from __future__ import division
import os
import copy
import logging
import subprocess

import numpy as np
import pandas as pd

from .base import BaseParser
from ..core import Table
from ..utils import (scale_image, scale_pdf, segments_in_bbox, text_in_bbox,
                     merge_close_lines, get_table_index, compute_accuracy,
                     compute_whitespace, setup_logging, encode_)
from ..image_processing import (adaptive_threshold, find_lines,
                                find_table_contours, find_table_joints)


logger = setup_logging(__name__)


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

    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.
    process_background : bool, optional (default: False)
        Whether or not to process lines that are in background.
    line_size_scaling : int, optional (default: 15)
        Factor by which the page dimensions will be divided to get
        smallest length of lines that should be detected.

        The larger this value, smaller the detected lines. Making it
        too large will lead to text being detected as lines.
    copy_text : list, optional (default: None)
        {'h', 'v'}
        Select one or more strings from above and pass them as a list
        to specify the direction in which text should be copied over
        when a cell spans multiple rows or columns.
    shift_text : list, optional (default: ['l', 't'])
        {'l', 'r', 't', 'b'}
        Select one or more strings from above and pass them as a list
        to specify where the text in a spanning cell should flow.
    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)
    line_close_tol : int, optional (default: 2)
        Tolerance parameter used to merge vertical and horizontal
        detected lines which lie close to each other.
    joint_close_tol : int, optional (default: 2)
        Tolerance parameter used to decide whether the detected lines
        and points lie close to each other.
    threshold_blocksize : int, optional (default: 15)
        Size of a pixel neighborhood that is used to calculate a
        threshold value for the pixel: 3, 5, 7, and so on.

        For more information, refer `OpenCV's adaptiveThreshold <https://docs.opencv.org/2.4/modules/imgproc/doc/miscellaneous_transformations.html#adaptivethreshold>`_.
    threshold_constant : int, optional (default: -2)
        Constant subtracted from the mean or weighted mean.
        Normally, it is positive but may be zero or negative as well.

        For more information, refer `OpenCV's adaptiveThreshold <https://docs.opencv.org/2.4/modules/imgproc/doc/miscellaneous_transformations.html#adaptivethreshold>`_.
    iterations : int, optional (default: 0)
        Number of times for erosion/dilation is applied.

        For more information, refer `OpenCV's dilate <https://docs.opencv.org/2.4/modules/imgproc/doc/filtering.html#dilate>`_.
    margins : tuple
        PDFMiner margins. (char_margin, line_margin, word_margin)

        For more information, refer `PDFMiner docs <https://euske.github.io/pdfminer/>`_.
    debug : bool, optional (default: False)
        Whether or not to return all text objects on the page
        which can be used to generate a matplotlib plot, to get
        values for table_area(s) and debugging.

    """
    def __init__(self, table_area=None, process_background=False,
                 line_size_scaling=15, copy_text=None, shift_text=['l', 't'],
                 split_text=False, flag_size=False, line_close_tol=2,
                 joint_close_tol=2, threshold_blocksize=15, threshold_constant=-2,
                 iterations=0, margins=(1.0, 0.5, 0.1), debug=False):
        self.table_area = table_area
        self.process_background = process_background
        self.line_size_scaling = line_size_scaling
        self.copy_text = copy_text
        self.shift_text = shift_text
        self.split_text = split_text
        self.flag_size = flag_size
        self.line_close_tol = line_close_tol
        self.joint_close_tol = joint_close_tol
        self.threshold_blocksize = threshold_blocksize
        self.threshold_constant = threshold_constant
        self.iterations = iterations
        self.char_margin, self.line_margin, self.word_margin = margins
        self.debug = debug

    @staticmethod
    def _reduce_index(t, idx, shift_text):
        """Reduces index of a text object if it lies within a spanning
        cell.

        Parameters
        ----------
        table : camelot.core.Table
        idx : list
            List of tuples of the form (r_idx, c_idx, text).
        shift_text : list
            {'l', 'r', 't', 'b'}
            Select one or more strings from above and pass them as a
            list to specify where the text in a spanning cell should
            flow.

        Returns
        -------
        indices : list
            List of tuples of the form (r_idx, c_idx, text) where
            r_idx and c_idx are new row and column indices for text.

        """
        indices = []
        for r_idx, c_idx, text in idx:
            for d in shift_text:
                if d == 'l':
                    if t.cells[r_idx][c_idx].hspan:
                        while not t.cells[r_idx][c_idx].left:
                            c_idx -= 1
                if d == 'r':
                    if t.cells[r_idx][c_idx].hspan:
                        while not t.cells[r_idx][c_idx].right:
                            c_idx += 1
                if d == 't':
                    if t.cells[r_idx][c_idx].vspan:
                        while not t.cells[r_idx][c_idx].top:
                            r_idx -= 1
                if d == 'b':
                    if t.cells[r_idx][c_idx].vspan:
                        while not t.cells[r_idx][c_idx].bottom:
                            r_idx += 1
            indices.append((r_idx, c_idx, text))
        return indices

    @staticmethod
    def _copy_spanning_text(t, copy_text=None):
        """Copies over text in empty spanning cells.

        Parameters
        ----------
        t : camelot.core.Table
        copy_text : list, optional (default: None)
            {'h', 'v'}
            Select one or more strings from above and pass them as a list
            to specify the direction in which text should be copied over
            when a cell spans multiple rows or columns.

        Returns
        -------
        t : camelot.core.Table

        """
        for f in copy_text:
            if f == "h":
                for i in range(len(t.cells)):
                    for j in range(len(t.cells[i])):
                        if t.cells[i][j].text.strip() == '':
                            if t.cells[i][j].hspan and not t.cells[i][j].left:
                                t.cells[i][j].text = t.cells[i][j - 1].text
            elif f == "v":
                for i in range(len(t.cells)):
                    for j in range(len(t.cells[i])):
                        if t.cells[i][j].text.strip() == '':
                            if t.cells[i][j].vspan and not t.cells[i][j].top:
                                t.cells[i][j].text = t.cells[i - 1][j].text
        return t

    def _generate_image(self):
        self.imagename = ''.join([self.rootname, '.png'])
        gs_call = [
            "-q", "-sDEVICE=png16m", "-o", self.imagename, "-r600", self.filename
        ]
        if "ghostscript" in subprocess.check_output(["gs", "-version"]).lower():
            gs_call.insert(0, "gs")
        else:
            gs_call.insert(0, "gsc")
        subprocess.call(gs_call, stdout=open(os.devnull, 'w'),
            stderr=subprocess.STDOUT)

    def _generate_table_bbox(self):
        self.image, self.threshold = adaptive_threshold(self.imagename, process_background=self.process_background,
            blocksize=self.threshold_blocksize, c=self.threshold_constant)
        image_width = self.image.shape[1]
        image_height = self.image.shape[0]
        image_width_scaler = image_width / float(self.pdf_width)
        image_height_scaler = image_height / float(self.pdf_height)
        pdf_width_scaler = self.pdf_width / float(image_width)
        pdf_height_scaler = self.pdf_height / float(image_height)
        image_scalers = (image_width_scaler, image_height_scaler, self.pdf_height)
        pdf_scalers = (pdf_width_scaler, pdf_height_scaler, image_height)

        vertical_mask, vertical_segments = find_lines(
            self.threshold, direction='vertical',
            line_size_scaling=self.line_size_scaling, iterations=self.iterations)
        horizontal_mask, horizontal_segments = find_lines(
            self.threshold, direction='horizontal',
            line_size_scaling=self.line_size_scaling, iterations=self.iterations)

        if self.table_area is not None:
            areas = []
            for area in self.table_area:
                x1, y1, x2, y2 = area.split(",")
                x1 = float(x1)
                y1 = float(y1)
                x2 = float(x2)
                y2 = float(y2)
                x1, y1, x2, y2 = scale_pdf((x1, y1, x2, y2), image_scalers)
                areas.append((x1, y1, abs(x2 - x1), abs(y2 - y1)))
            table_bbox = find_table_joints(areas, vertical_mask, horizontal_mask)
        else:
            contours = find_table_contours(vertical_mask, horizontal_mask)
            table_bbox = find_table_joints(contours, vertical_mask, horizontal_mask)

        self.table_bbox_unscaled = copy.deepcopy(table_bbox)

        self.table_bbox, self.vertical_segments, self.horizontal_segments = scale_image(
            table_bbox, vertical_segments, horizontal_segments, pdf_scalers)

    def _generate_columns_and_rows(self, table_idx, tk):
        # select elements which lie within table_bbox
        t_bbox = {}
        v_s, h_s = segments_in_bbox(
            tk, self.vertical_segments, self.horizontal_segments)
        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 t_bbox:
            t_bbox[direction].sort(key=lambda x: (-x.y0, x.x0))

        cols, rows = zip(*self.table_bbox[tk])
        cols, rows = list(cols), list(rows)
        cols.extend([tk[0], tk[2]])
        rows.extend([tk[1], tk[3]])
        # sort horizontal and vertical segments
        cols = merge_close_lines(
            sorted(cols), line_close_tol=self.line_close_tol)
        rows = merge_close_lines(
            sorted(rows, reverse=True), line_close_tol=self.line_close_tol)
        # make grid using x and y coord of shortlisted rows and cols
        cols = [(cols[i], cols[i + 1])
                for i in range(0, len(cols) - 1)]
        rows = [(rows[i], rows[i + 1])
                for i in range(0, len(rows) - 1)]

        return cols, rows, v_s, h_s

    def _generate_table(self, table_idx, cols, rows, **kwargs):
        v_s = kwargs.get('v_s')
        h_s = kwargs.get('h_s')
        if v_s is None or h_s is None:
            raise ValueError('No segments found on {}'.format(self.rootname))

        table = Table(cols, rows)
        # set table edges to True using ver+hor lines
        table = table.set_edges(v_s, h_s, joint_close_tol=self.joint_close_tol)
        # set table border edges to True
        table = table.set_border()
        # set spanning cells to True
        table = table.set_span()

        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)
                    indices = Lattice._reduce_index(table, indices, shift_text=self.shift_text)
                    for r_idx, c_idx, text in indices:
                        table.cells[r_idx][c_idx].text = text
        accuracy = compute_accuracy([[100, pos_errors]])

        if self.copy_text is not None:
            table = Lattice._copy_spanning_text(table, copy_text=self.copy_text)

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

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

        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.g

        self._generate_image()
        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, v_s, h_s = self._generate_columns_and_rows(table_idx, tk)
            table = self._generate_table(table_idx, cols, rows, v_s=v_s, h_s=h_s)
            _tables.append(table)

        if self.debug:
            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])
            self.g.text = text
            self.g.images = (self.image, self.table_bbox_unscaled)
            self.g.segments = (self.vertical_segments, self.horizontal_segments)
            self.g.tables = _tables

        return _tables, self.g