oxigdal-workflow 0.1.6

//! Workflow scheduler for managing workflow executions.
//!
//! Provides multiple scheduling strategies:
//! - Cron-based scheduling
//! - Event-driven triggers
//! - Interval-based scheduling
//! - Cross-workflow dependencies

pub mod cron;
pub mod dependency;
pub mod event;
pub mod interval;

use crate::engine::WorkflowDefinition;
use crate::error::{Result, WorkflowError};
use chrono::{DateTime, Utc};
use dashmap::DashMap;
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use tokio::sync::RwLock;
use uuid::Uuid;

pub use self::cron::{CronSchedule, CronScheduler};
pub use self::dependency::{DependencyScheduler, WorkflowDependency};
pub use self::event::{EventScheduler, EventTrigger};
pub use self::interval::{IntervalSchedule, IntervalScheduler};

/// Scheduler configuration.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SchedulerConfig {
    /// Maximum number of concurrent workflow executions.
    pub max_concurrent_executions: usize,
    /// Enable missed execution handling.
    pub handle_missed_executions: bool,
    /// Maximum number of missed executions to handle.
    pub max_missed_executions: usize,
    /// Execution timeout in seconds.
    pub execution_timeout_secs: u64,
    /// Enable scheduler state persistence.
    pub enable_persistence: bool,
    /// Persistence directory path.
    pub persistence_path: Option<String>,
    /// Scheduler tick interval in milliseconds.
    pub tick_interval_ms: u64,
    /// Time zone for scheduling (IANA timezone name).
    pub timezone: String,
}

impl Default for SchedulerConfig {
    fn default() -> Self {
        Self {
            max_concurrent_executions: 100,
            handle_missed_executions: true,
            max_missed_executions: 10,
            execution_timeout_secs: 3600,
            enable_persistence: true,
            persistence_path: None,
            tick_interval_ms: 100,
            timezone: "UTC".to_string(),
        }
    }
}

/// Scheduled workflow entry.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ScheduledWorkflow {
    /// Unique schedule ID.
    pub schedule_id: String,
    /// Workflow definition.
    pub workflow: WorkflowDefinition,
    /// Schedule type.
    pub schedule_type: ScheduleType,
    /// Whether the schedule is enabled.
    pub enabled: bool,
    /// Last execution time.
    pub last_execution: Option<DateTime<Utc>>,
    /// Next scheduled execution time.
    pub next_execution: Option<DateTime<Utc>>,
    /// Execution history (last N executions).
    pub execution_history: Vec<ScheduleExecution>,
    /// Maximum number of history entries to keep.
    pub max_history: usize,
    /// Schedule metadata.
    pub metadata: ScheduleMetadata,
}

/// Schedule type enumeration.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "type")]
pub enum ScheduleType {
    /// Cron-based scheduling.
    Cron {
        /// Cron expression.
        expression: String,
    },
    /// Interval-based scheduling.
    Interval {
        /// Interval in seconds.
        interval_secs: u64,
    },
    /// Event-driven trigger.
    Event {
        /// Event pattern to match.
        event_pattern: String,
    },
    /// Manual trigger only.
    Manual,
    /// Dependency-based trigger.
    Dependency {
        /// Workflow dependencies.
        dependencies: Vec<String>,
    },
}

/// Schedule execution record.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ScheduleExecution {
    /// Execution ID.
    pub execution_id: String,
    /// Execution start time.
    pub start_time: DateTime<Utc>,
    /// Execution end time.
    pub end_time: Option<DateTime<Utc>>,
    /// Execution status.
    pub status: ExecutionStatus,
    /// Error message if failed.
    pub error_message: Option<String>,
}

/// Execution status.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ExecutionStatus {
    /// Execution is pending.
    Pending,
    /// Execution is running.
    Running,
    /// Execution completed successfully.
    Success,
    /// Execution failed.
    Failed,
    /// Execution was cancelled.
    Cancelled,
    /// Execution timed out.
    TimedOut,
}

/// Schedule metadata.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ScheduleMetadata {
    /// Schedule creation time.
    pub created_at: DateTime<Utc>,
    /// Schedule last update time.
    pub updated_at: DateTime<Utc>,
    /// Schedule creator.
    pub created_by: String,
    /// Schedule description.
    pub description: Option<String>,
    /// Schedule tags.
    pub tags: Vec<String>,
}

/// Main workflow scheduler.
pub struct Scheduler {
    config: SchedulerConfig,
    schedules: Arc<DashMap<String, ScheduledWorkflow>>,
    cron_scheduler: Arc<RwLock<CronScheduler>>,
    interval_scheduler: Arc<RwLock<IntervalScheduler>>,
    event_scheduler: Arc<RwLock<EventScheduler>>,
    dependency_scheduler: Arc<RwLock<DependencyScheduler>>,
    running: Arc<RwLock<bool>>,
}

impl Scheduler {
    /// Create a new scheduler with the given configuration.
    pub fn new(config: SchedulerConfig) -> Self {
        Self {
            config: config.clone(),
            schedules: Arc::new(DashMap::new()),
            cron_scheduler: Arc::new(RwLock::new(CronScheduler::new(config.clone()))),
            interval_scheduler: Arc::new(RwLock::new(IntervalScheduler::new(config.clone()))),
            event_scheduler: Arc::new(RwLock::new(EventScheduler::new(config.clone()))),
            dependency_scheduler: Arc::new(RwLock::new(DependencyScheduler::new(config.clone()))),
            running: Arc::new(RwLock::new(false)),
        }
    }

    /// Create a new scheduler with default configuration.
    pub fn with_defaults() -> Self {
        Self::new(SchedulerConfig::default())
    }

    /// Add a scheduled workflow.
    pub async fn add_schedule(
        &self,
        workflow: WorkflowDefinition,
        schedule_type: ScheduleType,
    ) -> Result<String> {
        let schedule_id = Uuid::new_v4().to_string();
        let now = Utc::now();

        let next_execution = match &schedule_type {
            ScheduleType::Cron { expression } => {
                let scheduler = self.cron_scheduler.write().await;
                scheduler.calculate_next_execution(expression, now)?
            }
            ScheduleType::Interval { interval_secs } => Some(
                now + chrono::Duration::try_seconds(*interval_secs as i64)
                    .ok_or_else(|| WorkflowError::scheduling("Invalid interval"))?,
            ),
            ScheduleType::Event { .. } | ScheduleType::Dependency { .. } => None,
            ScheduleType::Manual => None,
        };

        let scheduled = ScheduledWorkflow {
            schedule_id: schedule_id.clone(),
            workflow,
            schedule_type,
            enabled: true,
            last_execution: None,
            next_execution,
            execution_history: Vec::new(),
            max_history: 100,
            metadata: ScheduleMetadata {
                created_at: now,
                updated_at: now,
                created_by: "system".to_string(),
                description: None,
                tags: Vec::new(),
            },
        };

        self.schedules.insert(schedule_id.clone(), scheduled);

        if self.config.enable_persistence {
            self.persist_state().await?;
        }

        Ok(schedule_id)
    }

    /// Remove a scheduled workflow.
    pub async fn remove_schedule(&self, schedule_id: &str) -> Result<()> {
        self.schedules
            .remove(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;

        if self.config.enable_persistence {
            self.persist_state().await?;
        }

        Ok(())
    }

    /// Enable a schedule.
    pub async fn enable_schedule(&self, schedule_id: &str) -> Result<()> {
        let mut schedule = self
            .schedules
            .get_mut(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;
        schedule.enabled = true;
        schedule.metadata.updated_at = Utc::now();
        Ok(())
    }

    /// Disable a schedule.
    pub async fn disable_schedule(&self, schedule_id: &str) -> Result<()> {
        let mut schedule = self
            .schedules
            .get_mut(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;
        schedule.enabled = false;
        schedule.metadata.updated_at = Utc::now();
        Ok(())
    }

    /// Start the scheduler.
    pub async fn start(&self) -> Result<()> {
        let mut running = self.running.write().await;
        if *running {
            return Err(WorkflowError::scheduling("Scheduler already running"));
        }
        *running = true;
        drop(running);

        // Start all sub-schedulers
        let cron_scheduler = self.cron_scheduler.clone();
        let interval_scheduler = self.interval_scheduler.clone();
        let event_scheduler = self.event_scheduler.clone();
        let dependency_scheduler = self.dependency_scheduler.clone();

        tokio::spawn(async move {
            let _ = cron_scheduler.write().await;
            // Scheduler loop would go here
        });

        tokio::spawn(async move {
            let _ = interval_scheduler.write().await;
            // Scheduler loop would go here
        });

        tokio::spawn(async move {
            let _ = event_scheduler.write().await;
            // Scheduler loop would go here
        });

        tokio::spawn(async move {
            let _ = dependency_scheduler.write().await;
            // Scheduler loop would go here
        });

        Ok(())
    }

    /// Stop the scheduler.
    pub async fn stop(&self) -> Result<()> {
        let mut running = self.running.write().await;
        if !*running {
            return Err(WorkflowError::scheduling("Scheduler not running"));
        }
        *running = false;
        Ok(())
    }

    /// Check if the scheduler is running.
    pub async fn is_running(&self) -> bool {
        *self.running.read().await
    }

    /// Get all schedules.
    pub fn get_schedules(&self) -> Vec<ScheduledWorkflow> {
        self.schedules
            .iter()
            .map(|entry| entry.value().clone())
            .collect()
    }

    /// Get a specific schedule.
    pub fn get_schedule(&self, schedule_id: &str) -> Option<ScheduledWorkflow> {
        self.schedules.get(schedule_id).map(|entry| entry.clone())
    }

    /// Trigger a manual execution.
    pub async fn trigger_manual(&self, schedule_id: &str) -> Result<String> {
        let schedule = self
            .schedules
            .get(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;

        if !schedule.enabled {
            return Err(WorkflowError::scheduling("Schedule is disabled"));
        }

        let execution_id = Uuid::new_v4().to_string();

        // Record execution start
        let execution = ScheduleExecution {
            execution_id: execution_id.clone(),
            start_time: Utc::now(),
            end_time: None,
            status: ExecutionStatus::Pending,
            error_message: None,
        };

        drop(schedule);

        let mut schedule_mut = self
            .schedules
            .get_mut(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;
        schedule_mut.execution_history.push(execution);
        if schedule_mut.execution_history.len() > schedule_mut.max_history {
            schedule_mut.execution_history.remove(0);
        }

        Ok(execution_id)
    }

    /// Update execution status.
    pub async fn update_execution_status(
        &self,
        schedule_id: &str,
        execution_id: &str,
        status: ExecutionStatus,
        error_message: Option<String>,
    ) -> Result<()> {
        let mut schedule = self
            .schedules
            .get_mut(schedule_id)
            .ok_or_else(|| WorkflowError::not_found(schedule_id))?;

        if let Some(execution) = schedule
            .execution_history
            .iter_mut()
            .find(|e| e.execution_id == execution_id)
        {
            execution.status = status;
            execution.error_message = error_message;
            if matches!(
                status,
                ExecutionStatus::Success
                    | ExecutionStatus::Failed
                    | ExecutionStatus::Cancelled
                    | ExecutionStatus::TimedOut
            ) {
                execution.end_time = Some(Utc::now());
            }
        }

        // Release the DashMap lock before async I/O.
        drop(schedule);

        if self.config.enable_persistence {
            if let Err(e) = self.persist_state().await {
                tracing::warn!(
                    "scheduler: failed to persist state after status update: {}",
                    e
                );
            }
        }

        Ok(())
    }

    /// Persist scheduler state atomically using write-to-tmp-then-rename.
    ///
    /// Each `ScheduledWorkflow` is serialized as a single JSON line (JSON-Lines format).
    /// The write is crash-safe: data is first written to a `.tmp` sibling file, then
    /// atomically renamed into place, so a mid-write crash never leaves a corrupt file.
    async fn persist_state(&self) -> Result<()> {
        let path_str = match &self.config.persistence_path {
            Some(p) => p.clone(),
            None => return Ok(()),
        };

        let path = std::path::PathBuf::from(&path_str);

        // Ensure the parent directory exists.
        if let Some(parent) = path.parent() {
            if !parent.as_os_str().is_empty() {
                tokio::fs::create_dir_all(parent).await?;
            }
        }

        // Snapshot the DashMap into a sorted Vec for deterministic output.
        let mut snapshot: Vec<ScheduledWorkflow> = self
            .schedules
            .iter()
            .map(|entry| entry.value().clone())
            .collect();
        snapshot.sort_by(|a, b| a.schedule_id.cmp(&b.schedule_id));

        // Build JSON-Lines payload: one compact JSON object per line.
        let mut payload = String::with_capacity(snapshot.len() * 256);
        for workflow in &snapshot {
            let line = serde_json::to_string(workflow)?;
            payload.push_str(&line);
            payload.push('\n');
        }

        // Atomic write: write to a `.tmp` sibling, then rename into place.
        let tmp_path = {
            let mut p = path.clone();
            let ext = match p.extension() {
                Some(e) => format!("{}.tmp", e.to_string_lossy()),
                None => "tmp".to_string(),
            };
            p.set_extension(ext);
            p
        };

        tokio::fs::write(&tmp_path, payload.as_bytes()).await?;
        tokio::fs::rename(&tmp_path, &path).await?;

        tracing::debug!(
            "scheduler::persist_state: wrote {} schedules to {}",
            snapshot.len(),
            path.display()
        );

        Ok(())
    }

    /// Load scheduler state from the persistence file.
    ///
    /// Reads the JSON-Lines file written by `persist_state`.  Corrupt or
    /// unparseable lines are skipped with a `warn!` log; the method still
    /// returns `Ok(())` so that a partially-corrupt file does not prevent
    /// the scheduler from starting.
    pub async fn load_state(&self) -> Result<()> {
        let path_str = match &self.config.persistence_path {
            Some(p) => p.clone(),
            None => return Ok(()),
        };

        let path = std::path::PathBuf::from(&path_str);

        // First startup — no persistence file exists yet.
        if !path.exists() {
            return Ok(());
        }

        let content = tokio::fs::read_to_string(&path).await?;
        let mut loaded_count = 0usize;
        let mut failed_count = 0usize;

        for (line_no, raw_line) in content.lines().enumerate() {
            let line = raw_line.trim();
            if line.is_empty() {
                continue;
            }

            match serde_json::from_str::<ScheduledWorkflow>(line) {
                Ok(workflow) => {
                    self.schedules
                        .insert(workflow.schedule_id.clone(), workflow);
                    loaded_count += 1;
                }
                Err(e) => {
                    tracing::warn!(
                        "scheduler::load_state: skipping corrupt line {} in {}: {}",
                        line_no + 1,
                        path.display(),
                        e
                    );
                    failed_count += 1;
                }
            }
        }

        if failed_count > 0 {
            tracing::warn!(
                "scheduler::load_state: {}/{} lines failed to parse in {}",
                failed_count,
                loaded_count + failed_count,
                path.display()
            );
        }

        tracing::debug!(
            "scheduler::load_state: loaded {} schedules from {}",
            loaded_count,
            path.display()
        );

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::dag::WorkflowDag;

    #[tokio::test]
    async fn test_scheduler_creation() {
        let scheduler = Scheduler::with_defaults();
        assert!(!scheduler.is_running().await);
    }

    #[tokio::test]
    async fn test_add_remove_schedule() {
        let scheduler = Scheduler::with_defaults();
        let workflow = WorkflowDefinition {
            id: "test-workflow".to_string(),
            name: "Test Workflow".to_string(),
            description: None,
            version: "1.0.0".to_string(),
            dag: WorkflowDag::new(),
        };

        let schedule_id = scheduler
            .add_schedule(workflow, ScheduleType::Manual)
            .await
            .expect("Failed to add schedule");

        assert!(scheduler.get_schedule(&schedule_id).is_some());

        scheduler
            .remove_schedule(&schedule_id)
            .await
            .expect("Failed to remove schedule");

        assert!(scheduler.get_schedule(&schedule_id).is_none());
    }

    #[tokio::test]
    async fn test_enable_disable_schedule() {
        let scheduler = Scheduler::with_defaults();
        let workflow = WorkflowDefinition {
            id: "test-workflow".to_string(),
            name: "Test Workflow".to_string(),
            description: None,
            version: "1.0.0".to_string(),
            dag: WorkflowDag::new(),
        };

        let schedule_id = scheduler
            .add_schedule(workflow, ScheduleType::Manual)
            .await
            .expect("Failed to add schedule");

        scheduler
            .disable_schedule(&schedule_id)
            .await
            .expect("Failed to disable");
        assert!(
            !scheduler
                .get_schedule(&schedule_id)
                .is_some_and(|s| s.enabled)
        );

        scheduler
            .enable_schedule(&schedule_id)
            .await
            .expect("Failed to enable");
        assert!(
            scheduler
                .get_schedule(&schedule_id)
                .is_some_and(|s| s.enabled)
        );
    }
}