#include "ShaderPackageRegistry.h"

#include <chrono>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <map>
#include <string>
#include <vector>

namespace
{
int gFailures = 0;

void Expect(bool condition, const char* message)
{
	if (condition)
		return;

	std::cerr << "FAIL: " << message << "\n";
	++gFailures;
}

std::filesystem::path MakeTestRoot()
{
	const auto stamp = std::chrono::steady_clock::now().time_since_epoch().count();
	std::filesystem::path root = std::filesystem::temp_directory_path() / ("video-shader-registry-tests-" + std::to_string(stamp));
	std::filesystem::create_directories(root);
	return root;
}

void WriteFile(const std::filesystem::path& path, const std::string& contents)
{
	std::filesystem::create_directories(path.parent_path());
	std::ofstream output(path, std::ios::binary);
	output << contents;
}

void WriteShaderPackage(const std::filesystem::path& root, const std::string& directoryName, const std::string& manifest)
{
	const std::filesystem::path packageRoot = root / directoryName;
	WriteFile(packageRoot / "shader.json", manifest);
	WriteFile(packageRoot / "shader.slang", "float4 shadeVideo(float2 uv) { return float4(uv, 0.0, 1.0); }\n");
}

void TestValidManifest()
{
	const std::filesystem::path root = MakeTestRoot();
	WriteFile(root / "look" / "mask.png", "not a real png, but enough for existence checks");
	WriteShaderPackage(root, "look", R"({
		"id": "look-01",
		"name": "Look 01",
		"description": "Test package",
		"category": "Tests",
		"entryPoint": "shadeVideo",
		"textures": [{ "id": "maskTex", "path": "mask.png" }],
		"temporal": { "enabled": true, "historySource": "source", "historyLength": 8 },
		"parameters": [
			{ "id": "gain", "label": "Gain", "type": "float", "default": 0.5, "min": 0, "max": 1 },
			{ "id": "mode", "label": "Mode", "type": "enum", "default": "soft", "options": [
				{ "value": "soft", "label": "Soft" },
				{ "value": "hard", "label": "Hard" }
			] }
		]
	})");

	ShaderPackageRegistry registry(4);
	ShaderPackage package;
	std::string error;
	Expect(registry.ParseManifest(root / "look" / "shader.json", package, error), "valid manifest parses");
	Expect(package.id == "look-01", "manifest id is preserved");
	Expect(package.textureAssets.size() == 1 && package.textureAssets[0].id == "maskTex", "texture assets parse");
	Expect(package.temporal.enabled && package.temporal.effectiveHistoryLength == 4, "temporal history is capped");
	Expect(package.parameters.size() == 2, "parameters parse");

	std::filesystem::remove_all(root);
}

void TestInvalidManifest()
{
	const std::filesystem::path root = MakeTestRoot();
	WriteShaderPackage(root, "bad", R"({
		"id": "bad",
		"name": "Bad",
		"entryPoint": "not-valid!",
		"parameters": []
	})");

	ShaderPackageRegistry registry(4);
	ShaderPackage package;
	std::string error;
	Expect(!registry.ParseManifest(root / "bad" / "shader.json", package, error), "invalid shader identifier is rejected");
	Expect(error.find("entryPoint") != std::string::npos, "invalid manifest error names the bad field");

	std::filesystem::remove_all(root);
}

void TestDuplicateScan()
{
	const std::filesystem::path root = MakeTestRoot();
	WriteShaderPackage(root, "a", R"({ "id": "dupe", "name": "A", "parameters": [] })");
	WriteShaderPackage(root, "b", R"({ "id": "dupe", "name": "B", "parameters": [] })");

	ShaderPackageRegistry registry(4);
	std::map<std::string, ShaderPackage> packages;
	std::vector<std::string> order;
	std::string error;
	Expect(!registry.Scan(root, packages, order, error), "duplicate package ids are rejected");
	Expect(error.find("Duplicate shader id") != std::string::npos, "duplicate scan error is clear");

	std::filesystem::remove_all(root);
}
}

int main()
{
	TestValidManifest();
	TestInvalidManifest();
	TestDuplicateScan();

	if (gFailures != 0)
	{
		std::cerr << gFailures << " ShaderPackageRegistry test failure(s).\n";
		return 1;
	}

	std::cout << "ShaderPackageRegistry tests passed.\n";
	return 0;
}