import math
import operator as op
import itertools as it
import functools as ft
import collections as cl
from pathlib import Path
from dataclasses import fields, asdict

import pandas as pd
import gradio as gr
import seaborn as sns
import matplotlib.pyplot as plt
from datasets import load_dataset
from scipy.special import expit

from hdinterval import HDI, HDInterval

TabGroup = cl.namedtuple('TabGroup', 'name, docs, dataset')

#
#
#
def load(repo):
    parameter = 'parameter'
    model = 'model'
    items = [
        'chain',
        'sample',
        parameter,
        model,
        'value',
    ]
    dataset = load_dataset(str(repo))

    return (dataset
            .get('train')
            .to_pandas()
            .rename(columns={'element': model})
            .filter(items=items)
            .query(f'{parameter} == "alpha"')
            .drop(columns=parameter))

def summarize(df, ci=0.95):
    def _aggregate(i, g):
        values = g['value']
        hdi = HDInterval(values)
        interval = hdi(ci)

        agg = {
            'model': i,
            'ability': values.median(),
            'uncertainty': interval.width(),
        }
        agg.update(asdict(interval))

        return agg

    groups = df.groupby('model', sort=False)
    records = it.starmap(_aggregate, groups)

    return pd.DataFrame.from_records(records)

def rank(df, ascending, name='rank'):
    df = (df
          .sort_values(by=['ability',  'uncertainty'],
                       ascending=[ascending, not ascending])
          .drop(columns='uncertainty')
          .reset_index(drop=True))
    df.index += 1

    return df.reset_index(names=name)

def compare(df, model_1, model_2):
    mcol = 'model'
    models = [
        model_1,
        model_2,
    ]
    view = (df
            .query(f'{mcol} in @models')
            .pivot(index=['chain', 'sample'],
                   columns=mcol,
                   values='value'))

    return expit(view[model_1] - view[model_2])

#
#
#
class DataPlotter:
    def __init__(self, df):
        self.df = df

    def plot(self):
        fig = plt.figure(dpi=200)

        ax = fig.gca()
        self.draw(ax)
        ax.grid(visible=True,
                axis='both',
                alpha=0.25,
                linestyle='dotted')
        fig.tight_layout()

        return fig

    def draw(self, ax):
        raise NotImplementedError()

class RankPlotter(DataPlotter):
    _y = 'y'

    @ft.cached_property
    def y(self):
        return self.df[self._y]

    def __init__(self, df, top=10):
        view = rank(summarize(df), True, self._y)
        view = (view
                .tail(top)
                .sort_values(by=self._y, ascending=False))
        super().__init__(view)

    def draw(self, ax):
        self.df.plot.scatter('ability', self._y, ax=ax)
        ax.hlines(self.y,
                  xmin=self.df['lower'],
                  xmax=self.df['upper'],
                  alpha=0.5)
        ax.set_xlabel(ax.get_xlabel().title())
        ax.set_ylabel('')
        ax.set_yticks(self.y, self.df['model'])

class ComparisonPlotter(DataPlotter):
    def __init__(self, df, model_1, model_2, ci):
        super().__init__(compare(df, model_1, model_2))
        self.hdi = HDInterval(self.df)
        self.ci = ci

    def draw(self, ax):
        interval = self.hdi(self.ci)

        sns.ecdfplot(self.df, ax=ax)

        (_, color, *_) = sns.color_palette()
        ax.axvline(x=self.df.median(),
                   color=color,
                   linestyle='dashed')
        ax.axvspan(xmin=interval.lower,
                   xmax=interval.upper,
                   alpha=0.15,
                   color=color)
        ax.set_xlabel('Pr(M$_{1}$ \u003E M$_{2}$)')

        try:
            ci_mid = self.hdi.at(0.5)
            ax.text(x=0.01,
                    y=0.99,
                    s=f'0.5-min HDI: {ci_mid:.0%}',
                    horizontalalignment='left',
                    verticalalignment='top',
                    transform=ax.transAxes)
        except ArithmeticError:
            pass

class ComparisonMenu:
    def __init__(self, df, ci=0.95):
        self.df = df
        self.ci = ci

    def __call__(self, model_1, model_2, ci):
        cp = ComparisonPlotter(self.df, model_1, model_2, ci)
        return cp.plot()

    def build_and_get(self):
        models = self.df['model'].unique()
        choices = sorted(models, key=lambda x: x.lower())

        for i in range(1, 3):
            label = f'Model {i}'
            yield gr.Dropdown(label=label, choices=choices)

        yield gr.Number(value=self.ci,
                        label='HDI',
                        minimum=0,
                        maximum=1,
                        step=1e-2)

#
#
#
class DocumentationReader:
    _suffix = '.md'

    def __init__(self, root):
        self.root = root

    def __getitem__(self, item):
        return (self
                .root
                .joinpath(item)
                .with_suffix(self._suffix)
                .read_text())

#
#
#
def layout(tab):
    df = load(Path('jerome-white', tab.dataset))
    docs = DocumentationReader(Path('docs', t.docs))

    with gr.Row():
        with gr.Column():
            gr.Markdown(docs['readme'])

        with gr.Column():
            plotter = RankPlotter(df)
            gr.Plot(plotter.plot())

    with gr.Row():
        view = rank(summarize(df), False)
        columns = { x.name: f'HDI {x.name}' for x in fields(HDI) }
        for i in view.columns:
            columns.setdefault(i, i.title())
        view = (view
                .rename(columns=columns)
                .style.format(precision=4))

        gr.Dataframe(view)

    with gr.Row():
        with gr.Column(scale=3):
            display = gr.Plot()

        with gr.Row():
            with gr.Column():
                gr.Markdown('''

                Probability that Model 1 is preferred to Model 2. The
                solid blue curve is a CDF of that distribution;
                formally the inverse logit of the difference in model
                abilities. The dashed orange vertical line is the
                median, while the band surrounding it is the [highest
                density
                interval](https://cran.r-project.org/package=HDInterval)
                of your choice (default 95%).

                ''')
            with gr.Column():
                menu = ComparisonMenu(df)
                inputs = list(menu.build_and_get())
                button = gr.Button(value='Compare!')
                button.click(menu, inputs=inputs, outputs=[display])

    with gr.Accordion('Disclaimer', open=False):
        gr.Markdown(docs['disclaimer'])

#
#
#
with gr.Blocks() as demo:
    tabs = it.starmap(TabGroup, (
        ('Alpaca', 'alpaca', 'alpaca-bt-stan'),
        ('Chatbot Arena', 'arena', 'arena-bt-stan'),
    ))

    for t in tabs:
        with gr.Tab(t.name):
            layout(t)

demo.launch()