// TechTree::SetResearched's unlock cascade, the prerequisite test and the newly-available
// collector. Every case here is a property read out of the instruction stream, not a guess about
// what a tech tree "should" do -- the four that are easiest to get wrong are the sticky
// turnAvailable, the signed costRP minimum against an INT_MAX sentinel, the empty prerequisite
// group, and the self-resolving index both sweeps go through.
#include "game/sim/techgraph.h"

#include <string>
#include <vector>

#include "check.h"

using namespace sots::sim;

namespace {

// A tree of `n` nodes, every slot present, every node resolving to itself, all hidden.
TechGraph make_tree(std::size_t n, int turn = 5) {
    TechGraph g;
    g.nodes.resize(n);
    for (std::size_t i = 0; i < n; ++i) {
        g.nodes[i].present = true;
        g.nodes[i].selfIndex = static_cast<int>(i);
    }
    g.hasOwner = true;
    g.turn = turn;
    return g;
}

void link(TechGraph& g, int parent, int child, int costRP) {
    g.nodes[static_cast<std::size_t>(parent)].children.push_back(TechEdgeRef{child, costRP});
}

// Counts how many times the cost hook and the owner callback were reached, and lets a test make
// a chosen node free so the recursive branch fires.
struct Env {
    std::vector<int> freeNodes;
    int costCalls = 0;
    std::vector<int> researchedCallbacks;
    std::vector<bool> silentSeen;

    static int Cost(void* ctx, int i) {
        Env& e = *static_cast<Env*>(ctx);
        ++e.costCalls;
        for (int f : e.freeNodes)
            if (f == i) return 0;
        return 1000;
    }
    static void OnResearched(void* ctx, int i, bool silent) {
        Env& e = *static_cast<Env*>(ctx);
        e.researchedCallbacks.push_back(i);
        e.silentSeen.push_back(silent);
    }
    TechCascadeEnv env() {
        TechCascadeEnv v;
        v.cost = &Cost;
        v.onResearched = &OnResearched;
        v.ctx = this;
        return v;
    }
};

// ---------------------------------------------------------------------------------------

void test_prereqs() {
    TechGraph g = make_tree(5);
    // No groups at all: satisfied. The original returns `count == count` with both zero.
    CHECK(TechPrereqsMet(g, 0));

    // One group, one tech, not researched.
    g.nodes[0].prereqs.groups = {{3}};
    CHECK(!TechPrereqsMet(g, 0));
    g.nodes[3].state = static_cast<int>(TechState::Researched);
    CHECK(TechPrereqsMet(g, 0));

    // A group is an OR: any one member satisfies it.
    g.nodes[0].prereqs.groups = {{1, 2, 3}};
    CHECK(TechPrereqsMet(g, 0));
    g.nodes[3].state = static_cast<int>(TechState::Available);
    CHECK(!TechPrereqsMet(g, 0));

    // Groups are an AND: every one must be satisfied.
    g.nodes[1].state = static_cast<int>(TechState::Researched);
    g.nodes[0].prereqs.groups = {{1}, {2}};
    CHECK(!TechPrereqsMet(g, 0));
    g.nodes[2].state = static_cast<int>(TechState::Researched);
    CHECK(TechPrereqsMet(g, 0));

    // An EMPTY group fails the whole test -- the inner loop cannot break, so the outer one
    // breaks with the group uncounted. This is the case a "vacuously true" reading gets wrong.
    g.nodes[0].prereqs.groups = {{1}, {}};
    CHECK(!TechPrereqsMet(g, 0));

    // A listed tech whose node the tree does not hold satisfies nothing.
    g.nodes[0].prereqs.groups = {{4}};
    g.nodes[4].present = false;
    g.nodes[4].state = static_cast<int>(TechState::Researched);
    CHECK(!TechPrereqsMet(g, 0));

    // An unreadable structure is "not met", never "met by default".
    g.nodes[0].prereqs.groups.clear();
    g.nodes[0].prereqs.unreadable = true;
    CHECK(!TechPrereqsMet(g, 0));
}

void test_completion_stamps() {
    TechGraph g = make_tree(3, /*turn=*/7);
    g.orderCounter = 22;
    g.nodes[0].state = static_cast<int>(TechState::CurrentTarget);
    Env e;

    const TechCascadeResult r = SetResearched(g, 0, kTechForce, e.env());
    CHECK(r.ran);
    CHECK(!r.alreadyResearched);
    CHECK_EQ(g.nodes[0].state, static_cast<int>(TechState::Researched));
    CHECK_EQ(g.nodes[0].turnResearched, 7);
    CHECK_EQ(g.nodes[0].order, 22);
    CHECK_EQ(g.orderCounter, 23);
    // ProcessResearch passes flags = 2, so bit 2 is clear and the callback is NOT silent --
    // which is what makes the completion event fire.
    CHECK_EQ(e.researchedCallbacks.size(), std::size_t{1});
    CHECK(!e.silentSeen[0]);

    // Re-completing writes nothing at all: not the order stamp, not the counter.
    Env e2;
    const TechCascadeResult again = SetResearched(g, 0, kTechForce, e2.env());
    CHECK(again.alreadyResearched);
    CHECK(again.ran);
    CHECK_EQ(g.nodes[0].order, 22);
    CHECK_EQ(g.orderCounter, 23);
    CHECK_EQ(e2.researchedCallbacks.size(), std::size_t{0});

    // With no owner the turn stamp is a literal 0, not the turn.
    TechGraph h = make_tree(1, /*turn=*/7);
    h.hasOwner = false;
    Env e3;
    SetResearched(h, 0, kTechForce, e3.env());
    CHECK_EQ(h.nodes[0].turnResearched, 0);
    CHECK_EQ(e3.researchedCallbacks.size(), std::size_t{0});  // no owner, no callback
}

void test_force_and_prereq_gate() {
    TechGraph g = make_tree(2);
    g.nodes[0].prereqs.groups = {{1}};  // node 1 is not researched
    Env e;
    // Unforced, the gate holds and nothing is written.
    CHECK(!SetResearched(g, 0, 0u, e.env()).ran);
    CHECK_EQ(g.nodes[0].state, static_cast<int>(TechState::Hidden));
    CHECK_EQ(g.orderCounter, 0);
    // ProcessResearch's flags = 2 skips the gate: the roll has already been won.
    CHECK(SetResearched(g, 0, kTechForce, e.env()).ran);
    CHECK_EQ(g.nodes[0].state, static_cast<int>(TechState::Researched));

    // An absent node is a no-op, not a completion.
    TechGraph h = make_tree(1);
    h.nodes[0].present = false;
    Env e2;
    const TechCascadeResult r = SetResearched(h, 0, kTechForce, e2.env());
    CHECK(!r.ran);
    CHECK(!r.alreadyResearched);
}

void test_sweep1_costs_and_states() {
    TechGraph g = make_tree(4, /*turn=*/4);
    link(g, 0, 1, 10000);
    link(g, 0, 2, 16000);
    g.nodes[3].state = static_cast<int>(TechState::Available);   // untouched by this cascade
    g.nodes[3].turnAvailable = 2;
    Env e;

    SetResearched(g, 0, kTechForce, e.env());

    // Hidden children become ParentResearched, then the second sweep makes them Available and
    // stamps this turn.
    CHECK_EQ(g.nodes[1].costRP, 10000);
    CHECK_EQ(g.nodes[2].costRP, 16000);
    CHECK_EQ(g.nodes[1].state, static_cast<int>(TechState::Available));
    CHECK_EQ(g.nodes[2].state, static_cast<int>(TechState::Available));
    CHECK_EQ(g.nodes[1].turnAvailable, 4);
    CHECK_EQ(g.nodes[2].turnAvailable, 4);
    // A node that was already available keeps its original availability turn.
    CHECK_EQ(g.nodes[3].turnAvailable, 2);

    // The collector sees the two new ones and not the old one.
    const std::vector<int> unlocked = CollectNewlyAvailable(g, 4);
    CHECK_EQ(unlocked.size(), std::size_t{2});
    CHECK_EQ(unlocked[0], 1);
    CHECK_EQ(unlocked[1], 2);
    CHECK_EQ(CollectNewlyAvailable(g, 2).size(), std::size_t{1});
}

void test_cost_minimum_is_signed_and_monotone() {
    // Two parents reach the same child at different costs; the sentinel is INT_MAX, the compare
    // is signed, so the FIRST researched parent sets the cost and later parents only lower it.
    TechGraph g = make_tree(3);
    link(g, 0, 2, 8000);
    link(g, 1, 2, 12000);
    Env e;

    CHECK_EQ(g.nodes[2].costRP, kNoResearchCost);
    SetResearched(g, 1, kTechForce, e.env());
    CHECK_EQ(g.nodes[2].costRP, 12000);
    SetResearched(g, 0, kTechForce, e.env());
    CHECK_EQ(g.nodes[2].costRP, 8000);   // cheaper: lowered
    // And the expensive parent cannot raise it back.
    TechGraph h = make_tree(3);
    link(h, 0, 2, 8000);
    link(h, 1, 2, 12000);
    Env e2;
    SetResearched(h, 0, kTechForce, e2.env());
    SetResearched(h, 1, kTechForce, e2.env());
    CHECK_EQ(h.nodes[2].costRP, 8000);
}

void test_turn_available_is_sticky() {
    TechGraph g = make_tree(2, /*turn=*/3);
    link(g, 0, 1, 500);
    Env e;
    SetResearched(g, 0, kTechForce, e.env());
    CHECK_EQ(g.nodes[1].turnAvailable, 3);

    // Push the child back to ParentResearched and re-run the cascade on a later turn. The state
    // returns to Available but turnAvailable keeps its first value, so the collector does NOT
    // re-announce it. This is the property that makes EVENT_TECHS_UNLOCKED fire once per tech.
    g.nodes[1].state = static_cast<int>(TechState::ParentResearched);
    g.turn = 9;
    TechGraph g2 = g;
    g2.nodes[0].state = static_cast<int>(TechState::CurrentTarget);
    Env e2;
    SetResearched(g2, 0, kTechForce, e2.env());
    CHECK_EQ(g2.nodes[1].state, static_cast<int>(TechState::Available));
    CHECK_EQ(g2.nodes[1].turnAvailable, 3);
    CHECK_EQ(CollectNewlyAvailable(g2, 9).size(), std::size_t{0});
}

void test_excluded_byte_blocks_the_sweep() {
    TechGraph g = make_tree(2, /*turn=*/6);
    link(g, 0, 1, 500);
    g.nodes[1].excludedFromSweep = true;
    Env e;
    SetResearched(g, 0, kTechForce, e.env());
    // Sweep 1 still runs on it -- the exclusion byte is only tested in sweep 2 -- so the state
    // and the cost move, but it never becomes Available and never stamps a turn.
    CHECK_EQ(g.nodes[1].costRP, 500);
    CHECK_EQ(g.nodes[1].state, static_cast<int>(TechState::ParentResearched));
    CHECK_EQ(g.nodes[1].turnAvailable, -1);
    CHECK_EQ(CollectNewlyAvailable(g, 6).size(), std::size_t{0});
}

void test_free_child_completes_recursively() {
    TechGraph g = make_tree(3, /*turn=*/5);
    g.orderCounter = 10;
    link(g, 0, 1, 0);
    link(g, 1, 2, 700);
    Env e;
    e.freeNodes = {1};

    const TechCascadeResult r = SetResearched(g, 0, kTechForce, e.env());
    // Node 1 became available at zero cost, so the sweep researched it, and ITS cascade unlocked
    // node 2 in the same call.
    CHECK_EQ(r.completed.size(), std::size_t{2});
    CHECK_EQ(r.completed[0], 0);
    CHECK_EQ(r.completed[1], 1);
    CHECK_EQ(g.nodes[1].state, static_cast<int>(TechState::Researched));
    CHECK_EQ(g.nodes[1].order, 11);
    CHECK_EQ(g.nodes[2].state, static_cast<int>(TechState::Available));
    CHECK_EQ(g.nodes[2].costRP, 700);
    CHECK_EQ(e.researchedCallbacks.size(), std::size_t{2});
    // The free node never appears in the unlocked list: it left state 2 before the collector ran.
    const std::vector<int> unlocked = CollectNewlyAvailable(g, 5);
    CHECK_EQ(unlocked.size(), std::size_t{1});
    CHECK_EQ(unlocked[0], 2);
    CHECK(!r.depthExceeded);
}

void test_zero_cost_cycle_terminates() {
    // A zero-cost cycle does NOT hang: the state-4 early return is what makes the recursion
    // well founded, and it is the only thing that does. Worth pinning, because the depth cap
    // below would otherwise look like the reason.
    TechGraph g = make_tree(2);
    link(g, 0, 1, 0);
    link(g, 1, 0, 0);
    Env e;
    e.freeNodes = {0, 1};
    const TechCascadeResult r = SetResearched(g, 0, kTechForce, e.env());
    CHECK(!r.depthExceeded);
    CHECK_EQ(r.completed.size(), std::size_t{2});
    CHECK_EQ(g.nodes[0].state, static_cast<int>(TechState::Researched));
    CHECK_EQ(g.nodes[1].state, static_cast<int>(TechState::Researched));
}

void test_recursion_is_capped_not_hung() {
    // A long enough chain of free techs recurses once per link. The original has no guard at
    // all; a reimplementation running inside the game must report rather than blow the stack.
    TechGraph g = make_tree(10);
    for (int i = 0; i + 1 < 10; ++i) link(g, i, i + 1, 0);
    Env e;
    for (int i = 0; i < 10; ++i) e.freeNodes.push_back(i);
    TechCascadeEnv env = e.env();
    env.maxDepth = 4;
    const TechCascadeResult r = SetResearched(g, 0, kTechForce, env);
    CHECK(r.depthExceeded);
    // With the cap lifted the same tree completes the whole chain.
    TechGraph h = make_tree(10);
    for (int i = 0; i + 1 < 10; ++i) link(h, i, i + 1, 0);
    Env e2;
    for (int i = 0; i < 10; ++i) e2.freeNodes.push_back(i);
    const TechCascadeResult r2 = SetResearched(h, 0, kTechForce, e2.env());
    CHECK(!r2.depthExceeded);
    CHECK_EQ(r2.completed.size(), std::size_t{10});
}

void test_self_index_indirection() {
    // Both sweeps and the collector test the state of `nodes[node->def->techId]`, not of the
    // node they are iterating. A tree where those differ behaves accordingly; this pins that the
    // indirection is reproduced rather than shortcut.
    TechGraph g = make_tree(3, /*turn=*/8);
    link(g, 0, 1, 400);
    g.nodes[1].selfIndex = 2;                                        // node 1 resolves to node 2
    g.nodes[2].state = static_cast<int>(TechState::ParentResearched);
    g.nodes[2].excludedFromSweep = true;   // so the sweep cannot promote node 2 on its own pass
    Env e;
    SetResearched(g, 0, kTechForce, e.env());
    // Node 1's own state went to ParentResearched via sweep 1, but sweep 2 tests node 2's state
    // (which IS ParentResearched), so it is node 1 that is written to Available.
    CHECK_EQ(g.nodes[1].state, static_cast<int>(TechState::Available));
    CHECK_EQ(g.nodes[1].turnAvailable, 8);
    // ...and the collector then tests node 2's state again, which is still 1, not 2, so node 1
    // is not collected even though node 1 itself is available.
    CHECK_EQ(g.nodes[2].state, static_cast<int>(TechState::ParentResearched));
    CHECK_EQ(CollectNewlyAvailable(g, 8).size(), std::size_t{0});
}

void test_absent_slots_are_skipped() {
    TechGraph g = make_tree(4, /*turn=*/2);
    link(g, 0, 1, 100);
    link(g, 0, 3, 200);
    g.nodes[1].present = false;   // a tech this species' tree does not hold
    Env e;
    SetResearched(g, 0, kTechForce, e.env());
    CHECK_EQ(g.nodes[3].state, static_cast<int>(TechState::Available));
    const std::vector<int> unlocked = CollectNewlyAvailable(g, 2);
    CHECK_EQ(unlocked.size(), std::size_t{1});
    CHECK_EQ(unlocked[0], 3);
}

// The shape lane V measured live on 2026-09-08: one completion unlocking three children, whose
// costs come from the edges and whose availability turn is the completion turn. Reproduced here
// as a regression pin on the numbers that appeared in the compare report.
void test_live_shape_call3() {
    TechGraph g = make_tree(150, /*turn=*/4);
    g.orderCounter = 22;
    g.nodes[144].state = static_cast<int>(TechState::CurrentTarget);
    link(g, 144, 132, 10000);
    link(g, 144, 136, 16000);
    link(g, 144, 142, 8000);
    Env e;

    SetResearched(g, 144, kTechForce, e.env());

    CHECK_EQ(g.nodes[144].order, 22);
    CHECK_EQ(g.nodes[144].turnResearched, 4);
    CHECK_EQ(g.nodes[132].costRP, 10000);
    CHECK_EQ(g.nodes[136].costRP, 16000);
    CHECK_EQ(g.nodes[142].costRP, 8000);
    for (int i : {132, 136, 142}) {
        CHECK_EQ(g.nodes[static_cast<std::size_t>(i)].state, static_cast<int>(TechState::Available));
        CHECK_EQ(g.nodes[static_cast<std::size_t>(i)].turnAvailable, 4);
    }
    CHECK_EQ(CollectNewlyAvailable(g, 4).size(), std::size_t{3});
}

}  // namespace

int main() {
    test_prereqs();
    test_completion_stamps();
    test_force_and_prereq_gate();
    test_sweep1_costs_and_states();
    test_cost_minimum_is_signed_and_monotone();
    test_turn_available_is_sticky();
    test_excluded_byte_blocks_the_sweep();
    test_free_child_completes_recursively();
    test_zero_cost_cycle_terminates();
    test_recursion_is_capped_not_hung();
    test_self_index_indirection();
    test_absent_slots_are_skipped();
    test_live_shape_call3();
    return simtest::finish("game_sim_techgraph");
}