// Copyright © 2020 Jakob L. Kreuze <zerodaysfordays@sdf.org>
//
// This file is part of бирка-тян.
//
// бирка-тян 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.
//
// бирка-тян 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 бирка-тян. If not, see <http://www.gnu.org/licenses/>.

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate anyhow;
extern crate image;
#[macro_use]
extern crate rocket;
extern crate rocket_contrib;
#[macro_use]
extern crate serde_derive;

mod database;

use anyhow::Result;
use database::{hash_file, Query, TagDatabase};
use image::ImageFormat;
use rocket::{Data, State};
use rocket_contrib::json::Json;
use rocket_contrib::serve::StaticFiles;
use rocket_contrib::templates::Template;
use std::env;
use std::fs;
use std::fs::File;
use std::os::unix::fs::symlink;
use std::path::Path;
use std::sync::Mutex;

/// Maximum number of results returned by any API endpoint.
const RESULTS_PER_QUERY: i64 = 50;

/// Shorthand for the state that is passed to all handlers.
type SiteState<'a> = State<'a, Mutex<DatabaseConnection>>;

/// Collection of data necessary to serve images from the tag database.
struct DatabaseConnection {
    tb: TagDatabase,
    image_dir: String,
}

impl DatabaseConnection {
    fn new() -> Result<Self> {
        let bin = env::current_exe()?.canonicalize()?;
        let bin_dir = bin.parent().unwrap();
        let image_dir = String::from(bin_dir.join("image/").to_str().unwrap());
        let tb_path = bin_dir.join("birka.db");
        let tb = TagDatabase::new(tb_path.to_str().unwrap())?;
        Ok(DatabaseConnection { tb, image_dir })
    }
}

/// Information about an image, as returned by the 'posts' endpoint.
#[derive(Serialize)]
struct ImageResult {
    id: i64,
    filename: String,
    thumb_filename: String,
    tags: Vec<String>,
}

/// Return the file name of the thumbnail for the image at `filename`.
fn thumb_filename(filename: &str) -> String {
    String::from(format!(
        "{}_thumb.png",
        // Strip extension.
        if let Some(n) = filename.rfind('.') {
            &filename[..n]
        } else {
            &filename[..]
        }
    ))
}

#[get("/posts?<tags>&<last>")]
fn get_posts(conn: SiteState, tags: String, last: Option<i64>) -> Json<Vec<ImageResult>> {
    let tb = &conn.inner().lock().unwrap().tb;

    // Ensure that an empty vector is passed to `tb.query` if no tags were
    // specified.
    let tags = if !tags.is_empty() {
        tags.split(",").collect::<Vec<&str>>()
    } else {
        vec![]
    };
    let results = tb
        .query(Query {
            tags: &tags[..],
            last_id: last,
            limit: Some(RESULTS_PER_QUERY),
        })
        .unwrap();

    Json(
        results
            .iter()
            .map(|image| ImageResult {
                id: image.id,
                filename: image.filename.clone(),
                thumb_filename: thumb_filename(&image.filename),
                tags: tb.tags_for_image(image.id).unwrap(),
            })
            .collect(),
    )
}

#[post("/posts/<filename>", data = "<data>")]
fn put_posts(conn: SiteState, filename: String, data: Data) -> Json<&str> {
    let conn = conn.inner().lock().unwrap();
    let path = Path::new(&conn.image_dir).join(filename);
    data.stream_to_file(&path).unwrap();
    conn.tb
        .import_image(&path, &hash_file(&path).unwrap())
        .unwrap();

    Json("uploaded!")
}

#[get("/")]
fn index(conn: SiteState) -> Template {
    display_posts(conn, String::from(""), None)
}

#[get("/posts?<tags>&<last>")]
fn display_posts(conn: SiteState, tags: String, last: Option<i64>) -> Template {
    #[derive(Serialize)]
    struct TagResult {
        name: String,
        count: i64,
    }

    #[derive(Serialize)]
    struct Context {
        tags: Vec<TagResult>,
        images: Vec<ImageResult>,
        next_page: String,
    }

    let base_params = format!("/posts?tags={}", tags);
    let tag_results = {
        // This is done in a block because `tb` needs to go out of scope before
        // calling out to `get_posts` to perform the query. Otherwise, we
        // deadlock because the mutex is locked for the entirety of
        // `display_posts`.
        let tb = &conn.inner().lock().unwrap().tb;
        tb.top_tags(20)
            .unwrap()
            .iter()
            .map(|tup| TagResult {
                name: tup.1.clone(),
                count: tup.0,
            })
            .collect()
    };
    let images = get_posts(conn, tags, last).into_inner();
    let context = Context {
        tags: tag_results,
        next_page: if images.len() as i64 == RESULTS_PER_QUERY {
            let last_image = images.last().unwrap();
            format!("{}&last={}", base_params, last_image.id)
        } else {
            String::from("")
        },
        images,
    };
    Template::render("index", context)
}

/// Maybe initialize the directory for storing image symlinks and thumbnails.
fn create_image_directory(conn: &DatabaseConnection) {
    fs::create_dir(&conn.image_dir).ok();

    for image in conn.tb.images_by_tags(&vec![][..]).unwrap() {
        let src = Path::new(&image.orig_dir).join(&image.filename);
        let dst = Path::new(&conn.image_dir).join(&image.filename);
        symlink(&src, &dst).ok();

        let stem = dst.file_stem().unwrap().to_str().unwrap();
        let thumb_path = Path::new(&conn.image_dir).join(&thumb_filename(&stem));
        if !thumb_path.exists() {
            let im = image::open(&Path::new(&src)).unwrap();
            let out = &mut File::create(&thumb_path).unwrap();
            im.thumbnail(100, 100)
                .write_to(out, ImageFormat::Png)
                .unwrap();
        }
    }
}

fn main() {
    let conn = DatabaseConnection::new().unwrap();
    create_image_directory(&conn);
    rocket::ignite()
        .mount("/public", StaticFiles::from("./static/"))
        .mount("/image", StaticFiles::from(&conn.image_dir))
        .mount("/", routes![index, display_posts])
        .mount("/api", routes![get_posts, put_posts])
        .attach(Template::fairing())
        .manage(Mutex::new(conn))
        .launch();
}