import sqlite3
import json
import os
from typing import Union, List, Dict
from pathlib import Path
from itertools import chain
from simple_ddl_parser import parse_from_file
 
class DBParser:
    def __init__(self, db_path:Union[str, Path]) -> None:
        self.db_path = db_path
        self.suffix:str =".sql"
        self.primary_key_token:str = "primary key:"
        self.foreign_key_token:str = "foreign_key:"
        self.separator:str = " [SEP] "

    @staticmethod
    def dump_sqlite_to_sql(path_to_sqlite: Union[str, Path], output_path: Union[str, Path]) -> None:
        assert path_to_sqlite.endswith('.sqlite')
        con = sqlite3.connect(path_to_sqlite)
        with open(output_path, 'w') as f:
            for line in con.iterdump():
                f.write('%s\n' % line)

    def parse_table(self, table_schema:dict) -> str:
        normal_keys = " ".join(list(chain.from_iterable((column["name"], column["type"], ",") for column in table_schema["columns"] if column["references"] is None)))
        foreign_keys =" ".join(list(chain.from_iterable((column["name"], column["type"],"from", column["references"]["table"], column["references"]["column"], ",") for column in table_schema["columns"] if column["references"] is not None)))
        primary_keys = " ".join(table_schema["primary_key"])
        return " ".join([table_schema["table_name"], normal_keys, self.foreign_key_token, foreign_keys, self.primary_key_token, primary_keys])

    def parse_schema(self, schema:List[dict]) -> str:
        table_schemas: List[str] = [self.parse_table(table) for table in schema if 'columns' in table]
        return self.separator.join(table_schemas)
    
    def create_db_prompt_dict(self, output_file: str = 'db_schemas.json') -> Dict[str, str]:
        db_schema_dict = {}
        for dir in os.listdir(self.db_path):
            print("Processing database: ", dir)
            filenames = [i for i in os.listdir(Path(self.db_path, dir)) if i.endswith(self.suffix)]
            path_to_db = Path(self.db_path, dir,filenames[0])
            schema = parse_from_file(path_to_db)
            db_schema_dict[dir]=self.parse_schema(schema)
        with open(output_file, 'w') as f:
            f.write(json.dumps(db_schema_dict))
        return db_schema_dict
    
# # Usage
# db_parser = DBParser(<PATH_To_DATABASES>)
# db_parser.create_db_prompt_dict()