# This is where we handle translating css styles into openpyxl styles
# and cascading those from parent to child in the dom.

try:
    from openpyxl.cell import cell
    from openpyxl.styles import (
        Font,
        Alignment,
        PatternFill,
        NamedStyle,
        Border,
        Side,
        Color,
    )
    from openpyxl.styles.fills import FILL_SOLID
    from openpyxl.styles.numbers import FORMAT_CURRENCY_USD_SIMPLE, FORMAT_PERCENTAGE
    from openpyxl.styles.colors import BLACK
except:
    import warnings

    warnings.warn(
        "Can not import openpyxl, some functions in the ppstructure may not work. Please manually install openpyxl before using ppstructure."
    )

FORMAT_DATE_MMDDYYYY = "mm/dd/yyyy"


def colormap(color):
    """
    Convenience for looking up known colors
    """
    cmap = {"black": BLACK}
    return cmap.get(color, color)


def style_string_to_dict(style):
    """
    Convert css style string to a python dictionary
    """

    def clean_split(string, delim):
        return (s.strip() for s in string.split(delim))

    styles = [clean_split(s, ":") for s in style.split(";") if ":" in s]
    return dict(styles)


def get_side(style, name):
    return {
        "border_style": style.get("border-{}-style".format(name)),
        "color": colormap(style.get("border-{}-color".format(name))),
    }


known_styles = {}


def style_dict_to_named_style(style_dict, number_format=None):
    """
    Change css style (stored in a python dictionary) to openpyxl NamedStyle
    """

    style_and_format_string = str(
        {
            "style_dict": style_dict,
            "parent": style_dict.parent,
            "number_format": number_format,
        }
    )

    if style_and_format_string not in known_styles:
        # Font
        font = Font(
            bold=style_dict.get("font-weight") == "bold",
            color=style_dict.get_color("color", None),
            size=style_dict.get("font-size"),
        )

        # Alignment
        alignment = Alignment(
            horizontal=style_dict.get("text-align", "general"),
            vertical=style_dict.get("vertical-align"),
            wrap_text=style_dict.get("white-space", "nowrap") == "normal",
        )

        # Fill
        bg_color = style_dict.get_color("background-color")
        fg_color = style_dict.get_color("foreground-color", Color())
        fill_type = style_dict.get("fill-type")
        if bg_color and bg_color != "transparent":
            fill = PatternFill(
                fill_type=fill_type or FILL_SOLID,
                start_color=bg_color,
                end_color=fg_color,
            )
        else:
            fill = PatternFill()

        # Border
        border = Border(
            left=Side(**get_side(style_dict, "left")),
            right=Side(**get_side(style_dict, "right")),
            top=Side(**get_side(style_dict, "top")),
            bottom=Side(**get_side(style_dict, "bottom")),
            diagonal=Side(**get_side(style_dict, "diagonal")),
            diagonal_direction=None,
            outline=Side(**get_side(style_dict, "outline")),
            vertical=None,
            horizontal=None,
        )

        name = "Style {}".format(len(known_styles) + 1)

        pyxl_style = NamedStyle(
            name=name,
            font=font,
            fill=fill,
            alignment=alignment,
            border=border,
            number_format=number_format,
        )

        known_styles[style_and_format_string] = pyxl_style

    return known_styles[style_and_format_string]


class StyleDict(dict):
    """
    It's like a dictionary, but it looks for items in the parent dictionary
    """

    def __init__(self, *args, **kwargs):
        self.parent = kwargs.pop("parent", None)
        super(StyleDict, self).__init__(*args, **kwargs)

    def __getitem__(self, item):
        if item in self:
            return super(StyleDict, self).__getitem__(item)
        elif self.parent:
            return self.parent[item]
        else:
            raise KeyError("{} not found".format(item))

    def __hash__(self):
        return hash(tuple([(k, self.get(k)) for k in self._keys()]))

    # Yielding the keys avoids creating unnecessary data structures
    # and happily works with both python2 and python3 where the
    # .keys() method is a dictionary_view in python3 and a list in python2.
    def _keys(self):
        yielded = set()
        for k in self.keys():
            yielded.add(k)
            yield k
        if self.parent:
            for k in self.parent._keys():
                if k not in yielded:
                    yielded.add(k)
                    yield k

    def get(self, k, d=None):
        try:
            return self[k]
        except KeyError:
            return d

    def get_color(self, k, d=None):
        """
        Strip leading # off colors if necessary
        """
        color = self.get(k, d)
        if hasattr(color, "startswith") and color.startswith("#"):
            color = color[1:]
            if (
                len(color) == 3
            ):  # Premailers reduces colors like #00ff00 to #0f0, openpyxl doesn't like that
                color = "".join(2 * c for c in color)
        return color


class Element(object):
    """
    Our base class for representing an html element along with a cascading style.
    The element is created along with a parent so that the StyleDict that we store
    can point to the parent's StyleDict.
    """

    def __init__(self, element, parent=None):
        self.element = element
        self.number_format = None
        parent_style = parent.style_dict if parent else None
        self.style_dict = StyleDict(
            style_string_to_dict(element.get("style", "")), parent=parent_style
        )
        self._style_cache = None

    def style(self):
        """
        Turn the css styles for this element into an openpyxl NamedStyle.
        """
        if not self._style_cache:
            self._style_cache = style_dict_to_named_style(
                self.style_dict, number_format=self.number_format
            )
        return self._style_cache

    def get_dimension(self, dimension_key):
        """
        Extracts the dimension from the style dict of the Element and returns it as a float.
        """
        dimension = self.style_dict.get(dimension_key)
        if dimension:
            if dimension[-2:] in ["px", "em", "pt", "in", "cm"]:
                dimension = dimension[:-2]
            dimension = float(dimension)
        return dimension


class Table(Element):
    """
    The concrete implementations of Elements are semantically named for the types of elements we are interested in.
    This defines a very concrete tree structure for html tables that we expect to deal with. I prefer this compared to
    allowing Element to have an arbitrary number of children and dealing with an abstract element tree.
    """

    def __init__(self, table):
        """
        takes an html table object (from lxml)
        """
        super(Table, self).__init__(table)
        table_head = table.find("thead")
        self.head = (
            TableHead(table_head, parent=self) if table_head is not None else None
        )
        table_body = table.find("tbody")
        self.body = TableBody(
            table_body if table_body is not None else table, parent=self
        )


class TableHead(Element):
    """
    This class maps to the `<th>` element of the html table.
    """

    def __init__(self, head, parent=None):
        super(TableHead, self).__init__(head, parent=parent)
        self.rows = [TableRow(tr, parent=self) for tr in head.findall("tr")]


class TableBody(Element):
    """
    This class maps to the `<tbody>` element of the html table.
    """

    def __init__(self, body, parent=None):
        super(TableBody, self).__init__(body, parent=parent)
        self.rows = [TableRow(tr, parent=self) for tr in body.findall("tr")]


class TableRow(Element):
    """
    This class maps to the `<tr>` element of the html table.
    """

    def __init__(self, tr, parent=None):
        super(TableRow, self).__init__(tr, parent=parent)
        self.cells = [
            TableCell(cell, parent=self) for cell in tr.findall("th") + tr.findall("td")
        ]


def element_to_string(el):
    return _element_to_string(el).strip()


def _element_to_string(el):
    string = ""

    for x in el.iterchildren():
        string += "\n" + _element_to_string(x)

    text = el.text.strip() if el.text else ""
    tail = el.tail.strip() if el.tail else ""

    return text + string + "\n" + tail


class TableCell(Element):
    """
    This class maps to the `<td>` element of the html table.
    """

    CELL_TYPES = {
        "TYPE_STRING",
        "TYPE_FORMULA",
        "TYPE_NUMERIC",
        "TYPE_BOOL",
        "TYPE_CURRENCY",
        "TYPE_PERCENTAGE",
        "TYPE_NULL",
        "TYPE_INLINE",
        "TYPE_ERROR",
        "TYPE_FORMULA_CACHE_STRING",
        "TYPE_INTEGER",
    }

    def __init__(self, cell, parent=None):
        super(TableCell, self).__init__(cell, parent=parent)
        self.value = element_to_string(cell)
        self.number_format = self.get_number_format()

    def data_type(self):
        cell_types = self.CELL_TYPES & set(self.element.get("class", "").split())
        if cell_types:
            if "TYPE_FORMULA" in cell_types:
                # Make sure TYPE_FORMULA takes precedence over the other classes in the set.
                cell_type = "TYPE_FORMULA"
            elif cell_types & {"TYPE_CURRENCY", "TYPE_INTEGER", "TYPE_PERCENTAGE"}:
                cell_type = "TYPE_NUMERIC"
            else:
                cell_type = cell_types.pop()
        else:
            cell_type = "TYPE_STRING"
        return getattr(cell, cell_type)

    def get_number_format(self):
        if "TYPE_CURRENCY" in self.element.get("class", "").split():
            return FORMAT_CURRENCY_USD_SIMPLE
        if "TYPE_INTEGER" in self.element.get("class", "").split():
            return "#,##0"
        if "TYPE_PERCENTAGE" in self.element.get("class", "").split():
            return FORMAT_PERCENTAGE
        if "TYPE_DATE" in self.element.get("class", "").split():
            return FORMAT_DATE_MMDDYYYY
        if self.data_type() == cell.TYPE_NUMERIC:
            try:
                int(self.value)
            except ValueError:
                return "#,##0.##"
            else:
                return "#,##0"

    def format(self, cell):
        cell.style = self.style()
        data_type = self.data_type()
        if data_type:
            cell.data_type = data_type
