#!/usr/bin/env python3

import json
import re
from typing import Optional

import bs4
from praw.models import Submission

from bdfr.exceptions import SiteDownloaderError
from bdfr.resource import Resource
from bdfr.site_authenticator import SiteAuthenticator
from bdfr.site_downloaders.base_downloader import BaseDownloader


class Imgur(BaseDownloader):
    def __init__(self, post: Submission):
        super().__init__(post)
        self.raw_data = {}

    def find_resources(self, authenticator: Optional[SiteAuthenticator] = None) -> list[Resource]:
        self.raw_data = self._get_data(self.post.url)

        out = []
        if "album_images" in self.raw_data:
            images = self.raw_data["album_images"]
            for image in images["images"]:
                out.append(self._compute_image_url(image))
        else:
            out.append(self._compute_image_url(self.raw_data))
        return out

    def _compute_image_url(self, image: dict) -> Resource:
        ext = self._validate_extension(image["ext"])
        if image.get("prefer_video", False):
            ext = ".mp4"

        image_url = "https://i.imgur.com/" + image["hash"] + ext
        return Resource(self.post, image_url, Resource.retry_download(image_url))

    @staticmethod
    def _get_data(link: str) -> dict:
        try:
            imgur_id = re.match(r".*/(.*?)(\..{0,})?$", link).group(1)
            gallery = "a/" if re.search(r".*/(.*?)(gallery/|a/)", link) else ""
            link = f"https://imgur.com/{gallery}{imgur_id}"
        except AttributeError:
            raise SiteDownloaderError(f"Could not extract Imgur ID from {link}")

        res = Imgur.retrieve_url(link, cookies={"over18": "1", "postpagebeta": "0"})

        soup = bs4.BeautifulSoup(res.text, "html.parser")
        scripts = soup.find_all("script", attrs={"type": "text/javascript"})
        scripts = [script.string.replace("\n", "") for script in scripts if script.string]

        script_regex = re.compile(r"\s*\(function\(widgetFactory\)\s*{\s*widgetFactory\.mergeConfig\(\'gallery\'")
        chosen_script = list(filter(lambda s: re.search(script_regex, s), scripts))
        if len(chosen_script) != 1:
            raise SiteDownloaderError(f"Could not read page source from {link}")

        chosen_script = chosen_script[0]

        outer_regex = re.compile(r"widgetFactory\.mergeConfig\(\'gallery\', ({.*})\);")
        inner_regex = re.compile(r"image\s*:(.*),\s*group")
        try:
            image_dict = re.search(outer_regex, chosen_script).group(1)
            image_dict = re.search(inner_regex, image_dict).group(1)
        except AttributeError:
            raise SiteDownloaderError(f"Could not find image dictionary in page source")

        try:
            image_dict = json.loads(image_dict)
        except json.JSONDecodeError as e:
            raise SiteDownloaderError(f"Could not parse received dict as JSON: {e}")

        return image_dict

    @staticmethod
    def _validate_extension(extension_suffix: str) -> str:
        extension_suffix = re.sub(r"\?.*", "", extension_suffix)
        possible_extensions = (".jpg", ".png", ".mp4", ".gif")
        selection = [ext for ext in possible_extensions if ext == extension_suffix]
        if len(selection) == 1:
            return selection[0]
        else:
            raise SiteDownloaderError(f'"{extension_suffix}" is not recognized as a valid extension for Imgur')