# copyright 2003-2012 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common.  If not, see <http://www.gnu.org/licenses/>.
"""Table management module."""

from types import CodeType
from typing import Any, List, Optional, Tuple, Union, Dict, Iterator
from _io import StringIO

import re

__docformat__ = "restructuredtext en"


class Table(object):
    """Table defines a data table with column and row names.
    inv::

        len(self.data) <= len(self.row_names)
        forall(self.data, lambda x: len(x) <= len(self.col_names))
    """

    def __init__(
        self,
        default_value: int = 0,
        col_names: Optional[List[str]] = None,
        row_names: Optional[Any] = None,
    ) -> None:
        self.col_names: List = []
        self.row_names: List = []
        self.data: List = []
        self.default_value: int = default_value
        if col_names:
            self.create_columns(col_names)
        if row_names:
            self.create_rows(row_names)

    def _next_row_name(self) -> str:
        return "row%s" % (len(self.row_names) + 1)

    def __iter__(self) -> Iterator:
        return iter(self.data)

    # def __eq__(self, other: Union[List[List[int]], List[Tuple[str, str, str, float]]]) -> bool:
    def __eq__(self, other: object) -> bool:
        def is_iterable(variable: Any) -> bool:
            try:
                iter(variable)
            except TypeError:
                return False
            else:
                return True

        if other is None:
            return False
        elif is_iterable(other):
            # mypy: No overload variant of "list" matches argument type "object"
            # checked before
            return list(self) == list(other)  # type: ignore
        else:
            return False

    __hash__ = object.__hash__

    def __ne__(self, other):
        return not self == other

    def __len__(self) -> int:
        return len(self.row_names)

    # Rows / Columns creation #################################################
    def create_rows(self, row_names: List[str]) -> None:
        """Appends row_names to the list of existing rows"""
        self.row_names.extend(row_names)
        for row_name in row_names:
            self.data.append([self.default_value] * len(self.col_names))

    def create_columns(self, col_names: List[str]) -> None:
        """Appends col_names to the list of existing columns"""
        for col_name in col_names:
            self.create_column(col_name)

    def create_row(self, row_name: str = None) -> None:
        """Creates a rowname to the row_names list"""
        row_name = row_name or self._next_row_name()
        self.row_names.append(row_name)
        self.data.append([self.default_value] * len(self.col_names))

    def create_column(self, col_name: str) -> None:
        """Creates a colname to the col_names list"""
        self.col_names.append(col_name)
        for row in self.data:
            row.append(self.default_value)

    # Sort by column ##########################################################
    def sort_by_column_id(self, col_id: str, method: str = "asc") -> None:
        """Sorts the table (in-place) according to data stored in col_id"""
        try:
            col_index = self.col_names.index(col_id)
            self.sort_by_column_index(col_index, method)
        except ValueError:
            raise KeyError("Col (%s) not found in table" % (col_id))

    def sort_by_column_index(self, col_index: int, method: str = "asc") -> None:
        """Sorts the table 'in-place' according to data stored in col_index

        method should be in ('asc', 'desc')
        """
        sort_list = sorted(
            [(row[col_index], row, row_name) for row, row_name in zip(self.data, self.row_names)]
        )
        # Sorting sort_list will sort according to col_index
        # If we want reverse sort, then reverse list
        if method.lower() == "desc":
            sort_list.reverse()

        # Rebuild data / row names
        self.data = []
        self.row_names = []
        for val, row, row_name in sort_list:
            self.data.append(row)
            self.row_names.append(row_name)

    def groupby(
        self, colname: str, *others: str
    ) -> Union[Dict[str, Dict[str, "Table"]], Dict[str, "Table"]]:
        """builds indexes of data
        :returns: nested dictionaries pointing to actual rows
        """
        groups: Dict = {}
        colnames = (colname,) + others
        col_indexes = [self.col_names.index(col_id) for col_id in colnames]
        for row in self.data:
            ptr = groups
            for col_index in col_indexes[:-1]:
                ptr = ptr.setdefault(row[col_index], {})
            table = ptr.setdefault(
                row[col_indexes[-1]],
                Table(default_value=self.default_value, col_names=self.col_names),
            )
            table.append_row(tuple(row))
        return groups

    def select(self, colname: str, value: str) -> "Table":
        grouped = self.groupby(colname)
        try:
            # mypy: Incompatible return value type (got "Union[Dict[str, Table], Table]",
            # mypy: expected "Table")
            # I guess we are sure we'll get a Table here?
            return grouped[value]  # type: ignore
        except KeyError:
            return Table()

    def remove(self, colname, value):
        col_index = self.col_names.index(colname)
        for row in self.data[:]:
            if row[col_index] == value:
                self.data.remove(row)

    # The 'setter' part #######################################################
    def set_cell(self, row_index: int, col_index: int, data: int) -> None:
        """sets value of cell 'row_indew', 'col_index' to data"""
        self.data[row_index][col_index] = data

    def set_cell_by_ids(self, row_id: str, col_id: str, data: Union[int, str]) -> None:
        """sets value of cell mapped by row_id and col_id to data
        Raises a KeyError if row_id or col_id are not found in the table
        """
        try:
            row_index = self.row_names.index(row_id)
        except ValueError:
            raise KeyError("Row (%s) not found in table" % (row_id))
        else:
            try:
                col_index = self.col_names.index(col_id)
                self.data[row_index][col_index] = data
            except ValueError:
                raise KeyError("Column (%s) not found in table" % (col_id))

    def set_row(self, row_index: int, row_data: Union[List[float], List[int], List[str]]) -> None:
        """sets the 'row_index' row
        pre::

            type(row_data) == types.ListType
            len(row_data) == len(self.col_names)
        """
        self.data[row_index] = row_data

    def set_row_by_id(self, row_id: str, row_data: List[str]) -> None:
        """sets the 'row_id' column
        pre::

            type(row_data) == types.ListType
            len(row_data) == len(self.row_names)

        Raises a KeyError if row_id is not found
        """
        try:
            row_index = self.row_names.index(row_id)
            self.set_row(row_index, row_data)
        except ValueError:
            raise KeyError("Row (%s) not found in table" % (row_id))

    def append_row(
        self, row_data: Union[List[Union[float, str]], List[int]], row_name: Optional[str] = None
    ) -> int:
        """Appends a row to the table
        pre::

            type(row_data) == types.ListType
            len(row_data) == len(self.col_names)
        """
        row_name = row_name or self._next_row_name()
        self.row_names.append(row_name)
        self.data.append(row_data)
        return len(self.data) - 1

    def insert_row(self, index: int, row_data: List[str], row_name: str = None) -> None:
        """Appends row_data before 'index' in the table. To make 'insert'
        behave like 'list.insert', inserting in an out of range index will
        insert row_data to the end of the list
        pre::

            type(row_data) == types.ListType
            len(row_data) == len(self.col_names)
        """
        row_name = row_name or self._next_row_name()
        self.row_names.insert(index, row_name)
        self.data.insert(index, row_data)

    def delete_row(self, index: int) -> List[str]:
        """Deletes the 'index' row in the table, and returns it.
        Raises an IndexError if index is out of range
        """
        self.row_names.pop(index)
        return self.data.pop(index)

    def delete_row_by_id(self, row_id: str) -> None:
        """Deletes the 'row_id' row in the table.
        Raises a KeyError if row_id was not found.
        """
        try:
            row_index = self.row_names.index(row_id)
            self.delete_row(row_index)
        except ValueError:
            raise KeyError("Row (%s) not found in table" % (row_id))

    def set_column(self, col_index: int, col_data: Union[List[int], range]) -> None:
        """sets the 'col_index' column
        pre::

            type(col_data) == types.ListType
            len(col_data) == len(self.row_names)
        """

        for row_index, cell_data in enumerate(col_data):
            self.data[row_index][col_index] = cell_data

    def set_column_by_id(self, col_id: str, col_data: Union[List[int], range]) -> None:
        """sets the 'col_id' column
        pre::

            type(col_data) == types.ListType
            len(col_data) == len(self.col_names)

        Raises a KeyError if col_id is not found
        """
        try:
            col_index = self.col_names.index(col_id)
            self.set_column(col_index, col_data)
        except ValueError:
            raise KeyError("Column (%s) not found in table" % (col_id))

    def append_column(self, col_data: range, col_name: str) -> None:
        """Appends the 'col_index' column
        pre::

            type(col_data) == types.ListType
            len(col_data) == len(self.row_names)
        """
        self.col_names.append(col_name)
        for row_index, cell_data in enumerate(col_data):
            self.data[row_index].append(cell_data)

    def insert_column(self, index: int, col_data: range, col_name: str) -> None:
        """Appends col_data before 'index' in the table. To make 'insert'
        behave like 'list.insert', inserting in an out of range index will
        insert col_data to the end of the list
        pre::

            type(col_data) == types.ListType
            len(col_data) == len(self.row_names)
        """
        self.col_names.insert(index, col_name)
        for row_index, cell_data in enumerate(col_data):
            self.data[row_index].insert(index, cell_data)

    def delete_column(self, index: int) -> List[int]:
        """Deletes the 'index' column in the table, and returns it.
        Raises an IndexError if index is out of range
        """
        self.col_names.pop(index)
        return [row.pop(index) for row in self.data]

    def delete_column_by_id(self, col_id: str) -> None:
        """Deletes the 'col_id' col in the table.
        Raises a KeyError if col_id was not found.
        """
        try:
            col_index = self.col_names.index(col_id)
            self.delete_column(col_index)
        except ValueError:
            raise KeyError("Column (%s) not found in table" % (col_id))

    # The 'getter' part #######################################################

    def get_shape(self) -> Tuple[int, int]:
        """Returns a tuple which represents the table's shape"""
        return len(self.row_names), len(self.col_names)

    shape = property(get_shape)

    def __getitem__(
        self, indices: Union[Tuple[Union[int, slice, str], Union[int, str]], int, slice]
    ) -> Any:
        """provided for convenience"""
        multirows: bool = False
        multicols: bool = False

        rows: slice
        cols: slice

        rows_indice: Union[int, slice, str]
        cols_indice: Union[int, str, None] = None

        if isinstance(indices, tuple):
            rows_indice = indices[0]
            if len(indices) > 1:
                cols_indice = indices[1]
        else:
            rows_indice = indices

        # define row slice
        if isinstance(rows_indice, str):
            try:
                rows_indice = self.row_names.index(rows_indice)
            except ValueError:
                raise KeyError("Row (%s) not found in table" % (rows_indice))

        if isinstance(rows_indice, int):
            rows = slice(rows_indice, rows_indice + 1)
            multirows = False
        else:
            rows = slice(None)
            multirows = True

        # define col slice
        if isinstance(cols_indice, str):
            try:
                cols_indice = self.col_names.index(cols_indice)
            except ValueError:
                raise KeyError("Column (%s) not found in table" % (cols_indice))

        if isinstance(cols_indice, int):
            cols = slice(cols_indice, cols_indice + 1)
            multicols = False
        else:
            cols = slice(None)
            multicols = True

        # get sub-table
        tab = Table()
        tab.default_value = self.default_value

        tab.create_rows(self.row_names[rows])
        tab.create_columns(self.col_names[cols])

        for idx, row in enumerate(self.data[rows]):
            tab.set_row(idx, row[cols])

        if multirows:
            if multicols:
                return tab
            else:
                return [item[0] for item in tab.data]
        else:
            if multicols:
                return tab.data[0]
            else:
                return tab.data[0][0]

    def get_cell_by_ids(self, row_id, col_id):
        """Returns the element at [row_id][col_id]"""
        try:
            row_index = self.row_names.index(row_id)
        except ValueError:
            raise KeyError("Row (%s) not found in table" % (row_id))
        else:
            try:
                col_index = self.col_names.index(col_id)
            except ValueError:
                raise KeyError("Column (%s) not found in table" % (col_id))
        return self.data[row_index][col_index]

    def get_row_by_id(self, row_id):
        """Returns the 'row_id' row"""
        try:
            row_index = self.row_names.index(row_id)
        except ValueError:
            raise KeyError("Row (%s) not found in table" % (row_id))
        return self.data[row_index]

    def get_column_by_id(self, col_id, distinct=False):
        """Returns the 'col_id' col"""
        try:
            col_index = self.col_names.index(col_id)
        except ValueError:
            raise KeyError("Column (%s) not found in table" % (col_id))
        return self.get_column(col_index, distinct)

    def get_columns(self) -> List[List[int]]:
        """Returns all the columns in the table"""
        return [self[:, index] for index in range(len(self.col_names))]

    def get_column(self, col_index, distinct=False):
        """get a column by index"""
        col = [row[col_index] for row in self.data]
        if distinct:
            col = list(set(col))
        return col

    def apply_stylesheet(self, stylesheet: "TableStyleSheet") -> None:
        """Applies the stylesheet to this table"""
        for instruction in stylesheet.instructions:
            eval(instruction)

    def transpose(self) -> "Table":
        """Keeps the self object intact, and returns the transposed (rotated)
        table.
        """
        transposed = Table()
        transposed.create_rows(self.col_names)
        transposed.create_columns(self.row_names)
        for col_index, column in enumerate(self.get_columns()):
            transposed.set_row(col_index, column)
        return transposed

    def pprint(self) -> str:
        """returns a string representing the table in a pretty
        printed 'text' format.
        """
        # The maximum row name (to know the start_index of the first col)
        max_row_name = 0
        for row_name in self.row_names:
            if len(row_name) > max_row_name:
                max_row_name = len(row_name)
        col_start = max_row_name + 5

        lines = []
        # Build the 'first' line <=> the col_names one
        # The first cell <=> an empty one
        col_names_line = [" " * col_start]
        for col_name in self.col_names:
            col_names_line.append(col_name + " " * 5)
        lines.append("|" + "|".join(col_names_line) + "|")
        max_line_length = len(lines[0])

        # Build the table
        for row_index, row in enumerate(self.data):
            line = []
            # First, build the row_name's cell
            row_name = self.row_names[row_index]
            line.append(row_name + " " * (col_start - len(row_name)))

            # Then, build all the table's cell for this line.
            for col_index, cell in enumerate(row):
                col_name_length = len(self.col_names[col_index]) + 5
                data = str(cell)
                line.append(data + " " * (col_name_length - len(data)))
            lines.append("|" + "|".join(line) + "|")
            if len(lines[-1]) > max_line_length:
                max_line_length = len(lines[-1])

        # Wrap the table with '-' to make a frame
        lines.insert(0, "-" * max_line_length)
        lines.append("-" * max_line_length)
        return "\n".join(lines)

    def __repr__(self) -> str:
        return repr(self.data)

    def as_text(self):
        data = []
        # We must convert cells into strings before joining them
        for row in self.data:
            data.append([str(cell) for cell in row])
        lines = ["\t".join(row) for row in data]
        return "\n".join(lines)


class TableStyle:
    """Defines a table's style"""

    def __init__(self, table: Table) -> None:
        self._table = table
        self.size = dict([(col_name, "1*") for col_name in table.col_names])
        # __row_column__ is a special key to define the first column which
        # actually has no name (<=> left most column <=> row names column)
        self.size["__row_column__"] = "1*"
        self.alignment = dict([(col_name, "right") for col_name in table.col_names])
        self.alignment["__row_column__"] = "right"

        # We shouldn't have to create an entry for
        # the 1st col (the row_column one)
        self.units = dict([(col_name, "") for col_name in table.col_names])
        self.units["__row_column__"] = ""

    # XXX FIXME : params order should be reversed for all set() methods
    def set_size(self, value: str, col_id: str) -> None:
        """sets the size of the specified col_id to value"""
        self.size[col_id] = value

    def set_size_by_index(self, value: str, col_index: int) -> None:
        """Allows to set the size according to the column index rather than
        using the column's id.
        BE CAREFUL : the '0' column is the '__row_column__' one !
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        self.size[col_id] = value

    def set_alignment(self, value: str, col_id: str) -> None:
        """sets the alignment of the specified col_id to value"""
        self.alignment[col_id] = value

    def set_alignment_by_index(self, value: str, col_index: int) -> None:
        """Allows to set the alignment according to the column index rather than
        using the column's id.
        BE CAREFUL : the '0' column is the '__row_column__' one !
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        self.alignment[col_id] = value

    def set_unit(self, value: str, col_id: str) -> None:
        """sets the unit of the specified col_id to value"""
        self.units[col_id] = value

    def set_unit_by_index(self, value: str, col_index: int) -> None:
        """Allows to set the unit according to the column index rather than
        using the column's id.
        BE CAREFUL :  the '0' column is the '__row_column__' one !
        (Note that in the 'unit' case, you shouldn't have to set a unit
        for the 1st column (the __row__column__ one))
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        self.units[col_id] = value

    def get_size(self, col_id: str) -> str:
        """Returns the size of the specified col_id"""
        return self.size[col_id]

    def get_size_by_index(self, col_index: int) -> str:
        """Allows to get the size  according to the column index rather than
        using the column's id.
        BE CAREFUL : the '0' column is the '__row_column__' one !
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        return self.size[col_id]

    def get_alignment(self, col_id: str) -> str:
        """Returns the alignment of the specified col_id"""
        return self.alignment[col_id]

    def get_alignment_by_index(self, col_index: int) -> str:
        """Allors to get the alignment according to the column index rather than
        using the column's id.
        BE CAREFUL : the '0' column is the '__row_column__' one !
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        return self.alignment[col_id]

    def get_unit(self, col_id: str) -> str:
        """Returns the unit of the specified col_id"""
        return self.units[col_id]

    def get_unit_by_index(self, col_index: int) -> str:
        """Allors to get the unit according to the column index rather than
        using the column's id.
        BE CAREFUL : the '0' column is the '__row_column__' one !
        """
        if col_index == 0:
            col_id = "__row_column__"
        else:
            col_id = self._table.col_names[col_index - 1]

        return self.units[col_id]


CELL_PROG = re.compile("([0-9]+)_([0-9]+)")


class TableStyleSheet:
    """A simple Table stylesheet
    Rules are expressions where cells are defined by the row_index
    and col_index separated by an underscore ('_').
    For example, suppose you want to say that the (2,5) cell must be
    the sum of its two preceding cells in the row, you would create
    the following rule ::

        2_5 = 2_3 + 2_4

    You can also use all the math.* operations you want. For example::

        2_5 = sqrt(2_3**2 + 2_4**2)
    """

    def __init__(self, rules: Optional[List[str]] = None) -> None:
        rules = rules or []

        self.rules: List[str] = []
        self.instructions: List[CodeType] = []

        for rule in rules:
            self.add_rule(rule)

    def add_rule(self, rule: str) -> None:
        """Adds a rule to the stylesheet rules"""
        try:
            source_code = ["from math import *"]
            source_code.append(CELL_PROG.sub(r"self.data[\1][\2]", rule))
            self.instructions.append(compile("\n".join(source_code), "table.py", "exec"))
            self.rules.append(rule)
        except SyntaxError:
            print("Bad Stylesheet Rule : %s [skipped]" % rule)

    def add_rowsum_rule(
        self, dest_cell: Tuple[int, int], row_index: int, start_col: int, end_col: int
    ) -> None:
        """Creates and adds a rule to sum over the row at row_index from
        start_col to end_col.
        dest_cell is a tuple of two elements (x,y) of the destination cell
        No check is done for indexes ranges.
        pre::

            start_col >= 0
            end_col > start_col
        """
        cell_list = ["%d_%d" % (row_index, index) for index in range(start_col, end_col + 1)]
        rule = "%d_%d=" % dest_cell + "+".join(cell_list)
        self.add_rule(rule)

    def add_rowavg_rule(
        self, dest_cell: Tuple[int, int], row_index: int, start_col: int, end_col: int
    ) -> None:
        """Creates and adds a rule to make the row average (from start_col
        to end_col)
        dest_cell is a tuple of two elements (x,y) of the destination cell
        No check is done for indexes ranges.
        pre::

            start_col >= 0
            end_col > start_col
        """
        cell_list = ["%d_%d" % (row_index, index) for index in range(start_col, end_col + 1)]
        num = end_col - start_col + 1
        rule = "%d_%d=" % dest_cell + "(" + "+".join(cell_list) + ")/%f" % num
        self.add_rule(rule)

    def add_colsum_rule(
        self, dest_cell: Tuple[int, int], col_index: int, start_row: int, end_row: int
    ) -> None:
        """Creates and adds a rule to sum over the col at col_index from
        start_row to end_row.
        dest_cell is a tuple of two elements (x,y) of the destination cell
        No check is done for indexes ranges.
        pre::

            start_row >= 0
            end_row > start_row
        """
        cell_list = ["%d_%d" % (index, col_index) for index in range(start_row, end_row + 1)]
        rule = "%d_%d=" % dest_cell + "+".join(cell_list)
        self.add_rule(rule)

    def add_colavg_rule(
        self, dest_cell: Tuple[int, int], col_index: int, start_row: int, end_row: int
    ) -> None:
        """Creates and adds a rule to make the col average (from start_row
        to end_row)
        dest_cell is a tuple of two elements (x,y) of the destination cell
        No check is done for indexes ranges.
        pre::

            start_row >= 0
            end_row > start_row
        """
        cell_list = ["%d_%d" % (index, col_index) for index in range(start_row, end_row + 1)]
        num = end_row - start_row + 1
        rule = "%d_%d=" % dest_cell + "(" + "+".join(cell_list) + ")/%f" % num
        self.add_rule(rule)


class TableCellRenderer:
    """Defines a simple text renderer"""

    def __init__(self, **properties: Any) -> None:
        """keywords should be properties with an associated boolean as value.
        For example :
            renderer = TableCellRenderer(units = True, alignment = False)
        An unspecified property will have a 'False' value by default.
        Possible properties are :
            alignment, unit
        """
        self.properties = properties

    def render_cell(
        self, cell_coord: Tuple[int, int], table: Table, table_style: TableStyle
    ) -> Union[str, int]:
        """Renders the cell at 'cell_coord' in the table, using table_style"""
        row_index, col_index = cell_coord
        cell_value = table.data[row_index][col_index]
        final_content = self._make_cell_content(cell_value, table_style, col_index + 1)
        return self._render_cell_content(final_content, table_style, col_index + 1)

    def render_row_cell(
        self, row_name: str, table: Table, table_style: TableStyle
    ) -> Union[str, int]:
        """Renders the cell for 'row_id' row"""
        cell_value = row_name
        return self._render_cell_content(cell_value, table_style, 0)

    def render_col_cell(
        self, col_name: str, table: Table, table_style: TableStyle
    ) -> Union[str, int]:
        """Renders the cell for 'col_id' row"""
        cell_value = col_name
        col_index = table.col_names.index(col_name)
        return self._render_cell_content(cell_value, table_style, col_index + 1)

    def _render_cell_content(
        self, content: Union[str, int], table_style: TableStyle, col_index: int
    ) -> Union[str, int]:
        """Makes the appropriate rendering for this cell content.
        Rendering properties will be searched using the
        *table_style.get_xxx_by_index(col_index)' methods

        **This method should be overridden in the derived renderer classes.**
        """
        return content

    def _make_cell_content(
        self, cell_content: int, table_style: TableStyle, col_index: int
    ) -> Union[int, str]:
        """Makes the cell content (adds decoration data, like units for
        example)
        """
        final_content: Union[int, str] = cell_content

        if "skip_zero" in self.properties:
            replacement_char = self.properties["skip_zero"]
        else:
            replacement_char = 0
        if replacement_char and final_content == 0:
            return replacement_char

        try:
            units_on = self.properties["units"]
            if units_on:
                final_content = self._add_unit(cell_content, table_style, col_index)
        except KeyError:
            pass

        return final_content

    def _add_unit(self, cell_content: int, table_style: TableStyle, col_index: int) -> str:
        """Adds unit to the cell_content if needed"""
        unit = table_style.get_unit_by_index(col_index)
        return str(cell_content) + " " + unit


class DocbookRenderer(TableCellRenderer):
    """Defines how to render a cell for a docboook table"""

    def define_col_header(self, col_index: int, table_style: TableStyle) -> str:
        """Computes the colspec element according to the style"""
        size = table_style.get_size_by_index(col_index)
        return '<colspec colname="c%d" colwidth="%s"/>\n' % (col_index, size)

    def _render_cell_content(
        self, cell_content: Union[int, str], table_style: TableStyle, col_index: int
    ) -> str:
        """Makes the appropriate rendering for this cell content.
        Rendering properties will be searched using the
        table_style.get_xxx_by_index(col_index)' methods.
        """
        try:
            align_on = self.properties["alignment"]
            alignment = table_style.get_alignment_by_index(col_index)
            if align_on:
                return "<entry align='%s'>%s</entry>\n" % (alignment, cell_content)
        except KeyError:
            # KeyError <=> Default alignment
            return "<entry>%s</entry>\n" % cell_content

        # XXX really?
        return ""


class TableWriter:
    """A class to write tables"""

    def __init__(
        self, stream: StringIO, table: Table, style: Optional[Any], **properties: Any
    ) -> None:
        self._stream = stream
        self.style = style or TableStyle(table)
        self._table = table
        self.properties = properties
        self.renderer: Optional[DocbookRenderer] = None

    def set_style(self, style):
        """sets the table's associated style"""
        self.style = style

    def set_renderer(self, renderer: DocbookRenderer) -> None:
        """sets the way to render cell"""
        self.renderer = renderer

    def update_properties(self, **properties):
        """Updates writer's properties (for cell rendering)"""
        self.properties.update(properties)

    def write_table(self, title: str = "") -> None:
        """Writes the table"""
        raise NotImplementedError("write_table must be implemented !")


class DocbookTableWriter(TableWriter):
    """Defines an implementation of TableWriter to write a table in Docbook"""

    def _write_headers(self) -> None:
        """Writes col headers"""
        assert self.renderer is not None

        # Define col_headers (colstpec elements)
        for col_index in range(len(self._table.col_names) + 1):
            self._stream.write(self.renderer.define_col_header(col_index, self.style))

        self._stream.write("<thead>\n<row>\n")
        # XXX FIXME : write an empty entry <=> the first (__row_column) column
        self._stream.write("<entry></entry>\n")
        for col_name in self._table.col_names:
            self._stream.write(self.renderer.render_col_cell(col_name, self._table, self.style))

        self._stream.write("</row>\n</thead>\n")

    def _write_body(self) -> None:
        """Writes the table body"""
        assert self.renderer is not None

        self._stream.write("<tbody>\n")

        for row_index, row in enumerate(self._table.data):
            self._stream.write("<row>\n")
            row_name = self._table.row_names[row_index]
            # Write the first entry (row_name)
            self._stream.write(self.renderer.render_row_cell(row_name, self._table, self.style))

            for col_index, cell in enumerate(row):
                self._stream.write(
                    self.renderer.render_cell((row_index, col_index), self._table, self.style)
                )

            self._stream.write("</row>\n")

        self._stream.write("</tbody>\n")

    def write_table(self, title: str = "") -> None:
        """Writes the table"""
        self._stream.write("<table>\n<title>%s></title>\n" % (title))
        self._stream.write(
            '<tgroup cols="%d" align="left" colsep="1" rowsep="1">\n'
            % (len(self._table.col_names) + 1)
        )
        self._write_headers()
        self._write_body()

        self._stream.write("</tgroup>\n</table>\n")