rrt/crates/rrt-runtime/src/step.rs

use serde::{Deserialize, Serialize};

use crate::{RuntimeState, RuntimeSummary, calendar::BoundaryEventKind};

const PERIODIC_TRIGGER_KIND_ORDER: [u8; 6] = [1, 0, 3, 2, 5, 4];

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "kind", rename_all = "snake_case")]
pub enum StepCommand {
    AdvanceTo { calendar: crate::CalendarPoint },
    StepCount { steps: u32 },
    ServiceTriggerKind { trigger_kind: u8 },
    ServicePeriodicBoundary,
}

impl StepCommand {
    pub fn validate(&self) -> Result<(), String> {
        match self {
            Self::AdvanceTo { calendar } => calendar.validate(),
            Self::StepCount { steps } => {
                if *steps == 0 {
                    return Err("step_count command requires steps > 0".to_string());
                }
                Ok(())
            }
            Self::ServiceTriggerKind { .. } | Self::ServicePeriodicBoundary => Ok(()),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct BoundaryEvent {
    pub kind: String,
    pub calendar: crate::CalendarPoint,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ServiceEvent {
    pub kind: String,
    pub trigger_kind: Option<u8>,
    pub serviced_record_ids: Vec<u32>,
    pub dirty_rerun: bool,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct StepResult {
    pub initial_summary: RuntimeSummary,
    pub final_summary: RuntimeSummary,
    pub steps_executed: u64,
    pub boundary_events: Vec<BoundaryEvent>,
    pub service_events: Vec<ServiceEvent>,
}

pub fn execute_step_command(
    state: &mut RuntimeState,
    command: &StepCommand,
) -> Result<StepResult, String> {
    state.validate()?;
    command.validate()?;

    let initial_summary = RuntimeSummary::from_state(state);
    let mut boundary_events = Vec::new();
    let mut service_events = Vec::new();
    let steps_executed = match command {
        StepCommand::AdvanceTo { calendar } => {
            advance_to_target_calendar_point(state, *calendar, &mut boundary_events)?
        }
        StepCommand::StepCount { steps } => step_count(state, *steps, &mut boundary_events),
        StepCommand::ServiceTriggerKind { trigger_kind } => {
            service_trigger_kind(state, *trigger_kind, &mut service_events);
            0
        }
        StepCommand::ServicePeriodicBoundary => {
            service_periodic_boundary(state, &mut service_events);
            0
        }
    };
    let final_summary = RuntimeSummary::from_state(state);

    Ok(StepResult {
        initial_summary,
        final_summary,
        steps_executed,
        boundary_events,
        service_events,
    })
}

fn advance_to_target_calendar_point(
    state: &mut RuntimeState,
    target: crate::CalendarPoint,
    boundary_events: &mut Vec<BoundaryEvent>,
) -> Result<u64, String> {
    target.validate()?;
    if target < state.calendar {
        return Err(format!(
            "advance_to target {:?} is earlier than current calendar {:?}",
            target, state.calendar
        ));
    }

    let mut steps = 0_u64;
    while state.calendar < target {
        step_once(state, boundary_events);
        steps += 1;
    }
    Ok(steps)
}

fn step_count(
    state: &mut RuntimeState,
    steps: u32,
    boundary_events: &mut Vec<BoundaryEvent>,
) -> u64 {
    for _ in 0..steps {
        step_once(state, boundary_events);
    }
    steps.into()
}

fn step_once(state: &mut RuntimeState, boundary_events: &mut Vec<BoundaryEvent>) {
    let boundary = state.calendar.step_forward();
    if boundary != BoundaryEventKind::Tick {
        boundary_events.push(BoundaryEvent {
            kind: boundary_kind_label(boundary).to_string(),
            calendar: state.calendar,
        });
    }
}

fn boundary_kind_label(boundary: BoundaryEventKind) -> &'static str {
    match boundary {
        BoundaryEventKind::Tick => "tick",
        BoundaryEventKind::PhaseRollover => "phase_rollover",
        BoundaryEventKind::MonthRollover => "month_rollover",
        BoundaryEventKind::YearRollover => "year_rollover",
    }
}

fn service_periodic_boundary(state: &mut RuntimeState, service_events: &mut Vec<ServiceEvent>) {
    state.service_state.periodic_boundary_calls += 1;

    for trigger_kind in PERIODIC_TRIGGER_KIND_ORDER {
        service_trigger_kind(state, trigger_kind, service_events);
    }
}

fn service_trigger_kind(
    state: &mut RuntimeState,
    trigger_kind: u8,
    service_events: &mut Vec<ServiceEvent>,
) {
    let mut serviced_record_ids = Vec::new();
    let mut dirty_rerun = false;

    *state
        .service_state
        .trigger_dispatch_counts
        .entry(trigger_kind)
        .or_insert(0) += 1;

    for record in &mut state.event_runtime_records {
        if record.active && record.trigger_kind == trigger_kind {
            record.service_count += 1;
            serviced_record_ids.push(record.record_id);
            state.service_state.total_event_record_services += 1;
            if trigger_kind != 0x0a && record.marks_collection_dirty {
                dirty_rerun = true;
            }
        }
    }

    service_events.push(ServiceEvent {
        kind: "trigger_dispatch".to_string(),
        trigger_kind: Some(trigger_kind),
        serviced_record_ids,
        dirty_rerun,
    });

    if dirty_rerun {
        state.service_state.dirty_rerun_count += 1;
        service_trigger_kind(state, 0x0a, service_events);
    }
}

#[cfg(test)]
mod tests {
    use std::collections::BTreeMap;

    use super::*;
    use crate::{
        CalendarPoint, RuntimeCompany, RuntimeEventRecord, RuntimeSaveProfileState,
        RuntimeServiceState, RuntimeWorldRestoreState,
    };

    fn state() -> RuntimeState {
        RuntimeState {
            calendar: CalendarPoint {
                year: 1830,
                month_slot: 0,
                phase_slot: 0,
                tick_slot: 0,
            },
            world_flags: BTreeMap::new(),
            save_profile: RuntimeSaveProfileState::default(),
            world_restore: RuntimeWorldRestoreState::default(),
            metadata: BTreeMap::new(),
            companies: vec![RuntimeCompany {
                company_id: 1,
                current_cash: 10,
                debt: 0,
            }],
            event_runtime_records: Vec::new(),
            candidate_availability: BTreeMap::new(),
            special_conditions: BTreeMap::new(),
            service_state: RuntimeServiceState::default(),
        }
    }

    #[test]
    fn advances_to_target() {
        let mut state = state();
        let result = execute_step_command(
            &mut state,
            &StepCommand::AdvanceTo {
                calendar: CalendarPoint {
                    year: 1830,
                    month_slot: 0,
                    phase_slot: 0,
                    tick_slot: 5,
                },
            },
        )
        .expect("advance_to should succeed");

        assert_eq!(result.steps_executed, 5);
        assert_eq!(state.calendar.tick_slot, 5);
    }

    #[test]
    fn rejects_backward_target() {
        let mut state = state();
        state.calendar.tick_slot = 3;

        let result = execute_step_command(
            &mut state,
            &StepCommand::AdvanceTo {
                calendar: CalendarPoint {
                    year: 1830,
                    month_slot: 0,
                    phase_slot: 0,
                    tick_slot: 2,
                },
            },
        );

        assert!(result.is_err());
    }

    #[test]
    fn services_periodic_trigger_order_and_dirty_rerun() {
        let mut state = RuntimeState {
            event_runtime_records: vec![
                RuntimeEventRecord {
                    record_id: 1,
                    trigger_kind: 1,
                    active: true,
                    service_count: 0,
                    marks_collection_dirty: true,
                },
                RuntimeEventRecord {
                    record_id: 2,
                    trigger_kind: 4,
                    active: true,
                    service_count: 0,
                    marks_collection_dirty: false,
                },
                RuntimeEventRecord {
                    record_id: 3,
                    trigger_kind: 0x0a,
                    active: true,
                    service_count: 0,
                    marks_collection_dirty: false,
                },
            ],
            ..state()
        };

        let result = execute_step_command(&mut state, &StepCommand::ServicePeriodicBoundary)
            .expect("periodic boundary service should succeed");

        assert_eq!(result.steps_executed, 0);
        assert_eq!(state.service_state.periodic_boundary_calls, 1);
        assert_eq!(state.service_state.total_event_record_services, 3);
        assert_eq!(state.service_state.dirty_rerun_count, 1);
        assert_eq!(state.event_runtime_records[0].service_count, 1);
        assert_eq!(state.event_runtime_records[1].service_count, 1);
        assert_eq!(state.event_runtime_records[2].service_count, 1);
        assert_eq!(
            state.service_state.trigger_dispatch_counts.get(&1),
            Some(&1)
        );
        assert_eq!(
            state.service_state.trigger_dispatch_counts.get(&4),
            Some(&1)
        );
        assert_eq!(
            state.service_state.trigger_dispatch_counts.get(&0x0a),
            Some(&1)
        );
    }
}