agentstategraph-reminders 1.4.2

//! `ReminderManager` — business logic layer over a `ReminderStore`.
//!
//! All state transitions, schedule advancement, and permission checks
//! live here so the store layer stays a plain CRUD surface.

use std::sync::Arc;

use chrono::Utc;

use crate::error::ReminderError;
use crate::store::ReminderStore;
use crate::types::{
    CreateReminder, ExecutionRecord, ExecutionResult, Reminder, ReminderFilter, ReminderStatus,
};

/// How many times a read-modify-write re-reads a reminder that changed under
/// it before giving up.
const MAX_UPDATE_ATTEMPTS: usize = 32;

fn write_conflict(id: &str) -> ReminderError {
    ReminderError::Store(format!(
        "write conflict: reminder {id} kept changing; gave up after {MAX_UPDATE_ATTEMPTS} attempts"
    ))
}

pub struct ReminderManager {
    store: Arc<dyn ReminderStore>,
}

impl ReminderManager {
    pub fn new(store: Arc<dyn ReminderStore>) -> Self {
        Self { store }
    }

    // -----------------------------------------------------------------------
    // Create / read
    // -----------------------------------------------------------------------

    /// Create and persist a new reminder. Returns the fully-populated record.
    pub fn create(&self, input: CreateReminder) -> Result<Reminder, ReminderError> {
        let reminder = input.into_reminder();
        self.store.save(&reminder)?;
        Ok(reminder)
    }

    /// Retrieve a reminder by ID.
    pub fn get(&self, id: &str) -> Result<Reminder, ReminderError> {
        self.store
            .get(id)?
            .ok_or_else(|| ReminderError::NotFound(id.to_string()))
    }

    // -----------------------------------------------------------------------
    // List / remind_me
    // -----------------------------------------------------------------------

    /// Return all reminders matching `filter`.
    pub fn list(&self, filter: &ReminderFilter) -> Result<Vec<Reminder>, ReminderError> {
        self.store.list(filter)
    }

    /// Return all reminders that are currently actionable: status `Due` or
    /// `AwaitingPermission`, ordered by priority then `due_at`.
    ///
    /// Also promotes `Pending` reminders whose `due_at <= now` to `Due`
    /// (lazy promotion — avoids the need for a background timer).
    pub fn remind_me(&self) -> Result<Vec<Reminder>, ReminderError> {
        let now = Utc::now();

        // Promote any pending reminders whose due_at has passed.
        let pending = self.store.list(&ReminderFilter {
            status: Some(ReminderStatus::Pending),
            ..Default::default()
        })?;
        for read in pending {
            if read.due_at <= now {
                // Non-autonomous reminders require approval before they become
                // actionable — route them to AwaitingPermission, not straight
                // to Due. (Autonomous ones are pre-approved.)
                let mut r = read.clone();
                r.status = if r.autonomous {
                    ReminderStatus::Due
                } else {
                    ReminderStatus::AwaitingPermission
                };
                // If it changed since the list (cancelled, snoozed), leave it:
                // writing back this snapshot would revert that change.
                self.store.update_if_unchanged(&read, &r)?;
            }
        }

        // Also promote snoozed reminders whose snooze has expired.
        let snoozed = self.store.list(&ReminderFilter {
            status: Some(ReminderStatus::Snoozed),
            ..Default::default()
        })?;
        for read in snoozed {
            let wake = read.snoozed_until.unwrap_or(read.due_at);
            if wake <= now {
                // Same approval gate on wake: a non-autonomous reminder must be
                // re-approved before it can run again.
                let mut r = read.clone();
                r.status = if r.autonomous {
                    ReminderStatus::Due
                } else {
                    ReminderStatus::AwaitingPermission
                };
                r.snoozed_until = None;
                self.store.update_if_unchanged(&read, &r)?;
            }
        }

        // Now return all actionable reminders.
        let mut due = self.store.list(&ReminderFilter {
            status: Some(ReminderStatus::Due),
            ..Default::default()
        })?;
        let mut awaiting = self.store.list(&ReminderFilter {
            status: Some(ReminderStatus::AwaitingPermission),
            ..Default::default()
        })?;
        due.append(&mut awaiting);
        due.sort_by(|a, b| a.priority.cmp(&b.priority).then(a.due_at.cmp(&b.due_at)));
        Ok(due)
    }

    // -----------------------------------------------------------------------
    // Lifecycle mutations
    // -----------------------------------------------------------------------

    /// Snooze a reminder until `until`. Valid from `Due`, `AwaitingPermission`,
    /// or `InProgress` states.
    pub fn snooze(
        &self,
        id: &str,
        until: chrono::DateTime<Utc>,
    ) -> Result<Reminder, ReminderError> {
        self.modify(id, |r| {
            if r.status.is_terminal() {
                return Err(ReminderError::AlreadyTerminal(id.to_string(), r.status));
            }
            r.status = ReminderStatus::Snoozed;
            r.snoozed_until = Some(until);
            Ok(())
        })
    }

    /// Cancel a reminder. Idempotent if already cancelled.
    pub fn cancel(&self, id: &str) -> Result<Reminder, ReminderError> {
        self.modify(id, |r| {
            if r.status == ReminderStatus::Completed {
                return Err(ReminderError::AlreadyTerminal(id.to_string(), r.status));
            }
            r.status = ReminderStatus::Cancelled;
            Ok(())
        })
    }

    /// Approve a non-autonomous reminder for execution, recording who approved.
    /// Transitions `AwaitingPermission` → `Due`.
    pub fn approve(&self, id: &str, approved_by: &str) -> Result<Reminder, ReminderError> {
        self.modify(id, |r| {
            match r.status {
                ReminderStatus::AwaitingPermission => {}
                ReminderStatus::Due => {
                    // Already approved / promoted; record the approver but don't error.
                }
                s if s.is_terminal() => {
                    return Err(ReminderError::AlreadyTerminal(id.to_string(), s));
                }
                s => {
                    return Err(ReminderError::InvalidTransition {
                        id: id.to_string(),
                        from: s,
                        to: ReminderStatus::Due,
                    });
                }
            }
            // Stamp the most recent pending execution record with the approver,
            // or leave that to record_execution if none exists yet.
            r.status = ReminderStatus::Due;
            // Store the approved_by on the reminder directly so record_execution
            // can pick it up without requiring the caller to pass it again.
            // We use a sentinel in the first partial execution record if present.
            if let Some(rec) = r.executions.last_mut() {
                if rec.completed_at.is_none() {
                    rec.approved_by = Some(approved_by.to_string());
                }
            }
            Ok(())
        })
    }

    /// Mark a reminder as in-progress. Transitions `Due` → `InProgress`.
    /// Non-autonomous reminders must be approved first.
    pub fn start(&self, id: &str, agent_id: &str) -> Result<Reminder, ReminderError> {
        self.modify(id, |r| {
            match r.status {
                ReminderStatus::Due => {}
                ReminderStatus::AwaitingPermission => {
                    if !r.autonomous {
                        return Err(ReminderError::RequiresApproval(id.to_string()));
                    }
                }
                s if s.is_terminal() => {
                    return Err(ReminderError::AlreadyTerminal(id.to_string(), s));
                }
                s => {
                    return Err(ReminderError::InvalidTransition {
                        id: id.to_string(),
                        from: s,
                        to: ReminderStatus::InProgress,
                    });
                }
            }
            // Open a partial execution record.
            r.executions.push(crate::types::ExecutionRecord {
                started_at: Utc::now(),
                completed_at: None,
                agent_id: agent_id.to_string(),
                approved_by: None,
                result: ExecutionResult::Deferred, // placeholder until record_execution
                notes: Vec::new(),
                task_id: None,
            });
            r.status = ReminderStatus::InProgress;
            Ok(())
        })
    }

    /// Complete an execution attempt, appending the `ExecutionRecord`.
    ///
    /// On `Success`:
    /// - If the reminder has a repeating schedule, compute `next_due` and
    ///   reset to `Pending`.
    /// - Otherwise mark `Completed`.
    ///
    /// On non-autonomous reminders that have not yet been approved, this
    /// method transitions to `AwaitingPermission` instead of `Due` after
    /// schedule advancement.
    pub fn record_execution(
        &self,
        id: &str,
        record: ExecutionRecord,
    ) -> Result<Reminder, ReminderError> {
        self.modify(id, |r| {
            if r.status.is_terminal() {
                return Err(ReminderError::AlreadyTerminal(id.to_string(), r.status));
            }

            let completed_at = Utc::now();
            let mut record = record.clone();
            record.completed_at = Some(completed_at);

            // If start() opened a partial record, update it in-place; otherwise push.
            match r.executions.last_mut() {
                Some(last) if last.completed_at.is_none() => {
                    last.completed_at = record.completed_at;
                    last.result = record.result.clone();
                    last.notes = record.notes.clone();
                    last.task_id = record.task_id.clone();
                    if record.approved_by.is_some() {
                        last.approved_by = record.approved_by.clone();
                    }
                }
                _ => r.executions.push(record.clone()),
            }

            match &record.result {
                ExecutionResult::Success => {
                    match r.schedule.as_ref().and_then(|s| s.next_due(completed_at)) {
                        Some(next) => {
                            r.due_at = next;
                            r.snoozed_until = None;
                            r.status = if r.autonomous {
                                ReminderStatus::Pending
                            } else {
                                ReminderStatus::AwaitingPermission
                            };
                        }
                        None => {
                            r.status = ReminderStatus::Completed;
                        }
                    }
                }
                ExecutionResult::Snoozed => {
                    // Snooze was set separately via snooze(); just record.
                    if r.status != ReminderStatus::Snoozed {
                        r.status = ReminderStatus::Snoozed;
                    }
                }
                ExecutionResult::Cancelled => {
                    r.status = ReminderStatus::Cancelled;
                }
                ExecutionResult::Failed | ExecutionResult::Deferred => {
                    // Leave status as-is (InProgress or Due); caller decides next step.
                    if r.status == ReminderStatus::InProgress {
                        r.status = ReminderStatus::Due;
                    }
                }
            }
            Ok(())
        })
    }

    /// Mark a ref as stale by `ref_id`. Returns the number of refs updated.
    pub fn mark_ref_stale(&self, id: &str, ref_id: &str) -> Result<usize, ReminderError> {
        for _ in 0..MAX_UPDATE_ATTEMPTS {
            let read = self.get(id)?;
            let mut r = read.clone();
            let mut count = 0;
            for rf in r.refs.iter_mut() {
                if rf.id == ref_id && !rf.stale {
                    rf.stale = true;
                    count += 1;
                }
            }
            if count == 0 || self.store.update_if_unchanged(&read, &r)? {
                return Ok(count);
            }
        }
        Err(write_conflict(id))
    }

    /// Read-modify-write one reminder without losing a concurrent change:
    /// read, apply `change` to a copy, and write it only if the stored record
    /// still matches what was read; otherwise re-read and re-apply (which also
    /// re-validates the transition). Every lifecycle method used to write back
    /// its read unconditionally, so a concurrent cancel, snooze, or execution
    /// record was silently reverted while both calls returned Ok.
    fn modify<F>(&self, id: &str, mut change: F) -> Result<Reminder, ReminderError>
    where
        F: FnMut(&mut Reminder) -> Result<(), ReminderError>,
    {
        for _ in 0..MAX_UPDATE_ATTEMPTS {
            let read = self.get(id)?;
            let mut r = read.clone();
            change(&mut r)?;
            if self.store.update_if_unchanged(&read, &r)? {
                return Ok(r);
            }
        }
        Err(write_conflict(id))
    }
}