#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""A text-based simple histogram helper class."""

import math
from dataclasses import dataclass
from typing import Dict, Generic, Iterable, List, Optional, Tuple, TypeVar

T = TypeVar("T", int, float)
Bound = int
Count = int


@dataclass
class BucketDetails:
    """A collection of details about the internal histogram buckets."""

    num_populated_buckets: int = 0
    max_population: Optional[int] = None
    last_bucket_start: Optional[int] = None
    lowest_start: Optional[int] = None
    highest_end: Optional[int] = None
    max_label_width: Optional[int] = None


class SimpleHistogram(Generic[T]):
    """A simple histogram."""

    # Useful in defining wide open bottom/top bucket bounds:
    POSITIVE_INFINITY = math.inf
    NEGATIVE_INFINITY = -math.inf

    def __init__(self, buckets: List[Tuple[Bound, Bound]]):
        from math_utils import NumericPopulation

        self.buckets: Dict[Tuple[Bound, Bound], Count] = {}
        for start_end in buckets:
            if self._get_bucket(start_end[0]) is not None:
                raise Exception("Buckets overlap?!")
            self.buckets[start_end] = 0
        self.sigma: float = 0.0
        self.stats: NumericPopulation = NumericPopulation()
        self.maximum: Optional[T] = None
        self.minimum: Optional[T] = None
        self.count: Count = 0

    @staticmethod
    def n_evenly_spaced_buckets(
        min_bound: T,
        max_bound: T,
        n: int,
    ) -> List[Tuple[int, int]]:
        ret: List[Tuple[int, int]] = []
        stride = int((max_bound - min_bound) / n)
        if stride <= 0:
            raise Exception("Min must be < Max")
        imax = math.ceil(max_bound)
        imin = math.floor(min_bound)
        for bucket_start in range(imin, imax, stride):
            ret.append((bucket_start, bucket_start + stride))
        return ret

    def _get_bucket(self, item: T) -> Optional[Tuple[int, int]]:
        for start_end in self.buckets:
            if start_end[0] <= item < start_end[1]:
                return start_end
        return None

    def add_item(self, item: T) -> bool:
        bucket = self._get_bucket(item)
        if bucket is None:
            return False
        self.count += 1
        self.buckets[bucket] += 1
        self.sigma += item
        self.stats.add_number(item)
        if self.maximum is None or item > self.maximum:
            self.maximum = item
        if self.minimum is None or item < self.minimum:
            self.minimum = item
        return True

    def add_items(self, lst: Iterable[T]) -> bool:
        all_true = True
        for item in lst:
            all_true = all_true and self.add_item(item)
        return all_true

    def get_bucket_details(self, label_formatter: str) -> BucketDetails:
        details = BucketDetails()
        for (start, end), pop in sorted(self.buckets.items(), key=lambda x: x[0]):
            if pop > 0:
                details.num_populated_buckets += 1
                details.last_bucket_start = start
                if details.max_population is None or pop > details.max_population:
                    details.max_population = pop
                if details.lowest_start is None or start < details.lowest_start:
                    details.lowest_start = start
                if details.highest_end is None or end > details.highest_end:
                    details.highest_end = end
                label = f'[{label_formatter}..{label_formatter}): ' % (start, end)
                label_width = len(label)
                if details.max_label_width is None or label_width > details.max_label_width:
                    details.max_label_width = label_width
        return details

    def __repr__(self, *, width: int = 80, label_formatter: str = '%d') -> str:
        from text_utils import bar_graph

        details = self.get_bucket_details(label_formatter)
        txt = ""
        if details.num_populated_buckets == 0:
            return txt
        assert details.max_label_width is not None
        assert details.lowest_start is not None
        assert details.highest_end is not None
        assert details.max_population is not None
        sigma_label = f'[{label_formatter}..{label_formatter}): ' % (
            details.lowest_start,
            details.highest_end,
        )
        if len(sigma_label) > details.max_label_width:
            details.max_label_width = len(sigma_label)
        bar_width = width - (details.max_label_width + 16)

        for (start, end), pop in sorted(self.buckets.items(), key=lambda x: x[0]):
            label = f'[{label_formatter}..{label_formatter}): ' % (start, end)
            bar = bar_graph(
                (pop / details.max_population),
                include_text=False,
                width=bar_width,
                left_end="",
                right_end="",
            )
            txt += label.rjust(details.max_label_width)
            txt += bar
            txt += f"({pop/self.count*100.0:5.2f}% n={pop})\n"
            if start == details.last_bucket_start:
                break
        txt += '-' * width + '\n'
        txt += sigma_label.rjust(details.max_label_width)
        txt += ' ' * (bar_width - 2)
        txt += f'Σ=(100.00% n={self.count})\n'
        txt += ' ' * (bar_width + details.max_label_width - 2)
        txt += f'mean(μ)={self.stats.get_mean():.3f}\n'
        txt += ' ' * (bar_width + details.max_label_width - 2)
        txt += f'p50(η)={self.stats.get_median():.3f}\n'
        txt += ' ' * (bar_width + details.max_label_width - 2)
        txt += f'stdev(σ)={self.stats.get_stdev():.3f}\n'
        txt += '\n'
        return txt