import re
from . import Parser, BlockState
from .tokens import ALPHANUM

from .tokens import (
    Token,
    CommentToken,
    StringToken,
    UnterminatedStringToken,
    IdentifierToken,
    NonIdentifierToken,
    KeywordToken,
    NumberToken,
)

# todo: compiler directives (or how do you call these things starting with #)


class MultilineCommentToken(CommentToken):
    """Characters representing a multi-line comment."""

    defaultStyle = "fore:#007F00"


class CharToken(Token):
    """Single-quoted char"""

    defaultStyle = "fore:#7F007F"


# This regexp is used to find special stuff, such as comments, numbers and
# strings.
tokenProg = re.compile(
    "(["
    + ALPHANUM
    + "_]+)|"  # Identifiers/numbers (group 1) or
    + "(//)|"  # Single line comment (group 2)
    + "(/\\*)|"  # Comment (group 3) or
    + "('\\\\?.')|"  # char (group 4)
    + '(")'  # string (group 5)
)


# For a string, get the RegExp
# program that matches the end. (^|[^\\]) means: start of the line
# or something that is not \ (since \ is supposed to escape the following
# quote) (\\\\)* means: any number of two slashes \\ since each slash will
# escape the next one
stringEndProg = re.compile(r'(^|[^\\])(\\\\)*"')
commentEndProg = re.compile(r"\*/")


class CParser(Parser):
    """A C parser."""

    _extensions = [".c", ".h", ".cpp", "cxx", "hxx"]
    _keywords = ["int", "const", "char", "void", "short", "long", "case"]

    def parseLine(self, line, previousState=0):
        """Parses a line of C code, returning a list of tokens."""

        pos = 0  # Position following the previous match

        tokensForLine = []

        # identifierState and previousstate values:
        # 0: nothing special
        # 1: string
        # 2: multiline comment /* */

        # First determine whether we should look for the end of a string,
        # or if we should process a token.
        if previousState == 1:
            token = StringToken(line, 0, 0)
            tokens = self._findEndOfString(line, token)
            # Process tokens
            for token in tokens:
                tokensForLine.append(token)
                if isinstance(token, BlockState):
                    return tokensForLine
            pos = token.end
        elif previousState == 2:
            token = MultilineCommentToken(line, 0, 0)
            tokens = self._findEndOfComment(line, token)
            # Process tokens
            for token in tokens:
                tokensForLine.append(token)
                if isinstance(token, BlockState):
                    return tokensForLine
            pos = token.end

        # Enter the main loop that iterates over the tokens and skips strings
        while True:
            # Get next tokens
            tokens = self._findNextToken(line, pos)
            if not tokens:
                return tokensForLine
            elif isinstance(tokens[-1], StringToken):
                moreTokens = self._findEndOfString(line, tokens[-1])
                tokens = tokens[:-1] + moreTokens
            elif isinstance(tokens[-1], MultilineCommentToken):
                moreTokens = self._findEndOfComment(line, tokens[-1])
                tokens = tokens[:-1] + moreTokens

            # Process tokens
            for token in tokens:
                tokensForLine.append(token)
                if isinstance(token, BlockState):
                    return tokensForLine
            pos = token.end

    def _findEndOfComment(self, line, token):
        """Find the matching comment end in the rest of the line"""

        # Do not use the start parameter of search, since ^ does not work then

        endMatch = commentEndProg.search(line, token.end)

        if endMatch:
            # The comment does end on this line
            token.end = endMatch.end()
            return [token]
        else:
            # The comment does not end on this line
            token.end = len(line)
            return [token, BlockState(2)]

    def _findEndOfString(self, line, token):
        """Find the matching string end in the rest of the line"""

        # todo: distinguish between single and double quote strings

        # Find the matching end in the rest of the line
        # Do not use the start parameter of search, since ^ does not work then
        endMatch = stringEndProg.search(line[token.end :])

        if endMatch:
            # The string does end on this line
            token.end = token.end + endMatch.end()
            return [token]
        else:
            # The string does not end on this line
            if line.strip().endswith("\\"):  # Multi line string
                token = StringToken(line, token.start, len(line))
                return [token, BlockState(1)]
            else:
                return [UnterminatedStringToken(line, token.start, len(line))]

    def _findNextToken(self, line, pos):
        """Returns a token or None if no new tokens can be found."""

        # Init tokens, if positing too large, stop now
        if pos > len(line):
            return None
        tokens = []

        # Find the start of the next string or comment
        match = tokenProg.search(line, pos)

        # Process the Non-Identifier between pos and match.start()
        # or end of line
        nonIdentifierEnd = match.start() if match else len(line)

        # Return the Non-Identifier token if non-null
        token = NonIdentifierToken(line, pos, nonIdentifierEnd)
        if token:
            tokens.append(token)

        # If no match, we are done processing the line
        if not match:
            return tokens

        # The rest is to establish what identifier we are dealing with

        # Identifier ("a word or number") Find out whether it is a key word
        if match.group(1) is not None:
            identifier = match.group(1)
            tokenArgs = line, match.start(), match.end()

            if identifier in self._keywords:
                tokens.append(KeywordToken(*tokenArgs))
            elif identifier[0] in "0123456789":
                # identifierState = 0
                tokens.append(NumberToken(*tokenArgs))
            else:
                tokens.append(IdentifierToken(*tokenArgs))

        # Single line comment
        elif match.group(2) is not None:
            tokens.append(CommentToken(line, match.start(), len(line)))
        elif match.group(3) is not None:
            tokens.append(MultilineCommentToken(line, match.start(), match.end()))
        elif match.group(4) is not None:  # Char
            tokens.append(CharToken(line, match.start(), match.end()))
        else:
            # We have matched a string-start
            tokens.append(StringToken(line, match.start(), match.end()))

        # Done
        return tokens


if __name__ == "__main__":
    parser = CParser()
    for token in parser.parseLine("void test(int i=2) /* test "):
        print(token.name, token)
