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/*
 * Copyright (C) 2021  Aravinth Manivannan <realaravinth@batsense.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
use std::path::Path;

use actix_web::web;
use graphql_client::{reqwest::post_graphql, GraphQLQuery};
use reqwest::Client;
use serde::{Deserialize, Serialize};
use sled::{Db, Tree};

use crate::SETTINGS;

const CACHE_VERSION: usize = 1;

#[derive(Clone)]
pub struct Data {
    pub client: Client,
    cache: Db,
    pub posts: Tree,
}

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "schemas/schema.graphql",
    query_path = "schemas/query.graphql",
    response_derives = "Debug, Serialize, Deserialize, Clone"
)]
pub struct GetPost;

pub type PostResp = get_post::GetPostPost;

pub type AppData = web::Data<Data>;

impl Data {
    pub fn new() -> AppData {
        let path = Path::new(SETTINGS.cache.as_ref().unwrap()).join("posts_cache");
        let cache = sled::open(path).unwrap();
        let posts = cache.open_tree("posts").unwrap();
        let res = Self {
            client: Client::new(),
            cache,
            posts,
        };
        res.migrate();

        AppData::new(res)
    }

    fn migrate(&self) {
        const KEY: &str = "POST_CACHE_VERSION";
        let mut clean = true;
        if let Ok(Some(v)) = self.posts.get(KEY) {
            let version = bincode::deserialize::<usize>(&v[..]).unwrap();
            clean = !(version == CACHE_VERSION);
        }

        if clean {
            self.posts.clear().unwrap();
            self.posts.flush().unwrap();
            self.posts
                .insert(KEY, bincode::serialize(&CACHE_VERSION).unwrap())
                .unwrap();
        }
    }

    pub async fn get_post(&self, id: &str) -> PostResp {
        match self.posts.get(id) {
            Ok(Some(v)) => bincode::deserialize(&v[..]).unwrap(),
            _ => {
                let vars = get_post::Variables { id: id.to_owned() };
                const URL: &str = "https://medium.com/_/graphql";

                let res = post_graphql::<GetPost, _>(&self.client, URL, vars)
                    .await
                    .unwrap();
                let res = res.data.expect("missing response data").post.unwrap();
                self.posts
                    .insert(id, bincode::serialize(&res).unwrap())
                    .unwrap();
                res
            }
        }
    }
}