//! Daily routine system (#88).
//!
//! Detects day-phase transitions (D-031) and issues PathRequests for NPCs
//! whose DailyRoutine has a location for the new phase.

use bevy_ecs::prelude::*;

use crate::npc::{DailyRoutine, Npc};
use crate::simulation::movement::TilePosition;
use crate::simulation::pathfinding::PathRequest;
use crate::simulation::time::{DayPhase, SimulationTime};

/// Resource tracking the previous day phase for transition detection.
#[derive(Resource, Debug, Clone)]
pub struct PreviousDayPhase {
    pub phase: DayPhase,
    pub day: u64,
}

impl Default for PreviousDayPhase {
    fn default() -> Self {
        Self {
            phase: DayPhase::Morning,
            day: 0,
        }
    }
}

/// System: detect day-phase transitions and issue PathRequests for NPC routines.
/// Runs after advance_tick so the current phase is up-to-date.
pub fn check_phase_transition(
    time: Res<SimulationTime>,
    mut previous: ResMut<PreviousDayPhase>,
    mut commands: Commands,
    npcs: Query<(Entity, &TilePosition, &DailyRoutine), With<Npc>>,
) {
    let current_phase = time.day_phase();
    let current_day = time.day();

    if current_phase == previous.phase && current_day == previous.day {
        return;
    }

    tracing::debug!(
        "Day phase transition: {:?} -> {:?} (day {} -> {})",
        previous.phase,
        current_phase,
        previous.day,
        current_day
    );

    previous.phase = current_phase;
    previous.day = current_day;

    for (entity, current_pos, routine) in npcs.iter() {
        if let Some(expected_location) = routine.expected_location(current_phase) {
            if *current_pos != expected_location {
                commands
                    .entity(entity)
                    .insert(PathRequest {
                        goal: expected_location,
                    });
                tracing::trace!(
                    "Entity {:?}: routine path request to {:?} for {:?}",
                    entity,
                    expected_location,
                    current_phase
                );
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::npc::RoutineEntry;
    use crate::simulation::time::{MINUTES_PER_PHASE, TICKS_PER_GAME_MINUTE};

    fn setup_world() -> bevy_ecs::world::World {
        let mut world = bevy_ecs::world::World::new();
        world.insert_resource(SimulationTime::default());
        world.init_resource::<PreviousDayPhase>();
        world
    }

    #[test]
    fn phase_transition_generates_path_request() {
        let mut world = setup_world();

        let afternoon_loc = TilePosition::new(10, 10, 0);
        let entity = world
            .spawn((
                Npc,
                TilePosition::new(5, 5, 0), // Not at afternoon location
                DailyRoutine {
                    entries: vec![RoutineEntry {
                        phase: DayPhase::Afternoon,
                        location: afternoon_loc,
                        activity: "Work".into(),
                    }],
                    description: "Test".into(),
                },
            ))
            .id();

        // Advance time to Afternoon boundary
        world.resource_mut::<SimulationTime>().tick =
            MINUTES_PER_PHASE * TICKS_PER_GAME_MINUTE;

        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(check_phase_transition);
        schedule.run(&mut world);

        let request = world.get::<PathRequest>(entity).unwrap();
        assert_eq!(request.goal, afternoon_loc);
    }

    #[test]
    fn no_transition_no_request() {
        let mut world = setup_world();

        let entity = world
            .spawn((
                Npc,
                TilePosition::new(5, 5, 0),
                DailyRoutine {
                    entries: vec![RoutineEntry {
                        phase: DayPhase::Afternoon,
                        location: TilePosition::new(10, 10, 0),
                        activity: "Work".into(),
                    }],
                    description: "Test".into(),
                },
            ))
            .id();

        // Time still at Morning (tick 0), same as PreviousDayPhase default
        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(check_phase_transition);
        schedule.run(&mut world);

        assert!(world.get::<PathRequest>(entity).is_none());
    }

    #[test]
    fn npc_already_at_destination_no_request() {
        let mut world = setup_world();

        let loc = TilePosition::new(10, 10, 0);
        let entity = world
            .spawn((
                Npc,
                loc, // Already at afternoon location
                DailyRoutine {
                    entries: vec![RoutineEntry {
                        phase: DayPhase::Afternoon,
                        location: loc,
                        activity: "Work".into(),
                    }],
                    description: "Test".into(),
                },
            ))
            .id();

        world.resource_mut::<SimulationTime>().tick =
            MINUTES_PER_PHASE * TICKS_PER_GAME_MINUTE;

        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(check_phase_transition);
        schedule.run(&mut world);

        assert!(world.get::<PathRequest>(entity).is_none());
    }

    #[test]
    fn npc_without_routine_entry_ignored() {
        let mut world = setup_world();

        let entity = world
            .spawn((
                Npc,
                TilePosition::new(5, 5, 0),
                DailyRoutine {
                    entries: vec![RoutineEntry {
                        phase: DayPhase::Morning,
                        location: TilePosition::new(5, 5, 0),
                        activity: "Sleep".into(),
                    }],
                    description: "Test".into(),
                },
            ))
            .id();

        // Transition to Afternoon, but NPC only has Morning entry
        world.resource_mut::<SimulationTime>().tick =
            MINUTES_PER_PHASE * TICKS_PER_GAME_MINUTE;

        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(check_phase_transition);
        schedule.run(&mut world);

        assert!(world.get::<PathRequest>(entity).is_none());
    }

    #[test]
    fn day_rollover_triggers_morning_routine() {
        let mut world = setup_world();

        // Start at Night
        let night_tick = 1080 * TICKS_PER_GAME_MINUTE;
        world.resource_mut::<SimulationTime>().tick = night_tick;
        world.resource_mut::<PreviousDayPhase>().phase = DayPhase::Night;
        world.resource_mut::<PreviousDayPhase>().day = 0;

        let morning_loc = TilePosition::new(3, 3, 0);
        let entity = world
            .spawn((
                Npc,
                TilePosition::new(20, 20, 0),
                DailyRoutine {
                    entries: vec![RoutineEntry {
                        phase: DayPhase::Morning,
                        location: morning_loc,
                        activity: "Wake up".into(),
                    }],
                    description: "Test".into(),
                },
            ))
            .id();

        // Advance to next day's Morning (day 1, tick 0 of new day)
        world.resource_mut::<SimulationTime>().tick = 1440 * TICKS_PER_GAME_MINUTE;

        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(check_phase_transition);
        schedule.run(&mut world);

        let request = world.get::<PathRequest>(entity).unwrap();
        assert_eq!(request.goal, morning_loc);
    }
}