#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <unistd.h>
#include <wlr/types/wlr_security_context_v1.h>
#include <wlr/util/log.h>
#include "security-context-v1-protocol.h"

#define SECURITY_CONTEXT_MANAGER_V1_VERSION 1

struct wlr_security_context_v1 {
	struct wlr_security_context_manager_v1 *manager;
	struct wlr_security_context_v1_state state;
	struct wl_list link; // wlr_security_context_manager_v1.contexts
	int listen_fd, close_fd;
	struct wl_event_source *listen_source, *close_source;
};

struct wlr_security_context_v1_client {
	struct wlr_security_context_v1_state state;
	struct wl_listener destroy;
};

static void resource_handle_destroy(struct wl_client *client,
		struct wl_resource *resource) {
	wl_resource_destroy(resource);
}

static const struct wp_security_context_manager_v1_interface manager_impl;
static const struct wp_security_context_v1_interface security_context_impl;

static struct wlr_security_context_manager_v1 *manager_from_resource(
		struct wl_resource *resource) {
	assert(wl_resource_instance_of(resource,
		&wp_security_context_manager_v1_interface, &manager_impl));
	struct wlr_security_context_manager_v1 *manager =
		wl_resource_get_user_data(resource);
	assert(manager != NULL);
	return manager;
}

/**
 * Get a struct wlr_security_context_v1 from a struct wl_resource.
 *
 * NULL is returned if the security context has been committed.
 */
static struct wlr_security_context_v1 *security_context_from_resource(
		struct wl_resource *resource) {
	assert(wl_resource_instance_of(resource,
		&wp_security_context_v1_interface, &security_context_impl));
	return wl_resource_get_user_data(resource);
}

static void security_context_state_finish(struct wlr_security_context_v1_state *state) {
	free(state->app_id);
	free(state->sandbox_engine);
	free(state->instance_id);
}

static bool copy_state_field(char **dst, const char *src) {
	if (src == NULL) {
		return true;
	}
	*dst = strdup(src);
	return *dst != NULL;
}

static bool security_context_state_copy(struct wlr_security_context_v1_state *dst,
		const struct wlr_security_context_v1_state *src) {
	bool ok = copy_state_field(&dst->app_id, src->app_id) &&
		copy_state_field(&dst->sandbox_engine, src->sandbox_engine) &&
		copy_state_field(&dst->instance_id, src->instance_id);
	if (!ok) {
		security_context_state_finish(dst);
	}
	return ok;
}

static void security_context_destroy(
		struct wlr_security_context_v1 *security_context) {
	if (security_context == NULL) {
		return;
	}

	if (security_context->listen_source != NULL) {
		wl_event_source_remove(security_context->listen_source);
	}
	if (security_context->close_source != NULL) {
		wl_event_source_remove(security_context->close_source);
	}

	close(security_context->listen_fd);
	close(security_context->close_fd);

	security_context_state_finish(&security_context->state);
	wl_list_remove(&security_context->link);
	free(security_context);
}

static void security_context_client_handle_destroy(struct wl_listener *listener,
		void *data) {
	struct wlr_security_context_v1_client *security_context_client =
		wl_container_of(listener, security_context_client, destroy);
	wl_list_remove(&security_context_client->destroy.link);
	security_context_state_finish(&security_context_client->state);
	free(security_context_client);
}

static int security_context_handle_listen_fd_event(int listen_fd, uint32_t mask,
		void *data) {
	struct wlr_security_context_v1 *security_context = data;

	if (mask & (WL_EVENT_HANGUP | WL_EVENT_ERROR)) {
		security_context_destroy(security_context);
		return 0;
	}

	if (mask & WL_EVENT_READABLE) {
		int client_fd = accept(listen_fd, NULL, NULL);
		if (client_fd < 0) {
			wlr_log_errno(WLR_ERROR, "accept failed");
			return 0;
		}

		struct wlr_security_context_v1_client *security_context_client =
			calloc(1, sizeof(*security_context_client));
		if (security_context_client == NULL) {
			wlr_log_errno(WLR_ERROR, "Allocation failed");
			close(client_fd);
			return 0;
		}

		struct wl_display *display =
			wl_global_get_display(security_context->manager->global);
		struct wl_client *client = wl_client_create(display, client_fd);
		if (client == NULL) {
			wlr_log(WLR_ERROR, "wl_client_create failed");
			close(client_fd);
			return 0;
		}

		if (!security_context_state_copy(&security_context_client->state,
				&security_context->state)) {
			wl_client_post_no_memory(client);
			return 0;
		}

		security_context_client->destroy.notify = security_context_client_handle_destroy;
		wl_client_add_destroy_listener(client, &security_context_client->destroy);
	}

	return 0;
}

static int security_context_handle_close_fd_event(int fd, uint32_t mask,
		void *data) {
	struct wlr_security_context_v1 *security_context = data;

	if (mask & (WL_EVENT_HANGUP | WL_EVENT_ERROR)) {
		security_context_destroy(security_context);
	}

	return 0;
}

static void security_context_handle_commit(struct wl_client *client,
		struct wl_resource *resource) {
	struct wlr_security_context_v1 *security_context =
		security_context_from_resource(resource);
	if (security_context == NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
			"Security context has already been committed");
		return;
	}

	// In theory the compositor should prevent this with a global filter, but
	// let's make sure it doesn't happen.
	if (wlr_security_context_manager_v1_lookup_client(security_context->manager,
			client) != NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_NESTED,
			"Nested security contexts are forbidden");
		return;
	}

	struct wl_display *display = wl_client_get_display(client);
	struct wl_event_loop *loop = wl_display_get_event_loop(display);

	security_context->listen_source = wl_event_loop_add_fd(loop,
		security_context->listen_fd, WL_EVENT_READABLE,
		security_context_handle_listen_fd_event, security_context);
	if (security_context->listen_source == NULL) {
		wl_resource_post_no_memory(resource);
		return;
	}

	security_context->close_source = wl_event_loop_add_fd(loop,
		security_context->close_fd, 0, security_context_handle_close_fd_event,
		security_context);
	if (security_context->close_source == NULL) {
		wl_resource_post_no_memory(resource);
		return;
	}

	wl_resource_set_user_data(resource, NULL);

	struct wlr_security_context_v1_commit_event event = {
		.state = &security_context->state,
		.parent_client = client,
	};
	wl_signal_emit_mutable(&security_context->manager->events.commit, &event);
}

static void security_context_handle_set_sandbox_engine(struct wl_client *client,
		struct wl_resource *resource, const char *sandbox_engine) {
	struct wlr_security_context_v1 *security_context =
		security_context_from_resource(resource);
	if (security_context == NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
			"Security context has already been committed");
		return;
	}

	if (security_context->state.sandbox_engine != NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
			"Sandbox engine has already been set");
		return;
	}

	security_context->state.sandbox_engine = strdup(sandbox_engine);
	if (security_context->state.sandbox_engine == NULL) {
		wl_resource_post_no_memory(resource);
	}
}

static void security_context_handle_set_app_id(struct wl_client *client,
		struct wl_resource *resource, const char *app_id) {
	struct wlr_security_context_v1 *security_context =
		security_context_from_resource(resource);
	if (security_context == NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
			"Security context has already been committed");
		return;
	}

	if (security_context->state.app_id != NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
			"App ID has already been set");
		return;
	}

	security_context->state.app_id = strdup(app_id);
	if (security_context->state.app_id == NULL) {
		wl_resource_post_no_memory(resource);
	}
}

static void security_context_handle_set_instance_id(struct wl_client *client,
		struct wl_resource *resource, const char *instance_id) {
	struct wlr_security_context_v1 *security_context =
		security_context_from_resource(resource);
	if (security_context == NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
			"Security context has already been committed");
		return;
	}

	if (security_context->state.instance_id != NULL) {
		wl_resource_post_error(resource,
			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
			"Instance ID has already been set");
		return;
	}

	security_context->state.instance_id = strdup(instance_id);
	if (security_context->state.instance_id == NULL) {
		wl_resource_post_no_memory(resource);
	}
}

static const struct wp_security_context_v1_interface security_context_impl = {
	.destroy = resource_handle_destroy,
	.commit = security_context_handle_commit,
	.set_sandbox_engine = security_context_handle_set_sandbox_engine,
	.set_app_id = security_context_handle_set_app_id,
	.set_instance_id = security_context_handle_set_instance_id,
};

static void security_context_resource_destroy(struct wl_resource *resource) {
	struct wlr_security_context_v1 *security_context =
		security_context_from_resource(resource);
	security_context_destroy(security_context);
}

static void manager_handle_create_listener(struct wl_client *client,
		struct wl_resource *manager_resource, uint32_t id,
		int listen_fd, int close_fd) {
	struct wlr_security_context_manager_v1 *manager =
		manager_from_resource(manager_resource);

	struct stat stat_buf = {0};
	if (fstat(listen_fd, &stat_buf) != 0) {
		wlr_log_errno(WLR_ERROR, "fstat failed on listen FD");
		wl_resource_post_error(manager_resource,
			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
			"Invalid listen_fd");
		return;
	} else if (!S_ISSOCK(stat_buf.st_mode)) {
		wl_resource_post_error(manager_resource,
			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
			"listen_fd is not a socket");
		return;
	}

	int accept_conn = 0;
	socklen_t accept_conn_size = sizeof(accept_conn);
	if (getsockopt(listen_fd, SOL_SOCKET, SO_ACCEPTCONN, &accept_conn,
			&accept_conn_size) != 0) {
		wlr_log_errno(WLR_ERROR, "getsockopt failed on listen FD");
		wl_resource_post_error(manager_resource,
			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
			"Invalid listen_fd");
		return;
	} else if (accept_conn == 0) {
		wl_resource_post_error(manager_resource,
			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
			"listen_fd is not a listening socket");
		return;
	}

	struct wlr_security_context_v1 *security_context =
		calloc(1, sizeof(*security_context));
	if (security_context == NULL) {
		wl_resource_post_no_memory(manager_resource);
		return;
	}

	security_context->manager = manager;
	security_context->listen_fd = listen_fd;
	security_context->close_fd = close_fd;

	uint32_t version = wl_resource_get_version(manager_resource);
	struct wl_resource *resource = wl_resource_create(client,
		&wp_security_context_v1_interface, version, id);
	if (resource == NULL) {
		free(security_context);
		wl_resource_post_no_memory(manager_resource);
		return;
	}
	wl_resource_set_implementation(resource, &security_context_impl,
		security_context, security_context_resource_destroy);

	wl_list_insert(&manager->contexts, &security_context->link);
}

static const struct wp_security_context_manager_v1_interface manager_impl = {
	.destroy = resource_handle_destroy,
	.create_listener = manager_handle_create_listener,
};

static void manager_bind(struct wl_client *client, void *data,
		uint32_t version, uint32_t id) {
	struct wlr_security_context_manager_v1 *manager = data;

	struct wl_resource *resource = wl_resource_create(client,
		&wp_security_context_manager_v1_interface, version, id);
	if (resource == NULL) {
		wl_client_post_no_memory(client);
		return;
	}
	wl_resource_set_implementation(resource, &manager_impl, manager, NULL);
}

static void handle_display_destroy(struct wl_listener *listener, void *data) {
	struct wlr_security_context_manager_v1 *manager =
		wl_container_of(listener, manager, display_destroy);
	wl_signal_emit_mutable(&manager->events.destroy, manager);
	assert(wl_list_empty(&manager->events.destroy.listener_list));
	assert(wl_list_empty(&manager->events.commit.listener_list));

	struct wlr_security_context_v1 *security_context, *tmp;
	wl_list_for_each_safe(security_context, tmp, &manager->contexts, link) {
		security_context_destroy(security_context);
	}

	wl_global_destroy(manager->global);
	wl_list_remove(&manager->display_destroy.link);
	free(manager);
}

struct wlr_security_context_manager_v1 *wlr_security_context_manager_v1_create(
		struct wl_display *display) {
	struct wlr_security_context_manager_v1 *manager = calloc(1, sizeof(*manager));
	if (manager == NULL) {
		return NULL;
	}

	manager->global = wl_global_create(display,
		&wp_security_context_manager_v1_interface,
		SECURITY_CONTEXT_MANAGER_V1_VERSION, manager, manager_bind);
	if (manager->global == NULL) {
		free(manager);
		return NULL;
	}

	wl_list_init(&manager->contexts);
	wl_signal_init(&manager->events.destroy);
	wl_signal_init(&manager->events.commit);

	manager->display_destroy.notify = handle_display_destroy;
	wl_display_add_destroy_listener(display, &manager->display_destroy);

	return manager;
}

const struct wlr_security_context_v1_state *wlr_security_context_manager_v1_lookup_client(
		struct wlr_security_context_manager_v1 *manager, struct wl_client *client) {
	struct wl_listener *listener = wl_client_get_destroy_listener(client,
		security_context_client_handle_destroy);
	if (listener == NULL) {
		return NULL;
	}

	struct wlr_security_context_v1_client *security_context_client =
		wl_container_of(listener, security_context_client, destroy);
	return &security_context_client->state;
}
