# This module contains abstractions for the input stream. You don't have to
# looks further, there are no pretty code.
#
# We define two classes here.
#
#   Mark(source, line, column)
# It's just a record and its only use is producing nice error messages.
# Parser does not use it for any other purposes.
#
#   Reader(source, data)
# Reader determines the encoding of `data` and converts it to unicode.
# Reader provides the following methods and attributes:
#   reader.peek(length=1) - return the next `length` characters
#   reader.forward(length=1) - move the current position to `length` characters.
#   reader.index - the number of the current character.
#   reader.line, stream.column - the line and the column of the current character.

__all__ = ["Reader", "ReaderError"]

from .error import YAMLError, Mark

import codecs, re


class ReaderError(YAMLError):
    def __init__(self, name, position, character, encoding, reason):
        self.name = name
        self.character = character
        self.position = position
        self.encoding = encoding
        self.reason = reason

    def __str__(self):
        if isinstance(self.character, bytes):
            return (
                "'%s' codec can't decode byte #x%02x: %s\n"
                '  in "%s", position %d'
                % (
                    self.encoding,
                    ord(self.character),
                    self.reason,
                    self.name,
                    self.position,
                )
            )
        else:
            return "unacceptable character #x%04x: %s\n" '  in "%s", position %d' % (
                self.character,
                self.reason,
                self.name,
                self.position,
            )


class Reader(object):
    # Reader:
    # - determines the data encoding and converts it to a unicode string,
    # - checks if characters are in allowed range,
    # - adds '\0' to the end.

    # Reader accepts
    #  - a `bytes` object,
    #  - a `str` object,
    #  - a file-like object with its `read` method returning `str`,
    #  - a file-like object with its `read` method returning `unicode`.

    # Yeah, it's ugly and slow.

    def __init__(self, stream):
        self.name = None
        self.stream = None
        self.stream_pointer = 0
        self.eof = True
        self.buffer = ""
        self.pointer = 0
        self.raw_buffer = None
        self.raw_decode = None
        self.encoding = None
        self.index = 0
        self.line = 0
        self.column = 0
        if isinstance(stream, str):
            self.name = "<unicode string>"
            self.check_printable(stream)
            self.buffer = stream + "\0"
        elif isinstance(stream, bytes):
            self.name = "<byte string>"
            self.raw_buffer = stream
            self.determine_encoding()
        else:
            self.stream = stream
            self.name = getattr(stream, "name", "<file>")
            self.eof = False
            self.raw_buffer = None
            self.determine_encoding()

    def peek(self, index=0):
        try:
            return self.buffer[self.pointer + index]
        except IndexError:
            self.update(index + 1)
            return self.buffer[self.pointer + index]

    def prefix(self, length=1):
        if self.pointer + length >= len(self.buffer):
            self.update(length)
        return self.buffer[self.pointer : self.pointer + length]

    def forward(self, length=1):
        if self.pointer + length + 1 >= len(self.buffer):
            self.update(length + 1)
        while length:
            ch = self.buffer[self.pointer]
            self.pointer += 1
            self.index += 1
            if ch in "\n\x85\u2028\u2029" or (
                ch == "\r" and self.buffer[self.pointer] != "\n"
            ):
                self.line += 1
                self.column = 0
            elif ch != "\uFEFF":
                self.column += 1
            length -= 1

    def get_mark(self):
        if self.stream is None:
            return Mark(
                self.name, self.index, self.line, self.column, self.buffer, self.pointer
            )
        else:
            return Mark(self.name, self.index, self.line, self.column, None, None)

    def determine_encoding(self):
        while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
            self.update_raw()
        if isinstance(self.raw_buffer, bytes):
            if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
                self.raw_decode = codecs.utf_16_le_decode
                self.encoding = "utf-16-le"
            elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
                self.raw_decode = codecs.utf_16_be_decode
                self.encoding = "utf-16-be"
            else:
                self.raw_decode = codecs.utf_8_decode
                self.encoding = "utf-8"
        self.update(1)

    NON_PRINTABLE = re.compile(
        "[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]"
    )

    def check_printable(self, data):
        match = self.NON_PRINTABLE.search(data)
        if match:
            character = match.group()
            position = self.index + (len(self.buffer) - self.pointer) + match.start()
            raise ReaderError(
                self.name,
                position,
                ord(character),
                "unicode",
                "special characters are not allowed",
            )

    def update(self, length):
        if self.raw_buffer is None:
            return
        self.buffer = self.buffer[self.pointer :]
        self.pointer = 0
        while len(self.buffer) < length:
            if not self.eof:
                self.update_raw()
            if self.raw_decode is not None:
                try:
                    data, converted = self.raw_decode(
                        self.raw_buffer, "strict", self.eof
                    )
                except UnicodeDecodeError as exc:
                    character = self.raw_buffer[exc.start]
                    if self.stream is not None:
                        position = (
                            self.stream_pointer - len(self.raw_buffer) + exc.start
                        )
                    else:
                        position = exc.start
                    raise ReaderError(
                        self.name, position, character, exc.encoding, exc.reason
                    )
            else:
                data = self.raw_buffer
                converted = len(data)
            self.check_printable(data)
            self.buffer += data
            self.raw_buffer = self.raw_buffer[converted:]
            if self.eof:
                self.buffer += "\0"
                self.raw_buffer = None
                break

    def update_raw(self, size=4096):
        data = self.stream.read(size)
        if self.raw_buffer is None:
            self.raw_buffer = data
        else:
            self.raw_buffer += data
        self.stream_pointer += len(data)
        if not data:
            self.eof = True