#include <stdlib.h>
#include <assert.h>
#include <pixman.h>
#include <time.h>
#include <wlr/types/wlr_matrix.h>
#include <wlr/util/transform.h>
#include "render/gles2.h"
#include "types/wlr_matrix.h"

#define MAX_QUADS 86 // 4kb

static const struct wlr_render_pass_impl render_pass_impl;

static struct wlr_gles2_render_pass *get_render_pass(struct wlr_render_pass *wlr_pass) {
	assert(wlr_pass->impl == &render_pass_impl);
	struct wlr_gles2_render_pass *pass = wl_container_of(wlr_pass, pass, base);
	return pass;
}

static bool render_pass_submit(struct wlr_render_pass *wlr_pass) {
	struct wlr_gles2_render_pass *pass = get_render_pass(wlr_pass);
	struct wlr_gles2_renderer *renderer = pass->buffer->renderer;
	struct wlr_gles2_render_timer *timer = pass->timer;

	push_gles2_debug(renderer);

	if (timer) {
		// clear disjoint flag
		GLint64 disjoint;
		renderer->procs.glGetInteger64vEXT(GL_GPU_DISJOINT_EXT, &disjoint);
		// set up the query
		renderer->procs.glQueryCounterEXT(timer->id, GL_TIMESTAMP_EXT);
		// get end-of-CPU-work time in GL time domain
		renderer->procs.glGetInteger64vEXT(GL_TIMESTAMP_EXT, &timer->gl_cpu_end);
		// get end-of-CPU-work time in CPU time domain
		clock_gettime(CLOCK_MONOTONIC, &timer->cpu_end);
	}

	glFlush();
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	pop_gles2_debug(renderer);
	wlr_egl_restore_context(&pass->prev_ctx);

	wlr_buffer_unlock(pass->buffer->buffer);
	free(pass);

	return true;
}

static void render(const struct wlr_box *box, const pixman_region32_t *clip, GLint attrib) {
	pixman_region32_t region;
	pixman_region32_init_rect(&region, box->x, box->y, box->width, box->height);

	if (clip) {
		pixman_region32_intersect(&region, &region, clip);
	}

	int rects_len;
	const pixman_box32_t *rects = pixman_region32_rectangles(&region, &rects_len);
	if (rects_len == 0) {
		pixman_region32_fini(&region);
		return;
	}

	glEnableVertexAttribArray(attrib);

	for (int i = 0; i < rects_len;) {
		int batch = rects_len - i < MAX_QUADS ? rects_len - i : MAX_QUADS;
		int batch_end = batch + i;

		size_t vert_index = 0;
		GLfloat verts[MAX_QUADS * 6 * 2];
		for (; i < batch_end; i++) {
			const pixman_box32_t *rect = &rects[i];

			verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height;
			verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height;
			verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height;
			verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y1 - box->y) / box->height;
			verts[vert_index++] = (GLfloat)(rect->x2 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height;
			verts[vert_index++] = (GLfloat)(rect->x1 - box->x) / box->width;
			verts[vert_index++] = (GLfloat)(rect->y2 - box->y) / box->height;
		}

		glVertexAttribPointer(attrib, 2, GL_FLOAT, GL_FALSE, 0, verts);
		glDrawArrays(GL_TRIANGLES, 0, batch * 6);
	}

	glDisableVertexAttribArray(attrib);

	pixman_region32_fini(&region);
}

static void set_proj_matrix(GLint loc, float proj[9], const struct wlr_box *box) {
	float gl_matrix[9];
	wlr_matrix_identity(gl_matrix);
	wlr_matrix_translate(gl_matrix, box->x, box->y);
	wlr_matrix_scale(gl_matrix, box->width, box->height);
	wlr_matrix_multiply(gl_matrix, proj, gl_matrix);
	glUniformMatrix3fv(loc, 1, GL_FALSE, gl_matrix);
}

static void set_tex_matrix(GLint loc, enum wl_output_transform trans,
		const struct wlr_fbox *box) {
	float tex_matrix[9];
	wlr_matrix_identity(tex_matrix);
	wlr_matrix_translate(tex_matrix, box->x, box->y);
	wlr_matrix_scale(tex_matrix, box->width, box->height);
	wlr_matrix_translate(tex_matrix, .5, .5);

	// since textures have a different origin point we have to transform
	// differently if we are rotating
	if (trans & WL_OUTPUT_TRANSFORM_90) {
		wlr_matrix_transform(tex_matrix, wlr_output_transform_invert(trans));
	} else {
		wlr_matrix_transform(tex_matrix, trans);
	}
	wlr_matrix_translate(tex_matrix, -.5, -.5);

	glUniformMatrix3fv(loc, 1, GL_FALSE, tex_matrix);
}

static void setup_blending(enum wlr_render_blend_mode mode) {
	switch (mode) {
	case WLR_RENDER_BLEND_MODE_PREMULTIPLIED:
		glEnable(GL_BLEND);
		break;
	case WLR_RENDER_BLEND_MODE_NONE:
		glDisable(GL_BLEND);
		break;
	}
}

static void render_pass_add_texture(struct wlr_render_pass *wlr_pass,
		const struct wlr_render_texture_options *options) {
	struct wlr_gles2_render_pass *pass = get_render_pass(wlr_pass);
	struct wlr_gles2_renderer *renderer = pass->buffer->renderer;
	struct wlr_gles2_texture *texture = gles2_get_texture(options->texture);

	struct wlr_gles2_tex_shader *shader = NULL;

	switch (texture->target) {
	case GL_TEXTURE_2D:
		if (texture->has_alpha) {
			shader = &renderer->shaders.tex_rgba;
		} else {
			shader = &renderer->shaders.tex_rgbx;
		}
		break;
	case GL_TEXTURE_EXTERNAL_OES:
		// EGL_EXT_image_dma_buf_import_modifiers requires
		// GL_OES_EGL_image_external
		assert(renderer->exts.OES_egl_image_external);
		shader = &renderer->shaders.tex_ext;
		break;
	default:
		abort();
	}

	struct wlr_box dst_box;
	struct wlr_fbox src_fbox;
	wlr_render_texture_options_get_src_box(options, &src_fbox);
	wlr_render_texture_options_get_dst_box(options, &dst_box);
	float alpha = wlr_render_texture_options_get_alpha(options);

	src_fbox.x /= options->texture->width;
	src_fbox.y /= options->texture->height;
	src_fbox.width /= options->texture->width;
	src_fbox.height /= options->texture->height;

	push_gles2_debug(renderer);
	setup_blending(!texture->has_alpha && alpha == 1.0 ?
		WLR_RENDER_BLEND_MODE_NONE : options->blend_mode);

	glUseProgram(shader->program);

	glActiveTexture(GL_TEXTURE0);
	glBindTexture(texture->target, texture->tex);

	switch (options->filter_mode) {
	case WLR_SCALE_FILTER_BILINEAR:
		glTexParameteri(texture->target, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(texture->target, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		break;
	case WLR_SCALE_FILTER_NEAREST:
		glTexParameteri(texture->target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexParameteri(texture->target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		break;
	}

	glUniform1i(shader->tex, 0);
	glUniform1f(shader->alpha, alpha);
	set_proj_matrix(shader->proj, pass->projection_matrix, &dst_box);
	set_tex_matrix(shader->tex_proj, options->transform, &src_fbox);

	render(&dst_box, options->clip, shader->pos_attrib);

	glBindTexture(texture->target, 0);
	pop_gles2_debug(renderer);
}

static void render_pass_add_rect(struct wlr_render_pass *wlr_pass,
		const struct wlr_render_rect_options *options) {
	struct wlr_gles2_render_pass *pass = get_render_pass(wlr_pass);
	struct wlr_gles2_renderer *renderer = pass->buffer->renderer;

	const struct wlr_render_color *color = &options->color;
	struct wlr_box box;
	wlr_render_rect_options_get_box(options, pass->buffer->buffer, &box);

	push_gles2_debug(renderer);
	setup_blending(color->a == 1.0 ? WLR_RENDER_BLEND_MODE_NONE : options->blend_mode);

	glUseProgram(renderer->shaders.quad.program);

	set_proj_matrix(renderer->shaders.quad.proj, pass->projection_matrix, &box);
	glUniform4f(renderer->shaders.quad.color, color->r, color->g, color->b, color->a);

	render(&box, options->clip, renderer->shaders.quad.pos_attrib);

	pop_gles2_debug(renderer);
}

static const struct wlr_render_pass_impl render_pass_impl = {
	.submit = render_pass_submit,
	.add_texture = render_pass_add_texture,
	.add_rect = render_pass_add_rect,
};

static const char *reset_status_str(GLenum status) {
	switch (status) {
	case GL_GUILTY_CONTEXT_RESET_KHR:
		return "guilty";
	case GL_INNOCENT_CONTEXT_RESET_KHR:
		return "innocent";
	case GL_UNKNOWN_CONTEXT_RESET_KHR:
		return "unknown";
	default:
		return "<invalid>";
	}
}

struct wlr_gles2_render_pass *begin_gles2_buffer_pass(struct wlr_gles2_buffer *buffer,
		struct wlr_egl_context *prev_ctx, struct wlr_gles2_render_timer *timer) {
	struct wlr_gles2_renderer *renderer = buffer->renderer;
	struct wlr_buffer *wlr_buffer = buffer->buffer;

	if (renderer->procs.glGetGraphicsResetStatusKHR) {
		GLenum status = renderer->procs.glGetGraphicsResetStatusKHR();
		if (status != GL_NO_ERROR) {
			wlr_log(WLR_ERROR, "GPU reset (%s)", reset_status_str(status));
			wl_signal_emit_mutable(&renderer->wlr_renderer.events.lost, NULL);
			return NULL;
		}
	}

	GLint fbo = gles2_buffer_get_fbo(buffer);
	if (!fbo) {
		return NULL;
	}

	struct wlr_gles2_render_pass *pass = calloc(1, sizeof(*pass));
	if (pass == NULL) {
		return NULL;
	}

	wlr_render_pass_init(&pass->base, &render_pass_impl);
	wlr_buffer_lock(wlr_buffer);
	pass->buffer = buffer;
	pass->timer = timer;
	pass->prev_ctx = *prev_ctx;

	matrix_projection(pass->projection_matrix, wlr_buffer->width, wlr_buffer->height,
		WL_OUTPUT_TRANSFORM_FLIPPED_180);

	push_gles2_debug(renderer);
	glBindFramebuffer(GL_FRAMEBUFFER, fbo);

	glViewport(0, 0, wlr_buffer->width, wlr_buffer->height);
	glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
	glDisable(GL_SCISSOR_TEST);
	pop_gles2_debug(renderer);

	return pass;
}
