cloudiful-scheduler 0.4.6

use super::{CronSchedule, JobTimeWindow};
use chrono::{DateTime, Utc};
use chrono_tz::{Asia::Shanghai, Tz};
use std::time::Duration;

/// Interval schedule with a stable phase derived from a seed.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct StaggeredIntervalSchedule {
    pub every: Duration,
    pub seed: Option<String>,
}

impl StaggeredIntervalSchedule {
    pub fn new(every: Duration) -> Self {
        Self { every, seed: None }
    }

    pub fn with_seed(mut self, seed: impl Into<String>) -> Self {
        self.seed = Some(seed.into());
        self
    }
}

/// Interval schedule that spreads members evenly across the interval.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GroupedIntervalSchedule {
    pub every: Duration,
    pub group_size: u32,
    pub member_index: u32,
    pub group_seed: Option<String>,
}

impl GroupedIntervalSchedule {
    pub fn new(every: Duration, group_size: u32, member_index: u32) -> Self {
        Self {
            every,
            group_size,
            member_index,
            group_seed: None,
        }
    }

    pub fn with_group_seed(mut self, group_seed: impl Into<String>) -> Self {
        self.group_seed = Some(group_seed.into());
        self
    }
}

/// Interval override for a matching time window.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct IntervalWindow {
    pub window: JobTimeWindow,
    pub every: Option<Duration>,
}

impl IntervalWindow {
    pub fn new(window: JobTimeWindow, every: Option<Duration>) -> Self {
        Self { window, every }
    }
}

/// Interval schedule with per-window frequencies.
///
/// `None` means no trigger is produced while that frequency is active.
/// Windows are evaluated in order; the first matching window wins.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct WindowedIntervalSchedule {
    pub default_every: Option<Duration>,
    pub windows: Vec<IntervalWindow>,
}

impl WindowedIntervalSchedule {
    pub fn new(default_every: Option<Duration>) -> Self {
        Self {
            default_every,
            windows: Vec::new(),
        }
    }

    pub fn with_window(mut self, window: JobTimeWindow, every: Option<Duration>) -> Self {
        self.windows.push(IntervalWindow::new(window, every));
        self
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Schedule {
    /// Trigger repeatedly after the given interval.
    Interval(Duration),
    /// Trigger repeatedly after the given interval with a stable phase.
    ///
    /// The first run is aligned to a deterministic phase derived from the
    /// seed. If no seed is provided, the job id is used.
    StaggeredInterval(StaggeredIntervalSchedule),
    /// Trigger repeatedly after the given interval with evenly spaced group
    /// members.
    ///
    /// The first run is aligned to a stable slot determined by the member
    /// index. An optional group seed can rotate the entire group without
    /// changing the spacing between members.
    GroupedInterval(GroupedIntervalSchedule),
    /// Trigger repeatedly with frequencies selected by local time windows.
    WindowedInterval(WindowedIntervalSchedule),
    /// Trigger at the listed wall-clock times.
    ///
    /// The list is sorted before execution starts. An empty list is treated as
    /// a no-op schedule and exits without running.
    AtTimes(Vec<DateTime<Tz>>),
    /// Trigger using a standard 5-field cron expression.
    ///
    /// The scheduler timezone is used to calculate the next matching wall-clock
    /// time. The expression itself does not carry timezone information.
    Cron(CronSchedule),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum MissedRunPolicy {
    Skip,
    #[default]
    CatchUpOnce,
    ReplayAll,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum OverlapPolicy {
    #[default]
    Forbid,
    QueueOne,
    AllowParallel,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum TerminalStatePolicy {
    #[default]
    Retain,
    Delete,
}

#[derive(Debug, Clone)]
pub struct SchedulerConfig {
    /// The timezone forwarded to each [`crate::RunContext`] and used to
    /// evaluate [`Schedule::Cron`] expressions.
    ///
    /// This does not rewrite [`Schedule::AtTimes`] values, which already carry
    /// their own timezone-aware timestamps.
    pub timezone: Tz,
    /// The maximum number of [`crate::RunRecord`] items kept in memory.
    pub history_limit: usize,
    /// Controls how persisted state is handled once a job reaches a terminal
    /// state (`next_run_at == None` and no further work is pending).
    pub terminal_state_policy: TerminalStatePolicy,
}

impl Default for SchedulerConfig {
    fn default() -> Self {
        Self {
            timezone: Shanghai,
            history_limit: 32,
            terminal_state_policy: TerminalStatePolicy::Retain,
        }
    }
}

impl Schedule {
    /// Create a staggered interval schedule that defaults to the job id as
    /// the phase seed.
    pub fn staggered_interval(every: Duration) -> Self {
        Self::StaggeredInterval(StaggeredIntervalSchedule::new(every))
    }

    /// Create a staggered interval schedule with an explicit phase seed.
    pub fn staggered_interval_with_seed(every: Duration, seed: impl Into<String>) -> Self {
        Self::StaggeredInterval(StaggeredIntervalSchedule::new(every).with_seed(seed))
    }

    /// Create a grouped interval schedule with evenly spaced members.
    pub fn grouped_interval(every: Duration, group_size: u32, member_index: u32) -> Self {
        Self::GroupedInterval(GroupedIntervalSchedule::new(
            every,
            group_size,
            member_index,
        ))
    }

    /// Create a grouped interval schedule and rotate the whole group with an
    /// explicit seed.
    pub fn grouped_interval_with_seed(
        every: Duration,
        group_size: u32,
        member_index: u32,
        group_seed: impl Into<String>,
    ) -> Self {
        Self::GroupedInterval(
            GroupedIntervalSchedule::new(every, group_size, member_index)
                .with_group_seed(group_seed),
        )
    }

    /// Create a windowed interval schedule.
    pub fn windowed_interval(default_every: Option<Duration>) -> Self {
        Self::WindowedInterval(WindowedIntervalSchedule::new(default_every))
    }
}

pub(crate) fn utc_time(value: DateTime<Tz>) -> DateTime<Utc> {
    value.with_timezone(&Utc)
}