import copy
import enum
import re
from collections import OrderedDict
from typing import Dict, Iterable, Iterator, List, Optional, Tuple
from xml.etree.cElementTree import Element, SubElement, tostring
from xml.sax.saxutils import unescape

from latex2mathml import commands
from latex2mathml.symbols_parser import convert_symbol
from latex2mathml.walker import Node, walk

COLUMN_ALIGNMENT_MAP = {"r": "right", "l": "left", "c": "center"}
OPERATORS = (
    "+",
    "-",
    "*",
    "/",
    "(",
    ")",
    "=",
    ",",
    "?",
    "[",
    "]",
    "|",
    r"\|",
    "!",
    r"\{",
    r"\}",
    r">",
    r"<",
    r".",
    r"\bigotimes",
    r"\centerdot",
    r"\dots",
    r"\dotsc",
    r"\dotso",
    r"\gt",
    r"\ldotp",
    r"\lt",
    r"\lvert",
    r"\lVert",
    r"\lvertneqq",
    r"\ngeqq",
    r"\omicron",
    r"\rvert",
    r"\rVert",
    r"\S",
    r"\smallfrown",
    r"\smallint",
    r"\smallsmile",
    r"\surd",
    r"\varsubsetneqq",
    r"\varsupsetneqq",
)
MATH_MODE_PATTERN = re.compile(r"\\\$|\$|\\?[^\\$]+")


class Mode(enum.Enum):
    TEXT = enum.auto()
    MATH = enum.auto()


def convert(latex: str, xmlns: str = "http://www.w3.org/1998/Math/MathML", display: str = "inline") -> str:
    math = Element("math", xmlns=xmlns, display=display)
    row = SubElement(math, "mrow")
    _convert_group(iter(walk(latex)), row)
    return _convert(math)


def _convert(tree: Element) -> str:
    return unescape(tostring(tree, encoding="unicode"))


def _convert_matrix(nodes: Iterator[Node], parent: Element, command: str, alignment: Optional[str] = None) -> None:
    row = None
    cell = None

    col_index = 0
    col_alignment = None

    max_col_size = 0

    row_index = 0
    row_lines = []

    hfil_indexes: List[bool] = []

    for node in nodes:
        if row is None:
            row = SubElement(parent, "mtr")

        if cell is None:
            col_alignment, col_index = _get_column_alignment(alignment, col_alignment, col_index)
            cell = _make_matrix_cell(row, col_alignment)

        if node.token == commands.BRACES:
            _convert_group(iter([node]), cell)
        elif node.token == "&":
            _set_cell_alignment(cell, hfil_indexes)
            hfil_indexes = []
            col_alignment, col_index = _get_column_alignment(alignment, col_alignment, col_index)
            cell = _make_matrix_cell(row, col_alignment)
            if command in (commands.SPLIT, commands.ALIGN) and col_index % 2 == 0:
                SubElement(cell, "mi")
        elif node.token in (commands.DOUBLEBACKSLASH, commands.CARRIAGE_RETURN):
            _set_cell_alignment(cell, hfil_indexes)
            hfil_indexes = []
            row_index += 1
            if col_index > max_col_size:
                max_col_size = col_index
            col_index = 0
            col_alignment, col_index = _get_column_alignment(alignment, col_alignment, col_index)
            row = SubElement(parent, "mtr")
            cell = _make_matrix_cell(row, col_alignment)
        elif node.token == commands.HLINE:
            row_lines.append("solid")
        elif node.token == commands.HDASHLINE:
            row_lines.append("dashed")
        elif node.token == commands.HFIL:
            hfil_indexes.append(True)
        else:
            if row_index > len(row_lines):
                row_lines.append("none")
            hfil_indexes.append(False)
            _convert_group(iter([node]), cell)

    if col_index > max_col_size:
        max_col_size = col_index

    if any(r == "solid" for r in row_lines):
        parent.set("rowlines", " ".join(row_lines))

    if row is not None and cell is not None and len(cell) == 0:
        # Remove last row if it does not contain anything
        parent.remove(row)

    if max_col_size and command == commands.ALIGN:
        spacing = ("0em", "2em")
        multiplier = max_col_size // len(spacing)
        parent.set("columnspacing", " ".join(spacing * multiplier))


def _set_cell_alignment(cell: Element, hfil_indexes: List[bool]) -> None:
    if cell is not None and any(hfil_indexes) and len(hfil_indexes) > 1:
        if hfil_indexes[0] and not hfil_indexes[-1]:
            cell.attrib["columnalign"] = "right"
        elif not hfil_indexes[0] and hfil_indexes[-1]:
            cell.attrib["columnalign"] = "left"


def _get_column_alignment(
    alignment: Optional[str], column_alignment: Optional[str], column_index: int
) -> Tuple[Optional[str], int]:
    if alignment:
        try:
            column_alignment = COLUMN_ALIGNMENT_MAP.get(alignment[column_index])
        except IndexError:
            column_alignment = COLUMN_ALIGNMENT_MAP.get(alignment[column_index % len(alignment)])
        column_index += 1
    return column_alignment, column_index


def _make_matrix_cell(row: Element, column_alignment: Optional[str]) -> Element:
    if column_alignment:
        return SubElement(row, "mtd", columnalign=column_alignment)
    return SubElement(row, "mtd")


def _convert_group(nodes: Iterable[Node], parent: Element, font: Optional[Dict[str, Optional[str]]] = None) -> None:
    _font = font
    for node in nodes:
        token = node.token
        if token in (*commands.MSTYLE_SIZES, *commands.STYLES):
            node = Node(token=token, children=tuple(n for n in nodes))
            _convert_command(node, parent, _font)
        elif token in commands.CONVERSION_MAP or token in (commands.MOD, commands.PMOD):
            _convert_command(node, parent, _font)
        elif token in commands.LOCAL_FONTS and node.children is not None:
            _convert_group(iter(node.children), parent, commands.LOCAL_FONTS[token])
        elif token.startswith(commands.MATH) and node.children is not None:
            _convert_group(iter(node.children), parent, _font)
        elif token in commands.GLOBAL_FONTS.keys():
            _font = commands.GLOBAL_FONTS.get(token)
        elif node.children is None:
            _convert_symbol(node, parent, _font)
        elif node.children is not None:
            attributes = node.attributes or {}
            _row = SubElement(parent, "mrow", attrib=attributes)
            _convert_group(iter(node.children), _row, _font)


def _get_alignment_and_column_lines(alignment: Optional[str] = None) -> Tuple[Optional[str], Optional[str]]:
    if alignment is None:
        return None, None
    if "|" not in alignment:
        return alignment, None
    _alignment = ""
    column_lines = []
    for c in alignment:
        if c == "|":
            column_lines.append("solid")
        else:
            _alignment += c
        if len(_alignment) - len(column_lines) == 2:
            column_lines.append("none")
    return _alignment, " ".join(column_lines)


def separate_by_mode(text: str) -> Iterator[Tuple[str, Mode]]:
    string = ""
    is_math_mode = False
    for match in MATH_MODE_PATTERN.findall(text):
        if match == "$":  # should match both $ and  $$
            yield string, Mode.MATH if is_math_mode else Mode.TEXT
            string = ""
            is_math_mode = not is_math_mode
        else:
            string += match
    if len(string):
        yield string, Mode.MATH if is_math_mode else Mode.TEXT
    # TODO: if stays in math mode, means not terminated properly, raise error


def _convert_command(node: Node, parent: Element, font: Optional[Dict[str, Optional[str]]] = None) -> None:
    command = node.token
    modifier = node.modifier

    if command in (commands.SUBSTACK, commands.SMALLMATRIX):
        parent = SubElement(parent, "mstyle", scriptlevel="1")
    elif command == commands.CASES:
        parent = SubElement(parent, "mrow")
        lbrace = SubElement(parent, "mo", OrderedDict([("stretchy", "true"), ("fence", "true"), ("form", "prefix")]))
        lbrace.text = "&#x{};".format(convert_symbol(commands.LBRACE))
    elif command in (commands.DBINOM, commands.DFRAC):
        parent = SubElement(parent, "mstyle", displaystyle="true", scriptlevel="0")
    elif command == commands.HPHANTOM:
        parent = SubElement(parent, "mpadded", height="0", depth="0")
    elif command == commands.VPHANTOM:
        parent = SubElement(parent, "mpadded", width="0")
    elif command in (commands.TBINOM, commands.HBOX, commands.MBOX, commands.TFRAC):
        parent = SubElement(parent, "mstyle", displaystyle="false", scriptlevel="0")
    elif command in (commands.MOD, commands.PMOD):
        SubElement(parent, "mspace", width="1em")

    tag, attributes = copy.deepcopy(commands.CONVERSION_MAP[command])

    if node.attributes is not None and node.token != commands.SKEW:
        attributes.update(node.attributes)

    if command == commands.LEFT:
        parent = SubElement(parent, "mrow")

    _append_prefix_element(node, parent)

    alignment, column_lines = _get_alignment_and_column_lines(node.alignment)

    if column_lines:
        attributes["columnlines"] = column_lines

    if command == commands.SUBSUP and node.children is not None and node.children[0].token == commands.GCD:
        tag = "munderover"
    elif command == commands.SUPERSCRIPT and modifier in (commands.LIMITS, commands.OVERBRACE):
        tag = "mover"
    elif command == commands.SUBSCRIPT and modifier in (commands.LIMITS, commands.UNDERBRACE):
        tag = "munder"
    elif command == commands.SUBSUP and modifier in (commands.LIMITS, commands.OVERBRACE, commands.UNDERBRACE):
        tag = "munderover"
    elif (
        command in (commands.XLEFTARROW, commands.XRIGHTARROW) and node.children is not None and len(node.children) == 2
    ):
        tag = "munderover"

    element = SubElement(parent, tag, attributes)

    if command in commands.LIMIT:
        element.text = command[1:]
    elif command in (commands.MOD, commands.PMOD):
        element.text = "mod"
        SubElement(parent, "mspace", width="0.333em")
    elif command == commands.BMOD:
        element.text = "mod"
    elif command in (commands.XLEFTARROW, commands.XRIGHTARROW):
        style = SubElement(element, "mstyle", scriptlevel="0")
        arrow = SubElement(style, "mo")
        if command == commands.XLEFTARROW:
            arrow.text = "&#x2190;"
        elif command == commands.XRIGHTARROW:
            arrow.text = "&#x2192;"
    elif node.text is not None:
        if command == commands.MIDDLE:
            element.text = "&#x{};".format(convert_symbol(node.text))
        elif command == commands.HBOX:
            mtext: Optional[Element] = element
            for text, mode in separate_by_mode(node.text):
                if mode == Mode.TEXT:
                    if mtext is None:
                        mtext = SubElement(parent, tag, attributes)
                    mtext.text = text.replace(" ", "&#x000A0;")
                    _set_font(mtext, "mtext", font)
                    mtext = None
                else:
                    _row = SubElement(parent, "mrow")
                    _convert_group(iter(walk(text)), _row)
        else:
            if command == commands.FBOX:
                element = SubElement(element, "mtext")
            element.text = node.text.replace(" ", "&#x000A0;")
            _set_font(element, "mtext", font)
    elif node.delimiter is not None and command not in (commands.FRAC, commands.GENFRAC):
        if node.delimiter != ".":
            symbol = convert_symbol(node.delimiter)
            element.text = node.delimiter if symbol is None else "&#x{};".format(symbol)

    if node.children is not None:
        _parent = element
        if command in (commands.LEFT, commands.MOD, commands.PMOD):
            _parent = parent
        if command in commands.MATRICES:
            if command == commands.CASES:
                alignment = "l"
            elif command in (commands.SPLIT, commands.ALIGN):
                alignment = "rl"
            _convert_matrix(iter(node.children), _parent, command, alignment=alignment)
        elif command == commands.CFRAC:
            for child in node.children:
                p = SubElement(_parent, "mstyle", displaystyle="false", scriptlevel="0")
                _convert_group(iter([child]), p, font)
        elif command == commands.SIDESET:
            Node(
                r"\style",
                children=(Node(r"\mspace", attributes={"width": "-0.167em"}),),
                attributes={"scriptlevel": "0"},
            ),
            left, right = node.children
            _convert_group(iter([left]), _parent, font)
            fill = SubElement(_parent, "mstyle", scriptlevel="0")
            SubElement(fill, "mspace", width="-0.167em")
            _convert_group(iter([right]), _parent, font)
        elif command == commands.SKEW:
            child = node.children[0]
            new_node = Node(
                token=child.token,
                children=(
                    Node(
                        token=commands.BRACES,
                        children=(*child.children, Node(token=commands.MKERN, attributes=node.attributes)),
                    ),
                ),
            )
            _convert_group(iter([new_node]), _parent, font)
        elif command in (commands.XLEFTARROW, commands.XRIGHTARROW):
            for child in node.children:
                padded = SubElement(
                    _parent,
                    "mpadded",
                    OrderedDict(
                        [("width", "+0.833em"), ("lspace", "0.556em"), ("voffset", "-.2em"), ("height", "-.2em")]
                    ),
                )
                _convert_group(iter([child]), padded, font)
                SubElement(padded, "mspace", depth=".25em")
        else:
            _convert_group(iter(node.children), _parent, font)

    _add_diacritic(command, element)

    _append_postfix_element(node, parent)


def _add_diacritic(command: str, parent: Element) -> None:
    if command in commands.DIACRITICS:
        text, attributes = copy.deepcopy(commands.DIACRITICS[command])
        element = SubElement(parent, "mo", attributes)
        element.text = text


def _convert_and_append_command(command: str, parent: Element, attributes: Optional[Dict[str, str]] = None) -> None:
    code_point = convert_symbol(command)
    mo = SubElement(parent, "mo", attributes if attributes is not None else {})
    mo.text = "&#x{};".format(code_point) if code_point else command


def _append_prefix_element(node: Node, parent: Element) -> None:
    size = "2.047em"
    if parent.attrib.get("displaystyle") == "false" or node.token == commands.TBINOM:
        size = "1.2em"
    if node.token in (r"\pmatrix", commands.PMOD):
        _convert_and_append_command(r"\lparen", parent)
    elif node.token in (commands.BINOM, commands.DBINOM, commands.TBINOM):
        _convert_and_append_command(r"\lparen", parent, {"minsize": size, "maxsize": size})
    elif node.token == r"\bmatrix":
        _convert_and_append_command(r"\lbrack", parent)
    elif node.token == r"\Bmatrix":
        _convert_and_append_command(r"\lbrace", parent)
    elif node.token == r"\vmatrix":
        _convert_and_append_command(r"\vert", parent)
    elif node.token == r"\Vmatrix":
        _convert_and_append_command(r"\Vert", parent)
    elif node.token in (commands.FRAC, commands.GENFRAC) and node.delimiter is not None and node.delimiter[0] != ".":
        # TODO: use 1.2em if inline
        _convert_and_append_command(node.delimiter[0], parent, {"minsize": size, "maxsize": size})


def _append_postfix_element(node: Node, parent: Element) -> None:
    size = "2.047em"
    if parent.attrib.get("displaystyle") == "false" or node.token == commands.TBINOM:
        size = "1.2em"
    if node.token in (r"\pmatrix", commands.PMOD):
        _convert_and_append_command(r"\rparen", parent)
    elif node.token in (commands.BINOM, commands.DBINOM, commands.TBINOM):
        _convert_and_append_command(r"\rparen", parent, {"minsize": size, "maxsize": size})
    elif node.token == r"\bmatrix":
        _convert_and_append_command(r"\rbrack", parent)
    elif node.token == r"\Bmatrix":
        _convert_and_append_command(r"\rbrace", parent)
    elif node.token == r"\vmatrix":
        _convert_and_append_command(r"\vert", parent)
    elif node.token == r"\Vmatrix":
        _convert_and_append_command(r"\Vert", parent)
    elif node.token in (commands.FRAC, commands.GENFRAC) and node.delimiter is not None and node.delimiter[1] != ".":
        # TODO: use 1.2em if inline
        _convert_and_append_command(node.delimiter[1], parent, {"minsize": size, "maxsize": size})
    elif node.token == commands.SKEW and node.attributes is not None:
        SubElement(parent, "mspace", width="-" + node.attributes["width"])


def _convert_symbol(node: Node, parent: Element, font: Optional[Dict[str, Optional[str]]] = None) -> None:
    token = node.token
    attributes = node.attributes or {}
    symbol = convert_symbol(token)
    if re.match(r"\d+(.\d+)?", token):
        element = SubElement(parent, "mn", attrib=attributes)
        element.text = token
        _set_font(element, element.tag, font)
    elif token in OPERATORS:
        element = SubElement(parent, "mo", attrib=attributes)
        element.text = token if symbol is None else "&#x{};".format(symbol)
        if token == r"\|":
            element.attrib["fence"] = "false"
        if token == r"\smallint":
            element.attrib["largeop"] = "false"
        if token in ("(", ")", "[", "]", "|", r"\|", r"\{", r"\}", r"\surd"):
            element.attrib["stretchy"] = "false"
            _set_font(element, "fence", font)
        else:
            _set_font(element, element.tag, font)
    elif (
        symbol
        and (
            int(symbol, 16) in range(int("2200", 16), int("22FF", 16) + 1)
            or int(symbol, 16) in range(int("2190", 16), int("21FF", 16) + 1)
        )
        or symbol == "."
    ):
        element = SubElement(parent, "mo", attrib=attributes)
        element.text = "&#x{};".format(symbol)
        _set_font(element, element.tag, font)
    elif token in (r"\ ", "~", commands.NOBREAKSPACE, commands.SPACE):
        element = SubElement(parent, "mtext", attrib=attributes)
        element.text = "&#x000A0;"
        _set_font(element, "mtext", font)
    elif token == commands.NOT:
        mpadded = SubElement(parent, "mpadded", width="0")
        element = SubElement(mpadded, "mtext")
        element.text = "&#x029F8;"
    elif token in (
        commands.DETERMINANT,
        commands.GCD,
        commands.INTOP,
        commands.INJLIM,
        commands.LIMINF,
        commands.LIMSUP,
        commands.PR,
        commands.PROJLIM,
    ):
        element = SubElement(parent, "mo", attrib={"movablelimits": "true", **attributes})
        texts = {
            commands.INJLIM: "inj&#x02006;lim",
            commands.INTOP: "&#x0222B;",
            commands.LIMINF: "lim&#x02006;inf",
            commands.LIMSUP: "lim&#x02006;sup",
            commands.PROJLIM: "proj&#x02006;lim",
        }
        element.text = texts.get(token, token[1:])
        _set_font(element, element.tag, font)
    elif token == commands.IDOTSINT:
        _parent = SubElement(parent, "mrow", attrib=attributes)
        for s in ("&#x0222B;", "&#x022EF;", "&#x0222B;"):
            element = SubElement(_parent, "mo")
            element.text = s
    elif token in (commands.LATEX, commands.TEX):
        _parent = SubElement(parent, "mrow", attrib=attributes)
        if token == commands.LATEX:
            mi_l = SubElement(_parent, "mi")
            mi_l.text = "L"
            SubElement(_parent, "mspace", width="-.325em")
            mpadded = SubElement(_parent, "mpadded", height="+.21ex", depth="-.21ex", voffset="+.21ex")
            mstyle = SubElement(mpadded, "mstyle", displaystyle="false", scriptlevel="1")
            mrow = SubElement(mstyle, "mrow")
            mi_a = SubElement(mrow, "mi")
            mi_a.text = "A"
            SubElement(_parent, "mspace", width="-.17em")
            _set_font(mi_l, mi_l.tag, font)
            _set_font(mi_a, mi_a.tag, font)
        mi_t = SubElement(_parent, "mi")
        mi_t.text = "T"
        SubElement(_parent, "mspace", width="-.14em")
        mpadded = SubElement(_parent, "mpadded", height="-.5ex", depth="+.5ex", voffset="-.5ex")
        mrow = SubElement(mpadded, "mrow")
        mi_e = SubElement(mrow, "mi")
        mi_e.text = "E"
        SubElement(_parent, "mspace", width="-.115em")
        mi_x = SubElement(_parent, "mi")
        mi_x.text = "X"
        _set_font(mi_t, mi_t.tag, font)
        _set_font(mi_e, mi_e.tag, font)
        _set_font(mi_x, mi_x.tag, font)
    elif token.startswith(commands.OPERATORNAME):
        element = SubElement(parent, "mo", attrib=attributes)
        element.text = token[14:-1]
    elif token.startswith(commands.BACKSLASH):
        element = SubElement(parent, "mi", attrib=attributes)
        if symbol:
            element.text = "&#x{};".format(symbol)
        elif token in commands.FUNCTIONS:
            element.text = token[1:]
        else:
            element.text = token
        _set_font(element, element.tag, font)
    else:
        element = SubElement(parent, "mi", attrib=attributes)
        element.text = token
        _set_font(element, element.tag, font)


def _set_font(element: Element, key: str, font: Optional[Dict[str, Optional[str]]]) -> None:
    if font is None:
        return
    _font = font[key]
    if _font is not None:
        element.attrib["mathvariant"] = _font


def main() -> None:  # pragma: no cover
    import argparse
    import sys

    import pkg_resources

    parser = argparse.ArgumentParser(description="Pure Python library for LaTeX to MathML conversion")
    parser.add_argument("-V", "--version", dest="version", action="store_true", required=False, help="Show version")
    parser.add_argument("-b", "--block", dest="block", action="store_true", required=False, help="Display block")

    required = parser.add_argument_group("required arguments")

    group = required.add_mutually_exclusive_group(required=False)
    group.add_argument("-t", "--text", dest="text", type=str, required=False, help="Text")
    group.add_argument("-f", "--file", dest="file", type=str, required=False, help="File")
    group.add_argument("-s", "--stdin", dest="stdin", action="store_true", required=False, help="Stdin")

    arguments = parser.parse_args()
    display = "block" if arguments.block else "inline"

    if arguments.version:
        version = pkg_resources.get_distribution("latex2mathml").version
        print("latex2mathml", version)
    elif arguments.text:
        print(convert(arguments.text, display=display))
    elif arguments.file:
        with open(arguments.file) as f:
            print(convert(f.read(), display=display))
    elif arguments.stdin:
        print(convert(sys.stdin.read(), display=display))


if __name__ == "__main__":  # pragma: no cover
    main()
