use std::sync::Arc;
use std::cell::RefCell;
use std::rc::Rc;
use std::ops::Deref;

use capnp::capability::Promise;
use capnp::Error;

use crate::db::machine::Status;
use crate::api::machine::*;
use crate::schema::machine_capnp::machine::{MachineState, Builder as MachineBuilder};
use crate::schema::machinesystem_capnp::machine_system;
use crate::schema::machinesystem_capnp::machine_system::info as machines;
use crate::network::Network;
use crate::db::user::UserId;
use crate::db::access::{PermRule, admin_perm, Permission, Perms};
use crate::connection::Session;
use crate::machine::Machine as NwMachine;

/// An implementation of the `Machines` API
#[derive(Clone)]
pub struct Machines {
    session: Rc<RefCell<Option<Session>>>,
    network: Arc<Network>,
}

impl Machines {
    pub fn new(session: Rc<RefCell<Option<Session>>>, network: Arc<Network>) -> Self {
        Self { session, network }
    }
}

impl machine_system::Server for Machines {
    // This function shouldn't exist. See fabaccess-api issue #16
    fn info(&mut self,
        _:machine_system::InfoParams,
        mut results: machine_system::InfoResults
        ) -> capnp::capability::Promise<(), capnp::Error>
    {
        results.get().set_info(capnp_rpc::new_client(self.clone()));
        Promise::ok(())
    }
}

impl machines::Server for Machines {
    fn get_machine_list(&mut self,
        _params: machines::GetMachineListParams,
        mut results: machines::GetMachineListResults)
        -> Promise<(), Error>
    {
        let rc = Rc::clone(&self.session);
        let session = self.session.borrow();
        if session.deref().is_some() {
            let v: Vec<(String, crate::machine::Machine)> = self.network.machines.iter()
                .map(|(n,m)| (n.clone(), m.clone()))
                .collect();

            let f = async move {
                let session = rc.borrow();
                let user = &session.as_ref().unwrap().authzid;
                let permissions = &session.as_ref().unwrap().perms;

                let mut filtered_v = Vec::with_capacity(v.len());
                for (id, machine) in v.into_iter() {
                    match machine.get_status().await {
                        // Always show a machine if they're in use by myself
                        Status::InUse(ref bywho) =>
                            if bywho.is_some() && bywho.as_ref().filter(|bywho| *bywho == user).is_some()
                            {
                                filtered_v.push((id, machine));
                            }
                        Status::Reserved(ref bywho) => if bywho == user {
                            filtered_v.push((id, machine));
                        }

                        // The rest depends on the actual priviledges below
                        _ => {
                            let required_disclose = &machine.desc.privs.disclose;
                            if session.as_ref().unwrap().perms.iter()
                                .any(|rule| rule.match_perm(required_disclose))
                            {
                                filtered_v.push((id, machine));
                            }
                        }
                    }

                }

                let mut machines = results.get().init_machine_list(filtered_v.len() as u32);
                for (i, (id, machine)) in filtered_v.into_iter().enumerate() {
                    let mut builder = machines.reborrow().get(i as u32);
                    fill_machine_builder(
                        &mut builder,
                        &machine,
                        &permissions[..],
                        &id,
                        user,
                    ).await
                }

                Ok(())
            };

            Promise::from_future(f)
        } else {
            Promise::ok(())
        }
    }

    fn get_machine(&mut self,
        params: machines::GetMachineParams,
        mut results: machines::GetMachineResults
        ) -> Promise<(), capnp::Error> {
        let rc = Rc::clone(&self.session);
        if self.session.borrow().is_some() {
            let id = {
                let params = pry!(params.get());
                pry!(params.get_id()).to_string()
            };

            let network = self.network.clone();
            let f = async move {
                let session = rc.borrow();
                let user = &session.as_ref().unwrap().authzid;
                let permissions = &session.as_ref().unwrap().perms;

                if let Some(machine) = network.machines.get(&id) {
                    let mut builder = results.get().init_machine();
                    fill_machine_builder(
                        &mut builder,
                        &machine,
                        &permissions[..],
                        &id,
                        user,
                    ).await

                };

                Ok(())
            };
            Promise::from_future(f)
        } else {
            Promise::ok(())
        }
    }

    fn get_machine_u_r_n(
        &mut self,
        params: machines::GetMachineURNParams,
        mut results: machines::GetMachineURNResults
    ) -> Promise<(), capnp::Error> {
        let rc = Rc::clone(&self.session);
        if self.session.borrow().is_some() {
            let id: Option<String> = {
                let urn = pry!(pry!(params.get()).get_urn());
                let mut parts = urn.split_terminator(':');
                let part_urn = parts.next().map(|u| u == "urn").unwrap_or(false);
                let part_fabaccess = parts.next().map(|f| f == "fabaccess").unwrap_or(false);
                let part_resource = parts.next().map(|r| r == "resource").unwrap_or(false);
                if !(part_urn && part_fabaccess && part_resource) {
                    return Promise::ok(())
                }
                parts.next().map(|s| s.to_string())
            };

            if let Some(id) = id {
                let network = self.network.clone();
                let f = async move {
                    let session = rc.borrow();
                    let user = &session.as_ref().unwrap().authzid;
                    let permissions = &session.as_ref().unwrap().perms;

                    if let Some(machine) = network.machines.get(&id) {
                        let mut builder = results.get().init_machine();
                        fill_machine_builder(
                            &mut builder,
                            &machine,
                            &permissions[..],
                            id,
                            user,
                        ).await
                    };

                    Ok(())
                };
                Promise::from_future(f)
            } else {
                Promise::ok(())
            }
        } else {
            Promise::ok(())
        }
    }
}

async fn fill_machine_builder(
    builder: &mut MachineBuilder<'_>,
    machine: &NwMachine,
    permissions: &[PermRule],
    id: impl AsRef<str>,
    user: &UserId,
) {
    let name = &machine.desc.name;
    let perms = Perms::get_for(&machine.desc.privs, permissions.iter());
    builder.set_id(id.as_ref());
    builder.set_name(name);
    if let Some(ref desc) = machine.desc.description {
        builder.set_description(desc);
    }
    if let Some(ref wiki) = machine.desc.wiki {
        builder.set_wiki(wiki);
    }
    builder.set_urn(&format!("urn:fabaccess:resource:{}", id.as_ref()));

    let machineapi = Machine::new(user.clone(), perms, machine.clone());
    let state = machine.get_status().await;
    if perms.write && state == Status::Free {
        builder.set_use(capnp_rpc::new_client(machineapi.clone()));
    }
    if perms.manage {
        //builder.set_transfer(capnp_rpc::new_client(machineapi.clone()));
        //builder.set_check(capnp_rpc::new_client(machineapi.clone()));
        builder.set_manage(capnp_rpc::new_client(machineapi.clone()));
    }
    if permissions.iter().any(|r| r.match_perm(&admin_perm())) {
        builder.set_admin(capnp_rpc::new_client(machineapi.clone()));
    }


    let s = match machine.get_status().await {
        Status::Free => MachineState::Free,
        Status::Disabled => MachineState::Disabled,
        Status::Blocked(_) => MachineState::Blocked,
        Status::InUse(u) => {
            if let Some(owner) = u.as_ref() {
                if owner == user {
                    builder.set_inuse(capnp_rpc::new_client(machineapi.clone()));
                }
            }
            MachineState::InUse
        },
        Status::Reserved(_) => MachineState::Reserved,
        Status::ToCheck(_) => MachineState::ToCheck,
    };
    builder.set_state(s);

    builder.set_info(capnp_rpc::new_client(machineapi));
}