// Internal monologue trigger system (#414)
//
// Selects monologue lines from loaded content pools based on trigger conditions.
// v0.1: enter_location (on first tick) + time_idle (periodic when player hasn't moved).
// Lines are written to MonologueBuffer for inclusion in ObserverSnapshot.

use bevy_ecs::prelude::*;
use rand::Rng;

use crate::bridge::types::MonologueEvent;
use crate::content::ContentStoreResource;
use crate::simulation::movement::{PlayerCharacter, TilePosition};
use crate::simulation::rng::SimRng;
use crate::simulation::time::SimulationTime;

/// Minimum ticks between monologue lines (prevents spam).
/// At 10 ticks/game-minute, 300 ticks = 30 game-minutes.
const COOLDOWN_TICKS: u64 = 300;

/// Ticks of idle (no movement) before a time_idle monologue fires.
/// 100 ticks = 10 game-minutes.
const IDLE_THRESHOLD_TICKS: u64 = 100;

/// Display duration for monologue text on client (seconds).
const DISPLAY_DURATION: f32 = 5.0;

/// Tracks monologue state for cooldown and trigger detection.
/// Attached to the PlayerCharacter entity.
#[derive(Component, Debug)]
pub struct MonologueState {
    /// Tick when the last monologue was fired.
    pub last_fired_tick: u64,
    /// Player position on the previous tick (for movement detection).
    pub last_position: Option<(i32, i32)>,
    /// Ticks since the player last moved (for time_idle trigger).
    pub idle_ticks: u64,
    /// Whether the enter_location monologue has fired this session.
    pub entered: bool,
    /// IDs of lines already shown (dedup within session).
    pub shown_ids: Vec<String>,
    /// Character type for pool filtering. v0.1: always "detective".
    pub character: String,
}

impl Default for MonologueState {
    fn default() -> Self {
        Self {
            last_fired_tick: 0,
            last_position: None,
            idle_ticks: 0,
            entered: false,
            shown_ids: Vec::new(),
            // v0.1: default to detective; character selection sets this
            character: "detective".to_string(),
        }
    }
}

/// Buffer holding the monologue event to include in the next snapshot.
/// `take()` drains the buffer (consumed once per snapshot).
#[derive(Component, Debug, Default)]
pub struct MonologueBuffer {
    event: Option<MonologueEvent>,
}

impl MonologueBuffer {
    /// Drain and return the monologue event, leaving the buffer empty.
    pub fn take(&mut self) -> Option<MonologueEvent> {
        self.event.take()
    }
}

/// Monologue trigger system.
///
/// Runs each tick. Checks trigger conditions against loaded content pools
/// and writes a MonologueEvent to MonologueBuffer when a line should fire.
///
/// v0.1 triggers:
/// - `enter_location`: fires once on first tick (session start)
/// - `time_idle`: fires after IDLE_THRESHOLD_TICKS of no player movement
pub fn trigger_monologue(
    time: Res<SimulationTime>,
    content: Option<Res<ContentStoreResource>>,
    mut rng: ResMut<SimRng>,
    mut query: Query<
        (&TilePosition, &mut MonologueState, &mut MonologueBuffer),
        With<PlayerCharacter>,
    >,
) {
    let Some(content) = content else { return };
    let Ok((pos, mut state, mut buffer)) = query.single_mut() else {
        return;
    };

    // Track idle time
    let current_pos = (pos.x, pos.y);
    if let Some(last) = state.last_position {
        if last == current_pos {
            state.idle_ticks += 1;
        } else {
            state.idle_ticks = 0;
        }
    }
    state.last_position = Some(current_pos);

    // Cooldown check
    if time.tick > 0 && time.tick - state.last_fired_tick < COOLDOWN_TICKS {
        return;
    }

    // Determine which trigger to attempt
    let trigger = if !state.entered {
        state.entered = true;
        Some("enter_location")
    } else if state.idle_ticks >= IDLE_THRESHOLD_TICKS {
        Some("time_idle")
    } else {
        None
    };

    let Some(trigger) = trigger else { return };

    // Collect candidate lines from all district monologue pools
    let character = state.character.as_str();
    let mut candidates: Vec<(&str, &str)> = Vec::new(); // (id, text)

    for (_district_id, district) in &content.0.districts {
        for pool in &district.monologue_pools {
            if pool.character != character {
                continue;
            }
            for line in &pool.lines {
                if line.trigger != trigger {
                    continue;
                }
                if state.shown_ids.contains(&line.id) {
                    continue;
                }
                candidates.push((&line.id, &line.text));
            }
        }
    }

    if candidates.is_empty() {
        // All lines for this trigger have been shown; allow repeats
        for (_district_id, district) in &content.0.districts {
            for pool in &district.monologue_pools {
                if pool.character != character {
                    continue;
                }
                for line in &pool.lines {
                    if line.trigger != trigger {
                        continue;
                    }
                    candidates.push((&line.id, &line.text));
                }
            }
        }
    }

    if candidates.is_empty() {
        return;
    }

    // Select a random line
    let index = rng.rng.random_range(0..candidates.len());
    let (id, text) = candidates[index];

    buffer.event = Some(MonologueEvent {
        id: id.to_string(),
        text: text.to_string(),
        duration_seconds: DISPLAY_DURATION,
    });

    state.shown_ids.push(id.to_string());
    state.last_fired_tick = time.tick;
    // Reset idle counter so time_idle doesn't fire again immediately
    state.idle_ticks = 0;

    tracing::debug!(
        "Monologue fired: trigger={}, id={}, tick={}",
        trigger,
        id,
        time.tick
    );
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::content::loader::{ContentStore, DistrictContent};
    use crate::content::types::{MonologueLine, MonologuePool};
    use crate::simulation::rng::SimRng;
    use crate::simulation::time::SimulationTime;
    use bevy_ecs::world::World;

    fn setup_world_with_content() -> World {
        let mut world = World::new();
        world.init_resource::<SimulationTime>();
        world.insert_resource(SimRng::new(42));

        // Create test monologue content
        let pool = MonologuePool {
            character: "detective".to_string(),
            location: "general".to_string(),
            lines: vec![
                MonologueLine {
                    id: "test_enter_001".to_string(),
                    text: "Sova Transit District. Let's narrow that down.".to_string(),
                    trigger: "enter_location".to_string(),
                    prerequisites: None,
                    priority: None,
                    cooldown: None,
                    tags: vec![],
                },
                MonologueLine {
                    id: "test_idle_001".to_string(),
                    text: "Everyone knows I'm Commission.".to_string(),
                    trigger: "time_idle".to_string(),
                    prerequisites: None,
                    priority: None,
                    cooldown: None,
                    tags: vec![],
                },
            ],
        };

        let mut district = DistrictContent::default();
        district.monologue_pools.push(pool);
        let mut store = ContentStore::default();
        store.districts.insert("test".to_string(), district);
        world.insert_resource(ContentStoreResource(store));

        world
    }

    #[test]
    fn enter_location_fires_on_first_tick() {
        let mut world = setup_world_with_content();
        world.spawn((
            PlayerCharacter,
            TilePosition::new(5, 5, 0),
            MonologueState::default(),
            MonologueBuffer::default(),
        ));

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

        let mut query = world.query::<&MonologueBuffer>();
        let buffer = query.single(&world).unwrap();
        assert!(buffer.event.is_some());
        let event = buffer.event.as_ref().unwrap();
        assert_eq!(event.id, "test_enter_001");
    }

    #[test]
    fn cooldown_prevents_spam() {
        let mut world = setup_world_with_content();
        world.spawn((
            PlayerCharacter,
            TilePosition::new(5, 5, 0),
            MonologueState::default(),
            MonologueBuffer::default(),
        ));

        let mut schedule = bevy_ecs::schedule::Schedule::default();
        schedule.add_systems(trigger_monologue);

        // First tick: should fire enter_location
        schedule.run(&mut world);

        // Consume the buffer
        let mut query = world.query::<&mut MonologueBuffer>();
        query.single_mut(&mut world).unwrap().take();

        // Advance a few ticks (still in cooldown)
        world.resource_mut::<SimulationTime>().tick = 10;

        // Set idle ticks high to try to trigger time_idle
        let mut state_query = world.query::<&mut MonologueState>();
        state_query.single_mut(&mut world).unwrap().idle_ticks = IDLE_THRESHOLD_TICKS + 1;

        schedule.run(&mut world);

        // Should NOT fire — cooldown active
        let mut query = world.query::<&MonologueBuffer>();
        let buffer = query.single(&world).unwrap();
        assert!(buffer.event.is_none());
    }

    #[test]
    fn time_idle_fires_after_threshold() {
        let mut world = setup_world_with_content();
        world.spawn((
            PlayerCharacter,
            TilePosition::new(5, 5, 0),
            MonologueState {
                entered: true, // Skip enter_location
                last_position: Some((5, 5)),
                idle_ticks: IDLE_THRESHOLD_TICKS, // At threshold
                ..Default::default()
            },
            MonologueBuffer::default(),
        ));

        // Advance past cooldown
        world.resource_mut::<SimulationTime>().tick = COOLDOWN_TICKS + 1;

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

        let mut query = world.query::<&MonologueBuffer>();
        let buffer = query.single(&world).unwrap();
        assert!(buffer.event.is_some());
        let event = buffer.event.as_ref().unwrap();
        assert_eq!(event.id, "test_idle_001");
    }
}