#include <gtest/gtest.h>
#include <pdfengine/graphics_state.hpp>

using namespace pdfengine;

TEST(MatrixTest, DefaultIdentity) {
    Matrix m;
    EXPECT_FLOAT_EQ(m.a, 1.0f);
    EXPECT_FLOAT_EQ(m.b, 0.0f);
    EXPECT_FLOAT_EQ(m.c, 0.0f);
    EXPECT_FLOAT_EQ(m.d, 1.0f);
    EXPECT_FLOAT_EQ(m.e, 0.0f);
    EXPECT_FLOAT_EQ(m.f, 0.0f);
}

TEST(MatrixTest, Multiply) {
    Matrix m1(2.0f, 0.0f, 0.0f, 2.0f, 10.0f, 20.0f);
    Matrix m2(0.5f, 0.0f, 0.0f, 0.5f, -5.0f, -10.0f);
    Matrix result = m1.multiply(m2);
    
    EXPECT_FLOAT_EQ(result.a, 1.0f);
    EXPECT_FLOAT_EQ(result.b, 0.0f);
    EXPECT_FLOAT_EQ(result.c, 0.0f);
    EXPECT_FLOAT_EQ(result.d, 1.0f);
    EXPECT_FLOAT_EQ(result.e, 0.0f);
    EXPECT_FLOAT_EQ(result.f, 0.0f);
}

TEST(MatrixTest, TransformPoint) {
    Matrix m(2.0f, 0.0f, 0.0f, 3.0f, 10.0f, 20.0f);
    float x = 5.0f;
    float y = 5.0f;
    m.transform(x, y);
    
    EXPECT_FLOAT_EQ(x, 20.0f); // 2*5 + 10
    EXPECT_FLOAT_EQ(y, 35.0f); // 3*5 + 20
}

TEST(GraphicsStateStackTest, PushPop) {
    GraphicsStateStack stack;
    
    // Initial state
    stack.current().lineWidth = 5.0f;
    
    // Push new state
    stack.push();
    EXPECT_FLOAT_EQ(stack.current().lineWidth, 5.0f);
    
    // Modify current state
    stack.current().lineWidth = 10.0f;
    EXPECT_FLOAT_EQ(stack.current().lineWidth, 10.0f);
    
    // Pop back to initial
    stack.pop();
    EXPECT_FLOAT_EQ(stack.current().lineWidth, 5.0f);
}

TEST(GraphicsStateStackTest, PopEmptyProtection) {
    GraphicsStateStack stack;
    // Attempting to pop the root state should be safe (ignored)
    stack.pop();
    stack.current().lineWidth = 2.0f; // Should still be valid
    EXPECT_FLOAT_EQ(stack.current().lineWidth, 2.0f);
}