#importing parent
from Model import Model

#importing objects
from PhysicalEntity import PhysicalEntity

class PhysicalModel ( Model ) :
    def CreateEntity(self, name):
        return PhysicalEntity(name)
   
    def HasRelation(self, e1, e2):
        for i in self.relations:
            # e2 references e1
            if i.entities[0].name == e1.name and i.entities[1].name == e2.name:
                return 1
            # e1 references e2
            if i.entities[0].name == e2.name and i.entities[1].name == e1.name:
                return -1
        return None
    
    def GetKey(self, e1, e2):
        # Returns a key sequence, that represents references between to entities. (if any)
        
        key = []
        key2 = []
        counter = 0
        counter2 = 0
        len = 0
        len2 = 0
        no_n_m = 0
        if e1 == e2:
            no_n_m = 1
        for j in e2.propertylinks:
            if j.primarykey == 1:
                counter2 += 1
        for i in e1.propertylinks:
            if i.primarykey == 1:
                counter += 1
                for j in e2.propertylinks:
                    if i.property.name == j.property.name and i.primarykey == 1 and j.primarykey != 1:
                        key.append(i.property)
                        len += 1
                    if no_n_m == 1:
                        continue
                    if i.property.name == j.property.name and i.primarykey == 1 and j.primarykey == 1:
                        key2.append(i.property)
                        len2 += 1
        if key == [] or len != counter:
            if key2 != [] and len2 < counter2:
                return key2
            else:
                key = None
        return key