// Copyright 2019 The Fuchsia Authors
//
// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to
// those terms.
//
use crate::{
    common::{App, CheckOptions, CheckTiming, ProtocolState, UpdateCheckSchedule},
    installer::Plan,
    policy::{CheckDecision, Policy, PolicyData, PolicyEngine, UpdateDecision},
    request_builder::RequestParams,
    time::TimeSource,
};
use futures::future::BoxFuture;
use futures::prelude::*;

/// A stub policy implementation that allows everything immediately.
pub struct StubPolicy<P: Plan> {
    _phantom_data: std::marker::PhantomData<P>,
}

impl<P: Plan> Policy for StubPolicy<P> {
    type ComputeNextUpdateTimePolicyData = PolicyData;
    type UpdateCheckAllowedPolicyData = ();
    type UpdateCanStartPolicyData = ();
    type RebootPolicyData = ();
    type InstallPlan = P;

    fn compute_next_update_time(
        policy_data: &Self::ComputeNextUpdateTimePolicyData,
        _apps: &[App],
        _scheduling: &UpdateCheckSchedule,
        _protocol_state: &ProtocolState,
    ) -> CheckTiming {
        CheckTiming::builder()
            .time(policy_data.current_time)
            .build()
    }

    fn update_check_allowed(
        _policy_data: &Self::UpdateCheckAllowedPolicyData,
        _apps: &[App],
        _scheduling: &UpdateCheckSchedule,
        _protocol_state: &ProtocolState,
        check_options: &CheckOptions,
    ) -> CheckDecision {
        CheckDecision::Ok(RequestParams {
            source: check_options.source,
            use_configured_proxies: true,
            ..RequestParams::default()
        })
    }

    fn update_can_start(
        _policy_data: &Self::UpdateCanStartPolicyData,
        _proposed_install_plan: &Self::InstallPlan,
    ) -> UpdateDecision {
        UpdateDecision::Ok
    }

    fn reboot_allowed(
        _policy_data: &Self::RebootPolicyData,
        _check_options: &CheckOptions,
    ) -> bool {
        true
    }

    fn reboot_needed(_install_plan: &Self::InstallPlan) -> bool {
        true
    }
}

/// A stub PolicyEngine that just gathers the current time and hands it off to the StubPolicy as the
/// PolicyData.
#[derive(Debug)]
pub struct StubPolicyEngine<P: Plan, T: TimeSource> {
    time_source: T,
    _phantom_data: std::marker::PhantomData<P>,
}

impl<P, T> StubPolicyEngine<P, T>
where
    T: TimeSource,
    P: Plan,
{
    pub fn new(time_source: T) -> Self {
        Self {
            time_source,
            _phantom_data: std::marker::PhantomData,
        }
    }
}

impl<P, T> PolicyEngine for StubPolicyEngine<P, T>
where
    T: TimeSource + Clone,
    P: Plan,
{
    type TimeSource = T;
    type InstallResult = ();
    type InstallPlan = P;

    fn time_source(&self) -> &Self::TimeSource {
        &self.time_source
    }

    fn compute_next_update_time(
        &mut self,
        apps: &[App],
        scheduling: &UpdateCheckSchedule,
        protocol_state: &ProtocolState,
    ) -> BoxFuture<'_, CheckTiming> {
        let check_timing = StubPolicy::<P>::compute_next_update_time(
            &PolicyData::builder()
                .current_time(self.time_source.now())
                .build(),
            apps,
            scheduling,
            protocol_state,
        );
        future::ready(check_timing).boxed()
    }

    fn update_check_allowed(
        &mut self,
        apps: &[App],
        scheduling: &UpdateCheckSchedule,
        protocol_state: &ProtocolState,
        check_options: &CheckOptions,
    ) -> BoxFuture<'_, CheckDecision> {
        let decision = StubPolicy::<P>::update_check_allowed(
            &(),
            apps,
            scheduling,
            protocol_state,
            check_options,
        );
        future::ready(decision).boxed()
    }

    fn update_can_start<'p>(
        &mut self,
        proposed_install_plan: &'p Self::InstallPlan,
    ) -> BoxFuture<'p, UpdateDecision> {
        let decision = StubPolicy::<P>::update_can_start(&(), proposed_install_plan);
        future::ready(decision).boxed()
    }

    fn reboot_allowed(
        &mut self,
        check_options: &CheckOptions,
        _install_result: &Self::InstallResult,
    ) -> BoxFuture<'_, bool> {
        let decision = StubPolicy::<P>::reboot_allowed(&(), check_options);
        future::ready(decision).boxed()
    }

    fn reboot_needed(&mut self, install_plan: &Self::InstallPlan) -> BoxFuture<'_, bool> {
        let decision = StubPolicy::<P>::reboot_needed(install_plan);
        future::ready(decision).boxed()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{
        installer::stub::StubPlan, protocol::request::InstallSource, time::MockTimeSource,
    };

    #[test]
    fn test_compute_next_update_time() {
        let policy_data = PolicyData::builder()
            .current_time(MockTimeSource::new_from_now().now())
            .build();
        let update_check_schedule = UpdateCheckSchedule::default();
        let result = StubPolicy::<StubPlan>::compute_next_update_time(
            &policy_data,
            &[],
            &update_check_schedule,
            &ProtocolState::default(),
        );
        let expected = CheckTiming::builder()
            .time(policy_data.current_time)
            .build();
        assert_eq!(result, expected);
    }

    #[test]
    fn test_update_check_allowed_on_demand() {
        let check_options = CheckOptions {
            source: InstallSource::OnDemand,
        };
        let result = StubPolicy::<StubPlan>::update_check_allowed(
            &(),
            &[],
            &UpdateCheckSchedule::default(),
            &ProtocolState::default(),
            &check_options,
        );
        let expected = CheckDecision::Ok(RequestParams {
            source: check_options.source,
            use_configured_proxies: true,
            ..RequestParams::default()
        });
        assert_eq!(result, expected);
    }

    #[test]
    fn test_update_check_allowed_scheduled_task() {
        let check_options = CheckOptions {
            source: InstallSource::ScheduledTask,
        };
        let result = StubPolicy::<StubPlan>::update_check_allowed(
            &(),
            &[],
            &UpdateCheckSchedule::default(),
            &ProtocolState::default(),
            &check_options,
        );
        let expected = CheckDecision::Ok(RequestParams {
            source: check_options.source,
            use_configured_proxies: true,
            ..RequestParams::default()
        });
        assert_eq!(result, expected);
    }

    #[test]
    fn test_update_can_start() {
        let result = StubPolicy::update_can_start(&(), &StubPlan);
        assert_eq!(result, UpdateDecision::Ok);
    }
}