// Headless test for civilization Step 2 (habitability + settlements). No display needed.
//
//   g++ -std=c++17 -O2 -Isrc/sim test_civ.cpp src/sim/IcoSphere.cpp src/sim/Planet.cpp
//       src/sim/PlanetTectonics.cpp src/sim/PlanetDrift.cpp src/sim/PlanetErosion.cpp
//       src/sim/PlanetHydrology.cpp src/sim/PlanetBiomes.cpp src/sim/PlanetClimate.cpp
//       src/sim/PlanetLive.cpp src/sim/PlanetOcean.cpp src/sim/PlanetWeather.cpp
//       src/sim/PlanetVolcano.cpp src/sim/PlanetBiota.cpp src/sim/PlanetFloraGen.cpp
//       src/sim/PlanetFaunaGen.cpp src/sim/PlanetFungiGen.cpp src/sim/NameGen.cpp
//       src/sim/PlanetGeography.cpp src/sim/PlanetEcoregions.cpp src/sim/PlanetCiv.cpp
//       src/sim/PlanetIO.cpp -o /tmp/tc && /tmp/tc
//
// Verifies: habitability range/zeros; placement spacing/cap/land + unique names; food-driven growth
// and decline; tiers; determinism + RNG isolation; population snapshot round-trip; v20 save; reseed clear;
// growth plateau (crowding + plague bound city size at a historical metropolis scale; villages untouched;
// plague waves are deterministic + step-back exact).

#include "Planet.hpp"
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <set>
#include <sstream>

static int failures = 0;
static void check(bool cond, const char* what) {
    std::printf("  [%s] %s\n", cond ? "PASS" : "FAIL", what);
    if (!cond) ++failures;
}
static void settle(Planet& p, int maxSteps = 800) {
    int run = 0;
    for (int s = 0; s < maxSteps; ++s) { double mc = p.step(); if (mc < 2.0) { if (++run >= 3) break; } else run = 0; }
    p.computeClimate(); p.classifyBiomes();
}
static void drift(Planet& p, int iters) {
    p.drifting = true;
    for (int k = 0; k < iters; ++k) { double dt = p.cflDtMy(); p.advect(dt); p.step(); p.erode(dt); if (k >= iters/2) p.hydrology(dt*0.2); }
    p.computeClimate(); p.classifyBiomes();
}

int main() {
    PlanetConfig cfg; cfg.subdivisions = 5; cfg.seed = 4242;
    Planet p; p.generate(cfg); settle(p); drift(p, 400);
    const int n = (int)p.cells.size();
    const double sea = p.cfg.seaLevel;
    const double yearH = p.cfg.dayLengthHours * p.cfg.yearLengthDays;

    std::printf("Civ: habitability field\n");
    p.computeHabitability();
    const auto& H = p.habitability();
    check((int)H.size() == n, "habitability sized n");
    bool ranged = true, zeroWaterIce = true, anyHabitable = false;
    for (int i = 0; i < n; ++i) {
        if (!(std::isfinite(H[i]) && H[i] >= 0.0 && H[i] <= 1.0)) ranged = false;
        if ((p.cells[i].elevation <= sea || p.cells[i].biome == Biome::Ice) && H[i] != 0.0) zeroWaterIce = false;
        if (H[i] > 0.3) anyHabitable = true;
    }
    check(ranged, "habitability in [0,1]");
    check(zeroWaterIce, "habitability 0 on ocean/ice");
    check(anyHabitable, "some land is habitable");

    std::printf("Civ: placement\n");
    p.placeSettlements();
    const auto& S = p.settlements;
    check(!S.empty(), "settlements placed");
    bool onLand = true, aboveMin = true, capOk = (int)S.size() <= p.cfg.civMaxSettlements;
    std::set<std::string> names; bool uniqueNames = true; std::set<int> distinctCells; bool distinct = true;
    double placedHabSum = 0.0;
    for (size_t a = 0; a < S.size(); ++a) {
        if (p.cells[S[a].cell].elevation <= sea) onLand = false;
        if (p.habitability()[S[a].cell] < p.cfg.civMinHabitability - 1e-9) aboveMin = false;
        if (!names.insert(S[a].name).second || S[a].name.empty()) uniqueNames = false;
        if (!distinctCells.insert(S[a].cell).second) distinct = false;     // one settlement per cell
        placedHabSum += p.habitability()[S[a].cell];
        if (p.cellSettlement()[S[a].cell] != (int)a) onLand = false;       // index consistency
    }
    // Nearest-neighbour spacing should VARY (clustered, not an even lattice).
    double nnMin = 1e9, nnMax = 0.0;
    for (size_t a = 0; a < S.size(); ++a) {
        double best = 1e9;
        for (size_t b = 0; b < S.size(); ++b) if (a != b)
            best = std::min(best, std::acos(std::clamp(p.cells[S[a].cell].unit.dot(p.cells[S[b].cell].unit), -1.0, 1.0)));
        if (best < 1e8) { nnMin = std::min(nnMin, best); nnMax = std::max(nnMax, best); }
    }
    double placedHabMean = S.empty() ? 0.0 : placedHabSum / S.size();
    double habMean = 0.0; int habN = 0;
    for (int i = 0; i < n; ++i) if (p.cells[i].elevation > sea && p.habitability()[i] >= p.cfg.civMinHabitability) { habMean += p.habitability()[i]; ++habN; }
    habMean = habN ? habMean / habN : 0.0;
    std::printf("    %d settlements  nn-dist %.3f..%.3f rad  placed-hab %.2f vs habitable-mean %.2f\n",
                (int)S.size(), nnMin, nnMax, placedHabMean, habMean);
    check(onLand && distinct, "settlements sit on distinct land cells + cellSettlement index consistent");
    check(aboveMin, "settlements only on cells >= civMinHabitability");
    check(nnMax > nnMin * 1.8, "nearest-neighbour spacing varies (clustered, not an even lattice)");
    check(placedHabMean > habMean + 0.02, "placement concentrates on the better land (clustering)");
    check(capOk, "settlement count within the cap");
    check(uniqueNames, "settlement names are unique + non-empty");

    std::printf("Civ: environment-driven growth (differentiated + dynamic)\n");
    {
        int gi = 0, lo = 0;
        for (size_t k = 0; k < S.size(); ++k) {
            if (p.habitability()[S[k].cell] > p.habitability()[S[gi].cell]) gi = (int)k;
            if (p.habitability()[S[k].cell] < p.habitability()[S[lo].cell]) lo = (int)k;
        }
        double g0 = p.settlements[gi].population;
        double lt = 0.0; bool anyDecline = false;
        std::vector<double> prev(p.settlements.size());
        for (int yr = 0; yr < 600; ++yr) {
            for (size_t k = 0; k < p.settlements.size(); ++k) prev[k] = p.settlements[k].population;
            lt += 2.0 * yearH;
            p.stepCivilization(2.0 * yearH, lt);                 // advance the clock so harvests/droughts vary
            for (size_t k = 0; k < p.settlements.size(); ++k)
                if (p.settlements[k].population > p.cfg.civAbandonPop && p.settlements[k].population < prev[k] * 0.999) anyDecline = true;
        }
        check(p.settlements[gi].population > g0 * 2.0, "a fertile settlement grows strongly");
        // The user's complaint was "they grow the same amount everywhere": now sizes must vary widely.
        std::vector<double> pops;
        for (const auto& s : p.settlements) if (s.population >= p.cfg.civAbandonPop) pops.push_back(s.population);
        std::sort(pops.begin(), pops.end());
        double med = pops.empty() ? 0.0 : pops[pops.size() / 2];
        double mx  = pops.empty() ? 0.0 : pops.back();
        std::printf("    alive %d  median %.0f  max %.0f  (max/median %.1f)\n",
                    (int)pops.size(), med, mx, med > 0 ? mx / med : 0.0);
        check(!pops.empty() && mx > med * 3.0, "settlement sizes vary widely (env-driven, not uniform growth)");
        check(p.settlements[gi].population > p.settlements[lo].population, "fertile ends larger than marginal");
        check(anyDecline, "settlements decline in bad years (harvest/drought dynamics, not monotonic)");
        // Over-capacity settlement declines toward its food limit.
        p.settlements[gi].population = 5.0e7;
        double over = p.settlements[gi].population;
        for (int yr = 0; yr < 200; ++yr) { lt += 2.0 * yearH; p.stepCivilization(2.0 * yearH, lt); }
        check(p.settlements[gi].population < over, "an over-capacity settlement declines toward its food limit");
    }

    std::printf("Civ: a hurricane over a town kills people\n");
    {
        Planet w; w.generate(cfg); settle(w); drift(w, 400); w.placeSettlements();
        if (!w.settlements.empty()) {
            int si = 0; for (size_t k = 0; k < w.settlements.size(); ++k) if (w.settlements[k].population > w.settlements[si].population) si = (int)k;
            w.settlements[si].population = 1.0e5;
            WeatherSnapshot snap = w.captureWeather();
            WeatherSystem ws; ws.id = 999; ws.pos = w.cells[w.settlements[si].cell].unit;
            ws.radius = 0.3; ws.strength = 1.0; ws.tropical = true; ws.life = 1e9;
            snap.storms.push_back(ws);
            w.restoreWeather(snap);                              // inject a stationary hurricane over the town
            double before = w.settlements[si].population;
            double lt = 0.0; for (int yr = 0; yr < 3; ++yr) { lt += yearH; w.stepCivilization(yearH, lt); }
            check(w.settlements[si].population < before * 0.9, "a hurricane parked over a town kills its population");
        }
    }

    std::printf("Civ: tiers\n");
    check(settleTierOf(100.0, p.cfg.civTownPop, p.cfg.civCityPop) == SettleTier::Village
       && settleTierOf(p.cfg.civTownPop, p.cfg.civTownPop, p.cfg.civCityPop) == SettleTier::Town
       && settleTierOf(p.cfg.civCityPop, p.cfg.civTownPop, p.cfg.civCityPop) == SettleTier::City,
       "tier thresholds (village/town/city)");

    std::printf("Civ: determinism\n");
    Planet q; q.generate(cfg); settle(q); drift(q, 400); q.placeSettlements();
    bool same = (q.settlements.size() == S.size());
    if (same) for (size_t k = 0; k < S.size(); ++k)
        if (q.settlements[k].cell != p.settlements[k].cell || q.settlements[k].name != p.settlements[k].name) { same = false; break; }
    check(same, "placeSettlements is deterministic");

    std::printf("Civ: RNG isolation from tectonics\n");
    Planet x; x.generate(cfg); settle(x);
    Planet y; y.generate(cfg); settle(y);
    for (int k = 0; k < 40; ++k) {
        double dx = x.cflDtMy(); x.advect(dx); x.step(); x.erode(dx);
        double dy = y.cflDtMy(); y.advect(dy); y.step(); y.erode(dy);
        if (k == 20) { y.placeSettlements(); y.stepCivilization(yearH, yearH); }
    }
    bool terrainSame = true;
    for (int i = 0; i < n; ++i) if (std::fabs(x.cells[i].elevation - y.cells[i].elevation) > 1e-9) terrainSame = false;
    check(terrainSame, "placeSettlements/stepCivilization never perturb tectonic evolution");

    std::printf("Civ: population snapshot round-trip\n");
    {
        WeatherSnapshot snap = p.captureWeather();
        for (auto& st : p.settlements) st.population = 12345.0;
        p.restoreWeather(snap);
        bool restored = true;
        for (size_t k = 0; k < p.settlements.size(); ++k) if (std::fabs(p.settlements[k].population - snap.settlementPop[k]) > 1e-9) restored = false;
        check(snap.settlementPop.size() == p.settlements.size() && restored, "captureWeather/restoreWeather round-trips populations");
    }

    std::printf("Civ: save v20 round-trip\n");
    {
        std::stringstream ss(std::ios::in | std::ios::out | std::ios::binary);
        p.writeState(ss);
        Planet r;
        bool ok = r.readState(ss, true, true, true, true, true, true, true, true, true, true, true);
        check(ok, "readState accepts a v20 stream");
        bool match = (r.settlements.size() == p.settlements.size());
        if (match) for (size_t k = 0; k < p.settlements.size(); ++k)
            if (r.settlements[k].cell != p.settlements[k].cell || r.settlements[k].name != p.settlements[k].name
                || std::fabs(r.settlements[k].population - p.settlements[k].population) > 1e-6) { match = false; break; }
        check(match, "settlements round-trip through save");
        check(r.cellSettlement() == p.cellSettlement(), "cellSettlement index rebuilt on load");
    }

    std::printf("Civ: growth plateau (crowding + plague keep cities at a historical scale)\n");
    {
        Planet base; base.generate(cfg); settle(base); drift(base, 400);
        base.placeSettlements();
        const double stepH = 2.0 * yearH;
        // One era: fixed cadence (territory/culture/trade every 10 steps so prosperity feeds K, like
        // the viewer's yearly rebuild but cheaper); returns the end clock so eras chain year-correctly.
        auto era = [&](Planet& x, int iters, double lt) {
            for (int it = 0; it < iters; ++it) {
                if (it % 10 == 0) { x.computeTerritory(); x.computeCultures(); x.computeTrade(); }
                lt += stepH;
                x.stepCivilization(stepH, lt);
            }
            return lt;
        };
        Planet A = base;                       // defaults: crowding + plague + good-year cap
        Planet B = base;                       // the old unbounded behaviour
        B.cfg.civCrowdingLoss = 0.0; B.cfg.civPlagueRate = 0.0; B.cfg.civCondBoomCap = 100.0;
        // Run A inline so we can watch every step: villages (< 30k) must never see plague.
        bool villagesClean = true;
        double ltA = 0.0;
        for (int it = 0; it < 2000; ++it) {    // 4000 years
            if (it % 10 == 0) { A.computeTerritory(); A.computeCultures(); A.computeTrade(); }
            ltA += stepH;
            A.stepCivilization(stepH, ltA);
            for (size_t k = 0; k < A.settlements.size(); ++k)
                if (A.settlements[k].population < 0.3 * A.cfg.civCityPop
                    && k < A.settlementPlague().size() && A.settlementPlague()[k] > 0.0) villagesClean = false;
        }
        era(B, 2000, 0.0);
        double mxA = 0.0, mxB = 0.0;
        for (const auto& s : A.settlements) mxA = std::max(mxA, s.population);
        for (const auto& s : B.settlements) mxB = std::max(mxB, s.population);
        std::printf("    max pop with plateau %.0f  without %.0f  (x%.1f)\n", mxA, mxB, mxA > 0 ? mxB / mxA : 0.0);
        check(mxA > 4.0e5 && mxA < 3.0e6, "the largest city plateaus at a historical metropolis scale (~1-2M)");
        check(mxB > mxA * 2.0, "without crowding/plague/boom-cap cities grow far larger (the old runaway)");
        check(villagesClean, "small settlements never suffer plague");

        // A plague wave hits the biggest hub within a few centuries, is deterministic and rewindable.
        int big = 0;
        for (size_t k = 0; k < A.settlements.size(); ++k)
            if (A.settlements[k].population > A.settlements[big].population) big = (int)k;
        bool sawPlague = false, dropInWave = false;
        double ltP = ltA;
        for (int yr = 0; yr < 400; ++yr) {
            double before = A.settlements[big].population;
            if (yr % 10 == 0) { A.computeTerritory(); A.computeCultures(); A.computeTrade(); }
            ltP += yearH;
            A.stepCivilization(yearH, ltP);
            if (A.settlementPlague()[big] > 0.02) {
                sawPlague = true;
                if (A.settlements[big].population < before * 0.98) dropInWave = true;
            }
        }
        std::printf("    plague hit the largest hub: %s\n", sawPlague ? "yes" : "no");
        check(sawPlague, "a plague wave strikes a large trade hub within a few centuries");
        check(dropInWave, "an active plague year visibly shrinks the city");

        // Determinism: two identical copies evolve identical populations through plague years.
        {
            Planet d1 = base, d2 = base;
            double l1 = era(d1, 200, 0.0), l2 = era(d2, 200, 0.0);
            bool same = (l1 == l2) && d1.settlements.size() == d2.settlements.size();
            for (size_t k = 0; same && k < d1.settlements.size(); ++k)
                if (d1.settlements[k].population != d2.settlements[k].population) same = false;
            check(same, "growth incl. plague/crowding is deterministic (bit-identical twins)");
        }
        // Step-back: capture -> 50 years (across plague waves) -> restore -> replay -> identical.
        {
            WeatherSnapshot snap = A.captureWeather();
            double lt0 = ltP;
            std::vector<double> endPops;
            double lt1 = era(A, 25, lt0);      // 50 years
            for (const auto& s : A.settlements) endPops.push_back(s.population);
            A.restoreWeather(snap);
            bool back = true;
            for (size_t k = 0; k < A.settlements.size(); ++k)
                if (A.settlements[k].population != snap.settlementPop[k]) back = false;
            check(back, "restoreWeather rewinds populations across plague years");
            double lt2 = era(A, 25, lt0);      // deterministic replay
            bool same = (lt1 == lt2);
            for (size_t k = 0; same && k < A.settlements.size(); ++k)
                if (A.settlements[k].population != endPops[k]) same = false;
            check(same, "replaying the same years reproduces the same populations (plague is stateless)");
        }
    }

    std::printf("Civ: reseed clears settlements\n");
    p.generate(cfg);
    check(p.settlements.empty() && (p.cellSettlement().empty() || p.cellSettlement()[0] == -1), "reseed clears the settlement set");

    std::printf(failures ? "\nFAILURES: %d\n" : "\nALL CIV CHECKS PASSED\n", failures);
    return failures ? 1 : 0;
}