from pathlib import Path
from typing import List, Optional

from pydantic import BaseModel

UNKNOWN_CATEGORY = "account2"


class CsvConfig(BaseModel):
    """
    Class to define how to parse a certain CSV file. We use the
    file_match_regex attribute to decide whether to apply a config for a file.
    If multiple configs match a single file we raise an exception.
    """

    class Config:
        extra = "forbid"

    account1: str
    file_match_regex: str
    fields: List[str]
    input_date_format: str = "%m/%d/%Y"
    output_date_format: str = "%Y/%m/%d"
    skip: int = 1
    delimiter: str = ","
    quotechar: str = '"'
    currency: str = "USD"


class Config(BaseModel):
    """
    Configuration class for managing file search and data processing settings.

    Attributes:
        input_directory (Path):  Where to search for 'ldg' and 'csv' files.
        mappings_file (Path):    The path to a 'json' file that contains account2 mappings.
        output_file (Path):      Location to which to write the output 'ldg' file.
        csv_configs:             List of CsvConfig which explains how to handle specific
                                 CSV files.
        categories (List[str]):  A list of account2s. An account has to be defined here
                                 before it can be used in a mapping. Otherwise, ledger will complain.
        commodities (List[str]): A list of commodities relevant to the data processing.
    """

    class Config:
        extra = "forbid"

    input_directory: Path
    mappings_file: Path
    output_file: Path = Path("output.ldg")
    csv_configs: List[CsvConfig]
    categories: List[str]
    model: Path = Path("transaction_classifier.pkl")


class Mapping(BaseModel):
    """Class for transaction mapping from mappings file."""

    class Config:
        extra = "forbid"

    account2: str
    count: int = 1
    narration: Optional[str] = None
    payee: Optional[str] = None
    tags: Optional[List[str]] = None


class Transaction(BaseModel):
    """Class for ledger transaction to render into ldg file."""

    class Config:
        extra = "forbid"

    currency: str
    debit: str
    credit: str
    date: str
    account1: str
    account2: str
    description: str
    csv_file: str
    row: str
    index: int
    mapping: Optional[Mapping] = None

    def key(self):
        return self.csv_file + ", " + self.row