import re
from datetime import datetime
from pathlib import Path
from typing import List

import pdfplumber

from backend.parsers.base import BaseBankParser, ParsedTransaction


def _normalize_amount(s: str) -> float:
    return float(s.replace("\u00a0", " ").replace(" ", "").replace(",", "."))


def _parse_date(d: str) -> str:
    """DD.MM.YYYY -> YYYY-MM-DD"""
    try:
        dt = datetime.strptime(d.strip(), "%d.%m.%Y")
        return dt.strftime("%Y-%m-%d")
    except ValueError:
        return d.strip()


def _parse_datetime(d: str, time_str: str) -> str:
    """Date DD.MM.YYYY + time HH:MM -> ISO"""
    try:
        part = d.strip() + " " + (time_str or "00:00").strip()
        dt = datetime.strptime(part, "%d.%m.%Y %H:%M")
        return dt.strftime("%Y-%m-%dT%H:%M:%S")
    except ValueError:
        return _parse_date(d) + "T00:00:00"


class BankTParser(BaseBankParser):
    """Парсер выписок Т-банка. Файлы Т-MM-YY.pdf."""

    # Первая строка операции: дата дата сумма ₽ сумма ₽ описание 4цифры (сумма может быть + или -)
    ROW_RE = re.compile(
        r"^(\d{2}\.\d{2}\.\d{4})\s+(\d{2}\.\d{2}\.\d{4})\s+([-+]?[\d\s,]+\.\d{2})\s*₽\s+([-+]?[\d\s,]+\.\d{2})\s*₽\s+(.+?)\s+(\d{4})\s*$",
        re.UNICODE,
    )
    # Вторая строка (время): HH:MM HH:MM остаток текста
    TIME_RE = re.compile(r"^(\d{1,2}:\d{2})\s+(\d{1,2}:\d{2})\s*(.*)$")

    def can_parse(self, filename: str) -> bool:
        name = Path(filename).name
        return name.startswith("Т-") and name.lower().endswith(".pdf")

    def parse(self, file_path: str) -> List[ParsedTransaction]:
        result: List[ParsedTransaction] = []
        with pdfplumber.open(file_path) as pdf:
            lines: List[str] = []
            for page in pdf.pages:
                text = page.extract_text()
                if text:
                    lines.extend(text.split("\n"))

        i = 0
        while i < len(lines):
            line = lines[i]
            m = self.ROW_RE.match(line.strip())
            if m:
                date_op, date_debit, amt_op, amt_card, desc, card_tail = m.groups()
                op_time, debit_time = "00:00", "00:00"
                if i + 1 < len(lines):
                    tm = self.TIME_RE.match(lines[i + 1].strip())
                    if tm:
                        op_time, debit_time, rest = tm.groups()
                        if rest:
                            desc = (desc + " " + rest).strip()
                        i += 1

                amount = _normalize_amount(amt_op)
                amount_card = _normalize_amount(amt_card) if amt_card else None
                result.append(
                    ParsedTransaction(
                        operation_date=_parse_datetime(date_op, op_time),
                        debit_date=_parse_datetime(date_debit, debit_time),
                        amount=amount,
                        amount_card_currency=amount_card,
                        description=(desc or "").strip(),
                        card_tail=card_tail,
                    )
                )
            i += 1
        return result