from pathlib import Path
from typing import Literal

import matplotlib.pyplot as plt
from sympy import sympify

from logic import (
    DataGenerationOptions,
    Dataset,
    PlotData,
    compute_plot_values,
    generate_dataset,
    load_dataset_from_csv,
)


class Manager:
    def __init__(self) -> None:
        self.dataset = Dataset(x=[], y=[])
        self.plots_data: PlotData | None = None

    def update_dataset(
        self,
        dataset_type: Literal["Generate", "CSV"],
        function: str,
        data_xmin: float,
        data_xmax: float,
        sigma: float,
        nsample: int,
        sample_method: Literal["Grid", "Random"],
        csv_path: str | Path | None,
        has_header: bool,
        xcol: int,
        ycol: int,
    ) -> None:
        if dataset_type == "Generate":
            try:
                parsed_function = sympify(function)
            except Exception as exc:
                raise ValueError(f"Invalid function: {exc}") from exc

            sampling = sample_method.lower()
            if sampling not in ["grid", "random"]:
                raise ValueError(f"Unknown sampling method: {sample_method}")

            self.dataset = generate_dataset(
                parsed_function,
                (data_xmin, data_xmax),
                DataGenerationOptions(
                    method=sampling,
                    num_samples=nsample,
                    noise=sigma,
                ),
            )
            return

        normalized_path = self._normalize_csv_path(csv_path)
        if normalized_path is None:
            raise ValueError("Please upload a CSV file.")

        self.dataset = load_dataset_from_csv(
            normalized_path,
            has_header,
            xcol,
            ycol,
        )

    def compute_plot_data(
        self,
        kernel: str,
        distribution: Literal["Prior", "Posterior"],
        plot_xmin: float,
        plot_xmax: float,
    ) -> None:
        self.plots_data = compute_plot_values(
            self.dataset,
            kernel,
            distribution,
            plot_xmin,
            plot_xmax,
        )

    def handle_generate_plots(
        self,
        dataset_type: Literal["Generate", "CSV"],
        function: str,
        data_xmin: float,
        data_xmax: float,
        sigma: float,
        nsample: int,
        sample_method: Literal["Grid", "Random"],
        csv_path: str | Path | None,
        has_header: bool,
        xcol: int,
        ycol: int,
        kernel: str,
        distribution: Literal["Prior", "Posterior"],
        plot_xmin: float,
        plot_xmax: float,
    ):
        self.update_dataset(
            dataset_type,
            function,
            data_xmin,
            data_xmax,
            sigma,
            nsample,
            sample_method,
            csv_path,
            has_header,
            xcol,
            ycol,
        )

        true_dataset = self._build_true_dataset(
            dataset_type,
            function,
            plot_xmin,
            plot_xmax,
        )

        self.compute_plot_data(
            kernel,
            distribution,
            plot_xmin,
            plot_xmax,
        )

        return self.generate_plot(true_dataset)

    def generate_plot(self, true_dataset: Dataset):
        if self.plots_data is None:
            raise ValueError("Plot data has not been computed.")

        fig, ax = plt.subplots(figsize=(12, 9))
        cmap = plt.get_cmap("tab20")

        ax.scatter(self.dataset.x, self.dataset.y, color=cmap(0), label="Data Points")

        if true_dataset.y is not None and len(true_dataset.y) > 0:
            ax.plot(true_dataset.x, true_dataset.y, color=cmap(1), label="True Function")

        ax.plot(self.plots_data.x, self.plots_data.pred_mean, color=cmap(2), label="Mean Prediction")

        ax.fill_between(
            self.plots_data.x,
            self.plots_data.pred_mean - 1.96 * self.plots_data.pred_std,
            self.plots_data.pred_mean + 1.96 * self.plots_data.pred_std,
            color=cmap(3),
            alpha=0.2,
            label="95% Confidence Interval",
        )

        ax.legend()
        return fig

    def _build_true_dataset(
        self,
        dataset_type: Literal["Generate", "CSV"],
        function: str,
        xmin: float,
        xmax: float,
    ) -> Dataset:
        if dataset_type == "CSV":
            return Dataset(x=[], y=[])

        try:
            parsed_function = sympify(function)
        except Exception as exc:
            raise ValueError(f"Invalid function: {exc}") from exc

        return generate_dataset(
            parsed_function,
            (xmin, xmax),
            DataGenerationOptions(
                method="grid",
                num_samples=1000,
                noise=0.0,
            ),
        )

    def _normalize_csv_path(self, csv_path: str | Path | None) -> str | None:
        if csv_path is None:
            return None

        if isinstance(csv_path, Path):
            return str(csv_path)

        if isinstance(csv_path, str):
            return csv_path

        name = getattr(csv_path, "name", None)
        if name:
            return str(name)

        return None