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

import sqlalchemy as sql
import re  # Converting string to sqlalchemy types
from Database import sqlutils


def init_db(dbconfname='default', alchemy_logs=None, schema=None):

    dbe = sqlutils.get_engine(dbconfname, alchemy_logs)
    meta = sqlutils.meta(dbe)
    meta.reflect()
    meta.drop_all(dbe)
    # refresh meta (maybe useless)
    meta = sqlutils.meta(dbe)
    meta.reflect()

    if schema is None:
        schema = get_schema()

    for table in schema:
        topt = table.copy()
        del topt['columns']
        name = topt['name']
        del topt['name']
        cur_table = sql.Table(name, meta, **topt)
        for col in table['columns']:
            cur_col = create_column(**col)
            cur_table.append_column(cur_col)

    meta.create_all(bind=dbe)


def get_schema():
    tables = []

    default_columns = [
        {"name": "uid", "type": "INTEGER", "extra": {"foreignkey": "uids.uid", "nullable": False, "primarykey": True}},
        {"name": "name", "type": "VARCHAR(50)", "extra": {"nullable": False, "unique": True}},
        {"name": "string", "type": "TEXT"},
        {"name": "help", "type": "TEXT"},
        {"name": "rank", "type": "INTEGER"},
        {"name": "date_create", "type": "DATETIME"},
        {"name": "date_update", "type": "DATETIME"},
    ]

    # Table listing all objects created by lodel, giving them an unique id
    uids = {
        "name": "uids",
        "columns": [
            {"name": "uid", "type": "INTEGER", "extra": {"nullable": False, "primarykey": True, 'autoincrement': True}},
            {"name": "table", "type": "VARCHAR(50)"}
        ]
    }
    tables.append(uids)

    # Table listing the classes
    em_class = {"name": "em_class"}
    em_class['columns'] = default_columns + [
        {"name": "classtype", "type": "VARCHAR(50)"},
        {"name": "sortcolumn", "type": "VARCHAR(50)", "extra": {"default": "rank"}},
        {"name": "icon", "type": "INTEGER"},
    ]
    tables.append(em_class)

    # Table listing the types
    em_type = {"name": "em_type"}
    em_type['columns'] = default_columns + [
        {"name": "class_id", "type": "INTEGER", "extra": {"foreignkey": "em_class.uid", "nullable": False}},
        {"name": "sortcolumn", "type": "VARCHAR(50)", "extra": {"default": "rank"}},
        {"name": "icon", "type": "INTEGER"},
    ]
    tables.append(em_type)

    # relation between types: which type can be a child of another
    em_type_hierarchy = {"name": "em_type_hierarchy"}
    em_type_hierarchy['columns'] = [
        {"name": "superior_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid", "nullable": False, "primarykey": True}},
        {"name": "subordinate_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid", "nullable": False, "primarykey": True}},
        {"name": "nature", "type": "VARCHAR(50)", "extra": {"primarykey": True}},
    ]
    tables.append(em_type_hierarchy)

   # Table listing the fieldgroups of a class
    em_fieldgroup = {"name": "em_fieldgroup"}
    em_fieldgroup['columns'] = default_columns + [
        {"name": "class_id", "type": "INTEGER", "extra": {"foreignkey": "em_class.uid", "nullable": False}},
    ]
    tables.append(em_fieldgroup)

    # Table listing the fields of a fieldgroup
    em_field = {"name": "em_field"}
    em_field['columns'] = default_columns + [
        {"name": "fieldtype", "type": "VARCHAR(50)", "extra": {"nullable": False}},
        {"name": "fieldgroup_id", "type": "INTEGER", "extra": {"foreignkey": "em_fieldgroup.uid", "nullable": False}},
        {"name": "rel_to_type_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid", "nullable": True, "server_default": sql.text('NULL')}},  # if relational: type this field refer to
        {"name": "rel_field_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid", "nullable": True, "server_default": sql.text('NULL')}},  # if relational: field that specify the rel_to_type_id
        {"name": "optional", "type": "BOOLEAN"},
        {"name": "internal", "type": "BOOLEAN"},
        {"name": "icon", "type": "INTEGER"},
    ]
    tables.append(em_field)

    # selected field for each type
    em_field_type = {"name": "em_field_type"}
    em_field_type['columns'] = [
        {"name": "type_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid", "nullable": False, "primarykey": True}},
        {"name": "field_id", "type": "INTEGER", "extra": {"foreignkey": "em_field.uid", "nullable": False, "primarykey": True}},
    ]
    tables.append(em_field_type)

    # Table of the objects created by the user (instance of the types)
    objects = {
        "name": "objects",
        "columns": [
            {"name": "uid", "type": "INTEGER", "extra": {"foreignkey": "uids.uid", "nullable": False, "primarykey": True}},
            {"name": "string", "type": "VARCHAR(50)"},
            {"name": "class_id", "type": "INTEGER", "extra": {"foreignkey": "em_class.uid"}},
            {"name": "type_id", "type": "INTEGER", "extra": {"foreignkey": "em_type.uid"}},
            {"name": "date_create", "type": "DATETIME"},
            {"name": "date_update", "type": "DATETIME"},
            {"name": "history", "type": "TEXT"}
        ]
    }
    tables.append(objects)

    # Table listing all files
    files = {
        "name": "files",
        "columns": [
            {"name": "uid", "type": "INTEGER", "extra": {"foreignkey": "uids.uid", "nullable": False, "primarykey": True}},
            {"name": "field1", "type": "VARCHAR(50)"}
        ]
    }
    tables.append(files)

    return tables


def create_column(**kwargs):
    #Converting parameters
    if 'type_' not in kwargs and 'type' in kwargs:
        kwargs['type_'] = string_to_sqla_type(kwargs['type'])
        del kwargs['type']

    if 'extra' in kwargs:
        # put the extra keys in kwargs
        for exname in kwargs['extra']:
            kwargs[exname] = kwargs['extra'][exname]
        del kwargs['extra']

    if 'foreignkey' in kwargs:
        # Instanciate a fk
        foreignkey = sql.ForeignKey(kwargs['foreignkey'])
        del kwargs['foreignkey']
    else:
        foreignkey = None

    if 'primarykey' in kwargs:
        # renaming primary_key in primarykey in kwargs
        kwargs['primary_key'] = kwargs['primarykey']
        del kwargs['primarykey']

    col = sql.Column(**kwargs)

    if foreignkey is not None:
        col.append_foreign_key(foreignkey)

    return col


def string_to_sqla_type(strtype):
    """ Convert a string to an sqlAlchemy column type """
    if 'VARCHAR' in strtype:
        return string_to_varchar(strtype)
    else:
        try:
            return getattr(sql, strtype)
        except AttributeError:
            raise NameError("Unknown type '" + strtype + "'")


def string_to_varchar(vstr):
    """ Convert a string like 'VARCHAR(XX)' (with XX an integer) to a SqlAlchemy varchar type"""
    check_length = re.search(re.compile('VARCHAR\(([\d]+)\)', re.IGNORECASE), vstr)
    column_length = int(check_length.groups()[0]) if check_length else None
    return sql.VARCHAR(length=column_length)