#define _POSIX_C_SOURCE 200809L
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <wlr/types/wlr_buffer.h>
#include <wlr/types/wlr_linux_dmabuf.h>
#include "sway/debug.h"
#include "sway/desktop/transaction.h"
#include "sway/output.h"
#include "sway/tree/container.h"
#include "sway/tree/view.h"
#include "list.h"
#include "log.h"

/**
 * How long we should wait for views to respond to the configure before giving
 * up and applying the transaction anyway.
 */
#define TIMEOUT_MS 200

struct sway_transaction {
	struct wl_event_source *timer;
	list_t *instructions;   // struct sway_transaction_instruction *
	list_t *damage;         // struct wlr_box *
	size_t num_waiting;
};

struct sway_transaction_instruction {
	struct sway_transaction *transaction;
	struct sway_container *container;
	struct sway_container_state state;
	uint32_t serial;
};

struct sway_transaction *transaction_create() {
	struct sway_transaction *transaction =
		calloc(1, sizeof(struct sway_transaction));
	transaction->instructions = create_list();
	transaction->damage = create_list();
	return transaction;
}

static void transaction_destroy(struct sway_transaction *transaction) {
	int i;
	// Free instructions
	for (i = 0; i < transaction->instructions->length; ++i) {
		struct sway_transaction_instruction *instruction =
			transaction->instructions->items[i];
		if (instruction->container->type == C_VIEW) {
			struct sway_view *view = instruction->container->sway_view;
			for (int j = 0; j < view->instructions->length; ++j) {
				if (view->instructions->items[j] == instruction) {
					list_del(view->instructions, j);
					break;
				}
			}
		}
		free(instruction);
	}
	list_free(transaction->instructions);

	// Free damage
	for (i = 0; i < transaction->damage->length; ++i) {
		struct wlr_box *box = transaction->damage->items[i];
		free(box);
	}
	list_free(transaction->damage);

	free(transaction);
}

void transaction_add_container(struct sway_transaction *transaction,
		struct sway_container *container) {
	struct sway_transaction_instruction *instruction =
		calloc(1, sizeof(struct sway_transaction_instruction));
	instruction->transaction = transaction;
	instruction->container = container;

	// Copy the container's main (pending) properties into the instruction state
	struct sway_container_state *state = &instruction->state;
	state->layout = container->layout;
	state->swayc_x = container->x;
	state->swayc_y = container->y;
	state->swayc_width = container->width;
	state->swayc_height = container->height;
	state->has_gaps = container->has_gaps;
	state->current_gaps = container->current_gaps;
	state->gaps_inner = container->gaps_inner;
	state->gaps_outer = container->gaps_outer;

	if (container->type == C_VIEW) {
		struct sway_view *view = container->sway_view;
		state->view_x = view->x;
		state->view_y = view->y;
		state->view_width = view->width;
		state->view_height = view->height;
		state->is_fullscreen = view->is_fullscreen;
		state->border = view->border;
		state->border_thickness = view->border_thickness;
		state->border_top = view->border_top;
		state->border_left = view->border_left;
		state->border_right = view->border_right;
		state->border_bottom = view->border_bottom;
	}

	list_add(transaction->instructions, instruction);
}

void transaction_add_damage(struct sway_transaction *transaction,
		struct wlr_box *_box) {
	struct wlr_box *box = calloc(1, sizeof(struct wlr_box));
	memcpy(box, _box, sizeof(struct wlr_box));
	list_add(transaction->damage, box);
}

static void save_view_buffer(struct sway_view *view) {
	if (view->saved_buffer) {
		wlr_buffer_unref(view->saved_buffer);
	}
	wlr_buffer_ref(view->surface->buffer);
	view->saved_buffer = view->surface->buffer;
	view->saved_surface_width = view->surface->current->width;
	view->saved_surface_height = view->surface->current->height;
}

static void remove_saved_view_buffer(struct sway_view *view) {
	if (view->saved_buffer) {
		wlr_buffer_unref(view->saved_buffer);
		view->saved_buffer = NULL;
		view->saved_surface_width = 0;
		view->saved_surface_height = 0;
	}
}

/**
 * Apply a transaction to the "current" state of the tree.
 *
 * This is mostly copying stuff from the pending state into the main swayc
 * properties, but also includes reparenting and deleting containers.
 */
static void transaction_apply(struct sway_transaction *transaction) {
	int i;
	for (i = 0; i < transaction->instructions->length; ++i) {
		struct sway_transaction_instruction *instruction =
			transaction->instructions->items[i];
		struct sway_container *container = instruction->container;

		memcpy(&instruction->container->current, &instruction->state,
				sizeof(struct sway_container_state));

		if (container->type == C_VIEW) {
			remove_saved_view_buffer(container->sway_view);
		}
	}

	// Damage
	for (i = 0; i < transaction->damage->length; ++i) {
		struct wlr_box *box = transaction->damage->items[i];
		for (int j = 0; j < root_container.children->length; ++j) {
			struct sway_container *output = root_container.children->items[j];
			output_damage_box(output->sway_output, box);
		}
	}

	update_debug_tree();
}

static int handle_timeout(void *data) {
	struct sway_transaction *transaction = data;
	wlr_log(L_DEBUG, "Transaction %p timed out (%li waiting), applying anyway",
			transaction, transaction->num_waiting);
	transaction_apply(transaction);
	transaction_destroy(transaction);
	return 0;
}

void transaction_commit(struct sway_transaction *transaction) {
	wlr_log(L_DEBUG, "Transaction %p committing with %i instructions",
			transaction, transaction->instructions->length);
	transaction->num_waiting = 0;
	for (int i = 0; i < transaction->instructions->length; ++i) {
		struct sway_transaction_instruction *instruction =
			transaction->instructions->items[i];
		struct sway_container *con = instruction->container;
		if (con->type == C_VIEW &&
				(con->current.view_width != instruction->state.view_width ||
				 con->current.view_height != instruction->state.view_height)) {
			instruction->serial = view_configure(con->sway_view,
					instruction->state.view_x,
					instruction->state.view_y,
					instruction->state.view_width,
					instruction->state.view_height);
			if (instruction->serial) {
				save_view_buffer(con->sway_view);
				list_add(con->sway_view->instructions, instruction);
				++transaction->num_waiting;
			}
		}
	}
	if (!transaction->num_waiting) {
		// This can happen if the transaction only contains xwayland views
		wlr_log(L_DEBUG, "Transaction %p has nothing to wait for, applying",
				transaction);
		transaction_apply(transaction);
		transaction_destroy(transaction);
		return;
	}

	// Set up a timer which the views must respond within
	transaction->timer = wl_event_loop_add_timer(server.wl_event_loop,
			handle_timeout, transaction);
	wl_event_source_timer_update(transaction->timer, TIMEOUT_MS);
}

void transaction_notify_view_ready(struct sway_view *view, uint32_t serial) {
	// Find the instruction
	struct sway_transaction_instruction *instruction = NULL;
	for (int i = 0; i < view->instructions->length; ++i) {
		struct sway_transaction_instruction *tmp_instruction =
			view->instructions->items[i];
		if (tmp_instruction->serial == serial) {
			instruction = tmp_instruction;
			list_del(view->instructions, i);
			break;
		}
	}
	if (!instruction) {
		// This can happen if the view acknowledges the configure after the
		// transaction has timed out and applied.
		return;
	}
	// If all views are ready, apply the transaction
	struct sway_transaction *transaction = instruction->transaction;
	if (--transaction->num_waiting == 0) {
		wlr_log(L_DEBUG, "Transaction %p is ready, applying", transaction);
		wl_event_source_timer_update(transaction->timer, 0);
		transaction_apply(transaction);
		transaction_destroy(transaction);
	}
}