ness.__init__

from django.core.exceptions import ObjectDoesNotExist

def add(item,parent_name='parent'):
    item = type(item).objects.get(pk=item.id)
    parent = getattr(item,parent_name)
    if parent:
        parent = type(parent).objects.get(pk=parent.id)
    if parent is None:
        item.ness_level = 1
        try:
            item.ness_left = type(item).objects.all().order_by(
                '-ness_right')[0].ness_right + 1
        except ObjectDoesNotExist:
            item.ness_left = 1
    else:
        item.ness_left = parent.ness_right
        item.ness_level = parent.ness_level + 1
        from django.db import connection
        cursor = connection.cursor()
        cursor.execute("""
            UPDATE """ + item._meta.db_table + """
            SET ness_right = ness_right + 2,
                ness_left = IF(ness_left > %s,
                    ness_left + 2, ness_left)
            WHERE ness_right >= %s""",
            (parent.ness_right,parent.ness_right))

    item.ness_right = item.ness_left + 1
    item.save()
    return item

def delete(item):
    item = type(item).objects.get(pk=item.id)
    from django.db import connection
    cursor = connection.cursor()

    ness_left = item.ness_left
    ness_right = item.ness_right
    item.delete()
    # following steps is not neccessary becouse
    # childre will be removed by the Django ORM
    # becouse of ForeignKey relation

    #cursor.execute("""
        #SELECT id
        #FROM """ + item._meta.db_table + """
        #WHERE ness_left >= %s AND ness_right <= %s""",
        #(item.ness_left,item.ness_right))
    #ids = []
    #for row in cursor.fetchall():
        #ids.append(row[0])
    #for id in ids:
        #type(item).objects.get(pk=id).delete()

    cursor.execute("""
        UPDATE """ + item._meta.db_table + """
        SET ness_left = IF(ness_left > %s,
            ness_left - (%s - %s + 1),ness_left),
            ness_right = ness_right - (%s - %s + 1)
        WHERE ness_right > %s""",
        (ness_left,
        ness_right,ness_left,
        ness_right,ness_left,
        ness_right))

def test1(Model):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT id
        FROM """ + Model._meta.db_table + """
        WHERE ness_left >= ness_right""")
    return 0 == len(cursor.fetchall())

def test2(Model):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT COUNT(id),MIN(ness_left),MAX(ness_right)
        FROM """ + Model._meta.db_table)
    vars = cursor.fetchone()
    if vars[2] != vars[0] * 2:
        return False
    if vars[1] != 1:
        return False
    return True

def test3(Model):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT id
        FROM """ + Model._meta.db_table + """
        WHERE MOD((ness_right - ness_left),2) = 0""")
    return 0 == len(cursor.fetchall())

def test4(Model):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT id
        FROM """ + Model._meta.db_table + """
        WHERE MOD((ness_left - ness_level + 2),2) = 1""")
    return 0 == len(cursor.fetchall())

#def test5(Model):
    #from django.db import connection
    #cursor = connection.cursor()
    #cursor.execute("""
        #SELECT t1.id, COUNT(t1.id) AS rep, MAX(t3.right_key) AS max_right FROM my_tree AS t1, my_tree AS t2, my_tree AS t3 WHERE t1.left_key <> t2.left_key AND t1.left_key <> t2.right_key AND t1.right_key <> t2.left_key AND t1.right_key <> t2.right_key GROUP BY t1.id HAVING max_right <> SQRT(4 * rep + 1) + 1
        #""")
    #return 0 == len(cursor.fetchall())

def childs(item,include=False):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT id
        FROM """ + item._meta.db_table + """
        WHERE ness_left > %s AND ness_right < %s
        ORDER BY ness_left""",
        (item.ness_left,item.ness_right))
    ids = [x[0] for x in cursor.fetchall()]
    childs = type(item).objects.in_bulk(ids).values()
    if include:
        childs.append(item)
    return childs

def parents(item,include=False):
    from django.db import connection
    cursor = connection.cursor()
    cursor.execute("""
        SELECT id
        FROM """ + item._meta.db_table + """
        WHERE ness_left < %s AND ness_right > %s
        ORDER BY ness_left""",
        (item.ness_left,item.ness_right))
    ids = [x[0] for x in cursor.fetchall()]
    parents = type(item).objects.in_bulk(ids).values()
    if include:
        parents.append(item)
    return parents

#TODO: write unit tests for branch()
#def branch(item):
    #from django.db import connection
    #cursor = connection.cursor()
    #cursor.execute("""
        #SELECT id
        #FROM """ + item._meta.db_table + """
        #WHERE ness_right > %s AND ness_left < %s
        #ORDER BY ness_left""",
        #(item.ness_left,item.ness_right))
    #ids = [x[0] for x in cursor.fetchall()]
    #return type(item).objects.in_bulk(ids).values()

#TODO: write unit test for parent()
#def parents(item):
    #from django.db import connection
    #cursor = connection.cursor()
    #cursor.execute("""
        #SELECT id
        #FROM """ + item._meta.db_table + """
        #WHERE ness_left <= %s AND ness_right >= %s
        #   AND ness_level = %s -1""",
        #(item.ness_left,item.ness_right,item.level))
    #id = cursor.fetchone()[0]
    #return type(item).objects.get(pk=id)