use crate::{
    error::Error,
    extensions::ProfileExt,
    middleware::UserProfile,
    nav::NavState,
    pagination::{Page, PageNum, PageSource, Pagination, SearchPage, SearchPagination},
    views::ProfileView,
    ActixLoader, State,
};
use actix_web::{web, HttpRequest, HttpResponse, Scope};
use hyaenidae_profiles::store::{File, Profile};
use hyaenidae_toolkit::{Button, TextInput};
use i18n_embed_fl::fl;
use std::collections::HashMap;
use uuid::Uuid;

const PER_PAGE: usize = 8;

pub(super) fn scope() -> Scope {
    web::scope("/discover").route("", web::get().to(profile_list))
}

async fn profile_list(
    loader: ActixLoader,
    req: HttpRequest,
    profile: UserProfile,
    page: Option<web::Query<ProfilePage>>,
    search: Option<web::Query<Search>>,
    page_num: Option<web::Query<PageNumQuery>>,
    nav_state: NavState,
    state: web::Data<State>,
) -> Result<HttpResponse, Error> {
    let page = page.map(|query| query.into_inner().into());
    let page_num = page_num.map(|query| query.into_inner().into());
    let search = search.and_then(|search_query| {
        if search_query.0.term.trim().is_empty() {
            None
        } else {
            Some(search_query.0.term.trim().to_owned())
        }
    });

    let state = if let Some(term) = search {
        ProfileListState::search(
            req.path().to_owned(),
            profile.0.id(),
            term,
            page_num,
            &state,
        )
        .await?
    } else {
        ProfileListState::build(req.path().to_owned(), profile.0.id(), page, &state).await?
    };

    crate::rendered(HttpResponse::Ok(), |cursor| {
        crate::templates::profiles::discover(cursor, &loader, &state, &nav_state)
    })
}

#[derive(Debug)]
enum PageKind {
    Linear(Page),
    Search(SearchPage),
}

#[derive(Debug)]
pub struct ProfileListState {
    path: String,
    cache: ProfileCache,
    profiles: PageKind,
}

#[derive(Clone, Copy, Debug, serde::Deserialize)]
#[serde(untagged)]
enum ProfilePage {
    Max { max: Uuid },
    Min { min: Uuid },
}

#[derive(Clone, Copy, Debug, serde::Deserialize)]
struct PageNumQuery {
    page: usize,
}

#[derive(Clone, Debug, serde::Deserialize)]
struct Search {
    term: String,
}

#[derive(Debug, Default)]
struct ProfileCache {
    profiles: HashMap<Uuid, Profile>,
    files: HashMap<Uuid, File>,
    blocks: HashMap<Uuid, bool>,
    following: HashMap<Uuid, bool>,
    follow_requested: HashMap<Uuid, bool>,
}

struct ProfilePager<'b> {
    cache: &'b mut ProfileCache,
    store: &'b hyaenidae_profiles::State,
    viewer: Uuid,
}

impl PageKind {
    fn items(&self) -> &[Uuid] {
        match self {
            PageKind::Linear(page) => &page.items,
            PageKind::Search(page) => &page.items,
        }
    }
}

impl ProfileListState {
    pub(crate) fn search_path(&self) -> &str {
        &self.path
    }

    pub(crate) fn search_input(&self, loader: &ActixLoader) -> TextInput {
        let input =
            TextInput::new("term").placeholder(&fl!(loader, "discover-users-search-placeholder"));

        match &self.profiles {
            PageKind::Search(search) => input.value(&search.term),
            _ => input,
        }
    }

    pub(crate) fn profiles<'a>(&'a self) -> impl Iterator<Item = ProfileView<'a>> + 'a {
        self.profiles.items().iter().filter_map(move |profile_id| {
            let profile = self.cache.profiles.get(profile_id)?;
            let icon = profile
                .icon()
                .and_then(|file_id| self.cache.files.get(&file_id));
            let banner = profile
                .banner()
                .and_then(|file_id| self.cache.files.get(&file_id));

            Some(ProfileView {
                profile,
                icon,
                banner,
            })
        })
    }

    pub(crate) fn profile_buttons<'a>(
        &'a self,
        loader: &ActixLoader,
        view: ProfileView<'a>,
    ) -> Vec<Button> {
        let mut buttons = vec![];

        if self
            .cache
            .follow_requested
            .get(&view.profile.id())
            .map(|b| *b)
            .unwrap_or(false)
        {
            buttons.push(
                Button::primary(&fl!(loader, "cancel-follow-button"))
                    .form(&view.profile.unfollow_path()),
            );
        } else if self
            .cache
            .following
            .get(&view.profile.id())
            .map(|b| *b)
            .unwrap_or(false)
        {
            buttons.push(
                Button::primary(&fl!(loader, "unfollow-button"))
                    .form(&view.profile.unfollow_path()),
            );
        } else {
            buttons.push(
                Button::primary(&fl!(loader, "follow-button")).form(&view.profile.follow_path()),
            );
        }

        buttons
    }

    pub(crate) fn has_nav(&self) -> bool {
        match &self.profiles {
            PageKind::Linear(page) => page.next.is_some() || page.prev.is_some(),
            PageKind::Search(page) => page.next.is_some() || page.prev.is_some(),
        }
    }

    pub(crate) fn nav(&self, loader: &ActixLoader) -> Vec<Button> {
        let mut nav = vec![];

        match &self.profiles {
            PageKind::Linear(page) => {
                if let Some(prev) = page.prev {
                    nav.push(
                        Button::secondary(&fl!(loader, "previous-button"))
                            .href(&format!("{}?min={}", self.path, prev)),
                    );
                }

                if let Some(next) = page.next {
                    nav.push(
                        Button::secondary(&fl!(loader, "next-button"))
                            .href(&format!("{}?max={}", self.path, next)),
                    );
                }
            }
            PageKind::Search(page) => {
                if let Some(prev) = page.prev {
                    nav.push(
                        Button::secondary(&fl!(loader, "previous-button"))
                            .href(&format!("{}?term={}&page={}", self.path, page.term, prev)),
                    );
                }

                if let Some(next) = page.next {
                    nav.push(
                        Button::secondary(&fl!(loader, "next-button"))
                            .href(&format!("{}?term={}&page={}", self.path, page.term, next)),
                    );
                }
            }
        };

        nav
    }

    async fn search(
        path: String,
        viewer: Uuid,
        term: String,
        page: Option<PageNum>,
        state: &State,
    ) -> Result<Self, Error> {
        let store = state.profiles.clone();

        let state = web::block(move || {
            let mut cache = ProfileCache::new();

            let profiles = SearchPage::from_pagination(
                ProfilePager {
                    cache: &mut cache,
                    store: &store,
                    viewer,
                },
                PER_PAGE,
                term,
                page,
            );

            let state = ProfileListState {
                path,
                cache,
                profiles: PageKind::Search(profiles),
            };

            Ok(state) as Result<_, Error>
        })
        .await?;

        Ok(state)
    }

    async fn build(
        path: String,
        viewer: Uuid,
        source: Option<PageSource>,
        state: &State,
    ) -> Result<Self, Error> {
        let store = state.profiles.clone();

        let state = web::block(move || {
            let mut cache = ProfileCache::new();

            let profiles = Page::from_pagination(
                ProfilePager {
                    cache: &mut cache,
                    store: &store,
                    viewer,
                },
                PER_PAGE,
                source,
            );

            let state = ProfileListState {
                path,
                cache,
                profiles: PageKind::Linear(profiles),
            };

            Ok(state) as Result<Self, Error>
        })
        .await?;

        Ok(state)
    }
}

impl ProfileCache {
    fn new() -> Self {
        Self::default()
    }
}

impl<'b> ProfilePager<'b> {
    fn filter_profile(&mut self, profile_id: Uuid) -> Option<Uuid> {
        if profile_id == self.viewer {
            return None;
        }

        if let Some(block) = self.cache.blocks.get(&profile_id) {
            if *block {
                return None;
            }
        } else {
            let block = self
                .store
                .store
                .view
                .blocks
                .by_forward(self.viewer, profile_id)
                .ok()?
                .is_some()
                || self
                    .store
                    .store
                    .view
                    .blocks
                    .by_forward(profile_id, self.viewer)
                    .ok()?
                    .is_some();

            self.cache.blocks.insert(profile_id, block);

            if block {
                return None;
            }
        }

        if !self.cache.following.contains_key(&profile_id) {
            let following = self
                .store
                .store
                .view
                .follows
                .by_forward(profile_id, self.viewer)
                .ok()?
                .is_some();

            self.cache.following.insert(profile_id, following);
        }

        if !self.cache.follow_requested.contains_key(&profile_id) {
            let follow_requested = self
                .store
                .store
                .view
                .follow_requests
                .by_forward(profile_id, self.viewer)
                .ok()?
                .is_some();

            self.cache
                .follow_requested
                .insert(profile_id, follow_requested);
        }

        if !self.cache.profiles.contains_key(&profile_id) {
            let profile = self.store.store.profiles.by_id(profile_id).ok()??;

            let mut file_ids = vec![];
            file_ids.extend(profile.icon());
            file_ids.extend(profile.banner());

            self.cache.profiles.insert(profile.id(), profile);

            for file_id in file_ids {
                if !self.cache.files.contains_key(&file_id) {
                    let file = self.store.store.files.by_id(file_id).ok()??;

                    self.cache.files.insert(file.id(), file);
                }
            }
        }

        Some(profile_id)
    }
}

impl<'b> Pagination for ProfilePager<'b> {
    fn from_max<'a>(&'a mut self, max: Uuid) -> Box<dyn DoubleEndedIterator<Item = Uuid> + 'a> {
        Box::new(
            self.store
                .store
                .profiles
                .older_than(max)
                .filter_map(move |profile_id| self.filter_profile(profile_id)),
        )
    }

    fn from_min<'a>(&'a mut self, min: Uuid) -> Box<dyn DoubleEndedIterator<Item = Uuid> + 'a> {
        Box::new(
            self.store
                .store
                .profiles
                .newer_than(min)
                .filter_map(move |profile_id| self.filter_profile(profile_id)),
        )
    }

    fn from_start<'a>(&'a mut self) -> Box<dyn DoubleEndedIterator<Item = Uuid> + 'a> {
        Box::new(
            self.store
                .store
                .profiles
                .all()
                .filter_map(move |profile_id| self.filter_profile(profile_id)),
        )
    }
}

impl<'b> SearchPagination for ProfilePager<'b> {
    fn from_term<'a>(
        &'a mut self,
        term: &'a str,
    ) -> Box<dyn DoubleEndedIterator<Item = Uuid> + 'a> {
        Box::new(
            self.store
                .store
                .profiles
                .search(term)
                .filter_map(move |profile_id| self.filter_profile(profile_id)),
        )
    }
}

impl From<ProfilePage> for PageSource {
    fn from(page: ProfilePage) -> Self {
        match page {
            ProfilePage::Max { max } => PageSource::OlderThan(max),
            ProfilePage::Min { min } => PageSource::NewerThan(min),
        }
    }
}

impl From<PageNumQuery> for PageNum {
    fn from(page: PageNumQuery) -> Self {
        PageNum { page: page.page }
    }
}