// The visibility phases, wired to the save shapes.
//
// Three phases of the turn touch the per-system visibility cluster, in two different
// drivers, and they are listed here together because they share one input -- the system's
// active-presence mask -- and nothing else in the turn reads it.
//
//   S29  the system's own last-observed stamp
//   T17  the per-(system, player) observation record
//   T21  the explored sweep
//
// The mask itself is READ FROM THE SAVE and never rebuilt. The original recomputes it on
// every fleet arrival and departure, which the standalone does not model; but neither
// reference pair moves a mask leaf, so the loaded value is the value these phases would
// see, and rebuilding it from an unmodelled movement pass would be a change with no
// evidence behind it. When that stops being true it will show up as a regression here
// first, which is the point of saying it out loud.
#pragma once

#include <string>
#include <vector>

#include "mars/stream/shapes.h"

namespace sots::app {

// What one visibility phase did, in the terms the run log prints.
struct VisibilityPhaseResult {
    int systemsVisited = 0;   // systems the phase looked at
    int systemsTouched = 0;   // systems where something moved
    int leafWrites = 0;       // save leaves this phase changed
    std::vector<std::string> notes;
};

// S29: `ltis`, the system's own last-observed turn. Written on every system some player can
// currently see; left alone on the rest.
VisibilityPhaseResult RunSystemObservedStamp(mars::stream::shapes::SaveGame& game);

// T21: the explored sweep -- every player who can see a system has now surveyed it.
VisibilityPhaseResult RunExploredSweep(mars::stream::shapes::SaveGame& game);

// T17: the per-(system, player) observation record.
VisibilityPhaseResult RunObservationRecords(mars::stream::shapes::SaveGame& game);

// The encounter parked at a system, as this model can recover it.
//
// The field the original reads is a star-system member that is NOT serialised: it is set
// once when the map is generated and never moves. The only observable that carries the same
// id is the encounter fleet sitting at the system, so that is what this reads -- and it is a
// HYPOTHESIS, not a reading. It agrees with the original on all six encounter fleets in the
// corpus and no save can separate it from the true rule, because no save kills an encounter
// while leaving its system visible. Returns -1 when there is none.
std::int32_t EncounterAtSystem(const mars::stream::shapes::SaveGame& game,
                               std::int32_t systemId);

}  // namespace sots::app