// 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.

#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;
    const double sepCos = std::cos(p.cfg.civMinSpacingRadians);
    bool spaced = true;
    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;
        for (size_t b = a + 1; b < S.size(); ++b)
            if (p.cells[S[a].cell].unit.dot(p.cells[S[b].cell].unit) > sepCos + 1e-9) spaced = false;
        if (p.cellSettlement()[S[a].cell] != (int)a) onLand = false;   // index consistency
    }
    std::printf("    %d settlements\n", (int)S.size());
    check(onLand, "settlements sit on land + cellSettlement index is consistent");
    check(aboveMin, "settlements only on cells >= civMinHabitability");
    check(spaced, "settlements respect the minimum spacing");
    check(capOk, "settlement count within the cap");
    check(uniqueNames, "settlement names are unique + non-empty");

    std::printf("Civ: food-driven growth + decline\n");
    {
        int gi = 0; for (size_t k = 0; k < S.size(); ++k) if (p.habitability()[S[k].cell] > p.habitability()[S[gi].cell]) gi = (int)k;
        double p0 = p.settlements[gi].population;
        for (int k = 0; k < 400; ++k) p.stepCivilization(5.0 * yearH);   // ~2000 yr of small steps
        check(p.settlements[gi].population > p0 * 2.0, "a high-habitability settlement grows");
        // Decline: push one well over its carrying capacity, then step -> it shrinks.
        p.settlements[gi].population = 5.0e7;
        double over = p.settlements[gi].population;
        for (int k = 0; k < 400; ++k) p.stepCivilization(5.0 * yearH);
        check(p.settlements[gi].population < over, "an over-capacity settlement declines toward its food limit");
    }

    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); }
    }
    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: 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;
}