import re
from pathlib import Path
from typing import Optional

from .constants import *
from .enums import TeXType, TeXFlavour
from .formatterif import FormatterIF
from .formatting_config import FormattingConfig
from .generic_text import GenericText
from ..logger import logger


class PyTeXFormatter(FormatterIF):
    def __init__(
            self,
            input_file: Optional[Path] = None,
            config: Optional[FormattingConfig] = None,
            tex_type: Optional[TeXType] = None,
            tex_flavour: Optional[TeXFlavour] = None,
            locate_file_config: bool = True,
            allow_infile_config: bool = True
    ):
        super().__init__(
            input_file=input_file,
            config=config
        )
        self._config: Optional[FormattingConfig] = self._config  # for type-hinting
        self._tex_type: Optional[TeXType] = tex_type
        self._tex_flavour: Optional[TeXFlavour] = tex_flavour
        self._allow_infile_config = allow_infile_config
        self._header: Optional[GenericText] = None
        if locate_file_config:
            file_config = self.parse_file_config()
            if allow_infile_config:
                infile_config = self.parse_infile_config()
                self._config = \
                    file_config.merge_with(
                        infile_config,
                        strict=True
                    ).merge_with(self._config, strict=False)
            else:
                self._config = file_config.merge_with(self._config)
        else:
            if allow_infile_config:
                infile_config = self.parse_infile_config()
                self._config = infile_config.merge_with(self._config)

    def parse_file_config(self) -> Optional[FormattingConfig]:
        config_file = self.input_file.with_name(self.input_file.name + PYTEX_CONFIG_FILE_EXTENSION)
        if config_file.exists():
            with open(config_file, 'r') as file:
                config = file.readlines()
            try:
                return FormattingConfig.from_yaml(config)
            except:
                raise NotImplementedError  # Invalid yaml file format
        else:
            return None

    def parse_infile_config(self) -> Optional[FormattingConfig]:
        with open(self._input_file, "r") as file:
            line = file.readline()
            if re.match(self.config.escape_character + INFILE_CONFIG_BEGIN_CONFIG, line):
                if not line.strip().lstrip('%').strip() == self.config.escape_character + INFILE_CONFIG_BEGIN_CONFIG:
                    logger.warning(
                        "File {file}: Start of infile config invalid."
                    )
                config = []
                while True:
                    line = file.readline()
                    if re.match(self.config.escape_character + INFILE_CONFIG_END_CONFIG, line):
                        if not line.strip().lstrip(
                                '%').strip() == self.config.escape_character + INFILE_CONFIG_END_CONFIG:
                            logger.warning(
                                "File {file}: End of infile config invalid."
                            )
                        break
                    if line == '':
                        raise NotImplementedError  # No matching end block
                    config.append(line.lstrip('%').rstrip())
                try:
                    return FormattingConfig.from_yaml(config)
                except:
                    raise NotImplementedError  # Invalid yaml file format
            else:
                return None

    @property
    def config(self) -> FormattingConfig:
        if self._config is None:
            raise NotImplementedError
        return self._config

    @property
    def header(self) -> GenericText:
        if self._header is None:
            if not (
                    self.config.include_extra_header
                    or self.config.include_build_time
                    or self.config.include_pytex_version
                    or self.config.include_pytex_info_text
                    or self.config.include_repo_version
                    or self.config.include_repo_info_text
            ):
                self._header = GenericText([])
            else:
                self._header = GenericText([])
                # TODO: handle license
                if self.config.include_extra_header:
                    self._header += self.config.extra_header + ['']
                if self.config.include_repo_info_text:
                    self._header += self.config.repo_info_text
                if self.config.include_pytex_info_text:
                    self._header += self.config.pytex_info_text + ['']

                ## TODO handle rest

        return self._header

    def make_header(self, **kwargs) -> str:
        return '\n'.join(
            [
                '%' * 80,
                self.header.format(**kwargs),  # TODO: add standard keywords here
                '%' * 80
            ]
        )