//! End-to-end tests for the template instantiation engine (#161).
//!
//! Verifies the full pipeline:
//!   load YAML → validate → spawn NPCs → generate triangles → lifecycle
//!
//! Spec refs:
//! - D-023: three-tier content model
//! - D-024: 10-axis NPC model, minimum 2 triangles per social site
//! - D-025: social site as atomic template unit, single-ownership
//! - D-010: determinism (same seed → same layout)

use std::path::PathBuf;

use bevy_ecs::prelude::*;
use settled_reach_server::{
    content::{
        instantiation::{
            instantiate_template, load_template_from_file, unload_template,
            ActiveTemplateInstances,
        },
        template::{TemplateId, TemplateOwnership, TriangleState},
    },
    knowledge::{registry::EntityRegistry, StableEntityId},
    simulation::rng::SimRng,
};

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

fn templates_dir() -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("data/templates")
}

fn make_test_world() -> World {
    let mut world = World::new();
    world.init_resource::<EntityRegistry>();
    world
}

// ---------------------------------------------------------------------------
// End-to-end: load logistics-hub YAML, instantiate, assert structure (#161)
// ---------------------------------------------------------------------------

#[test]
fn template_instantiation_end_to_end_logistics_hub() {
    let path = templates_dir().join("logistics-hub.yaml");
    let template_def =
        load_template_from_file(&path).expect("logistics-hub.yaml must load and parse");

    let mut world = make_test_world();
    let template_id = TemplateId::from_seed_and_slug(42, "logistics-hub");
    let mut rng = SimRng::new(42);

    let instance = instantiate_template(&mut world, &template_def, template_id, 42, &mut rng)
        .expect("logistics-hub must instantiate without validation errors");

    // --- NPCs: all 4 role slots filled ---
    assert_eq!(
        instance.npc_entities.len(),
        4,
        "logistics-hub has 4 role slots — 4 NPC entities expected"
    );

    // --- TemplateOwnership on every NPC ---
    let expected_roles = [
        "logistics-manager",
        "dock-worker",
        "ring-contact",
        "security-guard",
    ];
    let mut seen_roles: Vec<String> = Vec::new();
    for &entity in &instance.npc_entities {
        let ownership = world
            .get::<TemplateOwnership>(entity)
            .expect("every spawned NPC must have TemplateOwnership");
        assert_eq!(
            ownership.template_id, template_id,
            "TemplateOwnership.template_id must match the instantiated template"
        );
        let role = &ownership.role_id.0;
        assert!(
            expected_roles.contains(&role.as_str()),
            "unexpected role '{}' — not in logistics-hub role list",
            role,
        );
        seen_roles.push(role.clone());
    }
    // Every role slot must appear exactly once.
    for role in &expected_roles {
        assert_eq!(
            seen_roles.iter().filter(|r| r.as_str() == *role).count(),
            1,
            "role '{}' must appear exactly once",
            role,
        );
    }

    // --- 2+ TriangleState entities (D-024 minimum) ---
    assert!(
        instance.triangle_entities.len() >= 2,
        "logistics-hub must produce at least 2 TriangleState entities (D-024), got {}",
        instance.triangle_entities.len(),
    );
    for &entity in &instance.triangle_entities {
        assert!(
            world.get::<TriangleState>(entity).is_some(),
            "triangle entity {:?} must carry a TriangleState component",
            entity,
        );
    }

    // --- Instance registered in ActiveTemplateInstances ---
    let active = world.resource::<ActiveTemplateInstances>();
    assert!(
        active.get(template_id).is_some(),
        "instantiated template must be tracked in ActiveTemplateInstances",
    );
}

// ---------------------------------------------------------------------------
// Lifecycle: unload despawns all entities
// ---------------------------------------------------------------------------

#[test]
fn template_instantiation_unload_despawns_entities() {
    let path = templates_dir().join("logistics-hub.yaml");
    let template_def = load_template_from_file(&path).expect("must parse");

    let mut world = make_test_world();
    let template_id = TemplateId::from_seed_and_slug(99, "logistics-hub");
    let mut rng = SimRng::new(99);

    let instance =
        instantiate_template(&mut world, &template_def, template_id, 99, &mut rng)
            .expect("must instantiate");

    let all_entities: Vec<Entity> = instance
        .npc_entities
        .iter()
        .chain(instance.triangle_entities.iter())
        .cloned()
        .collect();

    assert!(!all_entities.is_empty(), "sanity: some entities were spawned");

    unload_template(&mut world, template_id);

    // All spawned entities must be gone.
    for entity in &all_entities {
        assert!(
            world.get_entity(*entity).is_err(),
            "entity {:?} must be despawned after unload_template",
            entity,
        );
    }

    // Instance removed from tracking.
    let active = world.resource::<ActiveTemplateInstances>();
    assert!(
        active.get(template_id).is_none(),
        "unloaded template must be removed from ActiveTemplateInstances",
    );
}

// ---------------------------------------------------------------------------
// Determinism: same seed → same NPC StableId assignment (D-010)
// ---------------------------------------------------------------------------

#[test]
fn template_instantiation_is_deterministic() {
    let path = templates_dir().join("logistics-hub.yaml");
    let template_def = load_template_from_file(&path).expect("must parse");
    let template_id = TemplateId::from_seed_and_slug(42, "logistics-hub");

    let mut world1 = make_test_world();
    let instance1 =
        instantiate_template(&mut world1, &template_def, template_id, 42, &mut SimRng::new(42))
            .expect("must instantiate");

    let mut world2 = make_test_world();
    let instance2 =
        instantiate_template(&mut world2, &template_def, template_id, 42, &mut SimRng::new(42))
            .expect("must instantiate");

    // Collect (role → StableId) pairs from each world and compare.
    let role_stable_ids = |world: &World, entities: &[Entity]| {
        let mut pairs: Vec<(String, u64)> = entities
            .iter()
            .map(|&e| {
                let role = world.get::<TemplateOwnership>(e).unwrap().role_id.0.clone();
                let sid = world.get::<StableEntityId>(e).unwrap().0 .0;
                (role, sid)
            })
            .collect();
        pairs.sort();
        pairs
    };

    let pairs1 = role_stable_ids(&world1, &instance1.npc_entities);
    let pairs2 = role_stable_ids(&world2, &instance2.npc_entities);

    assert_eq!(
        pairs1, pairs2,
        "instantiate_template must be deterministic (D-010): same seed → same layout"
    );
}

// ---------------------------------------------------------------------------
// YAML loading: invalid path returns Err
// ---------------------------------------------------------------------------

#[test]
fn load_template_from_file_nonexistent_path_returns_err() {
    let path = templates_dir().join("nonexistent-template-xyzzy.yaml");
    let result = load_template_from_file(&path);
    assert!(
        result.is_err(),
        "loading a nonexistent file must return Err"
    );
}