// Copyright 2024 The NativeLink Authors. All rights reserved.

//

// Licensed under the Functional Source License, Version 1.1, Apache 2.0 Future License (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//    See LICENSE file for details

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use std::sync::Arc;

use std::time::{SystemTime, UNIX_EPOCH};

use nativelink_error::{Error, ResultExt, make_input_err};

use nativelink_metric::{

    MetricFieldData, MetricKind, MetricPublishKnownKindData, MetricsComponent,

};

use nativelink_util::action_messages::{

    ActionInfo, ActionStage, ActionState, OperationId, WorkerId,

};

use nativelink_util::origin_event::OriginMetadata;

use opentelemetry::baggage::BaggageExt;

use opentelemetry::context::Context;

use opentelemetry_semantic_conventions::attribute::ENDUSER_ID;

use serde::{Deserialize, Serialize};

use static_assertions::{assert_eq_size, const_assert, const_assert_eq};

/// The version of the awaited action.

/// This number will always increment by one each time

/// the action is updated.

#[derive(Debug, Clone, Copy, Eq, PartialEq, Serialize, Deserialize)]

struct AwaitedActionVersion(i64);

impl MetricsComponent for AwaitedActionVersion {

    fn publish(

        &self,

        _kind: MetricKind,

        _field_metadata: MetricFieldData,

    ) -> Result<MetricPublishKnownKindData, nativelink_metric::Error> {

        Ok(MetricPublishKnownKindData::Counter(u64::from_ne_bytes(

            self.0.to_ne_bytes(),

        )))

    }

}

/// An action that is being awaited on and last known state.

#[derive(Debug, Clone, MetricsComponent, Serialize, Deserialize)]

pub struct AwaitedAction {

    /// The current version of the action.

    #[metric(help = "The version of the AwaitedAction")]

    version: AwaitedActionVersion,

    /// The action that is being awaited on.

    #[metric(help = "The action info of the AwaitedAction")]

    action_info: Arc<ActionInfo>,

    /// The operation id of the action.

    // If you need the client operation id, it may be set in

    // ActionState::operation_id.

    #[metric(help = "The operation id of the AwaitedAction")]

    operation_id: OperationId,

    /// The currentsort key used to order the actions.

    #[metric(help = "The sort key of the AwaitedAction")]

    sort_key: AwaitedActionSortKey,

    /// The time the action was last updated.

    #[metric(help = "The last time the worker updated the AwaitedAction")]

    last_worker_updated_timestamp: SystemTime,

    /// The last time the client sent a keepalive message.

    #[metric(help = "The last time the client sent a keepalive message")]

    last_client_keepalive_timestamp: SystemTime,

    /// Worker that is currently running this action, None if unassigned.

    #[metric(help = "The worker id of the AwaitedAction")]

    worker_id: Option<WorkerId>,

    /// The current state of the action.

    #[metric(help = "The state of the AwaitedAction")]

    state: Arc<ActionState>,

    /// The origin metadata of the action.

    maybe_origin_metadata: Option<OriginMetadata>,

    /// Number of attempts the job has been tried.

    #[metric(help = "The number of attempts the AwaitedAction has been tried")]

    pub attempts: usize,

}

impl AwaitedAction {

    pub fn new(operation_id: OperationId, action_info: Arc<ActionInfo>, now: SystemTime) -> Self {

        let sort_key = AwaitedActionSortKey::new_with_unique_key(

            action_info.priority,

            &action_info.insert_timestamp,

        );

        let action_state = Arc::new(ActionState {

            stage: ActionStage::Queued,

            // Note: We don't use the real client_operation_id here because

            // the only place AwaitedAction::new should ever be called is

            // when the action is first created and this struct will be stored

            // in the database, so we don't want to accidentally leak the

            // client_operation_id to all clients.

            client_operation_id: operation_id.clone(),

            action_digest: action_info.unique_qualifier.digest(),

            last_transition_timestamp: now,

        });

        let ctx = Context::current();

        let baggage = ctx.baggage();

        let maybe_origin_metadata = if baggage.is_empty() {

            None

        } else {

            Some(OriginMetadata {

                identity: baggage

                    .get(ENDUSER_ID)

                    .map(|v| v.as_str().to_string())

                    .unwrap_or_default(),

                bazel_metadata: None, // TODO(palfrey): Implement conversion.

            })

        };

        Self {

            version: AwaitedActionVersion(0),

            action_info,

            operation_id,

            sort_key,

            attempts: 0,

            last_worker_updated_timestamp: now,

            last_client_keepalive_timestamp: now,

            maybe_origin_metadata,

            worker_id: None,

            state: action_state,

        }

    }

    pub(crate) const fn version(&self) -> i64 {

        self.version.0

    }

    pub(crate) const fn set_version(&mut self, version: i64) {

        self.version = AwaitedActionVersion(version);

    }

    pub(crate) const fn increment_version(&mut self) {

        self.version = AwaitedActionVersion(self.version.0 + 1);

    }

    pub const fn action_info(&self) -> &Arc<ActionInfo> {

        &self.action_info

    }

    pub const fn operation_id(&self) -> &OperationId {

        &self.operation_id

    }

    pub(crate) const fn sort_key(&self) -> AwaitedActionSortKey {

        self.sort_key

    }

    pub const fn state(&self) -> &Arc<ActionState> {

        &self.state

    }

    pub fn is_complete(&self) -> bool {

        match &self.state.stage {

            ActionStage::Unknown

            | ActionStage::CacheCheck

            | ActionStage::Queued

            | ActionStage::Executing => false,

            ActionStage::Completed(_) | ActionStage::CompletedFromCache(_) => true,

        }

    }

    pub(crate) const fn maybe_origin_metadata(&self) -> Option<&OriginMetadata> {

        self.maybe_origin_metadata.as_ref()

    }

    pub(crate) const fn worker_id(&self) -> Option<&WorkerId> {

        self.worker_id.as_ref()

    }

    pub(crate) const fn last_worker_updated_timestamp(&self) -> SystemTime {

        self.last_worker_updated_timestamp

    }

    pub(crate) const fn worker_keep_alive(&mut self, now: SystemTime) {

        self.last_worker_updated_timestamp = now;

    }

    pub(crate) const fn last_client_keepalive_timestamp(&self) -> SystemTime {

        self.last_client_keepalive_timestamp

    }

    pub(crate) const fn update_client_keep_alive(&mut self, now: SystemTime) {

        self.last_client_keepalive_timestamp = now;

    }

    pub(crate) fn set_client_operation_id(&mut self, client_operation_id: OperationId) {

        Arc::make_mut(&mut self.state).client_operation_id = client_operation_id;

    }

    /// Sets the worker id that is currently processing this action.

    pub(crate) fn set_worker_id(&mut self, new_maybe_worker_id: Option<WorkerId>, now: SystemTime) {

        if self.worker_id != new_maybe_worker_id {

            self.worker_id = new_maybe_worker_id;

            self.worker_keep_alive(now);

        
}8

    }

    /// Sets the current state of the action and updates the last worker updated timestamp.

    pub fn worker_set_state(&mut self, mut state: Arc<ActionState>, now: SystemTime) {

        core::mem::swap(&mut self.state, &mut state);

        self.worker_keep_alive(now);

    }

}

impl TryFrom<&[u8]> for AwaitedAction {

    type Error = Error;

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {

        serde_json::from_slice(value)

            .map_err(|e| make_input_err!("{}", e.to_string()))

            .err_tip(|| "In AwaitedAction::TryFrom::&[u8]")

    }

}

/// The key used to sort the awaited actions.

///

/// The rules for sorting are as follows:

/// 1. priority of the action

/// 2. insert order of the action (lower = higher priority)

/// 3. (mostly random hash based on the action info)

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]

#[repr(transparent)]

pub struct AwaitedActionSortKey(u64);

impl MetricsComponent for AwaitedActionSortKey {

    fn publish(

        &self,

        _kind: MetricKind,

        _field_metadata: MetricFieldData,

    ) -> Result<MetricPublishKnownKindData, nativelink_metric::Error> {

        Ok(MetricPublishKnownKindData::Counter(self.0))

    }

}

impl AwaitedActionSortKey {

    const fn new(priority: i32, insert_timestamp: u32) -> Self {

        // Shift the signed i32 range [i32::MIN, i32::MAX] to the unsigned u32 range

        // [0, u32::MAX] to preserve ordering when we convert to bytes for sorting.

        let priority_u32 = i32::MIN.unsigned_abs().wrapping_add_signed(priority);

        let priority = priority_u32.to_be_bytes();

        // Invert our timestamp so the larger the timestamp the lower the number.

        // This makes timestamp descending order instead of ascending.

        let timestamp = (insert_timestamp ^ u32::MAX).to_be_bytes();

        Self(u64::from_be_bytes([

            priority[0],

            priority[1],

            priority[2],

            priority[3],

            timestamp[0],

            timestamp[1],

            timestamp[2],

            timestamp[3],

        ]))

    }

    fn new_with_unique_key(priority: i32, insert_timestamp: &SystemTime) -> Self {

        let timestamp = u32::try_from(

            insert_timestamp

                .duration_since(UNIX_EPOCH)

                .unwrap()

                .as_secs(),

        )

        .unwrap_or(u32::MAX);

        Self::new(priority, timestamp)

    }

    pub(crate) const fn as_u64(self) -> u64 {

        self.0

    }

}

// Ensure the size of the sort key is the same as a `u64`.

assert_eq_size!(AwaitedActionSortKey, u64);

const_assert_eq!(

    AwaitedActionSortKey::new(0x1234_5678, 0x9abc_def0).0,

    // Note: Result has 0x12345678 + 0x80000000 = 0x92345678 because we need

    // to shift the `i32::MIN` value to be represented by zero.

    // Note: `6543210f` are the inverted bits of `9abcdef0`.

    // This effectively inverts the priority to now have the highest priority

    // be the lowest timestamps.

    AwaitedActionSortKey(0x9234_5678_6543_210f).0

);

// Ensure the priority is used as the sort key first.

const_assert!(

    AwaitedActionSortKey::new(i32::MAX, 0).0 > AwaitedActionSortKey::new(i32::MAX - 1, 0).0

);

const_assert!(AwaitedActionSortKey::new(i32::MAX - 1, 0).0 > AwaitedActionSortKey::new(1, 0).0);

const_assert!(AwaitedActionSortKey::new(1, 0).0 > AwaitedActionSortKey::new(0, 0).0);

const_assert!(AwaitedActionSortKey::new(0, 0).0 > AwaitedActionSortKey::new(-1, 0).0);

const_assert!(AwaitedActionSortKey::new(-1, 0).0 > AwaitedActionSortKey::new(i32::MIN + 1, 0).0);

const_assert!(

    AwaitedActionSortKey::new(i32::MIN + 1, 0).0 > AwaitedActionSortKey::new(i32::MIN, 0).0

);

// Ensure the insert timestamp is used as the sort key second.

const_assert!(AwaitedActionSortKey::new(0, u32::MIN).0 > AwaitedActionSortKey::new(0, u32::MAX).0);