"""
Interactive Shiny app for inspecting processed PET SUV NIfTI images.

Run from project root:

    shiny run --reload app.py

Required packages:

    pip install shiny shinywidgets shinyswatch plotly pandas nibabel scipy scikit-image

Expected project structure:

project_root/
├── app.py
├── data/
│   ├── gen/
│   └── raw/
└── spatial_suv_charact/
    ├── image_io.py
    ├── metadata.py
    ├── plotting.py
    ├── spatial_features.py
    └── suv_stats.py
"""

from __future__ import annotations

from pathlib import Path
import sys
import traceback

import pandas as pd
import plotly.graph_objects as go

from shiny import App, Inputs, Outputs, Session, reactive, render, ui
from shinywidgets import output_widget, render_widget

# -----------------------------------------------------------------------------
# Project paths
# -----------------------------------------------------------------------------

APP_DIR = "."  # str(Path(__file__).resolve().parent)
PROJECT_ROOT = APP_DIR

if str(PROJECT_ROOT) not in sys.path:
    sys.path.insert(0, str(PROJECT_ROOT))

import os

DATA_RAW = os.path.join(PROJECT_ROOT, "data", "raw")
DATA_GEN = os.path.join(PROJECT_ROOT, "data", "gen")
DEFAULT_METADATA_PATH = os.path.join(DATA_GEN, "metadata.pkl")

# -----------------------------------------------------------------------------
# Local package imports
# -----------------------------------------------------------------------------

from spatial_suv_charact.metadata import (  # noqa: E402
    get_meta_data,
    flag_corrupted_files,
    flag_AE_patients,
)
from spatial_suv_charact.image_io import get_processed_image  # noqa: E402
from spatial_suv_charact.plotting import (  # noqa: E402
    plot_suv_pdf_plotly,
    plot_hot_voxels_plotly,
)
from spatial_suv_charact.spatial_features import compute_tail_spatial_features  # noqa: E402


# -----------------------------------------------------------------------------
# Helper functions
# -----------------------------------------------------------------------------


def _empty_figure(message: str = "No plot available") -> go.Figure:
    """Return an empty Plotly figure with a centered annotation."""
    fig = go.Figure()
    fig.add_annotation(
        text=message,
        xref="paper",
        yref="paper",
        x=0.5,
        y=0.5,
        showarrow=False,
    )
    fig.update_layout(
        template="plotly_white",
        xaxis={"visible": False},
        yaxis={"visible": False},
        height=500,
    )
    return fig


def _load_metadata() -> pd.DataFrame:
    """Load metadata table from disk or build it from DATA_RAW."""
    if DEFAULT_METADATA_PATH.exists():
        df_meta = pd.read_pickle(DEFAULT_METADATA_PATH)
    else:
        df_meta = get_meta_data(str(DATA_RAW))
        df_meta = flag_corrupted_files(df_meta)
        df_meta = flag_AE_patients(df_meta)

        DATA_GEN.mkdir(parents=True, exist_ok=True)
        df_meta.to_pickle(DEFAULT_METADATA_PATH)

    if not isinstance(df_meta.index, pd.MultiIndex):
        required_cols = {"patient_id", "organ", "visit"}
        if required_cols.issubset(df_meta.columns):
            df_meta = df_meta.set_index(["patient_id", "organ", "visit"])
        else:
            raise ValueError(
                "Metadata table must have MultiIndex (patient_id, organ, visit) "
                "or columns patient_id, organ, visit."
            )

    required_columns = {"PET_path", "SEG_path"}
    missing = required_columns.difference(df_meta.columns)
    if missing:
        raise ValueError(f"Metadata table is missing required columns: {missing}")

    return df_meta.sort_index()


DF_META = _load_metadata()


def _metadata_for_display(df_meta: pd.DataFrame) -> pd.DataFrame:
    """Return metadata with index columns exposed and an internal row_id."""
    df = df_meta.reset_index().copy()
    df.insert(0, "row_id", range(len(df)))

    preferred = [
        "row_id",
        "patient_id",
        "organ",
        "visit",
        "is_AE_patient",
        "is_corrupted",
        "PET_filename",
        "SEG_filename",
        "PET_path",
        "SEG_path",
    ]
    cols = [c for c in preferred if c in df.columns] + [
        c for c in df.columns if c not in preferred
    ]
    return df[cols]


DF_DISPLAY = _metadata_for_display(DF_META)


def _format_image_id(row: pd.Series) -> str:
    """Create a readable image identifier from a selected metadata row."""
    return f"{row['patient_id']}_{row['organ']}_VISIT_{row['visit']}"


def _parse_probs(prob_string: str) -> tuple[float, ...]:
    """Parse comma-separated percentile values from UI input."""
    values: list[float] = []
    for part in prob_string.split(","):
        part = part.strip()
        if not part:
            continue
        values.append(float(part))

    if not values:
        raise ValueError("At least one percentile must be supplied.")

    for value in values:
        if not (0 < value < 100):
            raise ValueError("Percentiles must be between 0 and 100.")

    return tuple(values)


def _safe_error_message(exc: BaseException) -> str:
    """Return a readable error message for the diagnostics tab."""
    return "\n".join(
        [
            f"{type(exc).__name__}: {exc}",
            "",
            traceback.format_exc(limit=8),
        ]
    )


# -----------------------------------------------------------------------------
# UI
# -----------------------------------------------------------------------------

app_ui = ui.page_fluid(
    ui.h2("Spatial SUV tail-feature explorer"),
    ui.layout_sidebar(
        ui.sidebar(
            ui.input_text(
                "probs",
                "Percentiles",
                value="80, 90, 95",
                placeholder="80, 90, 95",
            ),
            ui.input_numeric("bins", "Histogram bins", value=100, min=10, max=500),
            ui.input_numeric("min_suv", "Minimum SUV for PDF", value=0.1, min=0),
            ui.input_checkbox("log_x", "Log x-axis for SUV PDF", value=True),
            ui.hr(),
            ui.input_numeric(
                "min_component_voxels",
                "Minimum component voxels",
                value=3,
                min=1,
                step=1,
            ),
            ui.input_select(
                "component_connectivity",
                "Component connectivity",
                choices={"6": "6", "18": "18", "26": "26"},
                selected="26",
            ),
            ui.input_select(
                "contrast_connectivity",
                "Contrast connectivity",
                choices={"6": "6", "18": "18", "26": "26"},
                selected="26",
            ),
            ui.input_checkbox("compute_spread", "Compute spread", value=True),
            ui.input_checkbox("compute_local_contrast", "Compute local contrast", value=True),
            ui.input_checkbox("compute_sphericity", "Compute sphericity", value=True),
            ui.input_checkbox("crop_to_roi", "Crop to ROI", value=True),
            ui.hr(),
            ui.input_action_button("run", "Compute selected row", class_="btn-primary"),
            width=330,
        ),
        ui.navset_tab(
            ui.nav_panel(
                "Metadata table",
                ui.p("Select one row from the table, then click 'Compute selected row'."),
                ui.output_data_frame("metadata_table"),
            ),
            ui.nav_panel(
                "SUV PDF",
                ui.output_ui("selected_summary_pdf"),
                output_widget("suv_pdf_plot", height="560px"),
                ui.h4("SUV percentiles"),
                ui.output_data_frame("suv_percentiles_table"),
            ),
            ui.nav_panel(
                "Hot voxels",
                ui.output_ui("selected_summary_hot"),
                ui.output_ui("hot_voxel_tabs"),
            ),
            ui.nav_panel(
                "Spatial features",
                ui.output_ui("selected_summary_features"),
                ui.output_data_frame("features_table"),
            ),
            ui.nav_panel(
                "Errors / diagnostics",
                ui.output_text_verbatim("diagnostics"),
            ),
        ),
    ),
)


# -----------------------------------------------------------------------------
# Server
# -----------------------------------------------------------------------------


def server(input: Inputs, output: Outputs, session: Session):
    @render.data_frame
    def metadata_table():
        return render.DataGrid(
            DF_DISPLAY,
            selection_mode="row",
            filters=True,
            height="650px",
        )

    @reactive.calc
    def selected_row_display() -> pd.Series | None:
        selected = metadata_table.cell_selection()["rows"]
        if not selected:
            return None
        return DF_DISPLAY.iloc[int(selected[0])]

    @reactive.calc
    @reactive.event(input.run)
    def analysis_result():
        """Load selected image and compute all requested outputs once per click."""
        row_display = selected_row_display()
        if row_display is None:
            return {
                "ok": False,
                "error": "No row selected. Select a row in the metadata table first.",
            }

        try:
            probs = _parse_probs(input.probs())

            patient_id = row_display["patient_id"]
            organ = row_display["organ"]
            visit = int(row_display["visit"])
            index_key = (patient_id, organ, visit)

            row_meta, processed_image = get_processed_image(
                DF_META,
                patient_id=patient_id,
                organ=organ,
                visit=visit,
            )

            image_id = _format_image_id(row_display)

            pdf_fig, suv_percentiles = plot_suv_pdf_plotly(
                processed_image,
                percentiles=probs,
                bins=int(input.bins()),
                log_x=bool(input.log_x()),
                min_suv=float(input.min_suv()),
                title=f"SUV distribution: {image_id}",
            )

            hot_figs: dict[float, go.Figure] = {}
            for p in probs:
                threshold = float(
                    suv_percentiles.loc[
                        suv_percentiles["percentile"] == p,
                        "suv_threshold",
                    ].iloc[0]
                )

                hot_fig = plot_hot_voxels_plotly(
                    processed_image,
                    c=threshold,
                )
                hot_fig.update_layout(
                    title=f"Hot voxels: {image_id}, p{p:g}, SUV ≥ {threshold:.4g}"
                )
                hot_figs[p] = hot_fig

            features = compute_tail_spatial_features(
                image=processed_image,
                percentiles=probs,
                component_connectivity=int(input.component_connectivity()),
                contrast_connectivity=int(input.contrast_connectivity()),
                min_component_voxels=int(input.min_component_voxels()),
                compute_spread=bool(input.compute_spread()),
                compute_local_contrast=bool(input.compute_local_contrast()),
                compute_sphericity=bool(input.compute_sphericity()),
                crop_to_roi=bool(input.crop_to_roi()),
                image_id=index_key,
            )

            return {
                "ok": True,
                "row_display": row_display,
                "row_meta": row_meta,
                "image_id": image_id,
                "probs": probs,
                "pdf_fig": pdf_fig,
                "suv_percentiles": suv_percentiles,
                "hot_figs": hot_figs,
                "features": features,
                "diagnostics": f"Computed successfully for {image_id}",
            }

        except Exception as exc:
            return {
                "ok": False,
                "row_display": row_display,
                "error": _safe_error_message(exc),
            }

    def _selected_summary(result: dict) -> ui.TagList:
        if not result.get("ok"):
            return ui.TagList(ui.div(ui.strong("No successful computation yet.")))

        row = result["row_display"]
        return ui.TagList(
            ui.div(
                ui.strong("Selected image: "),
                f"{row['patient_id']} | {row['organ']} | VISIT_{row['visit']}",
            )
        )

    @render.ui
    def selected_summary_pdf():
        return _selected_summary(analysis_result())

    @render.ui
    def selected_summary_hot():
        return _selected_summary(analysis_result())

    @render.ui
    def selected_summary_features():
        return _selected_summary(analysis_result())

    @render_widget
    def suv_pdf_plot():
        result = analysis_result()
        if not result.get("ok"):
            return _empty_figure("Select a row and click 'Compute selected row' to show the SUV PDF.")
        return result["pdf_fig"]

    @render.data_frame
    def suv_percentiles_table():
        result = analysis_result()
        if not result.get("ok"):
            return pd.DataFrame()
        return render.DataGrid(result["suv_percentiles"], height="250px")

    @render.ui
    def hot_voxel_tabs():
        result = analysis_result()
        if not result.get("ok"):
            return ui.div(ui.em("Select a row and compute to show hot-voxel plots."))

        probs = list(result["probs"])
        max_plots = 5

        if len(probs) > max_plots:
            probs = probs[:max_plots]

        tabs = []
        for i, p in enumerate(probs):
            tabs.append(
                ui.nav_panel(
                    f"p{p:g}",
                    output_widget(f"hot_voxel_plot_{i}", height="760px"),
                )
            )

        return ui.navset_tab(*tabs)

    def _hot_voxel_figure_by_index(index: int):
        result = analysis_result()
        if not result.get("ok"):
            return _empty_figure("No hot-voxel plot available.")

        probs = list(result["probs"])
        if index >= len(probs):
            return _empty_figure("No percentile assigned to this plot.")

        p = probs[index]
        fig = result["hot_figs"].get(p)
        if fig is None:
            return _empty_figure(f"Percentile p{p:g} was not requested.")
        return fig

    @render_widget
    def hot_voxel_plot_0():
        return _hot_voxel_figure_by_index(0)

    @render_widget
    def hot_voxel_plot_1():
        return _hot_voxel_figure_by_index(1)

    @render_widget
    def hot_voxel_plot_2():
        return _hot_voxel_figure_by_index(2)

    @render_widget
    def hot_voxel_plot_3():
        return _hot_voxel_figure_by_index(3)

    @render_widget
    def hot_voxel_plot_4():
        return _hot_voxel_figure_by_index(4)

    @render.data_frame
    def features_table():
        result = analysis_result()
        if not result.get("ok"):
            return pd.DataFrame()
        return render.DataGrid(result["features"], height="420px")

    @render.text
    def diagnostics():
        result = analysis_result()
        if result.get("ok"):
            return result.get("diagnostics", "OK")
        return result.get("error", "Unknown error")


app = App(app_ui, server)


if __name__ == "__main__":
    from shiny import run_app

    run_app("app:app", host="127.0.0.1", port=8000, reload=True)