upend/src/util/jobs.rs

use anyhow::{anyhow, Result};
use serde::{Serialize, Serializer};
use std::{
    collections::HashMap,
    sync::{Arc, RwLock},
};
use tracing::warn;
use uuid::Uuid;

#[derive(Default, Serialize, Clone)]
pub struct Job {
    pub job_type: Option<JobType>,
    pub title: String,
    pub progress: Option<f32>,
    pub state: JobState,
}

pub type JobType = String;

#[derive(Serialize, Clone, Copy, PartialEq)]
pub enum JobState {
    InProgress,
    Done,
    Failed,
}

impl Default for JobState {
    fn default() -> Self {
        JobState::InProgress
    }
}

#[derive(Default)]
pub struct JobContainerData {
    jobs: HashMap<JobId, Job>,
}

#[derive(Debug, Clone)]
pub struct JobInProgessError(String);

impl std::fmt::Display for JobInProgessError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "job of type {} is already in progress", self.0)
    }
}

impl std::error::Error for JobInProgessError {}

#[derive(Clone)]
pub struct JobContainer(Arc<RwLock<JobContainerData>>);

impl JobContainer {
    pub fn new() -> Self {
        JobContainer(Arc::new(RwLock::new(JobContainerData::default())))
    }

    pub fn add_job<S, IS>(&mut self, job_type: IS, title: S) -> Result<JobHandle>
    where
        S: AsRef<str>,
        IS: Into<Option<S>>,
    {
        let jobs = &mut self
            .0
            .write()
            .map_err(|err| anyhow!("Couldn't lock job container for writing! {err:?}"))?
            .jobs;

        let job = Job {
            job_type: job_type.into().map(|jt| String::from(jt.as_ref())),
            title: String::from(title.as_ref()),
            ..Default::default()
        };

        if let Some(job_type) = &job.job_type {
            if jobs
                .iter()
                .any(|(_, j)| j.state == JobState::InProgress && j.job_type == job.job_type)
            {
                return Err(JobInProgessError(format!(
                    r#"Job of type "{}" currently in progress."#,
                    job_type
                ))
                .into());
            }
        }

        let job_id = JobId(Uuid::new_v4());
        jobs.insert(job_id, job);
        Ok(JobHandle {
            job_id,
            container: self.0.clone(),
        })
    }

    pub fn get_jobs(&self) -> Result<HashMap<JobId, Job>> {
        let jobs = &self
            .0
            .read()
            .map_err(|err| anyhow!("Couldn't lock job container for writing! {err:?}"))?
            .jobs;

        Ok(jobs.clone())
    }
}

#[derive(Clone, Hash, PartialEq, Eq, Copy)]
pub struct JobId(Uuid);

impl Serialize for JobId {
    fn serialize<S>(&self, serializer: S) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(format!("{}", self.0).as_str())
    }
}

pub struct JobHandle {
    job_id: JobId,
    container: Arc<RwLock<JobContainerData>>,
}

impl JobHandle {
    pub fn update_progress(&mut self, progress: f32) -> Result<()> {
        let jobs = &mut self
            .container
            .write()
            .map_err(|err| anyhow!("Couldn't lock job container for writing! {err:?}"))?
            .jobs;

        if let Some(job) = jobs.get_mut(&self.job_id) {
            job.progress = Some(progress);
            if progress >= 100.0 {
                job.state = JobState::Done;
            }
            Ok(())
        } else {
            Err(anyhow!("No such job."))
        }
    }

    pub fn update_state(&mut self, state: JobState) -> Result<()> {
        let jobs = &mut self
            .container
            .write()
            .map_err(|err| anyhow!("Couldn't lock job container for writing! {err:?}"))?
            .jobs;

        if let Some(job) = jobs.get_mut(&self.job_id) {
            job.state = state;
            Ok(())
        } else {
            Err(anyhow!("No such job."))
        }
    }
}

impl Drop for JobHandle {
    fn drop(&mut self) {
        let update_result = self.update_state(JobState::Failed);
        if let Err(err) = update_result {
            warn!("Handle dropped, but couldn't set self as failed! {:?}", err);
        }
    }
}