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

//

// Licensed under the Apache License, Version 2.0 (the "License");

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

// You may obtain a copy of the License at

//

//    http://www.apache.org/licenses/LICENSE-2.0

//

// 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::collections::HashMap;

use serde::Deserialize;

use crate::serde_utils::{convert_duration_with_shellexpand, convert_numeric_with_shellexpand};

use crate::stores::{GrpcEndpoint, Retry, StoreRefName};

#[allow(non_camel_case_types)]

#[derive(Deserialize, Debug)]

pub enum SchedulerConfig {

    simple(SimpleScheduler),

    grpc(GrpcScheduler),

    cache_lookup(CacheLookupScheduler),

    property_modifier(PropertyModifierScheduler),

}

/// When the scheduler matches tasks to workers that are capable of running

/// the task, this value will be used to determine how the property is treated.

#[allow(non_camel_case_types)]

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

pub enum PropertyType {

    /// Requires the platform property to be a u64 and when the scheduler looks

    /// for appropriate worker nodes that are capable of executing the task,

    /// the task will not run on a node that has less than this value.

    minimum,

    /// Requires the platform property to be a string and when the scheduler

    /// looks for appropriate worker nodes that are capable of executing the

    /// task, the task will not run on a node that does not have this property

    /// set to the value with exact string match.

    exact,

    /// Does not restrict on this value and instead will be passed to the worker

    /// as an informational piece.

    /// TODO(allada) In the future this will be used by the scheduler and worker

    /// to cause the scheduler to prefer certain workers over others, but not

    /// restrict them based on these values.

    priority,

}

/// When a worker is being searched for to run a job, this will be used

/// on how to choose which worker should run the job when multiple

/// workers are able to run the task.

#[allow(non_camel_case_types)]

#[derive(Copy, Clone, Deserialize, Debug, Default)]

pub enum WorkerAllocationStrategy {

    /// Prefer workers that have been least recently used to run a job.

    #[default]

    least_recently_used,

    /// Prefer workers that have been most recently used to run a job.

    most_recently_used,

}

#[derive(Deserialize, Debug, Default)]

#[serde(deny_unknown_fields)]

pub struct SimpleScheduler {

    /// A list of supported platform properties mapped to how these properties

    /// are used when the scheduler looks for worker nodes capable of running

    /// the task.

    ///

    /// For example, a value of:

    /// ```json

    /// { "cpu_count": "minimum", "cpu_arch": "exact" }

    /// ```

    /// With a job that contains:

    /// ```json

    /// { "cpu_count": "8", "cpu_arch": "arm" }

    /// ```

    /// Will result in the scheduler filtering out any workers that do not have

    /// "cpu_arch" = "arm" and filter out any workers that have less than 8 cpu

    /// cores available.

    ///

    /// The property names here must match the property keys provided by the

    /// worker nodes when they join the pool. In other words, the workers will

    /// publish their capabilities to the scheduler when they join the worker

    /// pool. If the worker fails to notify the scheduler of its (for example)

    /// "cpu_arch", the scheduler will never send any jobs to it, if all jobs

    /// have the "cpu_arch" label. There is no special treatment of any platform

    /// property labels other and entirely driven by worker configs and this

    /// config.

    pub supported_platform_properties: Option<HashMap<String, PropertyType>>,

    /// The amount of time to retain completed actions in memory for in case

    /// a WaitExecution is called after the action has completed.

    /// Default: 60 (seconds)

    #[serde(default, deserialize_with = "convert_duration_with_shellexpand")]

    pub retain_completed_for_s: u32,

    /// Remove workers from pool once the worker has not responded in this

    /// amount of time in seconds.

    /// Default: 5 (seconds)

    #[serde(default, deserialize_with = "convert_duration_with_shellexpand")]

    pub worker_timeout_s: u64,

    /// If a job returns an internal error or times out this many times when

    /// attempting to run on a worker the scheduler will return the last error

    /// to the client. Jobs will be retried and this configuration is to help

    /// prevent one rogue job from infinitely retrying and taking up a lot of

    /// resources when the task itself is the one causing the server to go

    /// into a bad state.

    /// Default: 3

    #[serde(default, deserialize_with = "convert_numeric_with_shellexpand")]

    pub max_job_retries: usize,

    /// The strategy used to assign workers jobs.

    #[serde(default)]

    pub allocation_strategy: WorkerAllocationStrategy,

    /// The storage backend to use for the scheduler.

    /// Default: memory

    pub experimental_backend: Option<ExperimentalSimpleSchedulerBackend>,

}

#[allow(non_camel_case_types)]

#[derive(Deserialize, Debug)]

pub enum ExperimentalSimpleSchedulerBackend {

    /// Use an in-memory store for the scheduler.

    memory,

    /// Use a redis store for the scheduler.

    redis(ExperimentalRedisSchedulerBackend),

}

#[derive(Deserialize, Debug, Default)]

#[serde(deny_unknown_fields)]

pub struct ExperimentalRedisSchedulerBackend {

    /// A reference to the redis store to use for the scheduler.

    /// Note: This MUST resolve to a RedisStore.

    pub redis_store: StoreRefName,

}

/// A scheduler that simply forwards requests to an upstream scheduler.  This

/// is useful to use when doing some kind of local action cache or CAS away from

/// the main cluster of workers.  In general, it's more efficient to point the

/// build at the main scheduler directly though.

#[derive(Deserialize, Debug)]

#[serde(deny_unknown_fields)]

pub struct GrpcScheduler {

    /// The upstream scheduler to forward requests to.

    pub endpoint: GrpcEndpoint,

    /// Retry configuration to use when a network request fails.

    #[serde(default)]

    pub retry: Retry,

    /// Limit the number of simultaneous upstream requests to this many.  A

    /// value of zero is treated as unlimited.  If the limit is reached the

    /// request is queued.

    #[serde(default)]

    pub max_concurrent_requests: usize,

    /// The number of connections to make to each specified endpoint to balance

    /// the load over multiple TCP connections.  Default 1.

    #[serde(default)]

    pub connections_per_endpoint: usize,

}

#[derive(Deserialize, Debug)]

#[serde(deny_unknown_fields)]

pub struct CacheLookupScheduler {

    /// The reference to the action cache store used to return cached

    /// actions from rather than running them again.

    /// To prevent unintended issues, this store should probably be a CompletenessCheckingStore.

    pub ac_store: StoreRefName,

    /// The nested scheduler to use if cache lookup fails.

    pub scheduler: Box<SchedulerConfig>,

}

#[derive(Deserialize, Debug, Clone)]

#[serde(deny_unknown_fields)]

pub struct PlatformPropertyAddition {

    /// The name of the property to add.

    pub name: String,

    /// The value to assign to the property.

    pub value: String,

}

#[allow(non_camel_case_types)]

#[derive(Deserialize, Debug, Clone)]

pub enum PropertyModification {

    /// Add a property to the action properties.

    add(PlatformPropertyAddition),

    /// Remove a named property from the action.

    remove(String),

}

#[derive(Deserialize, Debug)]

#[serde(deny_unknown_fields)]

pub struct PropertyModifierScheduler {

    /// A list of modifications to perform to incoming actions for the nested

    /// scheduler.  These are performed in order and blindly, so removing a

    /// property that doesn't exist is fine and overwriting an existing property

    /// is also fine.  If adding properties that do not exist in the nested

    /// scheduler is not supported and will likely cause unexpected behaviour.

    pub modifications: Vec<PropertyModification>,

    /// The nested scheduler to use after modifying the properties.

    pub scheduler: Box<SchedulerConfig>,

}