from __future__ import absolute_import, division, unicode_literals

from pip._vendor.six import unichr as chr

from collections import deque

from .constants import spaceCharacters
from .constants import entities
from .constants import asciiLetters, asciiUpper2Lower
from .constants import digits, hexDigits, EOF
from .constants import tokenTypes, tagTokenTypes
from .constants import replacementCharacters

from ._inputstream import HTMLInputStream

from ._trie import Trie

entitiesTrie = Trie(entities)


class HTMLTokenizer(object):
    """ This class takes care of tokenizing HTML.

    * self.currentToken
      Holds the token that is currently being processed.

    * self.state
      Holds a reference to the method to be invoked... XXX

    * self.stream
      Points to HTMLInputStream object.
    """

    def __init__(self, stream, parser=None, **kwargs):

        self.stream = HTMLInputStream(stream, **kwargs)
        self.parser = parser

        # Setup the initial tokenizer state
        self.escapeFlag = False
        self.lastFourChars = []
        self.state = self.dataState
        self.escape = False

        # The current token being created
        self.currentToken = None
        super(HTMLTokenizer, self).__init__()

    def __iter__(self):
        """ This is where the magic happens.

        We do our usually processing through the states and when we have a token
        to return we yield the token which pauses processing until the next token
        is requested.
        """
        self.tokenQueue = deque([])
        # Start processing. When EOF is reached self.state will return False
        # instead of True and the loop will terminate.
        while self.state():
            while self.stream.errors:
                yield {"type": tokenTypes["ParseError"], "data": self.stream.errors.pop(0)}
            while self.tokenQueue:
                yield self.tokenQueue.popleft()

    def consumeNumberEntity(self, isHex):
        """This function returns either U+FFFD or the character based on the
        decimal or hexadecimal representation. It also discards ";" if present.
        If not present self.tokenQueue.append({"type": tokenTypes["ParseError"]}) is invoked.
        """

        allowed = digits
        radix = 10
        if isHex:
            allowed = hexDigits
            radix = 16

        charStack = []

        # Consume all the characters that are in range while making sure we
        # don't hit an EOF.
        c = self.stream.char()
        while c in allowed and c is not EOF:
            charStack.append(c)
            c = self.stream.char()

        # Convert the set of characters consumed to an int.
        charAsInt = int("".join(charStack), radix)

        # Certain characters get replaced with others
        if charAsInt in replacementCharacters:
            char = replacementCharacters[charAsInt]
            self.tokenQueue.append({"type": tokenTypes["ParseError"], "data":
                                    "illegal-codepoint-for-numeric-entity",
                                    "datavars": {"charAsInt": charAsInt}})
        elif ((0xD800 <= charAsInt <= 0xDFFF) or
              (charAsInt > 0x10FFFF)):
            char = "\uFFFD"
            self.tokenQueue.append({"type": tokenTypes["ParseError"], "data":
                                    "illegal-codepoint-for-numeric-entity",
                                    "datavars": {"charAsInt": charAsInt}})
        else:
            # Should speed up this check somehow (e.g. move the set to a constant)
            if ((0x0001 <= charAsInt <= 0x0008) or
                (0x000E <= charAsInt <= 0x001F) or
                (0x007F <= charAsInt <= 0x009F) or
                (0xFDD0 <= charAsInt <= 0xFDEF) or
                charAsInt in frozenset([0x000B, 0xFFFE, 0xFFFF, 0x1FFFE,
                                        0x1FFFF, 0x2FFFE, 0x2FFFF, 0x3FFFE,
                                        0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE,
                                        0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE,
                                        0x7FFFF, 0x8FFFE, 0x8FFFF, 0x9FFFE,
                                        0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE,
                                        0xBFFFF, 0xCFFFE, 0xCFFFF, 0xDFFFE,
                                        0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE,
                                        0xFFFFF, 0x10FFFE, 0x10FFFF])):
                self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                        "data":
                                        "illegal-codepoint-for-numeric-entity",
                                        "datavars": {"charAsInt": charAsInt}})
            try:
                # Try/except needed as UCS-2 Python builds' unichar only works
                # within the BMP.
                char = chr(charAsInt)
            except ValueError:
                v = charAsInt - 0x10000
                char = chr(0xD800 | (v >> 10)) + chr(0xDC00 | (v & 0x3FF))

        # Discard the ; if present. Otherwise, put it back on the queue and
        # invoke parseError on parser.
        if c != ";":
            self.tokenQueue.append({"type": tokenTypes["ParseError"], "data":
                                    "numeric-entity-without-semicolon"})
            self.stream.unget(c)

        return char

    def consumeEntity(self, allowedChar=None, fromAttribute=False):
        # Initialise to the default output for when no entity is matched
        output = "&"

        charStack = [self.stream.char()]
        if (charStack[0] in spaceCharacters or charStack[0] in (EOF, "<", "&") or
                (allowedChar is not None and allowedChar == charStack[0])):
            self.stream.unget(charStack[0])

        elif charStack[0] == "#":
            # Read the next character to see if it's hex or decimal
            hex = False
            charStack.append(self.stream.char())
            if charStack[-1] in ("x", "X"):
                hex = True
                charStack.append(self.stream.char())

            # charStack[-1] should be the first digit
            if (hex and charStack[-1] in hexDigits) \
                    or (not hex and charStack[-1] in digits):
                # At least one digit found, so consume the whole number
                self.stream.unget(charStack[-1])
                output = self.consumeNumberEntity(hex)
            else:
                # No digits found
                self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                        "data": "expected-numeric-entity"})
                self.stream.unget(charStack.pop())
                output = "&" + "".join(charStack)

        else:
            # At this point in the process might have named entity. Entities
            # are stored in the global variable "entities".
            #
            # Consume characters and compare to these to a substring of the
            # entity names in the list until the substring no longer matches.
            while (charStack[-1] is not EOF):
                if not entitiesTrie.has_keys_with_prefix("".join(charStack)):
                    break
                charStack.append(self.stream.char())

            # At this point we have a string that starts with some characters
            # that may match an entity
            # Try to find the longest entity the string will match to take care
            # of &noti for instance.
            try:
                entityName = entitiesTrie.longest_prefix("".join(charStack[:-1]))
                entityLength = len(entityName)
            except KeyError:
                entityName = None

            if entityName is not None:
                if entityName[-1] != ";":
                    self.tokenQueue.append({"type": tokenTypes["ParseError"], "data":
                                            "named-entity-without-semicolon"})
                if (entityName[-1] != ";" and fromAttribute and
                    (charStack[entityLength] in asciiLetters or
                     charStack[entityLength] in digits or
                     charStack[entityLength] == "=")):
                    self.stream.unget(charStack.pop())
                    output = "&" + "".join(charStack)
                else:
                    output = entities[entityName]
                    self.stream.unget(charStack.pop())
                    output += "".join(charStack[entityLength:])
            else:
                self.tokenQueue.append({"type": tokenTypes["ParseError"], "data":
                                        "expected-named-entity"})
                self.stream.unget(charStack.pop())
                output = "&" + "".join(charStack)

        if fromAttribute:
            self.currentToken["data"][-1][1] += output
        else:
            if output in spaceCharacters:
                tokenType = "SpaceCharacters"
            else:
                tokenType = "Characters"
            self.tokenQueue.append({"type": tokenTypes[tokenType], "data": output})

    def processEntityInAttribute(self, allowedChar):
        """This method replaces the need for "entityInAttributeValueState".
        """
        self.consumeEntity(allowedChar=allowedChar, fromAttribute=True)

    def emitCurrentToken(self):
        """This method is a generic handler for emitting the tags. It also sets
        the state to "data" because that's what's needed after a token has been
        emitted.
        """
        token = self.currentToken
        # Add token to the queue to be yielded
        if (token["type"] in tagTokenTypes):
            token["name"] = token["name"].translate(asciiUpper2Lower)
            if token["type"] == tokenTypes["EndTag"]:
                if token["data"]:
                    self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                            "data": "attributes-in-end-tag"})
                if token["selfClosing"]:
                    self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                            "data": "self-closing-flag-on-end-tag"})
        self.tokenQueue.append(token)
        self.state = self.dataState

    # Below are the various tokenizer states worked out.
    def dataState(self):
        data = self.stream.char()
        if data == "&":
            self.state = self.entityDataState
        elif data == "<":
            self.state = self.tagOpenState
        elif data == "\u0000":
            self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                    "data": "invalid-codepoint"})
            self.tokenQueue.append({"type": tokenTypes["Characters"],
                                    "data": "\u0000"})
        elif data is EOF:
            # Tokenization ends.
            return False
        elif data in spaceCharacters:
            # Directly after emitting a token you switch back to the "data
            # state". At that point spaceCharacters are important so they are
            # emitted separately.
            self.tokenQueue.append({"type": tokenTypes["SpaceCharacters"], "data":
                                    data + self.stream.charsUntil(spaceCharacters, True)})
            # No need to update lastFourChars here, since the first space will
            # have already been appended to lastFourChars and will have broken
            # any <!-- or --> sequences
        else:
            chars = self.stream.charsUntil(("&", "<", "\u0000"))
            self.tokenQueue.append({"type": tokenTypes["Characters"], "data":
                                    data + chars})
        return True

    def entityDataState(self):
        self.consumeEntity()
        self.state = self.dataState
        return True

    def rcdataState(self):
        data = self.stream.char()
        if data == "&":
            self.state = self.characterReferenceInRcdata
        elif data == "<":
            self.state = self.rcdataLessThanSignState
        elif data == EOF:
            # Tokenization ends.
            return False
        elif data == "\u0000":
            self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                    "data": "invalid-codepoint"})
            self.tokenQueue.append({"type": tokenTypes["Characters"],
                                    "data": "\uFFFD"})
        elif data in spaceCharacters:
            # Directly after emitting a token you switch back to the "data
            # state". At that point spaceCharacters are important so they are
            # emitted separately.
            self.tokenQueue.append({"type": tokenTypes["SpaceCharacters"], "data":
                                    data + self.stream.charsUntil(spaceCharacters, True)})
            # No need to update lastFourChars here, since the first space will
            # have already been appended to lastFourChars and will have broken
            # any <!-- or --> sequences
        else:
            chars = self.stream.charsUntil(("&", "<", "\u0000"))
            self.tokenQueue.append({"type": tokenTypes["Characters"], "data":
                                    data + chars})
        return True

    def characterReferenceInRcdata(self):
        self.consumeEntity()
        self.state = self.rcdataState
        return True

    def rawtextState(self):
        data = self.stream.char()
        if data == "<":
            self.state = self.rawtextLessThanSignState
        elif data == "\u0000":
            self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                    "data": "invalid-codepoint"})
            self.tokenQueue.append({"type": tokenTypes["Characters"],
                                    "data": "\uFFFD"})
        elif data == EOF:
            # Tokenization ends.
            return False
        else:
            chars = self.stream.charsUntil(("<", "\u0000"))
            self.tokenQueue.append({"type": tokenTypes["Characters"], "data":
                                    data + chars})
        return True

    def scriptDataState(self):
        data = self.stream.char()
        if data == "<":
            self.state = self.scriptDataLessThanSignState
        elif data == "\u0000":
            self.tokenQueue.append({"type": tokenTypes["ParseError"],
                                    "data": "invalid-codepoint"})
            self.tokenQueue.append({"type": tokenTypes["Characters"],
                                    "data": "\uFFFD"})
        elif data == EOF:
            # Tokenization ends.
            return False
        else:
            chars = self.stream.charsUntil(("<", "\u0000"))
            self.tokenQueue.append({"type": tokenTypes["Characters"], "data":
                                    data + chars})
        return True