#!/usr/bin/env python3
# coding=utf-8
import datetime
import logging
import platform
import re
from pathlib import Path
from typing import Optional

from praw.models import Comment, Submission

from bdfr.exceptions import BulkDownloaderException
from bdfr.resource import Resource

logger = logging.getLogger(__name__)


class FileNameFormatter:
    key_terms = (
        'date',
        'flair',
        'postid',
        'redditor',
        'subreddit',
        'title',
        'upvotes',
    )

    def __init__(self, file_format_string: str, directory_format_string: str, time_format_string: str):
        if not self.validate_string(file_format_string):
            raise BulkDownloaderException(f'"{file_format_string}" is not a valid format string')
        self.file_format_string = file_format_string
        self.directory_format_string: list[str] = directory_format_string.split('/')
        self.time_format_string = time_format_string

    def _format_name(self, submission: (Comment, Submission), format_string: str) -> str:
        if isinstance(submission, Submission):
            attributes = self._generate_name_dict_from_submission(submission)
        elif isinstance(submission, Comment):
            attributes = self._generate_name_dict_from_comment(submission)
        else:
            raise BulkDownloaderException(f'Cannot name object {type(submission).__name__}')
        result = format_string
        for key in attributes.keys():
            if re.search(fr'(?i).*{{{key}}}.*', result):
                key_value = str(attributes.get(key, 'unknown'))
                key_value = FileNameFormatter._convert_unicode_escapes(key_value)
                key_value = key_value.replace('\\', '\\\\')
                result = re.sub(fr'(?i){{{key}}}', key_value, result)

        result = result.replace('/', '')

        if platform.system() == 'Windows':
            result = FileNameFormatter._format_for_windows(result)

        return result

    @staticmethod
    def _convert_unicode_escapes(in_string: str) -> str:
        pattern = re.compile(r'(\\u\d{4})')
        matches = re.search(pattern, in_string)
        if matches:
            for match in matches.groups():
                converted_match = bytes(match, 'utf-8').decode('unicode-escape')
                in_string = in_string.replace(match, converted_match)
        return in_string

    def _generate_name_dict_from_submission(self, submission: Submission) -> dict:
        submission_attributes = {
            'title': submission.title,
            'subreddit': submission.subreddit.display_name,
            'redditor': submission.author.name if submission.author else 'DELETED',
            'postid': submission.id,
            'upvotes': submission.score,
            'flair': submission.link_flair_text,
            'date': self._convert_timestamp(submission.created_utc),
        }
        return submission_attributes

    def _convert_timestamp(self, timestamp: float) -> str:
        input_time = datetime.datetime.fromtimestamp(timestamp)
        if self.time_format_string.upper().strip() == 'ISO':
            return input_time.isoformat()
        else:
            return input_time.strftime(self.time_format_string)

    def _generate_name_dict_from_comment(self, comment: Comment) -> dict:
        comment_attributes = {
            'title': comment.submission.title,
            'subreddit': comment.subreddit.display_name,
            'redditor': comment.author.name if comment.author else 'DELETED',
            'postid': comment.id,
            'upvotes': comment.score,
            'flair': '',
            'date': self._convert_timestamp(comment.created_utc),
        }
        return comment_attributes

    def format_path(
            self,
            resource: Resource,
            destination_directory: Path,
            index: Optional[int] = None,
    ) -> Path:
        subfolder = Path(
            destination_directory,
            *[self._format_name(resource.source_submission, part) for part in self.directory_format_string]
        )
        index = f'_{str(index)}' if index else ''
        if not resource.extension:
            raise BulkDownloaderException(f'Resource from {resource.url} has no extension')
        ending = index + resource.extension
        file_name = str(self._format_name(resource.source_submission, self.file_format_string))
        file_name = self._limit_file_name_length(file_name, ending)

        try:
            file_path = Path(subfolder, file_name)
        except TypeError:
            raise BulkDownloaderException(f'Could not determine path name: {subfolder}, {index}, {resource.extension}')
        return file_path

    @staticmethod
    def _limit_file_name_length(filename: str, ending: str) -> str:
        possible_id = re.search(r'((?:_\w{6})?$)', filename)
        if possible_id:
            ending = possible_id.group(1) + ending
            filename = filename[:possible_id.start()]
        max_length_chars = 255 - len(ending)
        max_length_bytes = 255 - len(ending.encode('utf-8'))
        while len(filename) > max_length_chars or len(filename.encode('utf-8')) > max_length_bytes:
            filename = filename[:-1]
        return filename + ending

    def format_resource_paths(
            self,
            resources: list[Resource],
            destination_directory: Path,
    ) -> list[tuple[Path, Resource]]:
        out = []
        if len(resources) == 1:
            try:
                out.append((self.format_path(resources[0], destination_directory, None), resources[0]))
            except BulkDownloaderException as e:
                logger.error(f'Could not generate file path for resource {resources[0].url}: {e}')
                logger.exception('Could not generate file path')
        else:
            for i, res in enumerate(resources, start=1):
                logger.log(9, f'Formatting filename with index {i}')
                try:
                    out.append((self.format_path(res, destination_directory, i), res))
                except BulkDownloaderException as e:
                    logger.error(f'Could not generate file path for resource {res.url}: {e}')
                    logger.exception('Could not generate file path')
        return out

    @staticmethod
    def validate_string(test_string: str) -> bool:
        if not test_string:
            return False
        result = any([f'{{{key}}}' in test_string.lower() for key in FileNameFormatter.key_terms])
        if result:
            if 'POSTID' not in test_string:
                logger.warning('Some files might not be downloaded due to name conflicts as filenames are'
                               ' not guaranteed to be be unique without {POSTID}')
            return True
        else:
            return False

    @staticmethod
    def _format_for_windows(input_string: str) -> str:
        invalid_characters = r'<>:"\/|?*'
        for char in invalid_characters:
            input_string = input_string.replace(char, '')
        input_string = FileNameFormatter._strip_emojis(input_string)
        return input_string

    @staticmethod
    def _strip_emojis(input_string: str) -> str:
        result = input_string.encode('ascii', errors='ignore').decode('utf-8')
        return result