#include "wayland-client-core.h"
#include <ctype.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <setjmp.h>
#include <wayland-client.h>
#include <libguile.h>

#ifdef __linux__
#include <features.h>
#ifdef __GLIBC__
#include<execinfo.h>
#endif
#endif

#include "river-layout-v3.h"
#include "ext-idle-notify-v1.h"
#include "river-control-unstable-v1.h"
#include "river-status-unstable-v1.h"

#include "load-script.h"
#include "call-exit-handler.h"
#include "riverguile.h"
#include "output.h"
#include "seat.h"

struct Context context = {
	/* Handlers are initially NULL instead of SCM_EOL because I am not sure whether
	 * scm_null_p() is safe to use outside of a guile context and if yes, whether
	 * that is intended or will disappear in the future. Special care must be taken
	 * to never call any scm_* function on these while they are NULL.
	 */
	.new_output_handler = NULL,
	.layout_demand_handler = NULL,
	.user_command_handler = NULL,
	.exit_handler = NULL,

	.loop = true,
	.ret = EXIT_SUCCESS,
};

jmp_buf skip_main_loop;

static void registry_handle_global (void *data, struct wl_registry *registry,
		uint32_t name, const char *interface, uint32_t version)
{
	if ( strcmp(interface, river_layout_manager_v3_interface.name) == 0 )
	{
		context.layout_manager = wl_registry_bind(
			registry, name, &river_layout_manager_v3_interface, 2
		);
	}
	else if ( strcmp(interface, zriver_control_v1_interface.name) == 0 )
	{
		context.river_control = wl_registry_bind(
			registry, name, &zriver_control_v1_interface, 1
		);
	}
	else if ( strcmp(interface, ext_idle_notifier_v1_interface.name) == 0 )
	{
		context.idle_notifier = wl_registry_bind(
			registry, name, &ext_idle_notifier_v1_interface, 1
		);
	}
	else if ( strcmp(interface, zriver_status_manager_v1_interface.name) == 0 )
	{
		context.status_manager = wl_registry_bind(
			registry, name, &zriver_status_manager_v1_interface, 4
		);
	}
	else if ( strcmp(interface, wl_output_interface.name) == 0 )
	{
		struct wl_output *wl_output = wl_registry_bind(
			registry, name, &wl_output_interface, 1
		);
		struct Output *output = output_create(wl_output, name);
		if ( output == NULL )
		{
			wl_output_destroy(wl_output);
			context.ret = EXIT_FAILURE;
			context.loop = false;
			return;
		}
		wl_list_insert(&context.outputs, &output->link);
	}
	else if ( strcmp(interface, wl_seat_interface.name) == 0 )
	{
		struct wl_seat *wl_seat = wl_registry_bind(
			registry, name, &wl_seat_interface, 1
		);
		struct Seat *seat = seat_create(wl_seat, name);
		if ( seat == NULL )
		{
			wl_seat_destroy(wl_seat);
			context.ret = EXIT_FAILURE;
			context.loop = false;
			return;
		}
		wl_list_insert(&context.seats, &seat->link);
	}
}

static void registry_handle_global_remove (void *data, struct wl_registry *registry,
		uint32_t name)
{
	struct Output *output, *tmp_o;
	wl_list_for_each_safe(output, tmp_o, &context.outputs, link)
	{
		if ( output->name != name )
			continue;
		wl_list_remove(&output->link);
		output_destroy(output);
		return;
	}

	struct Seat *seat, *tmp_s;
	wl_list_for_each_safe(seat, tmp_s, &context.seats, link)
	{
		if ( seat->name != name )
			continue;
		wl_list_remove(&seat->link);
		seat_destroy(seat);
		return;
	}
}

static const struct wl_registry_listener registry_listener = {
	.global        = registry_handle_global,
	.global_remove = registry_handle_global_remove,
};

static void sync_handle_done (void *, struct wl_callback *, uint32_t);
static const struct wl_callback_listener sync_callback_listener = {
	.done = sync_handle_done,
};

static void sync_handle_done (void *data, struct wl_callback *wl_callback, uint32_t other_data)
{
	static int i = 0;
	i++;
	if ( i > 2 )
	{
		assert(context.mode == ONESHOT);
		context.loop = false;
		return;
	}

	wl_callback_destroy(wl_callback);
	context.sync_callback = NULL;

	if (i == 1) {
		struct Output *output;
		wl_list_for_each(output, &context.outputs, link) {
			output_status_init(output);
		}

		struct Seat *seat;
		wl_list_for_each(seat, &context.seats, link) {
			seat_status_init(seat);
		}

		context.sync_callback = wl_display_sync(context.wl_display);
		wl_callback_add_listener(context.sync_callback, &sync_callback_listener, NULL);
		return;
	}

	/* Load the script after connecting to the server and binding interfaces
	 * to allow calling Wayland requests from it.
	 */
	assert(context.path != NULL);
	void *res = scm_with_guile(load_script, (void *)context.path);
	if ( res != NULL )
	{
		fputs((char *)res, stderr);
		context.ret = EXIT_FAILURE;
		context.loop = false;
		return;
	}

	if ( context.layout_demand_handler == NULL
		&& context.user_command_handler != NULL )
	{
		fputs("ERROR: Installing user-command handler without installing a layout-demand handler is not allowed.\n", stderr);
		fputs("INFO: This error is not fatal, but means riverguile will not provide any layout.\n", stderr);
	}

	switch (context.mode)
	{
		case ONESHOT:
			/* Oneshot mode. Sync again so we are sure that all commands
			 * have been send, then exit.
			 */
			context.sync_callback = wl_display_sync(context.wl_display);
			wl_callback_add_listener(context.sync_callback, &sync_callback_listener, NULL);
			fputs("INFO: No handlers installed: Riverguile will exit.\n", stderr);
			break;

		case CONTINOUS:
			fputs("INFO: At least one handler installed: Riverguile will run continously.\n", stderr);
			break;
	}
}

static void handle_interrupt (int signum)
{
	fputs("INFO: Killed 💀\n", stderr);
	context.loop = false;
	longjmp(skip_main_loop, 1);
}

/**
 * Intercept error signals (like SIGSEGV and SIGFPE) so that we can try to
 * print a fancy error message and a backtracke before letting the system kill us.
 */
static void handle_error (int signum)
{
	const char *msg =
		"\n"
		"┌──────────────────────────────────────────┐\n"
		"│                                          │\n"
		"│         riverguile has crashed.          │\n"
		"│                                          │\n"
		"│   This is most likely a bug, so please   │\n"
		"│     report this to the mailing list.     │\n"
		"│                                          │\n"
		"│  ~leon_plickat/public-inbox@lists.sr.ht  │\n"
		"│                                          │\n"
		"└──────────────────────────────────────────┘\n"
		"\n";
	fputs(msg, stderr);

	/* Set up the default handlers to deal with the rest. We do this before
	 * attempting to get a backtrace, because sometimes that could also
	 * cause a SEGFAULT and we don't want a funny signal loop to happen.
	 */
	signal(signum, SIG_DFL);

#ifdef __linux__
#ifdef __GLIBC__
	fputs("Attempting to get backtrace:\n", stderr);
	void *buffer[255];
	const int calls = backtrace(buffer, sizeof(buffer) / sizeof(void *));
	backtrace_symbols_fd(buffer, calls, fileno(stderr));
	fputs("\n", stderr);
#endif
#endif

	/* Easiest way of calling the default signal handler. */
	kill(getpid(), signum);
}

static char *formatted_buffer (const char *fmt, ...)
{
	/* Determine length of formatted text. */
	va_list args;
	va_start(args, fmt);
	/* +1 for NULL. */
	unsigned long len = (unsigned long)vsnprintf(NULL, 0, fmt, args) + 1;
	va_end(args);

	char *buffer = calloc(1, len);
	if ( buffer == NULL )
	{
		fprintf(stderr, "ERROR: calloc: %s\n", strerror(errno));
		return NULL;
	}

	/* Finally write formatted text into buffer. */
	va_start(args, fmt);
	vsnprintf(buffer, len, fmt, args);
	va_end(args);

	return buffer;
}

static char *get_script_path (char *relative_path)
{
	assert(relative_path != NULL);

	char *path = NULL;
	if ( relative_path[0] == '/' )
		path = formatted_buffer("%s", relative_path);
	else
	{
		/* When scm_primitive_load_path() receives a relative path, it
		 * tries to look it up in the guile module path. So we must
		 * always provide it an absolute path.
		 */
		char buffer[4 * 1024];
		char *cwd = getcwd(buffer, 4 * 1024);
		if ( cwd == NULL )
		{
			fprintf(stderr, "ERROR: getcwd: %s\n", strerror(errno));
			return NULL;
		}

		path = formatted_buffer("%s/%s", cwd, relative_path);
	}
	if ( path == NULL )
		return NULL;

	if ( access(path, R_OK) != 0 )
	{
		fprintf(stderr, "ERROR: Script '%s' is not readable.\n", path);
		free(path);
		return NULL;
	}

	return path;
}

int main (int argc, char *argv[])
{
	if ( argc != 2
		|| strcmp(argv[1], "--help") == 0
		|| strcmp(argv[1], "-h") == 0
		|| strcmp(argv[1], "-?") == 0 )
	{
		fprintf(stderr, "USAGE: %s path-to-script\n", argv[0]);
		return EXIT_FAILURE;
	}

	fputs("INFO: Welcome to riverguile!\n", stderr);

	signal(SIGSEGV, handle_error);
	signal(SIGFPE, handle_error);
	signal(SIGINT, handle_interrupt);

	context.path = get_script_path(argv[1]);
	if ( context.path == NULL )
	{
		context.ret = EXIT_FAILURE;
		goto early_exit;
	}
	fprintf(stderr, "INFO: Using script: %s\n", context.path);

	wl_list_init(&context.outputs);
	wl_list_init(&context.seats);

	/* We query the display name here instead of letting wl_display_connect()
	 * figure it out itself, because libwayland (for legacy reasons) falls
	 * back to using "wayland-0" when $WAYLAND_DISPLAY is not set, which is
	 * generally not desirable.
	 */
	const char *display_name = getenv("WAYLAND_DISPLAY");
	if ( display_name == NULL )
	{
		fputs("ERROR: WAYLAND_DISPLAY is not set.\n", stderr);
		context.ret = EXIT_FAILURE;
		goto early_exit;
	}

	context.wl_display = wl_display_connect(display_name);
	if ( context.wl_display == NULL )
	{
		fputs("ERROR: Can not connect to wayland display.\n", stderr);
		context.ret = EXIT_FAILURE;
		goto early_exit;
	}

	context.wl_registry = wl_display_get_registry(context.wl_display);
	wl_registry_add_listener(context.wl_registry, &registry_listener, NULL);

	context.sync_callback = wl_display_sync(context.wl_display);
	wl_callback_add_listener(context.sync_callback, &sync_callback_listener, NULL);

	if ( setjmp(skip_main_loop) == 0 )
		while ( context.loop && wl_display_dispatch(context.wl_display) > 0 );

	if ( context.exit_handler != NULL )
	{
		void *res = scm_with_guile(call_exit_handler, NULL);
		if ( res != NULL )
		{
			fputs((char *)res, stderr);
			context.ret = EXIT_FAILURE;
			context.loop = false;
		}
	}

	struct Output *output, *tmp_o;
	wl_list_for_each_safe(output, tmp_o, &context.outputs, link)
	{
		wl_list_remove(&output->link);
		output_destroy(output);
	}

	struct Seat *seat, *tmp_s;
	wl_list_for_each_safe(seat, tmp_s, &context.seats, link)
	{
		wl_list_remove(&seat->link);
		seat_destroy(seat);
	}

	if ( context.idle_notifier != NULL )
		ext_idle_notifier_v1_destroy(context.idle_notifier);
	if ( context.layout_manager != NULL )
		river_layout_manager_v3_destroy(context.layout_manager);
	if ( context.river_control != NULL )
		zriver_control_v1_destroy(context.river_control);
	if ( context.status_manager != NULL )
		zriver_status_manager_v1_destroy(context.status_manager);
	if ( context.sync_callback != NULL )
		wl_callback_destroy(context.sync_callback);
	if ( context.wl_registry != NULL )
		wl_registry_destroy(context.wl_registry);
	wl_display_disconnect(context.wl_display);

early_exit:
	if ( context.path != NULL )
		free(context.path);

	fputs("INFO: Exiting.\n", stderr);
	return context.ret;
}