        '''returns the lists of collision points and crossing zones'''
        predictedTrajectories1 = self.generatePredictedTrajectories(obj1, currentInstant)
        predictedTrajectories2 = self.generatePredictedTrajectories(obj2, currentInstant)

        collisionPoints = []
        crossingZones = []
        for et1 in predictedTrajectories1:
            for et2 in predictedTrajectories2:
                t, p1, p2 = computeCollisionTime(et1, et2, collisionDistanceThreshold, timeHorizon)

                if t <= timeHorizon:
                    collisionPoints.append(SafetyPoint((p1+p2).multiply(0.5), et1.probability*et2.probability, t))
                elif computeCZ: # check if there is a crossing zone
                    # TODO? zone should be around the points at which the traj are the closest
                    # look for CZ at different times, otherwise it would be a collision
                    # an approximation would be to look for close points at different times, ie the complementary of collision points
                    cz = None
                    t1 = 0
                    while not cz and t1 < timeHorizon: # t1 <= timeHorizon-1
                        t2 = 0
                        while not cz and t2 < timeHorizon:
                            #if (et1.predictPosition(t1)-et2.predictPosition(t2)).norm2() < collisionDistanceThreshold:
                            #    cz = (et1.predictPosition(t1)+et2.predictPosition(t2)).multiply(0.5)
                            cz = moving.segmentIntersection(et1.predictPosition(t1), et1.predictPosition(t1+1), et2.predictPosition(t2), et2.predictPosition(t2+1))
                            if cz:
                                crossingZones.append(SafetyPoint(cz, et1.probability*et2.probability, abs(t1-t2)))
                            t2 += 1
                        t1 += 1                        

        if debug:
            from matplotlib.pyplot import figure, axis, title
            figure()
            for et in predictedTrajectories1:
                et.predictPosition(timeHorizon)
                et.draw('rx')

            for et in predictedTrajectories2:
                et.predictPosition(timeHorizon)
                et.draw('bx')
            obj1.draw('r')
            obj2.draw('b')
            title('instant {0}'.format(currentInstant))
            axis('equal')

        return collisionPoints, crossingZones

    def computeCrossingsCollisions(self, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ = False, debug = False, timeInterval = None):
        '''Computes all crossing and collision points at each common instant for two road users. '''
        collisionPoints={}
        crossingZones={}
        if timeInterval:
            commonTimeInterval = timeInterval
        else:
            commonTimeInterval = obj1.commonTimeInterval(obj2)
        for i in list(commonTimeInterval)[:-1]: # do not look at the 1 last position/velocities, often with errors
            collisionPoints[i], crossingZones[i] = self.computeCrossingsCollisionsAtInstant(i, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ, debug)

        return collisionPoints, crossingZones

    def computeCollisionProbability(self, obj1, obj2, collisionDistanceThreshold, timeHorizon, debug = False, timeInterval = None):
        '''Computes only collision probabilities
        Returns for each instant the collision probability and number of samples drawn'''
        collisionProbabilities = {}
        if timeInterval:
            commonTimeInterval = timeInterval
        else:
            commonTimeInterval = obj1.commonTimeInterval(obj2)
        for i in list(commonTimeInterval)[:-1]:
            nCollisions = 0
            print(obj1.num, obj2.num, i)
            predictedTrajectories1 = self.generatePredictedTrajectories(obj1, i)
            predictedTrajectories2 = self.generatePredictedTrajectories(obj2, i)
            for et1 in predictedTrajectories1:
                for et2 in predictedTrajectories2:
                    t, p1, p2 = computeCollisionTime(et1, et2, collisionDistanceThreshold, timeHorizon)
                    if t <= timeHorizon:
                        nCollisions += 1
            # take into account probabilities ??
            nSamples = float(len(predictedTrajectories1)*len(predictedTrajectories2))
            collisionProbabilities[i] = [nSamples, float(nCollisions)/nSamples]

            if debug:
                from matplotlib.pyplot import figure, axis, title
                figure()
                for et in predictedTrajectories1:
                    et.predictPosition(timeHorizon)
                    et.draw('rx')

                for et in predictedTrajectories2:
                    et.predictPosition(timeHorizon)
                    et.draw('bx')
                obj1.draw('r')
                obj2.draw('b')
                title('instant {0}'.format(i))
                axis('equal')

        return collisionProbabilities

class ConstantPredictionParameters(PredictionParameters):
    def __init__(self, maxSpeed):
        PredictionParameters.__init__(self, 'constant velocity', maxSpeed)

    def generatePredictedTrajectories(self, obj, instant):
        return [PredictedTrajectoryConstant(obj.getPositionAtInstant(instant), obj.getVelocityAtInstant(instant), 
                                               maxSpeed = self.maxSpeed)]

class NormalAdaptationPredictionParameters(PredictionParameters):
    def __init__(self, maxSpeed, nPredictedTrajectories, accelerationDistribution, steeringDistribution, useFeatures = False):
        '''An example of acceleration and steering distributions is
        lambda: random.triangular(-self.maxAcceleration, self.maxAcceleration, 0.)
        '''
        if useFeatures:
            name = 'point set normal adaptation'
        else:
            name = 'normal adaptation'
        PredictionParameters.__init__(self, name, maxSpeed)
        self.nPredictedTrajectories = nPredictedTrajectories
        self.useFeatures = useFeatures
        self.accelerationDistribution = accelerationDistribution
        self.steeringDistribution = steeringDistribution
        
    def __str__(self):
        return PredictionParameters.__str__(self)+' {0} {1} {2}'.format(self.nPredictedTrajectories, 
                                                                        self.maxAcceleration, 
                                                                        self.maxSteering)

    def generatePredictedTrajectories(self, obj, instant):
        predictedTrajectories = []
        if self.useFeatures:
            features = [f for f in obj.features if f.existsAtInstant(instant)]
            positions = [f.getPositionAtInstant(instant) for f in features]
            velocities = [f.getVelocityAtInstant(instant) for f in features]
        else:
            positions = [obj.getPositionAtInstant(instant)]
            velocities = [obj.getVelocityAtInstant(instant)]
        for i in xrange(self.nPredictedTrajectories):
            for initialPosition,initialVelocity in zip(positions, velocities):
                predictedTrajectories.append(PredictedTrajectoryNormalAdaptation(initialPosition, 
                                                                                 initialVelocity, 
                                                                                 self.accelerationDistribution, 
                                                                                 self.steeringDistribution, 
                                                                                 maxSpeed = self.maxSpeed))
        return predictedTrajectories

class PointSetPredictionParameters(PredictionParameters):
    # todo generate several trajectories with normal adaptatoins from each position (feature)
    def __init__(self, nPredictedTrajectories, maxSpeed):
        PredictionParameters.__init__(self, 'point set', maxSpeed)
        self.nPredictedTrajectories = nPredictedTrajectories
    
    def generatePredictedTrajectories(self, obj, instant):
        predictedTrajectories = []        
        features = [f for f in obj.features if f.existsAtInstant(instant)]
        positions = [f.getPositionAtInstant(instant) for f in features]
        velocities = [f.getVelocityAtInstant(instant) for f in features]
        for i in xrange(self.nPredictedTrajectories):
            for initialPosition,initialVelocity in zip(positions, velocities):
                predictedTrajectories.append(PredictedTrajectoryConstant(initialPosition, initialVelocity, 
                                                                         maxSpeed = self.maxSpeed))
        return predictedTrajectories

class EvasiveActionPredictionParameters(PredictionParameters):
    def __init__(self, maxSpeed, nPredictedTrajectories, accelerationDistribution, steeringDistribution, useFeatures = False):
        '''Suggested acceleration distribution may not be symmetric, eg
        lambda: random.triangular(self.minAcceleration, self.maxAcceleration, 0.)'''

        if useFeatures:
            name = 'point set evasive action'
        else:
            name = 'evasive action'
        PredictionParameters.__init__(self, name, maxSpeed)
        self.nPredictedTrajectories = nPredictedTrajectories
        self.useFeatures = useFeatures
        self.accelerationDistribution = accelerationDistribution
        self.steeringDistribution = steeringDistribution

    def __str__(self):
        return PredictionParameters.__str__(self)+' {0} {1} {2} {3}'.format(self.nPredictedTrajectories, self.minAcceleration, self.maxAcceleration, self.maxSteering)

    def generatePredictedTrajectories(self, obj, instant):
        predictedTrajectories = []
        if self.useFeatures:
            features = [f for f in obj.features if f.existsAtInstant(instant)]
            positions = [f.getPositionAtInstant(instant) for f in features]
            velocities = [f.getVelocityAtInstant(instant) for f in features]
        else:
            positions = [obj.getPositionAtInstant(instant)]
            velocities = [obj.getVelocityAtInstant(instant)]
        for i in xrange(self.nPredictedTrajectories):
            for initialPosition,initialVelocity in zip(positions, velocities):
                predictedTrajectories.append(PredictedTrajectoryConstant(initialPosition, 
                                                                         initialVelocity, 
                                                                         moving.NormAngle(self.accelerationDistribution(), 
                                                                                          self.steeringDistribution()), 
                                                                         maxSpeed = self.maxSpeed))
        return predictedTrajectories


class CVDirectPredictionParameters(PredictionParameters):
    '''Prediction parameters of prediction at constant velocity
    using direct computation of the intersecting point'''
    
    def __init__(self):
        PredictionParameters.__init__(self, 'constant velocity (direct computation)', None)

    def computeCrossingsCollisionsAtInstant(self, currentInstant, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ = False, debug = False):
        collisionPoints = []
        crossingZones = []

        p1 = obj1.getPositionAtInstant(currentInstant)
        p2 = obj2.getPositionAtInstant(currentInstant)
        if (p1-p2).norm2() <= collisionDistanceThreshold:
            collisionPoints = [SafetyPoint((p1+p1).multiply(0.5), 1., 0.)]
        else:
            v1 = obj1.getVelocityAtInstant(currentInstant)
            v2 = obj2.getVelocityAtInstant(currentInstant)
            intersection = moving.intersection(p1, p2, v1, v2)

            if intersection != None:
                dp1 = intersection-p1
                dp2 = intersection-p2
                if moving.Point.dot(dp1, v1) > 0 and moving.Point.dot(dp2, v2) > 0: # if the road users are moving towards the intersection
                    dist1 = dp1.norm2()
                    dist2 = dp2.norm2()
                    s1 = v1.norm2()
                    s2 = v2.norm2()
                    halfCollisionDistanceThreshold = collisionDistanceThreshold/2.
                    timeInterval1 = moving.TimeInterval(max(0,dist1-halfCollisionDistanceThreshold)/s1, (dist1+halfCollisionDistanceThreshold)/s1)
                    timeInterval2 = moving.TimeInterval(max(0,dist2-halfCollisionDistanceThreshold)/s2, (dist2+halfCollisionDistanceThreshold)/s2)
                    collisionTimeInterval = moving.TimeInterval.intersection(timeInterval1, timeInterval2)
                    if computeCZ and collisionTimeInterval.empty():
                        crossingZones = [SafetyPoint(intersection, 1., timeInterval1.distance(timeInterval2))]
                    else:
                        collisionPoints = [SafetyPoint(intersection, 1., collisionTimeInterval.center())]
    
        if debug and intersection!= None:
            from matplotlib.pyplot import plot, figure, axis, title
            figure()
            plot([p1.x, intersection.x], [p1.y, intersection.y], 'r')
            plot([p2.x, intersection.x], [p2.y, intersection.y], 'b')
            intersection.draw()            
            obj1.draw('r')
            obj2.draw('b')
            title('instant {0}'.format(currentInstant))
            axis('equal')

        return collisionPoints, crossingZones

class CVExactPredictionParameters(PredictionParameters):
    '''Prediction parameters of prediction at constant velocity
    using direct computation of the intersecting point (solving for the equation'''
    
    def __init__(self):
        PredictionParameters.__init__(self, 'constant velocity (direct exact computation)', None)

    def computeCrossingsCollisionsAtInstant(self, currentInstant, obj1, obj2, collisionDistanceThreshold, timeHorizon, computeCZ = False, debug = False):
        'TODO add collision point coordinates, compute pPET'
        #collisionPoints = []
        #crossingZones = []

        p1 = obj1.getPositionAtInstant(currentInstant)
        p2 = obj2.getPositionAtInstant(currentInstant)
        v1 = obj1.getVelocityAtInstant(currentInstant)
        v2 = obj2.getVelocityAtInstant(currentInstant)
        
        ttc = moving.Point.timeToCollision(p1, p2, v1, v2, collisionDistanceThreshold)
        if ttc:
            return [SafetyPoint(moving.Point(), 1., ttc)], []
        else:
            return [],[]

####
# Other Methods
####





if __name__ == "__main__":
    import doctest
    import unittest
    suite = doctest.DocFileSuite('tests/prediction.txt')
    #suite = doctest.DocTestSuite()
    unittest.TextTestRunner().run(suite)
    #doctest.testmod()
    #doctest.testfile("example.txt")