module sapp

// EGL initialization and teardown.
// Shared between Wayland and X11 backends.

fn sapp_egl_choose_config() EGLConfig {
    samples := if g_sapp_state.desc.sample_count > 1 {
        EGLint(g_sapp_state.desc.sample_count)
    } else {
        EGLint(0)
    }
    alpha_size := if g_sapp_state.desc.alpha { EGLint(8) } else { EGLint(0) }
    sample_buffers := if g_sapp_state.desc.sample_count > 1 { EGLint(1) } else { EGLint(0) }

    config_attrs := [
        egl_surface_type,
        egl_window_bit,
        egl_renderable_type,
        egl_opengl_bit,
        egl_red_size,
        EGLint(8),
        egl_green_size,
        EGLint(8),
        egl_blue_size,
        EGLint(8),
        egl_alpha_size,
        alpha_size,
        egl_depth_size,
        EGLint(24),
        egl_stencil_size,
        EGLint(8),
        egl_sample_buffers,
        sample_buffers,
        egl_samples,
        samples,
        egl_none,
    ]!

    mut egl_configs := unsafe { [32]EGLConfig{} }
    mut config_count := EGLint(0)
    if C.eglChooseConfig(g_sapp_state.egl.display, &config_attrs[0], &egl_configs[0], 32, &config_count) == 0
        || config_count == 0 {
        eprintln('sokol_app: EGL: no configs found')
        return egl_configs[0]
    }

    mut config := egl_configs[0]
    for i in 0 .. int(config_count) {
        c := egl_configs[i]
        mut r := EGLint(0)
        mut g := EGLint(0)
        mut b := EGLint(0)
        mut a := EGLint(0)
        mut d := EGLint(0)
        mut s := EGLint(0)
        mut n := EGLint(0)
        if C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_red_size, &r) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_green_size, &g) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_blue_size, &b) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_alpha_size, &a) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_depth_size, &d) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_stencil_size, &s) != 0
            && C.eglGetConfigAttrib(g_sapp_state.egl.display, c, egl_samples, &n) != 0 && r == 8
            && g == 8 && b == 8 && a == alpha_size && d == 24 && s == 8 && n == samples {
            config = c
            break
        }
    }
    return config
}

fn sapp_egl_create_context(config EGLConfig) {
    gl_major := if g_sapp_state.desc.gl.major_version != 0 {
        g_sapp_state.desc.gl.major_version
    } else {
        4
    }
    gl_minor := if g_sapp_state.desc.gl.minor_version != 0 {
        g_sapp_state.desc.gl.minor_version
    } else {
        1
    }

    ctx_attrs := [
        egl_context_major_version,
        EGLint(gl_major),
        egl_context_minor_version,
        EGLint(gl_minor),
        egl_context_opengl_profile_mask,
        egl_context_opengl_core_profile_bit,
        egl_none,
    ]!

    g_sapp_state.egl.context = C.eglCreateContext(g_sapp_state.egl.display, config, unsafe { nil },
        &ctx_attrs[0])
    if g_sapp_state.egl.context == unsafe { nil } {
        eprintln('sokol_app: EGL: failed to create context')
    }
}

fn sapp_egl_create_surface(native_window voidptr) {
    config := sapp_egl_choose_config()
    g_sapp_state.egl.config = config
    g_sapp_state.egl.surface = C.eglCreateWindowSurface(g_sapp_state.egl.display, config,
        native_window, unsafe { nil })
    if g_sapp_state.egl.surface == unsafe { nil } {
        eprintln('sokol_app: EGL: failed to create window surface')
    }
    if g_sapp_state.egl.context == unsafe { nil } {
        sapp_egl_create_context(config)
    }
}

fn sapp_egl_make_current() {
    if C.eglMakeCurrent(g_sapp_state.egl.display, g_sapp_state.egl.surface,
        g_sapp_state.egl.surface, g_sapp_state.egl.context) == 0 {
        eprintln('sokol_app: EGL: eglMakeCurrent failed')
    }
    mut fb := i32(0)
    C.glGetIntegerv(gl_framebuffer_binding, &fb)
    g_sapp_state.gl.framebuffer = u32(fb)
    C.eglSwapInterval(g_sapp_state.egl.display, EGLint(g_sapp_state.swap_interval))
}

$if sokol_wayland ? {
    fn sapp_egl_init_wayland() {
        if C.eglBindAPI(egl_opengl_api) == 0 {
            eprintln('sokol_app: EGL: failed to bind OpenGL API')
        }

        g_sapp_state.egl.display = C.eglGetDisplay(voidptr(g_sapp_state.wl.display))
        if g_sapp_state.egl.display == unsafe { nil } {
            eprintln('sokol_app: EGL: failed to get display')
        }

        mut major := EGLint(0)
        mut minor := EGLint(0)
        if C.eglInitialize(g_sapp_state.egl.display, &major, &minor) == 0 {
            eprintln('sokol_app: EGL: failed to initialize')
        }
        g_sapp_state.gl.major = int(major)
        g_sapp_state.gl.minor = int(minor)
    }
}

fn sapp_egl_init_x11() {
    if C.eglBindAPI(egl_opengl_api) == 0 {
        eprintln('sokol_app: EGL: failed to bind OpenGL API')
    }

    g_sapp_state.egl.display = C.eglGetDisplay(voidptr(g_sapp_state.x11.display))
    if g_sapp_state.egl.display == unsafe { nil } {
        eprintln('sokol_app: EGL: failed to get display')
    }

    mut major := EGLint(0)
    mut minor := EGLint(0)
    if C.eglInitialize(g_sapp_state.egl.display, &major, &minor) == 0 {
        eprintln('sokol_app: EGL: failed to initialize')
    }
    g_sapp_state.gl.major = int(major)
    g_sapp_state.gl.minor = int(minor)

    config := sapp_egl_choose_config()

    mut visual_id := EGLint(0)
    if C.eglGetConfigAttrib(g_sapp_state.egl.display, config, EGLint(0x302E), &visual_id) == 0 {
        eprintln('sokol_app: EGL: failed to get native visual ID')
    }

    mut visual_info_template := C.XVisualInfo{}
    visual_info_template.visualid = VisualID(visual_id)

    mut num_visuals := 0
    visual_info := C.XGetVisualInfo(g_sapp_state.x11.display, visual_id_mask,
        &visual_info_template, &num_visuals)
    if visual_info == unsafe { nil } {
        eprintln('sokol_app: EGL: failed to get visual info')
    }

    x11_create_window(visual_info.visual, visual_info.depth)
    C.XFree(visual_info)

    g_sapp_state.egl.surface = C.eglCreateWindowSurface(g_sapp_state.egl.display, config,
        EGLNativeWindowType(g_sapp_state.x11.window), unsafe { nil })
    if g_sapp_state.egl.surface == unsafe { nil } {
        eprintln('sokol_app: EGL: failed to create window surface')
    }

    sapp_egl_create_context(config)
    sapp_egl_make_current()
}

fn sapp_egl_destroy() {
    if g_sapp_state.egl.display != unsafe { nil } {
        C.eglMakeCurrent(g_sapp_state.egl.display, unsafe { nil }, unsafe { nil }, unsafe { nil })

        if g_sapp_state.egl.context != unsafe { nil } {
            C.eglDestroyContext(g_sapp_state.egl.display, g_sapp_state.egl.context)
            g_sapp_state.egl.context = unsafe { nil }
        }

        if g_sapp_state.egl.surface != unsafe { nil } {
            C.eglDestroySurface(g_sapp_state.egl.display, g_sapp_state.egl.surface)
            g_sapp_state.egl.surface = unsafe { nil }
        }

        C.eglTerminate(g_sapp_state.egl.display)
        g_sapp_state.egl.display = unsafe { nil }
    }
}