use chrono::NaiveDate;
use pulldown_cmark::{html, Options, Parser};
use regex::Regex;
use rust_embed::RustEmbed;
use sailfish::TemplateOnce;
use std::cmp::{Eq, Ord, PartialEq, PartialOrd};
use std::str;

const BLOG_REGEX: &str = r"(?P<date>[\d]{4}-[\d]{2}-[\d]{2})(?P<title>[a-zA-Z0-9-_]*)";

#[derive(RustEmbed)]
#[folder = "content/posts/"]
struct PostAsset;

#[derive(TemplateOnce)]
#[template(path = "index.html")]
struct IndexTemplate {
    posts: Vec<BlogEntry>,
}

#[derive(TemplateOnce)]
#[template(path = "post.html")]
struct PostTemplate {
    content: String,
    title: String,
    date: String,
}

#[derive(PartialEq, Eq, PartialOrd, Ord)]
pub struct BlogEntry {
    pub title: String,
    pub datetime: NaiveDate,
    pub file: String,
}

impl BlogEntry {
    pub fn new(path: &String) -> BlogEntry {
        let re = Regex::new(BLOG_REGEX).unwrap();
        let caps = re.captures(path).unwrap();
        let date = &caps["date"];
        let title = str::replace(&caps["title"], "_", " ");

        BlogEntry {
            title: String::from(title),
            file: String::from(path),
            datetime: NaiveDate::parse_from_str(date, "%Y-%m-%d").unwrap(),
        }
    }

    pub fn read_assets() -> Vec<BlogEntry> {
        let mut entries: Vec<BlogEntry> = PostAsset::iter()
            .map(|e| format!("{}", e))
            .map(|e| BlogEntry::new(&e))
            .collect();

        entries.sort_by(|a, b| b.datetime.cmp(&a.datetime));

        entries
    }
}

fn get_file_content(path: &str) -> String {
    let buffer = PostAsset::get(path).unwrap().data.into_owned();
    let md = String::from_utf8(buffer).unwrap();
    let parser = Parser::new_ext(&md, Options::empty());
    let mut html_output = &mut String::new();
    html::push_html(&mut html_output, parser);
    return html_output.to_string();
}

pub fn render_post_page(path: &String) -> String {
    let blog = BlogEntry::new(path);

    PostTemplate {
        content: get_file_content(path),
        title: blog.title,
        date: blog.datetime.format("%Y-%m-%d").to_string(),
    }
    .render_once()
    .unwrap()
}

pub fn render_index_page() -> String {
    IndexTemplate {
        posts: BlogEntry::read_assets(),
    }
    .render_once()
    .unwrap()
}