// M0 T9a/b/c —— 全量解析 + 非退化谓词 + 直方图。见 docs/steps/M0-gr2-reader.md
//   gr2fuzz [assets-root] [--report out.json] [--list out.txt]
#include "gr2/gr2.h"
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <exception>
#include <filesystem>
#include <map>
#include <string>
#include <vector>

namespace fs = std::filesystem;

namespace {

struct Hist {
    std::map<std::string, uint64_t> m;
    void add(const std::string& k, uint64_t n = 1) { m[k] += n; }
};

struct Fails {
    std::vector<std::string> lines;
    void add(const std::string& path, const std::string& why) {
        lines.push_back(path + "\t" + why);
    }
};

// 非退化谓词。返回空 = 通过；否则第一条失败原因。
std::string check_predicates(const gr2::File& f) {
    const auto& fi = f.file_info();

    for (size_t s = 0; s < fi.skeletons.size(); ++s) {
        const auto& sk = fi.skeletons[s];
        if (sk.bones.empty() || sk.bones.size() > 512)
            return "skeleton bone count out of [1,512]: " + std::to_string(sk.bones.size());
        for (size_t i = 0; i < sk.bones.size(); ++i) {
            int32_t p = sk.bones[i].parent;
            if (p != -1 && (p < 0 || (size_t)p >= i))
                return "bone parent not < self or -1 at " + std::to_string(i);
            for (float v : sk.bones[i].local_transform)
                if (!std::isfinite(v)) return "non-finite local_transform at bone " + std::to_string(i);
            for (float v : sk.bones[i].inverse_world)
                if (!std::isfinite(v)) return "non-finite inverse_world at bone " + std::to_string(i);
        }
    }

    for (size_t mi = 0; mi < fi.meshes.size(); ++mi) {
        const auto& me = fi.meshes[mi];
        if (me.vertices.empty()) return "mesh " + std::to_string(mi) + " has 0 vertices";
        for (uint32_t idx : me.indices)
            if (idx >= me.vertices.size())
                return "mesh " + std::to_string(mi) + " index " + std::to_string(idx) +
                       " >= vertex count " + std::to_string(me.vertices.size());
        for (const auto& v : me.vertices)
            for (float c : v.pos)
                if (!std::isfinite(c)) return "mesh " + std::to_string(mi) + " non-finite position";
        for (const auto& g : me.tri_groups)
            if (g.tri_first < 0 || g.tri_count < 0 ||
                (int64_t)(g.tri_first + g.tri_count) * 3 > (int64_t)me.indices.size())
                return "mesh " + std::to_string(mi) + " tri group out of range";
        if (!me.rigid) {
            for (int32_t b : me.bone_bindings)
                if (b < 0) return "mesh " + std::to_string(mi) + " dangling bone binding";
            for (const auto& v : me.vertices) {
                int wsum = 0;
                for (int k = 0; k < 4; ++k) {
                    wsum += v.bone_weight[k];
                    if (!me.bone_bindings.empty() && v.bone_index[k] >= me.bone_bindings.size())
                        return "mesh " + std::to_string(mi) + " bone index out of range";
                }
                // u8 权重和：3 显式 + 1 隐式的情况下允许补齐，故用宽松带
                if (wsum < 200 || wsum > 262)   // 255 ± ~10%（含隐式第 4 权重补齐余量）
                    return "mesh " + std::to_string(mi) + " weight sum " + std::to_string(wsum) +
                           " out of [200,262]";
            }
        }
    }
    return {};
}

void dump_report(const fs::path& out, uint64_t total, uint64_t ok, uint64_t crashed,
                 uint64_t pred_fail, Hist& ver, Hist& comp, Hist& vkind, Hist& curve,
                 Hist& weights, Hist& ssuse, Hist& selfchk,
                 const Fails& crashes, const Fails& preds) {
    FILE* fp = std::fopen(out.string().c_str(), "wb");
    if (!fp) { std::fprintf(stderr, "cannot write %s\n", out.string().c_str()); return; }
    auto obj = [&](const char* name, Hist& h, bool last) {
        std::fprintf(fp, "  \"%s\": {", name);
        bool first = true;
        for (auto& [k, v] : h.m) {
            std::fprintf(fp, "%s\n    \"%s\": %llu", first ? "" : ",", k.c_str(),
                         (unsigned long long)v);
            first = false;
        }
        std::fprintf(fp, "\n  }%s\n", last ? "" : ",");
    };
    auto arr = [&](const char* name, const Fails& fl, bool last) {
        std::fprintf(fp, "  \"%s\": [", name);
        for (size_t i = 0; i < fl.lines.size(); ++i) {
            std::string s = fl.lines[i];
            std::string esc;
            for (char c : s) { if (c == '\\' || c == '"') esc += '\\'; esc += (c == '\t' ? ' ' : c); }
            std::fprintf(fp, "%s\n    \"%s\"", i ? "," : "", esc.c_str());
        }
        std::fprintf(fp, "\n  ]%s\n", last ? "" : ",");
    };
    std::fprintf(fp, "{\n");
    std::fprintf(fp, "  \"total\": %llu,\n  \"ok\": %llu,\n  \"crashed\": %llu,\n  \"predicate_fail\": %llu,\n",
                 (unsigned long long)total, (unsigned long long)ok,
                 (unsigned long long)crashed, (unsigned long long)pred_fail);
    obj("format_version", ver, false);
    obj("section_compression", comp, false);
    obj("vertex_kind", vkind, false);
	obj("bone_weight_slots", weights, false);
    obj("curve_subtype", curve, false);
    obj("scaleshear_usage", ssuse, false);
    obj("bind_pose_self_check", selfchk, false);
    arr("crashes", crashes, false);
    arr("predicate_failures", preds, true);
    std::fprintf(fp, "}\n");
    std::fclose(fp);
}

} // namespace

#ifndef XRENDER_ASSET_ROOT
#define XRENDER_ASSET_ROOT "."   // 无编译期默认：从命令行传资产根目录
#endif

int main(int argc, char** argv) {
    std::string root = XRENDER_ASSET_ROOT;
    fs::path report = "fuzz-report.json";
    fs::path listout;
    for (int i = 1; i < argc; ++i) {
        if (!std::strcmp(argv[i], "--report") && i + 1 < argc) report = argv[++i];
        else if (!std::strcmp(argv[i], "--list") && i + 1 < argc) listout = argv[++i];
        else root = argv[i];
    }
    if (!fs::exists(root)) {
        std::fprintf(stderr, "asset root not found: %s\n", root.c_str());
        return 2;
    }

    uint64_t total = 0, ok = 0, crashed = 0, pred_fail = 0;
    Hist ver, comp, vkind, curve, weights, ssuse, selfchk;
    Fails crashes, preds;
    std::vector<std::string> good_files;

    static const char* kK[] = {"PNT332", "PNT3322", "PNT332_Skinned", "PNT3322_Skinned", "Unknown"};

    for (auto& e : fs::recursive_directory_iterator(
             root, fs::directory_options::skip_permission_denied)) {
        if (!e.is_regular_file()) continue;
        auto p = e.path();
        std::string ext = p.extension().string();
        for (auto& c : ext) c = (char)std::tolower((unsigned char)c);
        if (ext != ".gr2") continue;
        ++total;

        gr2::LoadError err;
        std::optional<gr2::File> f;
        try {
            f = gr2::File::load_path(p.string(), &err);
        } catch (const std::exception& ex) {
            ++crashed; crashes.add(p.string(), std::string("exception: ") + ex.what());
            continue;
        } catch (...) {
            ++crashed; crashes.add(p.string(), "exception: unknown");
            continue;
        }
        if (!f) {
            ++crashed; crashes.add(p.string(), "load[" + err.stage + "]: " + err.message);
            continue;
        }

        ver.add(std::to_string(f->format_version()));
        for (const auto& s : f->sections()) {
            comp.add(gr2::compression_name(s.compression));
            if (s.expanded_size && s.decompress_status != 0) {
                ++crashed;
                crashes.add(p.string(), "decompress status " + std::to_string(s.decompress_status));
            }
        }

        const auto& fi = f->file_info();

        // bind pose 自洽（T5）：对每个 skeleton 取最好（最小）偏差，按量级分桶
        for (size_t s = 0; s < fi.skeletons.size(); ++s) {
            if (fi.skeletons[s].bones.size() < 2) continue;   // 单骨挂点跳过
            double dev = f->bind_pose_self_check(int(s));
            const char* bucket = dev < 1e-4 ? "<1e-4"
                               : dev < 1e-3 ? "<1e-3"
                               : dev < 1e-2 ? "<1e-2"
                               : dev < 1e-1 ? "<1e-1" : ">=1e-1";
            selfchk.add(bucket);
            if (dev >= 1e-1 && getenv("GR2_SELFCHK"))
                std::fprintf(stderr, "SELFCHK %.4f skel%zu bones=%zu %s\n",
                             dev, s, fi.skeletons[s].bones.size(), p.string().c_str());
        }

        for (const auto& me : fi.meshes) {
			vkind.add(kK[int(me.kind)]);
			if (!me.rigid) {
				weights.add(std::to_string(me.source_bone_weight_slots));
			}
		}
        for (const auto& sk : fi.skeletons) {
            uint64_t ss = 0;
            for (const auto& b : sk.bones) if (b.lt_flags & 0x4) ++ss;
            ssuse.add(ss ? "has_scaleshear" : "no_scaleshear", 1);
            ssuse.add("scaleshear_bones", ss);
        }
        for (const auto& an : fi.animations)
            for (const auto& t : an.tracks) {
                curve.add("pos:" + t.pos_type);
                curve.add("rot:" + t.rot_type);
                curve.add("scale:" + t.scale_type);
            }

        std::string why;
        try {
            why = check_predicates(*f);
        } catch (...) {
            why = "predicate check threw";
        }
        if (!why.empty()) { ++pred_fail; preds.add(p.string(), why); continue; }

        ++ok;
        good_files.push_back(p.string());
    }

    dump_report(report, total, ok, crashed, pred_fail, ver, comp, vkind, curve, weights, ssuse,
                selfchk, crashes, preds);

    if (!listout.empty()) {
        FILE* fp = std::fopen(listout.string().c_str(), "wb");
        if (fp) { for (auto& s : good_files) std::fprintf(fp, "%s\n", s.c_str()); std::fclose(fp); }
    }

    std::printf("gr2fuzz: total=%llu ok=%llu crashed=%llu predicate_fail=%llu\n",
                (unsigned long long)total, (unsigned long long)ok,
                (unsigned long long)crashed, (unsigned long long)pred_fail);
    std::printf("  report: %s\n", report.string().c_str());
    if (!crashes.lines.empty()) {
        std::printf("  first crashes:\n");
        for (size_t i = 0; i < crashes.lines.size() && i < 20; ++i)
            std::printf("    %s\n", crashes.lines[i].c_str());
    }
    if (!preds.lines.empty()) {
        std::printf("  first predicate failures:\n");
        for (size_t i = 0; i < preds.lines.size() && i < 20; ++i)
            std::printf("    %s\n", preds.lines[i].c_str());
    }
    return (crashed == 0 && pred_fail == 0) ? 0 : 1;
}