#include <gtest/gtest.h>
#include "app.hpp"
#include <fstream>
#include <filesystem>

namespace fs = std::filesystem;

class TodoServiceTest : public ::testing::Test {
protected:
    void SetUp() override {
        test_file_ = "test_todo.json";
        if (fs::exists(test_file_)) fs::remove(test_file_);
    }

    void TearDown() override {
        if (fs::exists(test_file_)) fs::remove(test_file_);
    }

    std::string test_file_;
};

TEST_F(TodoServiceTest, testLoadValidJsonFile) {
    std::ofstream ofs(test_file_);
    ofs << R"({
      "items": [
        {"id": 1, "title": "Task1", "description": "Desc1", "completed": false},
        {"id": 2, "title": "Task2", "description": "Desc2", "completed": true}
      ],
      "next_id": 3
    })";
    ofs.close();

    TodoService service(test_file_);
    auto items = service.get_all();
    ASSERT_EQ(items.size(), 2);
    EXPECT_EQ(items[0].id, 1);
    EXPECT_EQ(items[1].id, 2);
    EXPECT_EQ(items[1].completed, true);

    auto new_item = service.create("Task3", "Desc3");
    EXPECT_EQ(new_item.id, 3);
}

TEST_F(TodoServiceTest, testLoadEmptyFile) {
    std::ofstream ofs(test_file_);
    ofs.close();

    TodoService service(test_file_);
    auto items = service.get_all();
    EXPECT_TRUE(items.empty());

    auto new_item = service.create("Task", "Desc");
    EXPECT_EQ(new_item.id, 1);
}

TEST_F(TodoServiceTest, testLoadNonExistentFile) {
    TodoService service("nonexistent.json");
    auto items = service.get_all();
    EXPECT_TRUE(items.empty());

    auto new_item = service.create("Task", "Desc");
    EXPECT_EQ(new_item.id, 1);
}

TEST_F(TodoServiceTest, testLoadInvalidJson) {
    std::ofstream ofs(test_file_);
    ofs << "invalid json content";
    ofs.close();

    TodoService service(test_file_);
    auto items = service.get_all();
    EXPECT_TRUE(items.empty());

    auto new_item = service.create("Task", "Desc");
    EXPECT_EQ(new_item.id, 1);
}

TEST_F(TodoServiceTest, testLoadNextIdAdjustment) {
    std::ofstream ofs(test_file_);
    ofs << R"({
      "items": [
        {"id": 5, "title": "Task", "description": "Desc", "completed": false}
      ],
      "next_id": 3
    })";
    ofs.close();

    TodoService service(test_file_);
    auto new_item = service.create("NewTask", "NewDesc");
    EXPECT_EQ(new_item.id, 6);
}

TEST_F(TodoServiceTest, testSaveValidData) {
    TodoService service(test_file_);
    service.create("Task1", "Desc1");
    service.create("Task2", "Desc2");

    std::ifstream ifs(test_file_);
    std::string content((std::istreambuf_iterator<char>(ifs)), std::istreambuf_iterator<char>());
    EXPECT_NE(content.find("\"id\": 1"), std::string::npos);
    EXPECT_NE(content.find("\"id\": 2"), std::string::npos);
    EXPECT_NE(content.find("\"next_id\": 3"), std::string::npos);
}

TEST_F(TodoServiceTest, testSaveEmptyItems) {
    TodoService service(test_file_);
    auto item = service.create("Temp", "Desc");
    service.delete_item(item.id);

    std::ifstream ifs(test_file_);
    std::string content((std::istreambuf_iterator<char>(ifs)), std::istreambuf_iterator<char>());
    EXPECT_NE(content.find("\"items\": []"), std::string::npos);
    EXPECT_NE(content.find("\"next_id\": 2"), std::string::npos);
}

TEST_F(TodoServiceTest, testSaveInvalidPath) {
    TodoService service("/invalid/path/test.json");
    EXPECT_NO_THROW(service.create("Task", "Desc"));
    EXPECT_FALSE(fs::exists("/invalid/path/test.json"));
}