import datetime
import email.utils
import json
import os.path
import random
import urllib
from typing import Optional

import marko
import marko.inline

from .warko.strikethrough import StrikeThrough
from .warko.headinginjector import get_heading_injector
from .warko.extendedimage import get_image_renderer, ExtendedImageElement
from .warko.newtablink import get_new_tab_links
from ..config import Config

CONTENT_FILE_NAME = "content.md"
META_FILE_NAME = "meta.json"

TITLE_KEY = "title"
PUBLISH_DATE_KEY = "publish_date"
TAGS_KEY = "tags"
THUMBNAIL_KEY = "thumbnail"
INTRO_KEY = "intro"

INTRO_DESIRED_LENGTH = 320
INTRO_MAX_EXTRA_LENGTH = 100

posts_cache = []


def get_posts_from_cache() -> list('Post'):
    if len(posts_cache) == 0:
        raise Exception("Getting posts list from cache while it is still empty.")

    return posts_cache.copy()


class Post:
    PARSER = marko.Markdown(renderer=marko.HTMLRenderer
                            , extensions=[
            StrikeThrough
            , get_heading_injector("> ")
            , get_image_renderer(["blog.wazul.moe"])
            , get_new_tab_links(["blog.wazul.moe"])
        ]
                            )

    def __init__(self, path: str):
        self.path = path
        self.name = os.path.basename(path)

        with open(os.path.join(path, CONTENT_FILE_NAME)) as f:
            self.content = Post.PARSER.parse(f.read())

        self.html = Post.PARSER.render(self.content)

        with open(os.path.join(path, META_FILE_NAME)) as f:
            self.meta_data = json.load(f)

        self.subpages = []
        self.extra_files = []
        for elem in os.listdir(path):
            if elem != CONTENT_FILE_NAME and elem != META_FILE_NAME:
                if elem.endswith(".md"):
                    with open(os.path.join(path, elem)) as f:
                        subpage_content = Post.PARSER.parse(f.read())

                    self.subpages.append((os.path.basename(elem)[:-3], Post.PARSER.render(subpage_content)))
                else:
                    self.extra_files.append(elem)

        self.href = f"/posts/{self.get_publish_year()}/{self.name}"

        if THUMBNAIL_KEY in self.meta_data:
            self.thumbnail = self.meta_data[THUMBNAIL_KEY]
        else:
            self.thumbnail = Post._get_first_image_path(self.content)

        self.thumbnail = f"{self.href}/{self.thumbnail}"

        if INTRO_KEY in self.meta_data:
            self.intro = self.meta_data[INTRO_KEY]
        else:
            intro_str = Post._extract_first_paragraph_text(self.content)
            if len(intro_str) > 320:
                intro_str = intro_str[:320]  # cut to length
                # first try to cut at the last period, if it's not too far...
                last_dot_pos = intro_str.rfind(".")
                if 320 - last_dot_pos > 100:
                    intro_str = intro_str[:last_dot_pos + 1]
                else:
                    intro_str += "..."  # If too far, just add more dots

            self.intro = intro_str

    def title(self) -> str:
        return self.meta_data[TITLE_KEY]

    def get_tags(self) -> str:
        return " ".join(["<a href=\"{}/tags/{}.html\">{}</a>".format(Config.BLOG_ROOT_URL, tag, tag) for tag in
                         self.meta_data[TAGS_KEY]])

    def get_link(self):
        return urllib.parse.urljoin(Config.BLOG_ROOT_URL, self.href)

    def get_publish_time(self) -> str:
        return self.meta_data[PUBLISH_DATE_KEY]

    def get_publish_time_rfc2822(self) -> str:
        return email.utils.format_datetime(datetime.datetime.fromisoformat(self.get_publish_time() + " 12:00+02:00"))

    def get_publish_year(self) -> str:
        return self.meta_data[PUBLISH_DATE_KEY][0:4]

    def get_fake_path(self) -> str:
        return "~/posts/{}/{}".format(self.get_publish_year(), self.name)

    def get_prompt(self, cmd: str) -> str:
        return Config.get_prompt(self.get_fake_path(), cmd)

    def get_cat_prompt(self, file: str) -> str:
        return self.get_prompt(f"cat {file}")

    def get_index_prompt(self) -> str:
        return Config.get_prompt("~", f"head {self.get_fake_path()}/content")

    def get_similar_posts(self) -> list['Post']:
        ret_list = []

        posts = get_posts_from_cache()
        idx_self = posts.index(self)

        # TODO move to config
        MAX_SIMILAR_POST_COUNT = 5
        POSTS_AROUND_DISTANCE = 5

        # add the previous post
        if idx_self < len(posts) - 1:
            ret_list.append(posts.pop(idx_self + 1))

        # TODO add some tagbased search when I have more content

        # fallback: add random posts from around the current post
        posts_around = posts[idx_self - POSTS_AROUND_DISTANCE:idx_self + POSTS_AROUND_DISTANCE]
        posts_around.remove(self)

        while len(posts_around) > 0 and len(ret_list) < MAX_SIMILAR_POST_COUNT:
            rand_index = random.randint(0, len(posts_around) - 1)
            ret_list.append(posts_around.pop(rand_index))

        return ret_list

    def get_similar_posts_ls(self) -> str:
        # TODO fix
        return self.generate_similar_posts_ls([self, self, self])

    @staticmethod
    def generate_similar_posts_ls(other_posts: list['Post']) -> str:
        lines = ["total 0"]

        for post in other_posts:
            lines.append("lrwxrwxrwx 1 {} {} {} {} 11:11 '{}' -> {}".format(  # TODO random time and fix filename escape
                Config.BLOG_OWNER, Config.BLOG_OWNER, len(post.get_fake_path()), post.get_publish_time(), post.title(),
                post.get_fake_path())
            )

        return "<br>".join(lines)

    @staticmethod
    def _extract_first_paragraph_text(root) -> str:
        for child in root.children:
            if isinstance(child, marko.block.Paragraph):
                paragraph_str = ""
                for part in child.children:
                    if isinstance(part, marko.inline.RawText) and isinstance(part.children, str):
                        paragraph_str += part.children
                    if isinstance(part, marko.inline.LineBreak):
                        if paragraph_str[-1:] != " ":
                            paragraph_str += " "
                    if isinstance(part, marko.inline.Link):
                        for part_child in part.children:
                            if isinstance(part_child, marko.inline.RawText) and isinstance(part_child.children, str):
                                paragraph_str += part_child.children

                if len(paragraph_str) > INTRO_DESIRED_LENGTH:
                    paragraph_str = paragraph_str[:INTRO_DESIRED_LENGTH]  # cut to length
                    # first try to cut at the last period, if it's not too far...
                    last_dot_pos = paragraph_str.rfind(".")
                    if INTRO_DESIRED_LENGTH - last_dot_pos > INTRO_MAX_EXTRA_LENGTH:
                        intro_str = paragraph_str[:last_dot_pos + 1]
                    else:
                        paragraph_str += "..."  # If too far, just add more dots

                return paragraph_str  # return after the first paragraph

        return ""

    @staticmethod
    def _get_first_image_path(root) -> Optional[str]:
        if isinstance(root, marko.inline.Image):
            return root.dest

        if isinstance(root, ExtendedImageElement):
            return root.src

        if hasattr(root, 'children'):
            for elm in root.children:
                img = Post._get_first_image_path(elm)
                if img:
                    return img

        return None


def get_posts(path: str) -> list[Post]:
    return_list = []

    for directory in os.listdir(path):
        return_list.append(Post(os.path.join(path, directory)))

    return_list.sort(key=lambda post: post.meta_data[PUBLISH_DATE_KEY], reverse=True)

    posts_cache.clear()
    posts_cache.extend(return_list)

    return return_list