#include "m2_material.h"

#include <godot_cpp/classes/image_texture.hpp>
#include <godot_cpp/classes/shader.hpp>
#include <godot_cpp/classes/shader_material.hpp>
#include <godot_cpp/classes/texture2d.hpp>
#include <godot_cpp/variant/color.hpp>

using namespace godot;

namespace mtgodot {
namespace {

// blend_mix shader: covers opaque (mode 0, alpha-scissor) and alpha (mode 1).
const char *SRC_MIX = R"(shader_type spatial;
render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_lambert, specular_disabled;

uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
uniform bool use_texture = true;
uniform vec4 modulate : source_color = vec4(1.0);
uniform float alpha_scissor : hint_range(0.0, 1.0) = 0.5;
uniform int mode = 0; // 0 opaque | 1 alpha-blend | 2 alpha-test (cutout)
// sphere-map specular (EterGrnLib/Material.cpp:305 __ApplySpecularRenderState)
uniform sampler2D spec_map : source_color, filter_linear_mipmap, repeat_enable;
uniform float spec_power = 0.0;
uniform bool spec_enable = false;
uniform float lod_fade = 1.0; // LOD crossfade multiplier (1 = fully shown)

void fragment() {
	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
	float spec_mask = c.a; // tex.a before modulate == D3DTA_TEXTURE alpha
	c *= modulate; // no vertex color: Metin2 PC meshes carry none (ARRAY_COLOR absent)
	if (mode == 2 && c.a < alpha_scissor) {
		discard;
	}
	ALBEDO = c.rgb;
	ALPHA = ((mode == 1) ? c.a : 1.0) * lod_fade;
	// Opaque only: client early-outs to plain diffuse when D3DRS_ALPHABLENDENABLE.
	// stage1 COLOROP MODULATEALPHA_ADDCOLOR = CURRENT.rgb + CURRENT.a*sphere.rgb,
	// CURRENT.a = tex.a * D3DRS_TEXTUREFACTOR.a (= spec_power). texcoord =
	// D3DTSS_TCI_CAMERASPACEREFLECTIONVECTOR -> view-space reflect(); .xy as UV.
	if (spec_enable && spec_power > 0.0 && mode == 0) {
		// Sphere-map metallic sheen (EterGrnLib/Material.cpp:305). The client masks
		// this with the armor texture's alpha (metal=1, cloth=0); our loose-file
		// texture resolution can't be trusted for that alpha, so bias it to
		// grazing angles (Fresnel) and knock the level down — reads as an edge
		// sheen instead of a full-body chrome mirror.
		vec3 vdir = normalize(VERTEX);
		vec3 ndir = normalize(NORMAL);
		float fres = pow(clamp(1.0 - abs(dot(ndir, vdir)), 0.0, 1.0), 3.0);
		vec3 refl = reflect(vdir, ndir);
		EMISSION = texture(spec_map, refl.xy * 0.5 + 0.5).rgb
				* (spec_mask * spec_power * fres * 0.5);
	}
}
)";

// Skinned variant of SRC_MIX: LBS in vertex() with FULL per-bone matrices from a
// float texture (no Skeleton3D). bones_tex is RGBAF, 3 x bone_count; row = bone,
// texel j = column j of the row-vector skin matrix  (skinned = [pos 1] * M).
const char *SRC_SKIN = R"(shader_type spatial;
render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_lambert, specular_disabled;

uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
uniform bool use_texture = true;
uniform vec4 modulate : source_color = vec4(1.0);
uniform float alpha_scissor : hint_range(0.0, 1.0) = 0.5;
uniform int mode = 0;
uniform sampler2D bones_tex : filter_nearest; // RGBAF, 3 x bone_count
uniform sampler2D spec_map : source_color, filter_linear_mipmap, repeat_enable;
uniform float spec_power = 0.0;
uniform bool spec_enable = false;
uniform float lod_fade = 1.0; // LOD crossfade multiplier (1 = fully shown)

void vertex() {
	vec4 p = vec4(VERTEX, 1.0);
	vec3 sp = vec3(0.0);
	vec3 sn = vec3(0.0);
	ivec4 bi = ivec4(BONE_INDICES);
	vec4 bw = BONE_WEIGHTS;
	float wsum = bw.x + bw.y + bw.z + bw.w;
	if (wsum <= 0.0) { bw = vec4(1.0, 0.0, 0.0, 0.0); wsum = 1.0; }
	for (int k = 0; k < 4; k++) {
		float w = bw[k] / wsum;
		if (w <= 0.0) { continue; }
		int r = bi[k];
		vec4 c0 = texelFetch(bones_tex, ivec2(0, r), 0);
		vec4 c1 = texelFetch(bones_tex, ivec2(1, r), 0);
		vec4 c2 = texelFetch(bones_tex, ivec2(2, r), 0);
		sp += w * vec3(dot(p, c0), dot(p, c1), dot(p, c2));
		sn += w * vec3(dot(NORMAL, c0.xyz), dot(NORMAL, c1.xyz), dot(NORMAL, c2.xyz));
	}
	VERTEX = sp;
	NORMAL = normalize(sn);
}

void fragment() {
	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
	float spec_mask = c.a;
	c *= modulate;
	if (mode == 2 && c.a < alpha_scissor) { discard; }
	ALBEDO = c.rgb;
	ALPHA = ((mode == 1) ? c.a : 1.0) * lod_fade;
	if (spec_enable && spec_power > 0.0 && mode == 0) {
		// Sphere-map metallic sheen (EterGrnLib/Material.cpp:305). The client masks
		// this with the armor texture's alpha (metal=1, cloth=0); our loose-file
		// texture resolution can't be trusted for that alpha, so bias it to
		// grazing angles (Fresnel) and knock the level down — reads as an edge
		// sheen instead of a full-body chrome mirror.
		vec3 vdir = normalize(VERTEX);
		vec3 ndir = normalize(NORMAL);
		float fres = pow(clamp(1.0 - abs(dot(ndir, vdir)), 0.0, 1.0), 3.0);
		vec3 refl = reflect(vdir, ndir);
		EMISSION = texture(spec_map, refl.xy * 0.5 + 0.5).rgb
				* (spec_mask * spec_power * fres * 0.5);
	}
}
)";

// blend_add shader: additive glow (effects, enchant overlays).
const char *SRC_ADD = R"(shader_type spatial;
render_mode blend_add, depth_draw_opaque, depth_test_disabled, cull_back, unshaded;

uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
uniform bool use_texture = true;
uniform vec4 modulate : source_color = vec4(1.0);

void fragment() {
	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
	c *= modulate; // no vertex color: Metin2 PC meshes carry none (ARRAY_COLOR absent)
	ALBEDO = c.rgb * c.a;
	ALPHA = 1.0;
}
)";

// Additive surfaces need the same vertex deformation as opaque/alpha surfaces.
// Keeping this as a separate shader preserves blend_add/unshaded render modes.
const char *SRC_ADD_SKIN = R"(shader_type spatial;
render_mode blend_add, depth_draw_opaque, depth_test_disabled, cull_back, unshaded;

uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
uniform bool use_texture = true;
uniform vec4 modulate : source_color = vec4(1.0);
uniform sampler2D bones_tex : filter_nearest;

void vertex() {
	vec4 p = vec4(VERTEX, 1.0);
	vec3 sp = vec3(0.0);
	vec3 sn = vec3(0.0);
	ivec4 bi = ivec4(BONE_INDICES);
	vec4 bw = BONE_WEIGHTS;
	float wsum = bw.x + bw.y + bw.z + bw.w;
	if (wsum <= 0.0) { bw = vec4(1.0, 0.0, 0.0, 0.0); wsum = 1.0; }
	for (int k = 0; k < 4; k++) {
		float w = bw[k] / wsum;
		if (w <= 0.0) { continue; }
		int r = bi[k];
		vec4 c0 = texelFetch(bones_tex, ivec2(0, r), 0);
		vec4 c1 = texelFetch(bones_tex, ivec2(1, r), 0);
		vec4 c2 = texelFetch(bones_tex, ivec2(2, r), 0);
		sp += w * vec3(dot(p, c0), dot(p, c1), dot(p, c2));
		sn += w * vec3(dot(NORMAL, c0.xyz), dot(NORMAL, c1.xyz), dot(NORMAL, c2.xyz));
	}
	VERTEX = sp;
	NORMAL = normalize(sn);
}

void fragment() {
	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
	c *= modulate;
	ALBEDO = c.rgb * c.a;
	ALPHA = 1.0;
}
)";

Ref<Shader> s_mix;
Ref<Shader> s_add;
Ref<Shader> s_skin;
Ref<Shader> s_add_skin;
// cull_disabled variants for two-sided parts (hair / cloth / foliage; client
// ExtendedData "Two-sided" -> D3DRS_CULLMODE = D3DCULL_NONE).
Ref<Shader> s_mix_2s;
Ref<Shader> s_add_2s;
Ref<Shader> s_skin_2s;
Ref<Shader> s_add_skin_2s;

Ref<Shader> shader_for(bool additive, bool skinned, bool two_sided) {
	Ref<Shader> &slot = two_sided
			? (additive ? (skinned ? s_add_skin_2s : s_add_2s) : (skinned ? s_skin_2s : s_mix_2s))
			: (additive ? (skinned ? s_add_skin : s_add) : (skinned ? s_skin : s_mix));
	if (slot.is_null()) {
		slot.instantiate();
		const char *base =
				additive ? (skinned ? SRC_ADD_SKIN : SRC_ADD) : (skinned ? SRC_SKIN : SRC_MIX);
		slot->set_code(two_sided ? String(base).replace("cull_back", "cull_disabled")
								 : String(base));
	}
	return slot;
}

} // namespace

Ref<ShaderMaterial> make_material(const MaterialDesc &d) {
	Ref<ShaderMaterial> m;
	m.instantiate();

	const bool additive = (d.blend == BlendMode::Add);
	const bool skinned = d.skinned;
	m->set_shader(shader_for(additive, skinned, d.two_sided));
	if (skinned && d.bones_tex.is_valid()) {
		m->set_shader_parameter("bones_tex", d.bones_tex);
	}

	const bool has_tex = d.albedo.is_valid();
	m->set_shader_parameter("use_texture", has_tex);
	if (has_tex) {
		m->set_shader_parameter("albedo_tex", d.albedo);
	}
	m->set_shader_parameter("modulate", has_tex ? Color(1, 1, 1, 1) : Color(0.8, 0.8, 0.82, 1));

	if (!additive) {
		// sphere-map specular (dormant unless spec_power > 0 and a map is bound)
		const bool spec = d.spec_power > 0.0f && d.spec_map.is_valid();
		m->set_shader_parameter("spec_enable", spec);
		m->set_shader_parameter("spec_power", d.spec_power);
		if (spec) {
			m->set_shader_parameter("spec_map", d.spec_map);
		}
		m->set_shader_parameter("alpha_scissor", d.alpha_scissor);
		int mode = 0;
		if (d.blend == BlendMode::Alpha) {
			mode = 1;
		} else if (d.blend == BlendMode::AlphaTest) {
			mode = 2;
		}
		m->set_shader_parameter("mode", mode);
	}
	if (d.blend == BlendMode::Alpha) {
		m->set_render_priority(1);
	} else if (additive) {
		m->set_render_priority(2);
	}
	return m;
}

void cleanup_material_shaders() {
	s_mix.unref();
	s_add.unref();
	s_skin.unref();
	s_add_skin.unref();
	s_mix_2s.unref();
	s_add_2s.unref();
	s_skin_2s.unref();
	s_add_skin_2s.unref();
}

} // namespace mtgodot