# -*- coding: utf-8 -*-

from typing import Optional, List, Any

from .ColumnSet import ColumnSet
from .SingleForeignKey import SingleForeignKey

class CompositeForeignKey: # export

    def __init__(self, child_col_set: ColumnSet, parent_col_set: ColumnSet): # TODO: Implement alternative ways to construct

        def __table(s):
            ret = None
            for c in s:
                if ret is None:
                    ret = c.table
                else:
                    assert(ret == c.table)
            assert(ret is not None)
            return ret

        self.__child_col_set = child_col_set
        self.__parent_col_set = parent_col_set
        self.__child_table = __table(child_col_set)
        self.__parent_table = __table(parent_col_set)

        assert(len(self.__child_col_set) == len(self.__parent_col_set))
        self.__len = len(self.__child_col_set)
        self.__column_relations: Optional[List[SingleForeignKey]] = None

    def __table_rel_str(self):
        return f'{self.__child_table.name} => {self.__parent_table.name}'

    def __cols_rel_str(self, child, parent):
        return f'{child.name} -> {parent.name}'

    def __len__(self):
        return self.__len

    def __iter__(self):
        yield from self.column_relations

    def __repr__(self):
        ret = self.__table_rel_str()
        ret += '|| ' + ' | '.join([self.__cols_rel_str(rel.child_col, rel.parent_col) for rel in self.column_relations])
        return ret

    def __eq__(self, rhs):
        if rhs.__child_col_set != self.__child_col_set:
            return False
        if rhs.__parent_col_set != self.__parent_col_set:
            return False
        return True

    @property
    def child_table(self) -> Any:
        return self.__child_table

    @property
    def parent_table(self) -> Any:
        return self.__parent_table

    @property
    def child_columns(self) -> ColumnSet:
        return self.__child_col_set

    @property
    def parent_columns(self) -> ColumnSet:
        return self.__parent_col_set

    @property
    def column_relations(self) -> List[Any]:
        ret = []
        if self.__column_relations is None:
            for i in range(0, self.__len):
                ret.append(SingleForeignKey(self.__child_col_set[i], self.__parent_col_set[i]))
            self.__column_relations = ret
        return self.__column_relations