//! Unprompted disclosure system (D-081).
//!
//! Two-system pipeline:
//! - `derive_disclosure_candidates`: per-NPC KG filter, recomputed every 30 ticks
//! - `process_unprompted_disclosure`: trigger gates, StableId-ordered firing
//!
//! NPCs check only their own KG (D-010 principle 2 — no cross-entity KG reads).
//! Disclosure grants the fact to the player's KG via `KnowledgeGranted` event
//! and emits a placeholder `MonologueEvent` (Layer 4 line selection in #172).

use std::collections::BTreeSet;

use bevy_ecs::prelude::*;

use crate::bridge::types::MonologueEvent;
use crate::knowledge::events::{
    KnowledgeEvent, KnowledgeEventType, ProcessedFactGrant, ProcessedKnowledgeGrant,
};
use crate::knowledge::types::{
    FactId, KnowledgeConfidence, KnowledgeSource, KnowledgeState, RelationshipState, StableId,
};
use crate::knowledge::{KnowledgeEventQueue, KnowledgeGraph, StableEntityId};
use crate::npc::mood::{MoodState, NpcMood};
use crate::npc::relationships::RelationshipGraph;
use crate::npc::trait_modifiers::{traits_to_keys, TraitModifierConfig};
use crate::npc::{Contentment, Npc, PersonalityTraits};
use crate::simulation::monologue::MonologueBuffer;
use crate::simulation::movement::{PlayerCharacter, TilePosition};
use crate::simulation::spatial::{NaiveSpatialIndex, SpatialIndex};
use crate::simulation::tier::ActiveSim;
use crate::simulation::time::SimulationTime;

// ---------------------------------------------------------------------------
// Constants
// ---------------------------------------------------------------------------

/// Recompute `DisclosureCandidates` every N ticks (30 ticks = 3 game-minutes at 10 tps).
const CANDIDATE_REFRESH_TICKS: u64 = 30;

/// Per-NPC cooldown ticks after a disclosure fires (300 = 30 game-minutes).
const NPC_COOLDOWN_TICKS: u64 = 300;

/// Minimum ticks between any two disclosures (global rate limit).
const GLOBAL_RATE_LIMIT_TICKS: u64 = 10;

/// Max candidates retained in `DisclosureCandidates`.
const MAX_CANDIDATES: usize = 10;

/// Witness inhibition check radius (Manhattan distance, tiles).
const WITNESS_RADIUS: u32 = 5;

/// Minimum NPC→player trust for Surface-tier disclosure.
const SURFACE_TRUST: i8 = 0;

/// NPC→player trust at which witness inhibition is waived (Secret tier, D-081).
const SECRET_TRUST: i8 = 7;

/// Trust level below which a nearby NPC counts as an untrusted witness.
const REAL_TRUST: i8 = 3;

/// Player proximity range for candidate recompute (tiles). Matches voice range.
const PLAYER_RANGE_TILES: u32 = 8;

// ---------------------------------------------------------------------------
// Components
// ---------------------------------------------------------------------------

/// Per-NPC computed disclosure candidate pool (D-081).
///
/// Recomputed every `CANDIDATE_REFRESH_TICKS` ticks by `derive_disclosure_candidates`.
/// Consumed by `process_unprompted_disclosure` when all trigger gates pass.
///
/// Facts are sorted: confidence desc, then `acquired_tick` desc. Capped at
/// `MAX_CANDIDATES`.
#[derive(Component, Debug, Clone, Default)]
pub struct DisclosureCandidates {
    /// Fact IDs eligible for disclosure, ordered by priority.
    pub candidates: Vec<FactId>,
    /// Tick when this pool was last computed. 0 = never computed.
    pub computed_tick: u64,
}

/// Per-NPC disclosure cooldown state (D-081).
///
/// Tracks which facts have been disclosed during the current window
/// (primary narrative quality gate) and the per-NPC silence period.
#[derive(Component, Debug, Clone, Default)]
pub struct DisclosureCooldown {
    /// Facts disclosed this window — prevents repeating the same fact.
    pub per_fact_history: BTreeSet<FactId>,
    /// Tick when the per-NPC cooldown expires. 0 = no active cooldown.
    pub npc_cooldown_until: u64,
}

// ---------------------------------------------------------------------------
// Resources
// ---------------------------------------------------------------------------

/// Global rate limiter: at most 1 unprompted disclosure per `GLOBAL_RATE_LIMIT_TICKS`.
///
/// When multiple NPCs are eligible simultaneously, the one with the lowest
/// StableId fires first (deterministic, D-010 principle 4).
#[derive(Resource, Debug, Clone, Default)]
pub struct DisclosureGlobalRateLimit {
    pub last_disclosure_tick: u64,
}

// ---------------------------------------------------------------------------
// derive_disclosure_candidates
// ---------------------------------------------------------------------------

/// Recompute `DisclosureCandidates` for each Active NPC.
///
/// Runs every `CANDIDATE_REFRESH_TICKS` ticks (checked per-NPC via `computed_tick`).
/// Filters the NPC's own KG through:
///
/// - `KnowledgeState::Active` only
/// - Confidence >= `KnowsOf` (or trait-lowered threshold via `TraitModifierConfig`)
/// - Not in `per_fact_history`
/// - `disclosure_blocked != true`
/// - ToldBy exclusion if Cautious trait is configured
///
/// Applies Stage 1 trait filters from `TraitModifierConfig`. Sorted by
/// confidence desc then `acquired_tick` desc. Capped at `MAX_CANDIDATES`.
pub fn derive_disclosure_candidates(
    time: Res<SimulationTime>,
    trait_config: Res<TraitModifierConfig>,
    mut npc_query: Query<
        (
            &KnowledgeGraph,
            &DisclosureCooldown,
            Option<&PersonalityTraits>,
            &mut DisclosureCandidates,
        ),
        (With<Npc>, With<ActiveSim>),
    >,
) {
    let current_tick = time.tick;

    for (kg, cooldown, traits_opt, mut candidates) in &mut npc_query {
        // Only recompute when the refresh interval has elapsed.
        if candidates.computed_tick != 0
            && current_tick.saturating_sub(candidates.computed_tick) < CANDIDATE_REFRESH_TICKS
        {
            continue;
        }

        let trait_keys = traits_opt
            .map(|t| traits_to_keys(&t.traits))
            .unwrap_or_default();

        // Effective confidence floor.
        // `lowest_min_confidence` returns the most permissive threshold across
        // all traits (additive expansion — e.g., Gossipy sets Suspects,
        // which wins over Cautious raising to KnowsDetails).
        let min_confidence = trait_config
            .lowest_min_confidence(&trait_keys)
            .unwrap_or(KnowledgeConfidence::KnowsOf);

        // Cautious trait: exclude facts with ToldBy (rumour) source.
        let exclude_told_by = trait_keys.iter().any(|k| {
            trait_config
                .modifier_for(k)
                .is_some_and(|m| m.stage1.exclude_told_by)
        });

        // Loyal trait: exclude facts sourced from high-trust entities.
        // "Don't gossip about your friends" — if ToldBy source has Friendly
        // relationship in this NPC's KG, suppress the fact. D-081.
        let exclude_high_trust = trait_config.any_excludes_high_trust(&trait_keys);

        let mut pool: Vec<(FactId, u64, KnowledgeConfidence)> = kg
            .known_facts_iter()
            .filter(|(fact_id, fact)| {
                // Active state only.
                if fact.state != KnowledgeState::Active {
                    return false;
                }
                // Not already disclosed this window.
                if cooldown.per_fact_history.contains(*fact_id) {
                    return false;
                }
                // Existentially dangerous secrets never disclosed (D-080).
                if fact.disclosure_blocked {
                    return false;
                }
                // Confidence threshold.
                if fact.confidence < min_confidence {
                    return false;
                }
                // Cautious: skip ToldBy-source facts.
                if exclude_told_by && matches!(fact.source, KnowledgeSource::ToldBy { .. }) {
                    return false;
                }
                // Loyal: skip facts from high-trust (Friendly) source entities.
                if exclude_high_trust {
                    if let KnowledgeSource::ToldBy { source_id, .. } = &fact.source {
                        if kg.relationship_with(source_id) == RelationshipState::Friendly {
                            return false;
                        }
                    }
                }
                true
            })
            .map(|(id, fact)| (id.clone(), fact.acquired_tick, fact.confidence))
            .collect();

        // Sort: confidence desc, then acquired_tick desc (most recent first).
        pool.sort_by(|a, b| b.2.cmp(&a.2).then(b.1.cmp(&a.1)));
        pool.truncate(MAX_CANDIDATES);

        candidates.candidates = pool.into_iter().map(|(id, _, _)| id).collect();
        candidates.computed_tick = current_tick;
    }
}

// ---------------------------------------------------------------------------
// process_unprompted_disclosure
// ---------------------------------------------------------------------------

/// Collected during the read pass; used for sorting and winner selection.
struct EligibleNpc {
    entity: Entity,
    stable_id: StableId,
    pos: TilePosition,
    fact_id: FactId,
    override_witness: bool,
}

/// Fire one unprompted disclosure per tick window when all trigger gates pass (D-081).
///
/// Trigger gates (all must pass for a given NPC):
///
/// 1. NPC has a `StableEntityId` (required for trust lookup)
/// 2. `DisclosureCandidates` pool is non-empty
/// 3. NPC→player trust >= `SURFACE_TRUST`
/// 4. `MoodState` != `NpcMood::Hostile`
/// 5. `Contentment.level` >= −10
/// 6. Per-NPC cooldown not active
/// 7. Player within `PLAYER_RANGE_TILES`
/// 8. Witness inhibition: no untrusted NPCs within `WITNESS_RADIUS` tiles
///    (waived if NPC→player trust >= `SECRET_TRUST` or Talkative trait)
/// 9. Location privacy: stubbed as always-pass — full impl in #172
///
/// Multiple eligible NPCs sorted by ascending StableId (D-010 principle 4).
/// First in order that also passes witness inhibition fires.
/// Subject to global rate limit (`GLOBAL_RATE_LIMIT_TICKS`).
pub fn process_unprompted_disclosure(
    time: Res<SimulationTime>,
    spatial: Res<NaiveSpatialIndex>,
    relationship_graph: Res<RelationshipGraph>,
    trait_config: Res<TraitModifierConfig>,
    mut rate_limit: ResMut<DisclosureGlobalRateLimit>,
    mut event_queue: ResMut<KnowledgeEventQueue>,
    player_pos_query: Query<
        (Entity, &TilePosition, Option<&StableEntityId>),
        With<PlayerCharacter>,
    >,
    mut player_mono_query: Query<&mut MonologueBuffer, With<PlayerCharacter>>,
    mut npc_query: Query<
        (
            Entity,
            &TilePosition,
            Option<&StableEntityId>,
            Option<&MoodState>,
            Option<&Contentment>,
            Option<&PersonalityTraits>,
            &DisclosureCandidates,
            &mut DisclosureCooldown,
        ),
        (With<Npc>, With<ActiveSim>),
    >,
    witness_sid_query: Query<Option<&StableEntityId>, With<Npc>>,
) {
    let current_tick = time.tick;

    // Gate: global rate limit — at most 1 disclosure per GLOBAL_RATE_LIMIT_TICKS.
    if current_tick.saturating_sub(rate_limit.last_disclosure_tick) < GLOBAL_RATE_LIMIT_TICKS {
        return;
    }

    // Collect player state. Single-player assumption (D-010).
    let Ok((player_entity, player_pos_ref, player_sid_opt)) = player_pos_query.single() else {
        return;
    };
    let player_pos = *player_pos_ref;
    let player_sid: Option<StableId> = player_sid_opt.map(|s| s.0);

    // --- Read pass: collect all NPCs passing the non-spatial gates ---
    let mut eligible: Vec<EligibleNpc> = npc_query
        .iter()
        .filter_map(
            |(entity, pos, sid_opt, mood_opt, content_opt, traits_opt, candidates, cooldown)| {
                // Gate 1: must have a StableId for trust lookup.
                let npc_sid = sid_opt?.0;

                // Gate 2: candidate pool non-empty.
                // Takes highest-priority candidate (sorted by confidence desc,
                // then recency desc in derive_disclosure_candidates). Full Layer 4
                // line selection with variety tracking is deferred to #172.
                let fact_id = candidates.candidates.first()?.clone();

                // Gate 3: NPC→player trust >= Surface.
                let npc_player_trust = player_sid
                    .and_then(|psid| relationship_graph.get_relationship(&npc_sid, &psid))
                    .map(|e| e.trust)
                    .unwrap_or(0);
                if npc_player_trust < SURFACE_TRUST {
                    return None;
                }

                // Gate 4: mood not Hostile.
                if mood_opt.is_some_and(|ms| ms.mood == NpcMood::Hostile) {
                    return None;
                }

                // Gate 5: contentment >= -10.
                if content_opt.is_some_and(|c| c.level < -10) {
                    return None;
                }

                // Gate 6: per-NPC cooldown not active.
                if current_tick < cooldown.npc_cooldown_until {
                    return None;
                }

                // Gate 7: player within PLAYER_RANGE_TILES (same z-level only).
                let in_range = pos
                    .manhattan_distance(&player_pos)
                    .is_some_and(|d| d <= PLAYER_RANGE_TILES);
                if !in_range {
                    return None;
                }

                // Gate 9: location privacy — stubbed always-pass.
                // Full implementation deferred to #172 (Layer 4 disclosure pipeline).

                // Compute witness inhibition override for gate 8.
                let trait_keys = traits_opt
                    .map(|t| traits_to_keys(&t.traits))
                    .unwrap_or_default();
                let override_witness = npc_player_trust >= SECRET_TRUST
                    || trait_config.any_overrides_witness_inhibition(&trait_keys);

                Some(EligibleNpc {
                    entity,
                    stable_id: npc_sid,
                    pos: *pos,
                    fact_id,
                    override_witness,
                })
            },
        )
        .collect();

    if eligible.is_empty() {
        return;
    }

    // Sort by ascending StableId for determinism (D-010 principle 4).
    eligible.sort_by_key(|c| c.stable_id);

    // Gate 8: witness inhibition — find first NPC that passes spatial check.
    let winner = eligible.into_iter().find(|candidate| {
        if candidate.override_witness {
            return true;
        }
        !has_untrusted_witness(
            &candidate.pos,
            candidate.stable_id,
            player_entity,
            &spatial,
            &witness_sid_query,
            &relationship_graph,
        )
    });

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

    // --- Fire the disclosure ---

    // 1. Grant the fact to the player's KG via KnowledgeGranted event (ToldBy source).
    //    Confidence capped at KnowsOf (same rule as NPC-to-NPC transfer, D-080).
    event_queue.push(KnowledgeEvent {
        observer: player_entity,
        tick: current_tick,
        event_type: KnowledgeEventType::KnowledgeGranted {
            grant: ProcessedKnowledgeGrant::Fact(ProcessedFactGrant {
                fact_id: winner.fact_id.clone(),
                confidence: KnowledgeConfidence::KnowsOf,
            }),
            source: KnowledgeSource::ToldBy {
                source_id: winner.stable_id,
                tick: current_tick,
            },
        },
    });

    // 2. Placeholder monologue event — actual line selection deferred to #172
    //    (Layer 4 unprompted disclosure pipeline reads DisclosureCandidates).
    if let Ok(mut mono_buf) = player_mono_query.single_mut() {
        mono_buf.set(MonologueEvent {
            id: format!("disclosure_{}", winner.fact_id.0),
            text: String::from("(Layer 4 line selection — ticket #172)"),
            duration_seconds: 4.0,
        });
    }

    // 3. Update NPC cooldown state.
    // Note: re-queries npc_query mutably after the read pass above. This is
    // safe because the read pass only borrows shared refs and completes before
    // this point. The two-phase pattern (read → select winner → write) avoids
    // holding a mutable borrow during iteration.
    if let Ok((_, _, _, _, _, _, _, mut cooldown)) = npc_query.get_mut(winner.entity) {
        cooldown.per_fact_history.insert(winner.fact_id.clone());
        cooldown.npc_cooldown_until = current_tick + NPC_COOLDOWN_TICKS;
    }

    // 4. Advance global rate limit.
    rate_limit.last_disclosure_tick = current_tick;

    tracing::debug!(
        tick = current_tick,
        npc_sid = ?winner.stable_id,
        fact_id = %winner.fact_id.0,
        "unprompted disclosure fired"
    );
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

/// Returns true if any untrusted NPC is within `WITNESS_RADIUS` of `pos`.
///
/// "Untrusted" = the disclosing NPC's trust toward that witness is below
/// `REAL_TRUST`. The player entity is excluded (they are the target).
fn has_untrusted_witness(
    pos: &TilePosition,
    npc_sid: StableId,
    player_entity: Entity,
    spatial: &NaiveSpatialIndex,
    witness_sid_query: &Query<Option<&StableEntityId>, With<Npc>>,
    relationship_graph: &RelationshipGraph,
) -> bool {
    for witness_entity in spatial.entities_in_range(pos, WITNESS_RADIUS) {
        if witness_entity == player_entity {
            continue;
        }
        if let Ok(Some(witness_sid)) = witness_sid_query.get(witness_entity) {
            let trust = relationship_graph
                .get_relationship(&npc_sid, &witness_sid.0)
                .map(|e| e.trust)
                .unwrap_or(0);
            if trust < REAL_TRUST {
                return true;
            }
        }
    }
    false
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use bevy_app::prelude::*;

    use super::*;
    use crate::knowledge::graph::KnowledgeGraph;
    use crate::knowledge::types::{KnowledgeConfidence, KnowledgeSource, KnowledgeState};
    use crate::simulation::tier::ActiveSim;
    use crate::simulation::time::SimulationTime;

    fn make_fact(
        confidence: KnowledgeConfidence,
        state: KnowledgeState,
        acquired_tick: u64,
        disclosure_blocked: bool,
    ) -> crate::knowledge::types::FactKnowledge {
        crate::knowledge::types::FactKnowledge {
            confidence,
            source: KnowledgeSource::Background,
            state,
            acquired_tick,
            disclosure_blocked,
        }
    }

    fn make_kg(facts: Vec<(FactId, crate::knowledge::types::FactKnowledge)>) -> KnowledgeGraph {
        KnowledgeGraph::with_background(facts)
    }

    /// Build a minimal App for derive_disclosure_candidates tests.
    fn build_app() -> App {
        let mut app = App::new();
        app.init_resource::<SimulationTime>();
        app.init_resource::<TraitModifierConfig>();
        app.add_systems(Update, derive_disclosure_candidates);
        app
    }

    // -----------------------------------------------------------------------
    // derive_disclosure_candidates tests
    // -----------------------------------------------------------------------

    #[test]
    fn active_knowsof_fact_becomes_candidate() {
        let mut app = build_app();

        let fact_id = FactId("investigation.clue".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::KnowsOf,
                KnowledgeState::Active,
                5,
                false,
            ),
        )]);

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert!(
            candidates.candidates.contains(&fact_id),
            "Active KnowsOf fact should be in pool"
        );
    }

    #[test]
    fn disclosure_blocked_fact_excluded() {
        let mut app = build_app();

        let fact_id = FactId("secret.dangerous".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::KnowsDetails,
                KnowledgeState::Active,
                5,
                true,
            ),
        )]);

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert!(
            !candidates.candidates.contains(&fact_id),
            "disclosure_blocked fact must never be a candidate"
        );
    }

    #[test]
    fn stale_fact_excluded() {
        let mut app = build_app();

        let fact_id = FactId("cargo.manifest".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::KnowsOf,
                KnowledgeState::Stale,
                5,
                false,
            ),
        )]);

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert!(
            !candidates.candidates.contains(&fact_id),
            "Stale fact must be excluded"
        );
    }

    #[test]
    fn already_disclosed_fact_excluded() {
        let mut app = build_app();

        let fact_id = FactId("dock.schedule".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::KnowsOf,
                KnowledgeState::Active,
                5,
                false,
            ),
        )]);

        let mut cooldown = DisclosureCooldown::default();
        cooldown.per_fact_history.insert(fact_id.clone());

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                cooldown,
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert!(
            !candidates.candidates.contains(&fact_id),
            "Fact in per_fact_history must be excluded"
        );
    }

    #[test]
    fn candidates_capped_at_max() {
        let mut app = build_app();

        // Spawn 15 facts — only MAX_CANDIDATES should survive.
        let facts: Vec<_> = (0..15)
            .map(|i| {
                (
                    FactId(format!("fact.{:02}", i)),
                    make_fact(
                        KnowledgeConfidence::KnowsOf,
                        KnowledgeState::Active,
                        i as u64,
                        false,
                    ),
                )
            })
            .collect();

        let kg = make_kg(facts);
        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert_eq!(
            candidates.candidates.len(),
            MAX_CANDIDATES,
            "Candidate pool must be capped at MAX_CANDIDATES"
        );
    }

    #[test]
    fn refresh_skipped_within_interval() {
        let mut app = build_app();

        let fact_id = FactId("investigation.clue".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::KnowsOf,
                KnowledgeState::Active,
                5,
                false,
            ),
        )]);

        // Set computed_tick = 1 (non-zero). Tick 5 is within the 30-tick refresh window.
        let mut candidates = DisclosureCandidates::default();
        candidates.computed_tick = 1;

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                candidates,
            ))
            .id();

        // Advance tick to 5 (within CANDIDATE_REFRESH_TICKS = 30).
        app.world_mut().resource_mut::<SimulationTime>().tick = 5;

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert_eq!(
            candidates.computed_tick, 1,
            "Refresh should be skipped within the interval"
        );
        assert!(
            candidates.candidates.is_empty(),
            "Candidates should remain empty (no recompute)"
        );
    }

    #[test]
    fn suspects_confidence_below_default_floor_excluded() {
        let mut app = build_app();

        let fact_id = FactId("rumour.vague".to_string());
        let kg = make_kg(vec![(
            fact_id.clone(),
            make_fact(
                KnowledgeConfidence::Suspects,
                KnowledgeState::Active,
                5,
                false,
            ),
        )]);

        let npc = app
            .world_mut()
            .spawn((
                Npc,
                ActiveSim,
                kg,
                DisclosureCooldown::default(),
                DisclosureCandidates::default(),
            ))
            .id();

        app.update();

        let candidates = app.world().get::<DisclosureCandidates>(npc).unwrap();
        assert!(
            !candidates.candidates.contains(&fact_id),
            "Suspects-confidence fact must be below the KnowsOf default floor"
        );
    }
}