"""Application service coordinating I/O, validation and prediction."""

from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path

import pandas as pd

from .io import FrameReader
from .model import PredictionModel
from .validation import FrameValidator


@dataclass(frozen=True)
class DiagnosisResult:
    measurements: pd.DataFrame
    submission: pd.DataFrame
    diagnostics: pd.DataFrame
    warnings: tuple[str, ...] = ()

    @property
    def engine_ids(self) -> list[str]:
        return self.measurements["engine_id"].drop_duplicates().astype(str).tolist()

    def engine_measurements(self, engine_id: str) -> pd.DataFrame:
        frame = self.measurements[self.measurements["engine_id"].eq(engine_id)]
        if frame.empty:
            raise KeyError(f"Unknown engine_id={engine_id!r}")
        return frame.reset_index(drop=True)

    def engine_diagnostics(self, engine_id: str) -> pd.DataFrame:
        frame = self.diagnostics[self.diagnostics["engine_id"].eq(engine_id)]
        if frame.empty:
            raise KeyError(f"Unknown engine_id={engine_id!r}")
        return frame.reset_index(drop=True)


class DiagnosticService:
    """Constructor-injected use case; no Streamlit or global state dependencies."""

    def __init__(
        self,
        *,
        reader: FrameReader,
        validator: FrameValidator,
        model: PredictionModel,
    ) -> None:
        self._reader = reader
        self._validator = validator
        self._model = model

    def diagnose_bytes(self, payload: bytes) -> DiagnosisResult:
        return self.diagnose_frame(self._reader.read_bytes(payload))

    def diagnose_path(self, path: Path) -> DiagnosisResult:
        return self.diagnose_frame(self._reader.read_path(path))

    def diagnose_frame(self, frame: pd.DataFrame) -> DiagnosisResult:
        validated = self._validator.validate(frame)
        predicted = self._model.predict(validated.frame)
        return DiagnosisResult(
            measurements=validated.frame,
            submission=predicted.submission,
            diagnostics=predicted.diagnostics,
            warnings=validated.warnings,
        )