#include "metin2_model.h"

#include "dxt.h"
#include "gr2_bridge.h"
#include "m2_material.h"

#include <godot_cpp/classes/array_mesh.hpp>
#include <godot_cpp/classes/base_material3d.hpp>
#include <godot_cpp/classes/dir_access.hpp>
#include <godot_cpp/classes/file_access.hpp>
#include <godot_cpp/classes/image.hpp>
#include <godot_cpp/classes/image_texture.hpp>
#include <godot_cpp/classes/mesh_instance3d.hpp>
#include <godot_cpp/classes/os.hpp>
#include <godot_cpp/classes/shader_material.hpp>
#include <godot_cpp/classes/skeleton3d.hpp>
#include <godot_cpp/classes/skin.hpp>
#include <godot_cpp/classes/standard_material3d.hpp>
#include <godot_cpp/core/class_db.hpp>
#include <godot_cpp/variant/packed_byte_array.hpp>
#include <godot_cpp/variant/utility_functions.hpp>

#include <string>

using namespace godot;

namespace mtgodot {

Metin2Model::Metin2Model() {
	file = std::make_shared<std::optional<gr2::File>>();
}
Metin2Model::~Metin2Model() = default;

void Metin2Model::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_gr2_path", "path"), &Metin2Model::set_gr2_path);
	ClassDB::bind_method(D_METHOD("get_gr2_path"), &Metin2Model::get_gr2_path);
	ClassDB::bind_method(D_METHOD("set_texture_dir", "path"), &Metin2Model::set_texture_dir);
	ClassDB::bind_method(D_METHOD("get_texture_dir"), &Metin2Model::get_texture_dir);
	ClassDB::bind_method(D_METHOD("set_unit_scale", "s"), &Metin2Model::set_unit_scale);
	ClassDB::bind_method(D_METHOD("get_unit_scale"), &Metin2Model::get_unit_scale);
	ClassDB::bind_method(D_METHOD("set_flip_z", "v"), &Metin2Model::set_flip_z);
	ClassDB::bind_method(D_METHOD("get_flip_z"), &Metin2Model::get_flip_z);
	ClassDB::bind_method(D_METHOD("set_flip_winding", "v"), &Metin2Model::set_flip_winding);
	ClassDB::bind_method(D_METHOD("get_flip_winding"), &Metin2Model::get_flip_winding);
	ClassDB::bind_method(D_METHOD("set_material_mode", "m"), &Metin2Model::set_material_mode);
	ClassDB::bind_method(D_METHOD("get_material_mode"), &Metin2Model::get_material_mode);
	ClassDB::bind_method(D_METHOD("set_use_gr2_materials", "v"), &Metin2Model::set_use_gr2_materials);
	ClassDB::bind_method(D_METHOD("get_use_gr2_materials"), &Metin2Model::get_use_gr2_materials);
	ClassDB::bind_method(D_METHOD("set_surface_texture", "surface", "path"), &Metin2Model::set_surface_texture);
	ClassDB::bind_method(D_METHOD("reload"), &Metin2Model::reload);
	ClassDB::bind_method(D_METHOD("get_info"), &Metin2Model::get_info);
	ClassDB::bind_method(D_METHOD("probe_gr2", "path"), &Metin2Model::probe_gr2);

	ADD_PROPERTY(PropertyInfo(Variant::STRING, "gr2_path", PROPERTY_HINT_GLOBAL_FILE, "*.gr2"),
			"set_gr2_path", "get_gr2_path");
	ADD_PROPERTY(PropertyInfo(Variant::STRING, "texture_dir", PROPERTY_HINT_GLOBAL_DIR),
			"set_texture_dir", "get_texture_dir");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "unit_scale", PROPERTY_HINT_RANGE, "0.0001,1,0.0001"),
			"set_unit_scale", "get_unit_scale");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "flip_z"), "set_flip_z", "get_flip_z");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "flip_winding"), "set_flip_winding", "get_flip_winding");
	ADD_PROPERTY(PropertyInfo(Variant::STRING, "material_mode", PROPERTY_HINT_ENUM, "metin2,standard"),
			"set_material_mode", "get_material_mode");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "use_gr2_materials"),
			"set_use_gr2_materials", "get_use_gr2_materials");
}

void Metin2Model::set_material_mode(const String &m) {
	material_mode = m;
	if (is_inside_tree()) {
		reload();
	}
}

void Metin2Model::set_use_gr2_materials(bool v) {
	use_gr2_materials = v;
	if (is_inside_tree()) {
		_apply_materials();
	}
}

void Metin2Model::set_surface_texture(int surface, const String &path) {
	if (surface < 0) {
		return;
	}
	while (surface_tex_override.size() <= surface) {
		surface_tex_override.push_back(String());
	}
	surface_tex_override[surface] = path;
	if (is_inside_tree()) {
		_apply_materials();
	}
}

void Metin2Model::set_gr2_path(const String &p) {
	gr2_path = p;
	if (is_inside_tree()) {
		reload();
	}
}
void Metin2Model::set_texture_dir(const String &p) {
	texture_dir = p;
	if (is_inside_tree()) {
		reload();
	}
}
void Metin2Model::set_unit_scale(double s) {
	unit_scale = s;
	if (is_inside_tree()) {
		reload();
	}
}
void Metin2Model::set_flip_z(bool v) {
	flip_z = v;
	if (is_inside_tree()) {
		reload();
	}
}
void Metin2Model::set_flip_winding(bool v) {
	flip_winding = v;
	if (is_inside_tree()) {
		reload();
	}
}

void Metin2Model::_ready() {
	if (!gr2_path.is_empty()) {
		reload();
	}
}

void Metin2Model::_clear_children() {
	skel = nullptr;
	mi = nullptr;
	TypedArray<Node> kids = get_children();
	for (int i = 0; i < kids.size(); ++i) {
		Node *n = Object::cast_to<Node>(kids[i]);
		if (n) {
			remove_child(n);
			n->queue_free();
		}
	}
}

void Metin2Model::reload() {
	_clear_children();
	*file = std::nullopt;
	last_info = "";

	if (gr2_path.is_empty()) {
		return;
	}

	gr2::LoadError err;
	const std::string p(gr2_path.utf8().get_data());
	auto loaded = gr2::File::load_path(p, &err);
	if (!loaded) {
		UtilityFunctions::push_error(String("[Metin2Model] gr2 load failed [") +
				String(err.stage.c_str()) + "]: " + String(err.message.c_str()) + " (" + gr2_path + ")");
		return;
	}
	*file = std::move(loaded);
	const gr2::FileInfo &fi = (*file)->file_info();

	set_transform(make_conv((float)unit_scale, flip_z));

	// Skeleton (optional).
	const gr2::Skeleton *sk = fi.skeletons.empty() ? nullptr : &fi.skeletons[0];
	if (sk) {
		skel = build_skeleton(*sk);
		if (skel) {
			add_child(skel);
			skel->set_owner(get_owner() ? get_owner() : this);
		}
	}

	// Mesh.
	AABB bounds;
	Ref<ArrayMesh> mesh = build_mesh(fi, flip_winding, bounds);
	if (mesh->get_surface_count() > 0) {
		mi = memnew(MeshInstance3D);
		mi->set_name("MeshInstance3D");
		mi->set_mesh(mesh);
		add_child(mi);
		mi->set_owner(get_owner() ? get_owner() : this);
		if (skel && sk) {
			mi->set_skeleton_path(mi->get_path_to(skel));
			if (OS::get_singleton()->get_environment("MTGODOT_AUTOSKIN") == "1") {
				// let Godot derive the skin from skeleton rest poses
			} else {
				mi->set_skin(build_skin(*sk));
			}
		}
		mi->set_custom_aabb(bounds.grow(0.01));
	}

	materials = gr2::dump_materials(**file);

	_apply_materials();

	int vtot = 0;
	for (const auto &m : fi.meshes) {
		vtot += (int)m.vertices.size();
	}
	{
		int with_tex = 0;
		for (const auto &mm : materials) {
			if (!mm.diffuse_texture.empty()) {
				++with_tex;
			}
		}
		UtilityFunctions::print(vformat("[Metin2Model] gr2 materials: %d (%d with diffuse name)",
				(int)materials.size(), with_tex));
	}
	last_info = vformat("gr2 v%d | bones=%d meshes=%d surfaces=%d verts=%d | bounds=%s",
			(int)(*file)->format_version(),
			sk ? (int)sk->bones.size() : 0,
			(int)fi.meshes.size(),
			mesh->get_surface_count(),
			vtot,
			String(bounds));
	UtilityFunctions::print("[Metin2Model] ", last_info);
}

String Metin2Model::_guess_texture_dir() const {
	if (!texture_dir.is_empty()) {
		return texture_dir;
	}
	return gr2_path.get_base_dir();
}

Ref<godot::ImageTexture> Metin2Model::_load_dds(const String &path) {
	Ref<ImageTexture> t;
	if (tex_cache.has(path)) {
		return tex_cache[path];
	}
	if (FileAccess::file_exists(path)) {
		mtgodot::Image dds = mtgodot::load_dds_path(path.utf8().get_data());
		if (dds.ok()) {
			PackedByteArray bytes;
			bytes.resize((int)dds.rgba.size());
			memcpy(bytes.ptrw(), dds.rgba.data(), dds.rgba.size());
			Ref<godot::Image> img = godot::Image::create_from_data(
					dds.w, dds.h, false, godot::Image::FORMAT_RGBA8, bytes);
			if (img.is_valid()) {
				img->generate_mipmaps();
				t = ImageTexture::create_from_image(img);
			}
		}
	}
	tex_cache[path] = t;
	return t;
}

// Best-effort texture pick for a surface. libgr2's POD API gives no material or
// texture names yet (see GODOT-POC-PLAN.md §M2.5 gap list), so this is filename
// convention + a case-insensitive directory scan.
Ref<godot::ImageTexture> Metin2Model::_resolve_texture(const String &dir, const String &stem,
		const String &surface_name, const PackedStringArray &dds_files) {
	String sn = surface_name.to_lower();

	auto scan = [&](const String &needle) -> Ref<ImageTexture> {
		for (int i = 0; i < dds_files.size(); ++i) {
			if (dds_files[i].to_lower().find(needle) != -1) {
				Ref<ImageTexture> t = _load_dds(dir.path_join(dds_files[i]));
				if (t.is_valid()) {
					return t;
				}
			}
		}
		return Ref<ImageTexture>();
	};

	// 1. surface-name keyword slots
	if (sn.find("face") != -1) {
		Ref<ImageTexture> t = _load_dds(dir.path_join(stem + String("_face.dds")));
		if (t.is_null()) {
			t = scan("face");
		}
		if (t.is_valid()) {
			return t;
		}
	}
	if (sn.find("hair") != -1) {
		Ref<ImageTexture> t = _load_dds(dir.path_join(stem + String("_hair.dds")));
		if (t.is_null()) {
			t = scan("hair");
		}
		if (t.is_valid()) {
			return t;
		}
	}
	// 2. surface name used verbatim as a texture basename
	if (!sn.is_empty()) {
		Ref<ImageTexture> t = _load_dds(dir.path_join(surface_name + String(".dds")));
		if (t.is_valid()) {
			return t;
		}
	}
	// 3. exact stem
	Ref<ImageTexture> t = _load_dds(dir.path_join(stem + String(".dds")));
	if (t.is_valid()) {
		return t;
	}
	// 4. any dds whose name contains the stem, then any non-face/hair dds
	t = scan(stem);
	if (t.is_valid()) {
		return t;
	}
	for (int i = 0; i < dds_files.size(); ++i) {
		String f = dds_files[i].to_lower();
		if (f.find("face") == -1 && f.find("hair") == -1 && f.find("_lod") == -1) {
			Ref<ImageTexture> any = _load_dds(dir.path_join(dds_files[i]));
			if (any.is_valid()) {
				return any;
			}
		}
	}
	return Ref<ImageTexture>();
}

static mtgodot::BlendMode guess_blend(const String &surface_name) {
	String sn = surface_name.to_lower();
	if (sn.find("effect") != -1 || sn.find("glow") != -1 || sn.find("aura") != -1) {
		return mtgodot::BlendMode::Add;
	}
	if (sn.find("hair") != -1) {
		return mtgodot::BlendMode::AlphaTest; // Metin2 hair = alpha-test cutout
	}
	if (sn.find("cloak") != -1 || sn.find("cape") != -1 ||
			sn.find("skirt") != -1 || sn.find("ribbon") != -1) {
		return mtgodot::BlendMode::Alpha;
	}
	return mtgodot::BlendMode::Opaque;
}

void Metin2Model::_apply_materials() {
	if (!mi || !file || !*file) {
		return;
	}
	const String dir = _guess_texture_dir();
	const String stem = gr2_path.get_file().get_basename();

	PackedStringArray dds_files;
	{
		Ref<DirAccess> da = DirAccess::open(dir);
		if (da.is_valid()) {
			da->list_dir_begin();
			for (String f = da->get_next(); !f.is_empty(); f = da->get_next()) {
				if (!da->current_is_dir() && f.to_lower().ends_with(".dds")) {
					dds_files.push_back(f);
				}
			}
			da->list_dir_end();
		}
	}

	// Surface s corresponds to the s-th gr2 mesh that has geometry (same skip
	// rule as build_mesh). Recover that mapping to reach tri_groups/material_index.
	const gr2::FileInfo &fi = (*file)->file_info();
	std::vector<int> surf_to_mesh;
	for (int mi_ = 0; mi_ < (int)fi.meshes.size(); ++mi_) {
		if (!fi.meshes[mi_].vertices.empty() && !fi.meshes[mi_].indices.empty()) {
			surf_to_mesh.push_back(mi_);
		}
	}

	Ref<ArrayMesh> mesh = mi->get_mesh();
	int textured = 0;
	for (int s = 0; s < mesh->get_surface_count(); ++s) {
		const String sname = mesh->surface_get_name(s);
		Ref<ImageTexture> tex;
		auto mat_texture_name = [&]() -> String {
			if (s >= (int)surf_to_mesh.size()) {
				return String();
			}
			const gr2::Mesh &gm = fi.meshes[surf_to_mesh[s]];
			int matidx = gm.tri_groups.empty() ? -1 : gm.tri_groups[0].material_index;
			if (matidx < 0 || matidx >= (int)materials.size() ||
					materials[matidx].diffuse_texture.empty()) {
				return String();
			}
			return String(materials[matidx].diffuse_texture.c_str())
					.replace("\\", "/")
					.get_file()
					.get_basename()
					.to_lower();
		};

		if (s < surface_tex_override.size() && !String(surface_tex_override[s]).is_empty()) {
			tex = _load_dds(surface_tex_override[s]);
		}
		// gr2 material name -> texture, only when opted in (unverified vs oracle;
		// see GODOT-POC-PLAN.md §M2.5 T2.5.6).
		if (tex.is_null() && use_gr2_materials) {
			String want = mat_texture_name();
			if (!want.is_empty()) {
				for (int i = 0; i < dds_files.size(); ++i) {
					if (dds_files[i].get_basename().to_lower() == want) {
						tex = _load_dds(dir.path_join(dds_files[i]));
						break;
					}
				}
			}
		}
		// filename-convention resolution (default path)
		if (tex.is_null()) {
			tex = _resolve_texture(dir, stem, sname, dds_files);
		}
		if (tex.is_valid()) {
			++textured;
		}

		if (material_mode == String("standard")) {
			Ref<StandardMaterial3D> mat;
			mat.instantiate();
			mat->set_cull_mode(BaseMaterial3D::CULL_DISABLED);
			if (tex.is_valid()) {
				mat->set_texture(BaseMaterial3D::TEXTURE_ALBEDO, tex);
			} else {
				mat->set_albedo(Color(0.8, 0.8, 0.82));
			}
			mi->set_surface_override_material(s, mat);
		} else {
			mtgodot::MaterialDesc md;
			md.albedo = tex;
			md.blend = guess_blend(sname);
			mi->set_surface_override_material(s, mtgodot::make_material(md));
		}
	}
	UtilityFunctions::print(vformat("[Metin2Model] materials: %d/%d surfaces textured (dir=%s, %d dds)",
			textured, mesh->get_surface_count(), dir, (int)dds_files.size()));
}

const gr2::Skeleton *Metin2Model::gr2_skeleton() const {
	if (!file || !*file) {
		return nullptr;
	}
	const gr2::FileInfo &fi = (*file)->file_info();
	return fi.skeletons.empty() ? nullptr : &fi.skeletons[0];
}

const gr2::FileInfo *Metin2Model::gr2_fileinfo() const {
	return (file && *file) ? &(*file)->file_info() : nullptr;
}

namespace {
// row-major 4x4 (translation elem 12..14), row-vector: out = [v 1] * M
inline void xform_pt(const gr2::Mat4 &M, const float *v, float *o) {
	o[0] = v[0] * M[0] + v[1] * M[4] + v[2] * M[8] + M[12];
	o[1] = v[0] * M[1] + v[1] * M[5] + v[2] * M[9] + M[13];
	o[2] = v[0] * M[2] + v[1] * M[6] + v[2] * M[10] + M[14];
}
inline void xform_dir(const gr2::Mat4 &M, const float *v, float *o) {
	o[0] = v[0] * M[0] + v[1] * M[4] + v[2] * M[8];
	o[1] = v[0] * M[1] + v[1] * M[5] + v[2] * M[9];
	o[2] = v[0] * M[2] + v[1] * M[6] + v[2] * M[10];
}
} // namespace

void Metin2Model::enable_cpu_skin(bool on) {
	if (!mi || !file || !*file) {
		return;
	}
	if (on && cpu_mesh.is_null()) {
		AABB b;
		cpu_mesh = build_mesh((*file)->file_info(), flip_winding, b);
		cpu_surf_mesh.clear();
		const gr2::FileInfo &fi = (*file)->file_info();
		for (int i = 0; i < (int)fi.meshes.size(); ++i) {
			if (!fi.meshes[i].vertices.empty() && !fi.meshes[i].indices.empty()) {
				cpu_surf_mesh.push_back(i);
			}
		}
		mi->set_skeleton_path(NodePath());
		mi->set_skin(Ref<Skin>());
		mi->set_mesh(cpu_mesh);
		if (skel) {
			skel->set_show_rest_only(true);
		}
		UtilityFunctions::print("[Metin2Model] CPU-skin mode ON");
	}
}

void Metin2Model::cpu_skin(const std::vector<gr2::Mat4> &skin) {
	if (cpu_mesh.is_null() || !file || !*file) {
		return;
	}
	const gr2::FileInfo &fi = (*file)->file_info();
	static const gr2::Mat4 I{ 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };

	cpu_mesh->clear_surfaces();
	for (int s = 0; s < (int)cpu_surf_mesh.size(); ++s) {
		const gr2::Mesh &m = fi.meshes[cpu_surf_mesh[s]];
		const int nv = (int)m.vertices.size();
		PackedVector3Array pos;
		PackedVector3Array nrm;
		PackedVector2Array uv;
		PackedInt32Array idx;
		pos.resize(nv);
		nrm.resize(nv);
		uv.resize(nv);
		idx.resize((int)m.indices.size());
		Vector3 *pw = pos.ptrw();
		Vector3 *nw = nrm.ptrw();
		Vector2 *uw = uv.ptrw();
		int32_t *iw = idx.ptrw();
		auto bone_of = [&](int slot) -> const gr2::Mat4 & {
			if (slot < 0 || slot >= (int)m.bone_bindings.size()) {
				return I;
			}
			int b = m.bone_bindings[slot];
			return (b < 0 || b >= (int)skin.size()) ? I : skin[b];
		};
		for (int i = 0; i < nv; ++i) {
			const gr2::Vertex &v = m.vertices[i];
			float wq[4];
			float sw = 0;
			for (int k = 0; k < 4; ++k) {
				sw += v.bone_weight[k];
			}
			for (int k = 0; k < 4; ++k) {
				wq[k] = (sw > 0) ? v.bone_weight[k] / sw : (k == 0 ? 1.f : 0.f);
			}
			gr2::Mat4 M{};
			for (int k = 0; k < 4; ++k) {
				const gr2::Mat4 &bm = bone_of(v.bone_index[k]);
				for (int e = 0; e < 16; ++e) {
					M[e] += wq[k] * bm[e];
				}
			}
			gr2::Mat4 M3 = M;
			M3[12] = M3[13] = M3[14] = 0;
			float p[3], nn[3];
			xform_pt(M, v.pos, p);
			xform_dir(M3, v.normal, nn);
			float ln = std::sqrt(nn[0] * nn[0] + nn[1] * nn[1] + nn[2] * nn[2]);
			if (ln > 1e-8f) {
				nn[0] /= ln;
				nn[1] /= ln;
				nn[2] /= ln;
			}
			pw[i] = Vector3(p[0], p[1], p[2]);
			nw[i] = Vector3(nn[0], nn[1], nn[2]);
			uw[i] = Vector2(v.uv0[0], v.uv0[1]);
		}
		for (size_t t = 0; t < m.indices.size(); ++t) {
			iw[t] = (int)m.indices[t];
		}
		Array arrays;
		arrays.resize(Mesh::ARRAY_MAX);
		arrays[Mesh::ARRAY_VERTEX] = pos;
		arrays[Mesh::ARRAY_NORMAL] = nrm;
		arrays[Mesh::ARRAY_TEX_UV] = uv;
		arrays[Mesh::ARRAY_INDEX] = idx;
		cpu_mesh->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, arrays);
	}
	_apply_materials();
}

String Metin2Model::get_info() const {
	return last_info;
}

String Metin2Model::probe_gr2(const String &path) const {
	gr2::LoadError err;
	const std::string p(path.utf8().get_data());
	auto f = gr2::File::load_path(p, &err);
	if (!f) {
		return vformat("gr2 load FAILED [%s]: %s", String(err.stage.c_str()), String(err.message.c_str()));
	}
	return vformat("gr2 OK: format_version=%d sections=%d",
			(int)f->format_version(), (int)f->sections().size());
}

} // namespace mtgodot