from __future__ import division
import os
import logging

import numpy as np
import pandas as pd

from .base import BaseParser
from ..core import Table
from ..utils import (text_in_bbox, get_table_index, compute_accuracy,
                     compute_whitespace, setup_logging, encode_)


logger = setup_logging(__name__)


class Stream(BaseParser):
    """Stream method of parsing looks for spaces between text
    to form a table.

    If you want to specify columns when specifying multiple table
    areas, make sure that the length of both lists are equal.

    Parameters
    ----------
    table_area : list, optional (default: None)
        List of table areas to analyze as strings of the form
        x1,y1,x2,y2 where (x1, y1) -> left-top and
        (x2, y2) -> right-bottom in pdf coordinate space.
    columns : list, optional (default: None)
        List of column x-coordinates as strings where the coordinates
        are comma-separated.
    split_text : bool, optional (default: False)
        Whether or not to split a text line if it spans across
        multiple cells.
    flag_size : bool, optional (default: False)
        Whether or not to highlight a substring using <s></s>
        if its size is different from rest of the string. (Useful for
        super and subscripts)
    row_close_tol : int, optional (default: 2)
        Rows will be formed by combining text vertically
        within this tolerance.
    col_close_tol : int, optional (default: 0)
        Columns will be formed by combining text horizontally
        within this tolerance.
    margins : tuple, optional (default: (1.0, 0.5, 0.1))
        PDFMiner margins. (char_margin, line_margin, word_margin)

        For more information, refer `PDFMiner docs <https://euske.github.io/pdfminer/>`_.

    """
    def __init__(self, table_area=None, columns=None, split_text=False,
                 flag_size=False, row_close_tol=2, col_close_tol=0,
                 margins=(1.0, 0.5, 0.1)):
        self.table_area = table_area
        self.columns = columns
        self._validate_columns()
        self.split_text = split_text
        self.flag_size = flag_size
        self.row_close_tol = row_close_tol
        self.col_close_tol = col_close_tol
        self.char_margin, self.line_margin, self.word_margin = margins

    @staticmethod
    def _text_bbox(t_bbox):
        """Returns bounding box for the text present on a page.

        Parameters
        ----------
        t_bbox : dict
            Dict with two keys 'horizontal' and 'vertical' with lists of
            LTTextLineHorizontals and LTTextLineVerticals respectively.

        Returns
        -------
        text_bbox : tuple
            Tuple (x0, y0, x1, y1) in pdf coordinate space.

        """
        xmin = min([t.x0 for direction in t_bbox for t in t_bbox[direction]])
        ymin = min([t.y0 for direction in t_bbox for t in t_bbox[direction]])
        xmax = max([t.x1 for direction in t_bbox for t in t_bbox[direction]])
        ymax = max([t.y1 for direction in t_bbox for t in t_bbox[direction]])
        text_bbox = (xmin, ymin, xmax, ymax)
        return text_bbox

    @staticmethod
    def _group_rows(text, row_close_tol=2):
        """Groups PDFMiner text objects into rows vertically
        within a tolerance.

        Parameters
        ----------
        text : list
            List of PDFMiner text objects.
        row_close_tol : int, optional (default: 2)

        Returns
        -------
        rows : list
            Two-dimensional list of text objects grouped into rows.

        """
        row_y = 0
        rows = []
        temp = []
        for t in text:
            # is checking for upright necessary?
            # if t.get_text().strip() and all([obj.upright for obj in t._objs if
            # type(obj) is LTChar]):
            if t.get_text().strip():
                if not np.isclose(row_y, t.y0, atol=row_close_tol):
                    rows.append(sorted(temp, key=lambda t: t.x0))
                    temp = []
                    row_y = t.y0
                temp.append(t)
        rows.append(sorted(temp, key=lambda t: t.x0))
        __ = rows.pop(0) # hacky
        return rows

    @staticmethod
    def _merge_columns(l, col_close_tol=0):
        """Merges column boundaries horizontally if they overlap
        or lie within a tolerance.

        Parameters
        ----------
        l : list
            List of column x-coordinate tuples.
        col_close_tol : int, optional (default: 0)

        Returns
        -------
        merged : list
            List of merged column x-coordinate tuples.

        """
        merged = []
        for higher in l:
            if not merged:
                merged.append(higher)
            else:
                lower = merged[-1]
                if col_close_tol >= 0:
                    if (higher[0] <= lower[1] or
                            np.isclose(higher[0], lower[1], atol=col_close_tol)):
                        upper_bound = max(lower[1], higher[1])
                        lower_bound = min(lower[0], higher[0])
                        merged[-1] = (lower_bound, upper_bound)
                    else:
                        merged.append(higher)
                elif col_close_tol < 0:
                    if higher[0] <= lower[1]:
                        if np.isclose(higher[0], lower[1], atol=abs(col_close_tol)):
                            merged.append(higher)
                        else:
                            upper_bound = max(lower[1], higher[1])
                            lower_bound = min(lower[0], higher[0])
                            merged[-1] = (lower_bound, upper_bound)
                    else:
                        merged.append(higher)
        return merged

    @staticmethod
    def _join_rows(rows_grouped, text_y_max, text_y_min):
        """Makes row coordinates continuous.

        Parameters
        ----------
        rows_grouped : list
            Two-dimensional list of text objects grouped into rows.
        text_y_max : int
        text_y_min : int

        Returns
        -------
        rows : list
            List of continuous row y-coordinate tuples.

        """
        row_mids = [sum([(t.y0 + t.y1) / 2 for t in r]) / len(r)
                    if len(r) > 0 else 0 for r in rows_grouped]
        rows = [(row_mids[i] + row_mids[i - 1]) / 2 for i in range(1, len(row_mids))]
        rows.insert(0, text_y_max)
        rows.append(text_y_min)
        rows = [(rows[i], rows[i + 1])
                for i in range(0, len(rows) - 1)]
        return rows

    @staticmethod
    def _add_columns(cols, text, row_close_tol):
        """Adds columns to existing list by taking into account
        the text that lies outside the current column x-coordinates.

        Parameters
        ----------
        cols : list
            List of column x-coordinate tuples.
        text : list
            List of PDFMiner text objects.
        ytol : int

        Returns
        -------
        cols : list
            Updated list of column x-coordinate tuples.

        """
        if text:
            text = Stream._group_rows(text, row_close_tol=row_close_tol)
            elements = [len(r) for r in text]
            new_cols = [(t.x0, t.x1)
                for r in text if len(r) == max(elements) for t in r]
            cols.extend(Stream._merge_columns(sorted(new_cols)))
        return cols

    @staticmethod
    def _join_columns(cols, text_x_min, text_x_max):
        """Makes column coordinates continuous.

        Parameters
        ----------
        cols : list
            List of column x-coordinate tuples.
        text_x_min : int
        text_y_max : int

        Returns
        -------
        cols : list
            Updated list of column x-coordinate tuples.

        """
        cols = sorted(cols)
        cols = [(cols[i][0] + cols[i - 1][1]) / 2 for i in range(1, len(cols))]
        cols.insert(0, text_x_min)
        cols.append(text_x_max)
        cols = [(cols[i], cols[i + 1])
                for i in range(0, len(cols) - 1)]
        return cols

    def _validate_columns(self):
        if self.table_area is not None and self.columns is not None:
            if len(self.table_area) != len(self.columns):
                raise ValueError("Length of table_area and columns"
                                 " should be equal")

    def _generate_table_bbox(self):
        if self.table_area is not None:
            table_bbox = {}
            for area in self.table_area:
                x1, y1, x2, y2 = area.split(",")
                x1 = float(x1)
                y1 = float(y1)
                x2 = float(x2)
                y2 = float(y2)
                table_bbox[(x1, y2, x2, y1)] = None
        else:
            table_bbox = {(0, 0, self.pdf_width, self.pdf_height): None}
        self.table_bbox = table_bbox

    def _generate_columns_and_rows(self, table_idx, tk):
        # select elements which lie within table_bbox
        t_bbox = {}
        t_bbox['horizontal'] = text_in_bbox(tk, self.horizontal_text)
        t_bbox['vertical'] = text_in_bbox(tk, self.vertical_text)
        self.t_bbox = t_bbox

        for direction in self.t_bbox:
            self.t_bbox[direction].sort(key=lambda x: (-x.y0, x.x0))

        text_x_min, text_y_min, text_x_max, text_y_max = self._text_bbox(self.t_bbox)
        rows_grouped = self._group_rows(self.t_bbox['horizontal'], row_close_tol=self.row_close_tol)
        rows = self._join_rows(rows_grouped, text_y_max, text_y_min)
        elements = [len(r) for r in rows_grouped]

        if self.columns is not None and self.columns[table_idx] != "":
            # user has to input boundary columns too
            # take (0, pdf_width) by default
            # similar to else condition
            # len can't be 1
            cols = self.columns[table_idx].split(',')
            cols = [float(c) for c in cols]
            cols.insert(0, text_x_min)
            cols.append(text_x_max)
            cols = [(cols[i], cols[i + 1]) for i in range(0, len(cols) - 1)]
        else:
            ncols = max(set(elements), key=elements.count)
            if ncols == 1:
                logger.info("No tables found on {}".format(
                    os.path.basename(self.rootname)))
            cols = [(t.x0, t.x1) for r in rows_grouped if len(r) == ncols for t in r]
            cols = self._merge_columns(sorted(cols), col_close_tol=self.col_close_tol)
            inner_text = []
            for i in range(1, len(cols)):
                left = cols[i - 1][1]
                right = cols[i][0]
                inner_text.extend([t for direction in self.t_bbox
                                     for t in self.t_bbox[direction]
                                     if t.x0 > left and t.x1 < right])
            outer_text = [t for direction in self.t_bbox
                            for t in self.t_bbox[direction]
                            if t.x0 > cols[-1][1] or t.x1 < cols[0][0]]
            inner_text.extend(outer_text)
            cols = self._add_columns(cols, inner_text, self.row_close_tol)
            cols = self._join_columns(cols, text_x_min, text_x_max)

        return cols, rows

    def _generate_table(self, table_idx, cols, rows, **kwargs):
        table = Table(cols, rows)
        table = table.set_all_edges()
        pos_errors = []
        for direction in self.t_bbox:
            for t in self.t_bbox[direction]:
                indices, error = get_table_index(
                    table, t, direction, split_text=self.split_text,
                    flag_size=self.flag_size)
                if indices[:2] != (-1, -1):
                    pos_errors.append(error)
                    for r_idx, c_idx, text in indices:
                        table.cells[r_idx][c_idx].text = text
        accuracy = compute_accuracy([[100, pos_errors]])

        data = table.data
        data = encode_(data)
        table.df = pd.DataFrame(data)
        table.shape = table.df.shape

        whitespace = compute_whitespace(data)
        table.flavor = 'stream'
        table.accuracy = accuracy
        table.whitespace = whitespace
        table.order = table_idx + 1
        table.page = int(os.path.basename(self.rootname).replace('page-', ''))

        # for plotting
        _text = []
        _text.extend([(t.x0, t.y0, t.x1, t.y1) for t in self.horizontal_text])
        _text.extend([(t.x0, t.y0, t.x1, t.y1) for t in self.vertical_text])
        table._text = _text
        table._image = None
        table._segments = None

        return table

    def extract_tables(self, filename):
        logger.info('Processing {}'.format(os.path.basename(filename)))
        self._generate_layout(filename)

        if not self.horizontal_text:
            logger.info("No tables found on {}".format(
                os.path.basename(self.rootname)))
            return []

        self._generate_table_bbox()

        _tables = []
        # sort tables based on y-coord
        for table_idx, tk in enumerate(sorted(self.table_bbox.keys(),
                key=lambda x: x[1], reverse=True)):
            cols, rows = self._generate_columns_and_rows(table_idx, tk)
            table = self._generate_table(table_idx, cols, rows)
            _tables.append(table)

        return _tables