use activitypub::{
    activity::{Create, Delete, Update},
    link,
    object::{Article, Tombstone}
};
use canapi::{Error, Provider};
use chrono::{NaiveDateTime, TimeZone, Utc};
use diesel::{self, RunQueryDsl, QueryDsl, ExpressionMethods, BelongingToDsl};
use heck::{CamelCase, KebabCase};
use serde_json;

use plume_api::posts::PostEndpoint;
use plume_common::{
    activity_pub::{
        Hashtag, Source,
        PUBLIC_VISIBILTY, Id, IntoId,
        inbox::{Deletable, FromActivity}
    },
    utils::md_to_html
};
use {BASE_URL, ap_url, Connection};
use blogs::Blog;
use instance::Instance;
use likes::Like;
use mentions::Mention;
use post_authors::*;
use reshares::Reshare;
use tags::Tag;
use users::User;
use schema::posts;
use safe_string::SafeString;
use std::collections::HashSet;

#[derive(Queryable, Identifiable, Serialize, Clone, AsChangeset)]
#[changeset_options(treat_none_as_null = "true")]
pub struct Post {
    pub id: i32,
    pub blog_id: i32,
    pub slug: String,
    pub title: String,
    pub content: SafeString,
    pub published: bool,
    pub license: String,
    pub creation_date: NaiveDateTime,
    pub ap_url: String,
    pub subtitle: String,
    pub source: String,
    pub cover_id: Option<i32>,
}

#[derive(Insertable)]
#[table_name = "posts"]
pub struct NewPost {
    pub blog_id: i32,
    pub slug: String,
    pub title: String,
    pub content: SafeString,
    pub published: bool,
    pub license: String,
    pub creation_date: Option<NaiveDateTime>,
    pub ap_url: String,
    pub subtitle: String,
    pub source: String,
    pub cover_id: Option<i32>,
}

impl<'a> Provider<(&'a Connection, Option<i32>)> for Post {
    type Data = PostEndpoint;

    fn get((conn, user_id): &(&'a Connection, Option<i32>), id: i32) -> Result<PostEndpoint, Error> {
        if let Some(post) = Post::get(conn, id) {
            if !post.published && !user_id.map(|u| post.is_author(conn, u)).unwrap_or(false) {
                return Err(Error::Authorization("You are not authorized to access this post yet.".to_string()))
            }

            Ok(PostEndpoint {
                id: Some(post.id),
                title: Some(post.title.clone()),
                subtitle: Some(post.subtitle.clone()),
                content: Some(post.content.get().clone())
            })
        } else {
            Err(Error::NotFound("Request post was not found".to_string()))
        }
    }

    fn list((conn, user_id): &(&'a Connection, Option<i32>), filter: PostEndpoint) -> Vec<PostEndpoint> {
        let mut query = posts::table.into_boxed();
        if let Some(title) = filter.title {
            query = query.filter(posts::title.eq(title));
        }
        if let Some(subtitle) = filter.subtitle {
            query = query.filter(posts::subtitle.eq(subtitle));
        }
        if let Some(content) = filter.content {
            query = query.filter(posts::content.eq(content));
        }

        query.get_results::<Post>(*conn).map(|ps| ps.into_iter()
            .filter(|p| p.published || user_id.map(|u| p.is_author(conn, u)).unwrap_or(false))
            .map(|p| PostEndpoint {
                id: Some(p.id),
                title: Some(p.title.clone()),
                subtitle: Some(p.subtitle.clone()),
                content: Some(p.content.get().clone())
            })
            .collect()
        ).unwrap_or(vec![])
    }

    fn create((_conn, _user_id): &(&'a Connection, Option<i32>), _query: PostEndpoint) -> Result<PostEndpoint, Error> {
        unimplemented!()
    }

    fn update((_conn, _user_id): &(&'a Connection, Option<i32>), _id: i32, _new_data: PostEndpoint) -> Result<PostEndpoint, Error> {
        unimplemented!()
    }

    fn delete((conn, user_id): &(&'a Connection, Option<i32>), id: i32) {
        let user_id = user_id.expect("Post as Provider::delete: not authenticated");
        if let Some(post) = Post::get(conn, id) {
            if post.is_author(conn, user_id) {
                post.delete(conn);
            }
        }
    }
}

impl Post {
    insert!(posts, NewPost);
    get!(posts);
    update!(posts);
    find_by!(posts, find_by_slug, slug as String, blog_id as i32);
    find_by!(posts, find_by_ap_url, ap_url as String);

    pub fn list_by_tag(conn: &Connection, tag: String, (min, max): (i32, i32)) -> Vec<Post> {
        use schema::tags;

        let ids = tags::table.filter(tags::tag.eq(tag)).select(tags::post_id);
        posts::table.filter(posts::id.eq_any(ids))
            .filter(posts::published.eq(true))
            .order(posts::creation_date.desc())
            .offset(min.into())
            .limit((max - min).into())
            .load(conn)
            .expect("Post::list_by_tag: loading error")
    }

    pub fn count_for_tag(conn: &Connection, tag: String) -> i64 {
        use schema::tags;
        let ids = tags::table.filter(tags::tag.eq(tag)).select(tags::post_id);
        *posts::table.filter(posts::id.eq_any(ids))
            .filter(posts::published.eq(true))
            .count()
            .load(conn)
            .expect("Post::count_for_tag: counting error")
            .iter().next().expect("Post::count_for_tag: no result error")
    }

    pub fn count_local(conn: &Connection) -> usize {
        use schema::post_authors;
        use schema::users;
        let local_authors = users::table.filter(users::instance_id.eq(Instance::local_id(conn))).select(users::id);
        let local_posts_id = post_authors::table.filter(post_authors::author_id.eq_any(local_authors)).select(post_authors::post_id);
        posts::table.filter(posts::id.eq_any(local_posts_id))
            .filter(posts::published.eq(true))
            .load::<Post>(conn)
            .expect("Post::count_local: loading error")
            .len()// TODO count in database?
    }

    pub fn count(conn: &Connection) -> i64 {
        posts::table.filter(posts::published.eq(true))
            .count()
            .get_result(conn)
            .expect("Post::count: counting error")
    }

    pub fn get_recents(conn: &Connection, limit: i64) -> Vec<Post> {
        posts::table.order(posts::creation_date.desc())
            .filter(posts::published.eq(true))
            .limit(limit)
            .load::<Post>(conn)
            .expect("Post::get_recents: loading error")
    }

    pub fn get_recents_for_author(conn: &Connection, author: &User, limit: i64) -> Vec<Post> {
        use schema::post_authors;

        let posts = PostAuthor::belonging_to(author).select(post_authors::post_id);
        posts::table.filter(posts::id.eq_any(posts))
            .filter(posts::published.eq(true))
            .order(posts::creation_date.desc())
            .limit(limit)
            .load::<Post>(conn)
            .expect("Post::get_recents_for_author: loading error")
    }

    pub fn get_recents_for_blog(conn: &Connection, blog: &Blog, limit: i64) -> Vec<Post> {
        posts::table.filter(posts::blog_id.eq(blog.id))
            .filter(posts::published.eq(true))
            .order(posts::creation_date.desc())
            .limit(limit)
            .load::<Post>(conn)
            .expect("Post::get_recents_for_blog: loading error")
    }

    pub fn get_for_blog(conn: &Connection, blog:&Blog) -> Vec<Post> {
        posts::table.filter(posts::blog_id.eq(blog.id))
            .filter(posts::published.eq(true))
            .load::<Post>(conn)
            .expect("Post::get_for_blog:: loading error")
    }

    pub fn blog_page(conn: &Connection, blog: &Blog, (min, max): (i32, i32)) -> Vec<Post> {
        posts::table.filter(posts::blog_id.eq(blog.id))
            .filter(posts::published.eq(true))
            .order(posts::creation_date.desc())
            .offset(min.into())
            .limit((max - min).into())
            .load::<Post>(conn)
            .expect("Post::blog_page: loading error")
    }

    /// Give a page of all the recent posts known to this instance (= federated timeline)
    pub fn get_recents_page(conn: &Connection, (min, max): (i32, i32)) -> Vec<Post> {
        posts::table.order(posts::creation_date.desc())
            .filter(posts::published.eq(true))
            .offset(min.into())
            .limit((max - min).into())
            .load::<Post>(conn)
            .expect("Post::get_recents_page: loading error")
    }

    /// Give a page of posts from a specific instance
    pub fn get_instance_page(conn: &Connection, instance_id: i32, (min, max): (i32, i32)) -> Vec<Post> {
        use schema::blogs;

        let blog_ids = blogs::table.filter(blogs::instance_id.eq(instance_id)).select(blogs::id);

        posts::table.order(posts::creation_date.desc())
            .filter(posts::published.eq(true))
            .filter(posts::blog_id.eq_any(blog_ids))
            .offset(min.into())
            .limit((max - min).into())
            .load::<Post>(conn)
            .expect("Post::get_instance_page: loading error")
    }

    /// Give a page of customized user feed, based on a list of followed users
    pub fn user_feed_page(conn: &Connection, followed: Vec<i32>, (min, max): (i32, i32)) -> Vec<Post> {
        use schema::post_authors;
        let post_ids = post_authors::table
            .filter(post_authors::author_id.eq_any(followed))
            .select(post_authors::post_id);

        posts::table.order(posts::creation_date.desc())
            .filter(posts::published.eq(true))
            .filter(posts::id.eq_any(post_ids))
            .offset(min.into())
            .limit((max - min).into())
            .load::<Post>(conn)
            .expect("Post::user_feed_page: loading error")
    }

    pub fn drafts_by_author(conn: &Connection, author: &User) -> Vec<Post> {
        use schema::post_authors;

        let posts = PostAuthor::belonging_to(author).select(post_authors::post_id);
        posts::table.order(posts::creation_date.desc())
            .filter(posts::published.eq(false))
            .filter(posts::id.eq_any(posts))
            .load::<Post>(conn)
            .expect("Post::drafts_by_author: loading error")
    }

    pub fn get_authors(&self, conn: &Connection) -> Vec<User> {
        use schema::users;
        use schema::post_authors;
        let author_list = PostAuthor::belonging_to(self).select(post_authors::author_id);
        users::table.filter(users::id.eq_any(author_list)).load::<User>(conn).expect("Post::get_authors: loading error")
    }

    pub fn is_author(&self, conn: &Connection, author_id: i32) -> bool {
        use schema::post_authors;
        PostAuthor::belonging_to(self)
            .filter(post_authors::author_id.eq(author_id))
            .count()
            .get_result::<i64>(conn)
            .expect("Post::is_author: loading error") > 0
    }

    pub fn get_blog(&self, conn: &Connection) -> Blog {
        use schema::blogs;
        blogs::table.filter(blogs::id.eq(self.blog_id))
            .limit(1)
            .load::<Blog>(conn)
            .expect("Post::get_blog: loading error")
            .into_iter().nth(0).expect("Post::get_blog: no result error")
    }

    pub fn get_likes(&self, conn: &Connection) -> Vec<Like> {
        use schema::likes;
        likes::table.filter(likes::post_id.eq(self.id))
            .load::<Like>(conn)
            .expect("Post::get_likes: loading error")
    }

    pub fn get_reshares(&self, conn: &Connection) -> Vec<Reshare> {
        use schema::reshares;
        reshares::table.filter(reshares::post_id.eq(self.id))
            .load::<Reshare>(conn)
            .expect("Post::get_reshares: loading error")
    }

    pub fn update_ap_url(&self, conn: &Connection) -> Post {
        if self.ap_url.len() == 0 {
            diesel::update(self)
                .set(posts::ap_url.eq(self.compute_id(conn)))
                .execute(conn).expect("Post::update_ap_url: update error");
            Post::get(conn, self.id).expect("Post::update_ap_url: get error")
        } else {
            self.clone()
        }
    }

    pub fn get_receivers_urls(&self, conn: &Connection) -> Vec<String> {
        let followers = self.get_authors(conn).into_iter().map(|a| a.get_followers(conn)).collect::<Vec<Vec<User>>>();
        let to = followers.into_iter().fold(vec![], |mut acc, f| {
            for x in f {
                acc.push(x.ap_url);
            }
            acc
        });
        to
    }

    pub fn into_activity(&self, conn: &Connection) -> Article {
        let mut to = self.get_receivers_urls(conn);
        to.push(PUBLIC_VISIBILTY.to_string());

        let mut mentions_json = Mention::list_for_post(conn, self.id).into_iter().map(|m| json!(m.to_activity(conn))).collect::<Vec<serde_json::Value>>();
        let mut tags_json = Tag::for_post(conn, self.id).into_iter().map(|t| json!(t.into_activity(conn))).collect::<Vec<serde_json::Value>>();
        mentions_json.append(&mut tags_json);

        let mut article = Article::default();
        article.object_props.set_name_string(self.title.clone()).expect("Post::into_activity: name error");
        article.object_props.set_id_string(self.ap_url.clone()).expect("Post::into_activity: id error");

        let mut authors = self.get_authors(conn).into_iter().map(|x| Id::new(x.ap_url)).collect::<Vec<Id>>();
        authors.push(self.get_blog(conn).into_id()); // add the blog URL here too
        article.object_props.set_attributed_to_link_vec::<Id>(authors).expect("Post::into_activity: attributedTo error");
        article.object_props.set_content_string(self.content.get().clone()).expect("Post::into_activity: content error");
        article.ap_object_props.set_source_object(Source {
            content: self.source.clone(),
            media_type: String::from("text/markdown"),
        }).expect("Post::into_activity: source error");
        article.object_props.set_published_utctime(Utc.from_utc_datetime(&self.creation_date)).expect("Post::into_activity: published error");
        article.object_props.set_summary_string(self.subtitle.clone()).expect("Post::into_activity: summary error");
        article.object_props.tag = Some(json!(mentions_json));
        article.object_props.set_url_string(self.ap_url.clone()).expect("Post::into_activity: url error");
        article.object_props.set_to_link_vec::<Id>(to.into_iter().map(Id::new).collect()).expect("Post::into_activity: to error");
        article.object_props.set_cc_link_vec::<Id>(vec![]).expect("Post::into_activity: cc error");
        article
    }

    pub fn create_activity(&self, conn: &Connection) -> Create {
        let article = self.into_activity(conn);
        let mut act = Create::default();
        act.object_props.set_id_string(format!("{}activity", self.ap_url)).expect("Post::create_activity: id error");
        act.object_props.set_to_link_vec::<Id>(article.object_props.to_link_vec().expect("Post::create_activity: Couldn't copy 'to'"))
            .expect("Post::create_activity: to error");
        act.object_props.set_cc_link_vec::<Id>(article.object_props.cc_link_vec().expect("Post::create_activity: Couldn't copy 'cc'"))
            .expect("Post::create_activity: cc error");
        act.create_props.set_actor_link(Id::new(self.get_authors(conn)[0].clone().ap_url)).expect("Post::create_activity: actor error");
        act.create_props.set_object_object(article).expect("Post::create_activity: object error");
        act
    }

    pub fn update_activity(&self, conn: &Connection) -> Update {
        let article = self.into_activity(conn);
        let mut act = Update::default();
        act.object_props.set_id_string(format!("{}/update-{}", self.ap_url, Utc::now().timestamp())).expect("Post::update_activity: id error");
        act.object_props.set_to_link_vec::<Id>(article.object_props.to_link_vec().expect("Post::update_activity: Couldn't copy 'to'"))
            .expect("Post::update_activity: to error");
        act.object_props.set_cc_link_vec::<Id>(article.object_props.cc_link_vec().expect("Post::update_activity: Couldn't copy 'cc'"))
            .expect("Post::update_activity: cc error");
        act.update_props.set_actor_link(Id::new(self.get_authors(conn)[0].clone().ap_url)).expect("Post::update_activity: actor error");
        act.update_props.set_object_object(article).expect("Article::update_activity: object error");
        act
    }

    pub fn handle_update(conn: &Connection, updated: Article) {
        let id = updated.object_props.id_string().expect("Post::handle_update: id error");
        let mut post = Post::find_by_ap_url(conn, id).expect("Post::handle_update: finding error");

        if let Ok(title) = updated.object_props.name_string() {
            post.slug = title.to_kebab_case();
            post.title = title;
        }

        if let Ok(content) = updated.object_props.content_string() {
            post.content = SafeString::new(&content);
        }

        if let Ok(subtitle) = updated.object_props.summary_string() {
            post.subtitle = subtitle;
        }

        if let Ok(ap_url) = updated.object_props.url_string() {
            post.ap_url = ap_url;
        }

        if let Ok(source) = updated.ap_object_props.source_object::<Source>() {
            post.source = source.content;
        }

        let mut txt_hashtags = md_to_html(&post.source).2.into_iter().map(|s| s.to_camel_case()).collect::<HashSet<_>>();
        if let Some(serde_json::Value::Array(mention_tags)) = updated.object_props.tag.clone() {
            let mut mentions = vec![];
            let mut tags = vec![];
            let mut hashtags = vec![];
            for tag in mention_tags.into_iter() {
                serde_json::from_value::<link::Mention>(tag.clone())
                    .map(|m| mentions.push(m))
                    .ok();

                serde_json::from_value::<Hashtag>(tag.clone())
                    .map(|t| {
                        let tag_name = t.name_string().expect("Post::from_activity: tag name error");
                        if txt_hashtags.remove(&tag_name) {
                            hashtags.push(t);
                        } else {
                            tags.push(t);
                        }
                    }).ok();
            }
            post.update_mentions(conn, mentions);
            post.update_tags(conn, tags);
            post.update_hashtags(conn, hashtags);
        }

        post.update(conn);
    }

    pub fn update_mentions(&self, conn: &Connection, mentions: Vec<link::Mention>) {
        let mentions = mentions.into_iter().map(|m| (m.link_props.href_string().ok()
                                                .and_then(|ap_url| User::find_by_ap_url(conn, ap_url))
                                                .map(|u| u.id),m))
            .filter_map(|(id, m)| if let Some(id)=id {Some((m,id))} else {None}).collect::<Vec<_>>();

        let old_mentions = Mention::list_for_post(&conn, self.id);
        let old_user_mentioned = old_mentions.iter()
            .map(|m| m.mentioned_id).collect::<HashSet<_>>();
        for (m,id) in mentions.iter() {
           if !old_user_mentioned.contains(&id) {
                Mention::from_activity(&*conn, m.clone(), self.id, true, true);
            }
        }

        let new_mentions = mentions.into_iter().map(|(_m,id)| id).collect::<HashSet<_>>();
        for m in old_mentions.iter().filter(|m| !new_mentions.contains(&m.mentioned_id)) {
            m.delete(&conn);
        }
    }

    pub fn update_tags(&self, conn: &Connection, tags: Vec<Hashtag>) {
        let tags_name = tags.iter().filter_map(|t| t.name_string().ok()).collect::<HashSet<_>>();

        let old_tags = Tag::for_post(&*conn, self.id).into_iter().collect::<Vec<_>>();
        let old_tags_name = old_tags.iter().filter_map(|tag| if !tag.is_hashtag {Some(tag.tag.clone())} else {None}).collect::<HashSet<_>>();

        for t in tags.into_iter() {
            if !t.name_string().map(|n| old_tags_name.contains(&n)).unwrap_or(true) {
                Tag::from_activity(conn, t, self.id, false);
            }
        }

        for ot in old_tags {
            if !tags_name.contains(&ot.tag) {
                ot.delete(conn);
            }
        }
    }

    pub fn update_hashtags(&self, conn: &Connection, tags: Vec<Hashtag>) {
        let tags_name = tags.iter().filter_map(|t| t.name_string().ok()).collect::<HashSet<_>>();

        let old_tags = Tag::for_post(&*conn, self.id).into_iter().collect::<Vec<_>>();
        let old_tags_name = old_tags.iter().filter_map(|tag| if tag.is_hashtag {Some(tag.tag.clone())} else {None}).collect::<HashSet<_>>();

        for t in tags.into_iter() {
            if !t.name_string().map(|n| old_tags_name.contains(&n)).unwrap_or(true) {
                Tag::from_activity(conn, t, self.id, true);
            }
        }

        for ot in old_tags {
            if !tags_name.contains(&ot.tag) {
                ot.delete(conn);
            }
        }
    }

    pub fn to_json(&self, conn: &Connection) -> serde_json::Value {
        let blog = self.get_blog(conn);
        json!({
            "post": self,
            "author": self.get_authors(conn)[0].to_json(conn),
            "url": format!("/~/{}/{}/", blog.get_fqn(conn), self.slug),
            "date": self.creation_date.timestamp(),
            "blog": blog.to_json(conn),
            "tags": Tag::for_post(&*conn, self.id)
        })
    }

    pub fn compute_id(&self, conn: &Connection) -> String {
        ap_url(format!("{}/~/{}/{}/", BASE_URL.as_str(), self.get_blog(conn).get_fqn(conn), self.slug))
    }
}

impl FromActivity<Article, Connection> for Post {
    fn from_activity(conn: &Connection, article: Article, _actor: Id) -> Post {
        if let Some(post) = Post::find_by_ap_url(conn, article.object_props.id_string().unwrap_or(String::new())) {
            post
        } else {
            let (blog, authors) = article.object_props.attributed_to_link_vec::<Id>()
                .expect("Post::from_activity: attributedTo error")
                .into_iter()
                .fold((None, vec![]), |(blog, mut authors), link| {
                    let url: String = link.into();
                    match User::from_url(conn, url.clone()) {
                        Some(user) => {
                            authors.push(user);
                            (blog, authors)
                        },
                        None => (blog.or_else(|| Blog::from_url(conn, url)), authors)
                    }
                });

            let title = article.object_props.name_string().expect("Post::from_activity: title error");
            let post = Post::insert(conn, NewPost {
                blog_id: blog.expect("Post::from_activity: blog not found error").id,
                slug: title.to_kebab_case(),
                title: title,
                content: SafeString::new(&article.object_props.content_string().expect("Post::from_activity: content error")),
                published: true,
                license: String::from("CC-BY-SA"), // TODO
                // FIXME: This is wrong: with this logic, we may use the display URL as the AP ID. We need two different fields
                ap_url: article.object_props.url_string().unwrap_or(article.object_props.id_string().expect("Post::from_activity: url + id error")),
                creation_date: Some(article.object_props.published_utctime().expect("Post::from_activity: published error").naive_utc()),
                subtitle: article.object_props.summary_string().expect("Post::from_activity: summary error"),
                source: article.ap_object_props.source_object::<Source>().expect("Post::from_activity: source error").content,
                cover_id: None, // TODO
            });

            for author in authors.into_iter() {
                PostAuthor::insert(conn, NewPostAuthor {
                    post_id: post.id,
                    author_id: author.id
                });
            }

            // save mentions and tags
            let mut hashtags = md_to_html(&post.source).2.into_iter().map(|s| s.to_camel_case()).collect::<HashSet<_>>();
            if let Some(serde_json::Value::Array(tags)) = article.object_props.tag.clone() {
                for tag in tags.into_iter() {
                    serde_json::from_value::<link::Mention>(tag.clone())
                        .map(|m| Mention::from_activity(conn, m, post.id, true, true))
                        .ok();

                    serde_json::from_value::<Hashtag>(tag.clone())
                        .map(|t| {
                            let tag_name = t.name_string().expect("Post::from_activity: tag name error");
                            Tag::from_activity(conn, t, post.id, hashtags.remove(&tag_name));
                        })
                        .ok();
                }
            }
            post
        }
    }
}

impl Deletable<Connection, Delete> for Post {
    fn delete(&self, conn: &Connection) -> Delete {
        let mut act = Delete::default();
        act.delete_props.set_actor_link(self.get_authors(conn)[0].clone().into_id()).expect("Post::delete: actor error");

        let mut tombstone = Tombstone::default();
        tombstone.object_props.set_id_string(self.ap_url.clone()).expect("Post::delete: object.id error");
        act.delete_props.set_object_object(tombstone).expect("Post::delete: object error");

        act.object_props.set_id_string(format!("{}#delete", self.ap_url)).expect("Post::delete: id error");
        act.object_props.set_to_link_vec(vec![Id::new(PUBLIC_VISIBILTY)]).expect("Post::delete: to error");

        for m in Mention::list_for_post(&conn, self.id) {
            m.delete(conn);
        }
        diesel::delete(self).execute(conn).expect("Post::delete: DB error");
        act
    }

    fn delete_id(id: String, actor_id: String, conn: &Connection) {
        let actor = User::find_by_ap_url(conn, actor_id);
        let post = Post::find_by_ap_url(conn, id);
        let can_delete = actor.and_then(|act|
            post.clone().map(|p| p.get_authors(conn).into_iter().any(|a| act.id == a.id))
        ).unwrap_or(false);
        if can_delete {
            post.map(|p| p.delete(conn));
        }
    }
}

impl IntoId for Post {
    fn into_id(self) -> Id {
        Id::new(self.ap_url.clone())
    }
}