pub mod stats;

use crate::auth::Authorized;
use crate::database::latest::trees::{category, session};
use crate::status_json::StatusJson;
use bincode::{deserialize, serialize};
use rocket::http::Status;
use rocket::{get, State};
use rocket_contrib::templates::Template;
use rocket_contrib::uuid::Uuid;
use serde_derive::{Deserialize, Serialize};
use std::collections::{BTreeMap, HashMap};
use std::time::Duration;

#[get("/")]
pub fn index(_auth: Authorized, db: State<'_, sled::Db>) -> Result<Template, StatusJson> {
    #[derive(Debug, Serialize, Deserialize, PartialOrd, Ord, PartialEq, Eq)]
    struct Node {
        category: category::V,
        children: BTreeMap<category::K, Node>,
    }

    #[derive(Debug, Serialize, Deserialize)]
    struct TemplateContext {
        categories: BTreeMap<category::K, Node>,
    }

    let categories_tree = db.open_tree(category::NAME)?;
    let mut categories = category::get_all(&categories_tree)?;

    // filter archived categories
    categories.retain(|_, category| !category.deleted);

    // collect the top-level categories (those without a parent)
    let mut top_level_nodes: BTreeMap<category::K, Node> = categories
        .iter()
        .filter(|(_, c)| c.parent.is_none())
        .map(|(&id, category)| {
            let node = Node {
                category: category.clone(),
                children: Default::default(),
            };
            (id, node)
        })
        .collect();

    // remove top-level categories from the list
    for id in top_level_nodes.keys() {
        categories.remove(id);
    }

    /// populate `node.children  with entries from `remaining`
    fn populate_node(
        node_id: category::K,
        node: &mut Node,
        remaining: &mut HashMap<category::K, category::V>,
    ) {
        // make a list of the nodes children
        let mut new_children = vec![];
        for (&id, category) in remaining.iter() {
            if category.parent == Some(node_id) {
                new_children.push(id);
            }
        }

        // move the children from `remaining` to `node.children`
        for &id in &new_children {
            let child_node = Node {
                category: remaining.remove(&id).unwrap(),
                children: Default::default(),
            };
            node.children.insert(id, child_node);
        }

        // recursively populate the childrens children
        for (child_id, child) in node.children.iter_mut() {
            populate_node(*child_id, child, remaining);
        }
    }

    for (id, node) in top_level_nodes.iter_mut() {
        populate_node(*id, node, &mut categories);
    }

    let context = TemplateContext {
        categories: top_level_nodes,
    };

    Ok(Template::render("index", &context))
}

#[get("/session/<session_uuid>/edit")]
pub fn session_edit(
    _auth: Authorized,
    session_uuid: Uuid,
    db: State<'_, sled::Db>,
) -> Result<Template, StatusJson> {
    #[derive(Debug, Serialize, Deserialize)]
    struct SessionPageContext {
        session: session::V,
        session_id: uuid::Uuid,
    }

    let session_uuid_s = sled::IVec::from(serialize(&session_uuid.into_inner())?);

    let sessions_tree = db.open_tree(session::NAME)?;
    match sessions_tree.get(session_uuid_s)? {
        None => Err(Status::NotFound.into()),
        Some(data) => {
            let context = SessionPageContext {
                session: deserialize(&data).unwrap(),
                session_id: session_uuid.into_inner(),
            };

            Ok(Template::render("edit_session", &context))
        }
    }
}

#[get("/history")]
pub fn history(_auth: Authorized, db: State<'_, sled::Db>) -> Result<Template, StatusJson> {
    #[derive(Debug, Serialize, Deserialize)]
    struct HistoryEntryContext {
        category: category::V,
        session: session::V,
        session_id: uuid::Uuid,
        duration: Duration,
    }

    #[derive(Debug, Serialize, Deserialize)]
    struct TemplateContext {
        entries: Vec<HistoryEntryContext>,
    }

    let categories_tree = db.open_tree(category::NAME)?;
    let sessions_tree = db.open_tree(session::NAME)?;

    let categories: HashMap<category::K, category::V> = categories_tree
        .iter()
        .map(|result| {
            result.map(|(k, v)| deserialize(&k).and_then(|k| deserialize(&v).map(|v| (k, v))))
        })
        .collect::<Result<Result<_, _>, _>>()??;

    let sessions: HashMap<session::K, session::V> = sessions_tree
        .iter()
        .map(|result| {
            result.map(|(k, v)| deserialize(&k).and_then(|k| deserialize(&v).map(|v| (k, v))))
        })
        .collect::<Result<Result<_, _>, _>>()??;

    let mut context = TemplateContext {
        entries: sessions
            .into_iter()
            .map(|(session_id, session)| HistoryEntryContext {
                duration: (session.ended - session.started).to_std().unwrap(),
                category: categories.get(&session.category).unwrap().clone(),
                session,
                session_id,
            })
            .collect(),
    };

    // Newest entries first
    context.entries.sort_by_key(|entry| entry.session.started);
    context.entries.reverse();

    Ok(Template::render("history", &context))
}