"""Parser for the OHIP Physician Fee Schedule Master (fixed-width, 75 chars).

Official record layout (OHIP Fee Schedule Master Record Layout, 1-based):
    Fee Schedule code       start 1  len 4   (ANNN)
    Effective Date          start 5  len 8   (YYYYMMDD)
    Termination Date        start 13 len 8   (99999999 = indefinite)
    Provider Fee            start 21 len 11  (N, 4 decimal places)
    Assistant's fee         start 32 len 11  (N)
    Specialist fee          start 43 len 11  (N, 4 decimal places)
    Anaesthetist's fee      start 54 len 11  (N)
    Non-Anaesthetist's fee  start 65 len 11  (N)
"""
from __future__ import annotations

import datetime as dt
import logging
from dataclasses import dataclass, field
from pathlib import Path

from .config import settings

logger = logging.getLogger(__name__)

_INDEFINITE = "99999999"


@dataclass
class FeeRecord:
    billing_code: str
    effective_date: str  # YYYY-MM-DD
    termination_date: str | None  # YYYY-MM-DD or None (indefinite)
    provider_fee: float
    assistant_fee: float
    specialist_fee: float
    anaesthetist_fee: float
    non_anaesthetist_fee: float
    all_fees: dict = field(default_factory=dict)

    @property
    def primary_fee(self) -> float:
        """Best single fee for display: provider, else specialist, else max."""
        for f in (self.provider_fee, self.specialist_fee):
            if f > 0:
                return f
        return max(self.all_fees.values(), default=0.0)


def _fee(segment: str) -> float:
    seg = segment.strip() or "0"
    try:
        return int(seg) / 10000.0  # 4 implied decimal places
    except ValueError:
        return 0.0


def _date(segment: str) -> str | None:
    seg = segment.strip()
    if not seg or seg == _INDEFINITE:
        return None
    try:
        return dt.datetime.strptime(seg, "%Y%m%d").strftime("%Y-%m-%d")
    except ValueError:
        return None


def parse_line(line: str) -> FeeRecord | None:
    if len(line) < 75:
        line = line.ljust(75)
    code = line[0:4].strip()
    if not code:
        return None
    eff = _date(line[4:12]) or "1990-01-01"
    term = _date(line[12:20])
    provider = _fee(line[20:31])
    assistant = _fee(line[31:42])
    specialist = _fee(line[42:53])
    anaesthetist = _fee(line[53:64])
    non_anaesthetist = _fee(line[64:75])
    return FeeRecord(
        billing_code=code,
        effective_date=eff,
        termination_date=term,
        provider_fee=provider,
        assistant_fee=assistant,
        specialist_fee=specialist,
        anaesthetist_fee=anaesthetist,
        non_anaesthetist_fee=non_anaesthetist,
        all_fees={
            "provider": provider,
            "assistant": assistant,
            "specialist": specialist,
            "anaesthetist": anaesthetist,
            "non_anaesthetist": non_anaesthetist,
        },
    )


def _is_active(rec: FeeRecord, today: dt.date) -> bool:
    if rec.termination_date is None:
        return True
    return dt.date.fromisoformat(rec.termination_date) >= today


def parse_fsm(path: Path) -> list[FeeRecord]:
    today = dt.date.today()
    records: list[FeeRecord] = []
    text = Path(path).read_text(encoding="latin-1")
    for raw in text.splitlines():
        if not raw.strip():
            continue
        rec = parse_line(raw)
        if rec is None:
            continue
        if settings.active_codes_only and not _is_active(rec, today):
            continue
        records.append(rec)
    logger.info("Parsed %d active fee records from FSM", len(records))
    return records