// Headless test for the Live World weather cycle (humidity / cloud / rain). No display needed.
//
//   g++ -std=c++17 -O2 -Isrc/sim test_weather.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/PlanetBiota.cpp src/sim/PlanetFloraGen.cpp src/sim/PlanetFaunaGen.cpp \
//       src/sim/PlanetFungiGen.cpp src/sim/PlanetIO.cpp -o /tmp/tw && /tmp/tw
//
// Verifies: fields stay in range; oceans (the evaporation source) end up moister than land;
// clouds form and rain falls somewhere; the cycle is deterministic; and save v10 round-trips it.

#include "Planet.hpp"
#include <cstdio>
#include <cmath>
#include <algorithm>
#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;
}

// Run a fixed weather sequence on a planet (returns whether rain ever fell, max cloud + storms).
static void runWeather(Planet& p, bool& everRained, double& maxCloud, int& maxStorms) {
    p.initWeather();
    everRained = false; maxCloud = 0.0; maxStorms = 0;
    for (int k = 0; k < 300; ++k) {
        p.computeInsolation(0.25, std::fmod(0.3 + 0.01 * k, 1.0));   // sun advances
        p.stepWeather(1.0);                                         // 1-hour steps
        const std::vector<double>& rn = p.rain();
        const std::vector<double>& cl = p.cloud();
        for (size_t i = 0; i < rn.size(); ++i) {
            if (rn[i] > 0.0) everRained = true;
            maxCloud = std::max(maxCloud, cl[i]);
        }
        maxStorms = std::max(maxStorms, (int)p.storms().size());
    }
}

int main() {
    PlanetConfig cfg; cfg.subdivisions = 5; cfg.seed = 1337;
    Planet p; p.generate(cfg);
    const int n = (int)p.cells.size();

    std::printf("Weather: cycle\n");
    bool rained = false; double maxCloud = 0.0; int maxStorms = 0;
    runWeather(p, rained, maxCloud, maxStorms);

    bool inRange = true;
    for (int i = 0; i < n; ++i) {
        if (p.humidity()[i] < -1e-9) inRange = false;
        if (p.cloud()[i] < -1e-9 || p.cloud()[i] > 1.5 + 1e-9) inRange = false;
        if (p.rain()[i] < -1e-9) inRange = false;
    }
    check(inRange, "humidity/cloud/rain stay in range");
    check(maxCloud > 0.05, "clouds form");
    check(rained, "rain falls somewhere");

    // Oceans are the moisture source -> moister than land on average.
    double oh = 0, lh = 0; int oc = 0, lc = 0;
    for (int i = 0; i < n; ++i) {
        if (p.cells[i].elevation <= cfg.seaLevel) { oh += p.humidity()[i]; ++oc; }
        else { lh += p.humidity()[i]; ++lc; }
    }
    oh /= std::max(1, oc); lh /= std::max(1, lc);
    std::printf("    mean humidity: ocean %.3f, land %.3f\n", oh, lh);
    check(oh > lh, "oceans end up moister than land");

    std::printf("Weather: moving systems\n");
    std::printf("    max concurrent systems: %d\n", maxStorms);
    check(maxStorms > 0, "weather systems spawn over a run");
    if (!p.storms().empty()) {                          // cloud shield (no mutation of p)
        const auto& ws = p.storms()[0];
        double inSum = 0, allSum = 0; int inN = 0;
        for (int i = 0; i < n; ++i) {
            allSum += p.cloud()[i];
            double d = std::acos(std::clamp(p.cells[i].unit.dot(ws.pos), -1.0, 1.0));
            if (d < ws.radius) { inSum += p.cloud()[i]; ++inN; }
        }
        check(inN > 0 && inSum / inN > allSum / n, "cloud is thicker inside a weather system");
    }

    std::printf("Weather: RNG isolation\n");
    Planet z; z.generate(cfg);
    std::vector<double> elev0(n); for (int i = 0; i < n; ++i) elev0[i] = z.cells[i].elevation;
    z.initWeather();
    for (int k = 0; k < 60; ++k) { z.computeInsolation(0.25, std::fmod(0.3 + 0.01 * k, 1.0)); z.stepWeather(1.0); }
    bool terrainSame = true; for (int i = 0; i < n; ++i) if (z.cells[i].elevation != elev0[i]) terrainSame = false;
    check(terrainSame, "weather + storm RNG never perturb the terrain");

    std::printf("Weather: determinism\n");
    Planet p2; p2.generate(cfg);
    bool r2; double mc2; int ms2; runWeather(p2, r2, mc2, ms2);   // p and p2 both at 300 steps
    bool same = ((int)p2.storms().size() == (int)p.storms().size());
    for (int i = 0; i < n; ++i)
        if (p2.humidity()[i] != p.humidity()[i] || p2.cloud()[i] != p.cloud()[i]
            || p2.rain()[i] != p.rain()[i]) same = false;
    check(same, "same seed + sequence -> identical weather + systems");

    std::printf("Weather: systems move\n");
    if (!p.storms().empty()) {                          // one more step -> a system shifts position
        Vec3 before = p.storms()[0].pos;
        p.computeInsolation(0.25, 0.61); p.stepWeather(1.0);
        double best = -2.0; for (const auto& ws : p.storms()) best = std::max(best, before.dot(ws.pos));
        double ang = std::acos(std::clamp(best, -1.0, 1.0));
        check(ang > 1e-4 && ang < 0.3, "a weather system moves between steps");
    }

    std::printf("Weather: save v10\n");
    std::stringstream ss(std::ios::in | std::ios::out | std::ios::binary);
    p.writeState(ss);
    Planet q;
    bool ok = q.readState(ss, true, true, true, true);
    bool rt = ok && (int)q.cloud().size() == n;
    for (int i = 0; i < n && rt; ++i)
        if (q.humidity()[i] != p.humidity()[i] || q.cloud()[i] != p.cloud()[i] || q.rain()[i] != p.rain()[i])
            rt = false;
    check(rt, "save v10 round-trips the weather state");

    std::printf("Weather: snapshot round-trip (step-back undo)\n");
    {
        Planet wc; wc.generate(cfg); wc.initWeather();
        for (int k = 0; k < 60; ++k) { wc.computeInsolation(0.25, std::fmod(0.3 + 0.01 * k, 1.0)); wc.stepWeather(1.0); }
        WeatherSnapshot snap = wc.captureWeather();
        int s0 = (int)wc.storms().size();
        for (int k = 0; k < 30; ++k) { wc.computeInsolation(0.25, std::fmod(0.9 + 0.01 * k, 1.0)); wc.stepWeather(1.0); }
        wc.restoreWeather(snap);                          // step back to the saved frame
        bool rt = ((int)wc.storms().size() == s0);
        for (int i = 0; i < n && rt; ++i)
            if (wc.cloud()[i] != snap.cloud[i] || wc.humidity()[i] != snap.humidity[i] || wc.rain()[i] != snap.rain[i]) rt = false;
        check(rt, "captureWeather/restoreWeather round-trips the full weather state");
    }

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