#pragma once
#include <plot/core/status.hpp>
#include <plot/core/types.hpp>
#include <plot/gl/handle.hpp>

#include <cstdint>

namespace plottest {

using plot::u32;

/// A surfaceless EGL context plus an off-screen RGBA framebuffer, so renderer
/// output can be asserted pixel by pixel without a window or a display server.
///
/// Test-only: `plot_core` neither links nor includes EGL.
class HeadlessContext {
 public:
  explicit HeadlessContext(u32 w = 256, u32 h = 256) noexcept;
  ~HeadlessContext();

  HeadlessContext(const HeadlessContext&) = delete;
  HeadlessContext& operator=(const HeadlessContext&) = delete;

  /// Makes an OpenGL 3.3 core context current on this thread, resolves the GL
  /// entry points against it (`plot::gl::load(eglGetProcAddress)`) and
  /// allocates the colour attachment. Idempotent. On failure `st` (when
  /// non-null) carries the reason, every resource already created is released,
  /// and the error is also printed to stderr so a failing CTest run is
  /// diagnosable.
  bool create(plot::Status* st = nullptr) noexcept;

  /// Releases the framebuffer, the GL context and the EGL display. Safe to call
  /// more than once, and to call after a failed create().
  void destroy() noexcept;

  /// Binds the off-screen target and reads one RGBA8 pixel, in GL's
  /// origin-at-the-bottom-left convention. False when it cannot be read.
  bool read_pixel(u32 x, u32 y, std::uint8_t rgba[4]) const noexcept;

  u32 width = 0;
  u32 height = 0;
  /// The headless path create() selected ("egl surfaceless" or "egl pbuffer");
  /// empty before a successful create() and after destroy(). Setting
  /// PLOT_HEADLESS_FORCE_PBUFFER in the environment skips the surfaceless
  /// attempt, so the pbuffer fallback can be exercised on a driver that does
  /// support surfaceless contexts.
  const char* egl_path = "";

 private:
  plot::gl::Texture color_;
  plot::gl::Framebuffer framebuffer_;
  void* display_ = nullptr;  // EGLDisplay
  void* context_ = nullptr;  // EGLContext
  void* surface_ = nullptr;  // EGLSurface, null on the surfaceless path
};

}  // namespace plottest