#include "catch.hpp"

#include <QVector2D>

#include <algorithm>

#include "DespawnAtComponent.h"
#include "EntityAdmin.h"
#include "EntityHitTest.h"
#include "ScrapDataComponent.h"
#include "ScrapSystem.h"

namespace
{
bool contains(const std::vector<entt::entity>& v, entt::entity e)
{
    return std::find(v.begin(), v.end(), e) != v.end();
}
} // namespace

// ---------------------------------------------------------------------------
// Spawn
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: spawn returns a valid entity with correct scrap data", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(3.0f, 4.0f), 5, 100);

    REQUIRE(admin.isValid(e));
    REQUIRE(admin.get<ScrapDataComponent>(e).amount == 5);
    REQUIRE(admin.get<DespawnAtComponent>(e).tick == 100);
}

// ---------------------------------------------------------------------------
// Despawn timing
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: scrap still present one tick before despawnAt", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(0.0f, 0.0f), 1, 50);

    ss.tickDespawn(49);
    REQUIRE(admin.isValid(e));
}

TEST_CASE("ScrapSystem: scrap removed at despawnAt tick", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(0.0f, 0.0f), 1, 50);

    ss.tickDespawn(50);
    REQUIRE_FALSE(admin.isValid(e));
}

// ---------------------------------------------------------------------------
// Selective removal
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: tickDespawn removes only expired scraps", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity earlyE = ss.spawn(QVector2D(0.0f, 0.0f), 1, 30);
    const entt::entity lateE  = ss.spawn(QVector2D(1.0f, 0.0f), 2, 60);

    ss.tickDespawn(30);

    REQUIRE_FALSE(admin.isValid(earlyE));
    REQUIRE(admin.isValid(lateE));
}

// ---------------------------------------------------------------------------
// Consume
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: consume returns amount and destroys entity", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(0.0f, 0.0f), 7, 100);

    const std::optional<int> amount = ss.consume(e);
    REQUIRE(amount.has_value());
    REQUIRE(*amount == 7);
    REQUIRE_FALSE(admin.isValid(e));
}

TEST_CASE("ScrapSystem: consume returns nullopt for invalid entity", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const std::optional<int> amount = ss.consume(entt::null);
    REQUIRE_FALSE(amount.has_value());
}

// ---------------------------------------------------------------------------
// collectOne
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: collectOne depletes one scrap and keeps the pile until empty", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(0.0f, 0.0f), 3, 100);

    REQUIRE(ss.collectOne(e));
    REQUIRE(admin.isValid(e));
    REQUIRE(admin.get<ScrapDataComponent>(e).amount == 2);

    REQUIRE(ss.collectOne(e));
    REQUIRE(admin.isValid(e));
    REQUIRE(admin.get<ScrapDataComponent>(e).amount == 1);

    // Final unit collected: the pile is removed once depleted.
    REQUIRE(ss.collectOne(e));
    REQUIRE_FALSE(admin.isValid(e));
}

TEST_CASE("ScrapSystem: collectOne returns false for an invalid entity", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    REQUIRE_FALSE(ss.collectOne(entt::null));
}

// ---------------------------------------------------------------------------
// allScrapInfo
// ---------------------------------------------------------------------------

TEST_CASE("ScrapSystem: allScrapInfo returns all spawned scrap", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    ss.spawn(QVector2D(1.0f, 2.0f), 3, 100);
    ss.spawn(QVector2D(4.0f, 5.0f), 6, 200);

    const std::vector<ScrapInfo> info = ss.allScrapInfo();
    REQUIRE(info.size() == 2);
}

TEST_CASE("ScrapSystem: allScrapInfo reports each pile's remaining amount", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity a = ss.spawn(QVector2D(1.0f, 2.0f), 3, 100);
    const entt::entity b = ss.spawn(QVector2D(4.0f, 5.0f), 6, 200);

    const std::vector<ScrapInfo> info = ss.allScrapInfo();
    REQUIRE(info.size() == 2);
    for (const ScrapInfo& i : info)
    {
        if (i.entity == a) { REQUIRE(i.amount == 3); }
        else if (i.entity == b) { REQUIRE(i.amount == 6); }
        else { FAIL("unexpected scrap entity"); }
    }
}

// ---------------------------------------------------------------------------
// Selection hit-testing (REQ-UI-SCRAP-CLICK-SELECT, REQ-UI-SCRAP-MULTI-SELECT)
// ---------------------------------------------------------------------------

TEST_CASE("scrapAtWorldPos returns the pile near a point and null when far", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity e = ss.spawn(QVector2D(3.0f, 4.0f), 5, 100);

    // Extra parens keep Catch from decomposing the comparison, which is ambiguous
    // between Catch's expression templates and entt's entity operator==.
    REQUIRE((scrapAtWorldPos(admin, QVector2D(3.1f, 4.0f)) == e));
    REQUIRE((scrapAtWorldPos(admin, QVector2D(10.0f, 10.0f)) == entt::null));
}

TEST_CASE("scrapAtWorldPos returns the nearest of several piles", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity near = ss.spawn(QVector2D(2.0f, 2.0f), 1, 100);
    ss.spawn(QVector2D(2.4f, 2.0f), 1, 100);

    REQUIRE((scrapAtWorldPos(admin, QVector2D(2.05f, 2.0f)) == near));
}

TEST_CASE("entityAtWorldPos never returns a scrap pile", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    ss.spawn(QVector2D(3.0f, 4.0f), 5, 100);

    // Scrap has no HealthComponent, so the actor hit-test ignores it entirely.
    REQUIRE((entityAtWorldPos(admin, QVector2D(3.0f, 4.0f)) == entt::null));
}

TEST_CASE("scrapInBox returns exactly the piles inside the tile rectangle", "[scrap]")
{
    EntityAdmin admin;
    ScrapSystem ss(admin);

    const entt::entity inA  = ss.spawn(QVector2D(1.2f, 2.7f), 1, 100); // tile (1,2)
    const entt::entity inB  = ss.spawn(QVector2D(4.9f, 5.1f), 1, 100); // tile (4,5)
    const entt::entity outX = ss.spawn(QVector2D(10.0f, 10.0f), 1, 100);

    // Box given in reversed corner order to confirm normalization.
    const std::vector<entt::entity> hit = scrapInBox(admin, QPoint(5, 5), QPoint(0, 0));

    REQUIRE(hit.size() == 2);
    REQUIRE(contains(hit, inA));
    REQUIRE(contains(hit, inB));
    REQUIRE_FALSE(contains(hit, outX));
}