/* Copyright (c) 2015-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "hash.h"
#include "http-client.h"
#include "http-url.h"
#include "ioloop.h"
#include "istream.h"
#include "settings-parser.h"
#include "json-parser.h"
#include "mailbox-attribute.h"
#include "mail-storage-private.h"
#include "str.h"
#include "strescape.h"
#include "iostream-ssl.h"

#include "push-notification-plugin.h"
#include "push-notification-drivers.h"
#include "push-notification-event-messagenew.h"
#include "push-notification-events.h"
#include "push-notification-txn-msg.h"

#define OX_METADATA_KEY \
	MAILBOX_ATTRIBUTE_PREFIX_DOVECOT_PVT_SERVER \
	"vendor/vendor.dovecot/http-notify"

/* Default values. */
static const char *const default_events[] = { "MessageNew", NULL };
static const char *const default_mboxes[] = { "INBOX", NULL };
#define DEFAULT_CACHE_LIFETIME_SECS 60
#define DEFAULT_TIMEOUT_MSECS 2000
#define DEFAULT_RETRY_COUNT 1

/* This is data that is shared by all plugin users. */
struct push_notification_driver_ox_global {
	struct http_client *http_client;
	int refcount;
};
static struct push_notification_driver_ox_global *ox_global = NULL;

/* This is data specific to an OX driver. */
struct push_notification_driver_ox_config {
	struct http_url *http_url;
	struct event *event;
	unsigned int cached_ox_metadata_lifetime_secs;
	bool use_unsafe_username;
	unsigned int http_max_retries;
	unsigned int http_timeout_msecs;

	char *cached_ox_metadata;
	time_t cached_ox_metadata_timestamp;
};

/* This is data specific to an OX driver transaction. */
struct push_notification_driver_ox_txn {
	const char *unsafe_user;
};

static void
push_notification_driver_ox_init_global(
	struct mail_user *user,
	struct push_notification_driver_ox_config *config)
{
	struct http_client_settings http_set;
	struct ssl_iostream_settings ssl_set;

	if (ox_global->http_client == NULL) {
		/* This is going to use the first user's settings, but these are
		   unlikely to change between users so it shouldn't matter much.
		 */
		i_zero(&http_set);
		http_set.debug = user->mail_debug;
		http_set.max_attempts = config->http_max_retries+1;
		http_set.request_timeout_msecs = config->http_timeout_msecs;
		http_set.event_parent = user->event;
		mail_user_init_ssl_client_settings(user, &ssl_set);
		http_set.ssl = &ssl_set;

		ox_global->http_client = http_client_init(&http_set);
	}
}

static int
push_notification_driver_ox_init(struct push_notification_driver_config *config,
				 struct mail_user *user, pool_t pool,
				 void **context, const char **error_r)
{
	struct push_notification_driver_ox_config *dconfig;
	const char *error, *tmp;

	/* Valid config keys: cache_lifetime, url */
	tmp = hash_table_lookup(config->config, (const char *)"url");
	if (tmp == NULL) {
		*error_r = "Driver requires the url parameter";
		return -1;
	}

	dconfig = p_new(pool, struct push_notification_driver_ox_config, 1);
	dconfig->event = event_create(user->event);
	event_add_category(dconfig->event, &event_category_push_notification);
	event_set_append_log_prefix(dconfig->event, "push-notification-ox: ");

	if (http_url_parse(tmp, NULL, HTTP_URL_ALLOW_USERINFO_PART, pool,
			   &dconfig->http_url, &error) < 0) {
		event_unref(&dconfig->event);
		*error_r = t_strdup_printf("Failed to parse OX REST URL %s: %s",
					   tmp, error);
		return -1;
	}
	dconfig->use_unsafe_username =
		hash_table_lookup(config->config,
				  (const char *)"user_from_metadata") != NULL;

	e_debug(dconfig->event, "Using URL %s", tmp);

	tmp = hash_table_lookup(config->config, (const char *)"cache_lifetime");
	if (tmp == NULL) {
		dconfig->cached_ox_metadata_lifetime_secs =
			DEFAULT_CACHE_LIFETIME_SECS;
	} else if (settings_get_time(
		tmp, &dconfig->cached_ox_metadata_lifetime_secs, &error) < 0) {
		event_unref(&dconfig->event);
		*error_r = t_strdup_printf(
			"Failed to parse OX cache_lifetime %s: %s", tmp, error);
		return -1;
	}

	tmp = hash_table_lookup(config->config, (const char *)"max_retries");
	if ((tmp == NULL) ||
	    (str_to_uint(tmp, &dconfig->http_max_retries) < 0)) {
		dconfig->http_max_retries = DEFAULT_RETRY_COUNT;
	}
	tmp = hash_table_lookup(config->config, (const char *)"timeout_msecs");
	if ((tmp == NULL) ||
	    (str_to_uint(tmp, &dconfig->http_timeout_msecs) < 0)) {
		dconfig->http_timeout_msecs = DEFAULT_TIMEOUT_MSECS;
	}

	e_debug(dconfig->event, "Using cache lifetime: %u",
		dconfig->cached_ox_metadata_lifetime_secs);

	if (ox_global == NULL) {
		ox_global = i_new(struct push_notification_driver_ox_global, 1);
		ox_global->refcount = 0;
	}

	++ox_global->refcount;
	*context = dconfig;

	return 0;
}

static const char *
push_notification_driver_ox_get_metadata(
	struct push_notification_driver_txn *dtxn)
{
	struct push_notification_driver_ox_config *dconfig =
		dtxn->duser->context;
	struct mail_attribute_value attr;
	struct mailbox *inbox;
	struct mail_namespace *ns;
	bool success = FALSE, use_existing_txn = FALSE;
	int ret;

	if ((dconfig->cached_ox_metadata != NULL) &&
	    ((dconfig->cached_ox_metadata_timestamp +
	      (time_t)dconfig->cached_ox_metadata_lifetime_secs) >
		ioloop_time)) {
		return dconfig->cached_ox_metadata;
	}

	/* Get canonical INBOX, where private server-level metadata is stored.
	 * See imap/cmd-getmetadata.c */
	if ((dtxn->ptxn->t != NULL) && dtxn->ptxn->mbox->inbox_user) {
		inbox = dtxn->ptxn->mbox;
		use_existing_txn = TRUE;
	} else {
		ns = mail_namespace_find_inbox(dtxn->ptxn->muser->namespaces);
		inbox = mailbox_alloc(ns->list, "INBOX", MAILBOX_FLAG_READONLY);
	}

	ret = mailbox_attribute_get(inbox, MAIL_ATTRIBUTE_TYPE_PRIVATE,
				    OX_METADATA_KEY, &attr);
	if (ret < 0) {
		e_error(dconfig->event,
			"Skipped because unable to get attribute: %s",
			mailbox_get_last_internal_error(inbox, NULL));
	} else if (ret == 0) {
		e_debug(dconfig->event,
			"Skipped because not active "
			"(/private/"OX_METADATA_KEY" METADATA not set)");
	} else {
		success = TRUE;
	}

	if (!use_existing_txn)
		mailbox_free(&inbox);
	if (!success)
		return NULL;

	i_free(dconfig->cached_ox_metadata);
	dconfig->cached_ox_metadata = i_strdup(attr.value);
	dconfig->cached_ox_metadata_timestamp = ioloop_time;

	return dconfig->cached_ox_metadata;
}

static bool
push_notification_driver_ox_begin_txn(struct push_notification_driver_txn *dtxn)
{
	const char *const *args;
	struct push_notification_event_messagenew_config *config;
	const char *key, *mbox_curr, *md_value, *value;
	bool mbox_found = FALSE;
	struct push_notification_driver_ox_txn *txn;
	struct push_notification_driver_ox_config *dconfig =
		dtxn->duser->context;

	md_value = push_notification_driver_ox_get_metadata(dtxn);
	if (md_value == NULL)
		return FALSE;

	/* Unused keys: events, expire, folder */
	/* TODO: To be implemented later(?) */
	const char *const *events = default_events;
	time_t expire = INT_MAX;
	const char *const *mboxes = default_mboxes;

	if (expire < ioloop_time) {
		e_debug(dconfig->event, "Skipped due to expiration (%ld < %ld)",
			(long)expire, (long)ioloop_time);
		return FALSE;
	}

	mbox_curr = mailbox_get_vname(dtxn->ptxn->mbox);
	for (; *mboxes != NULL; mboxes++) {
		if (strcmp(mbox_curr, *mboxes) == 0) {
			mbox_found = TRUE;
			break;
		}
	}

	if (mbox_found == FALSE) {
		e_debug(dconfig->event,
			"Skipped because %s is not a watched mailbox",
			mbox_curr);
		return FALSE;
	}

	txn = p_new(dtxn->ptxn->pool,
		    struct push_notification_driver_ox_txn, 1);

	/* Valid keys: user */
	args = t_strsplit_tabescaped(md_value);
	for (; *args != NULL; args++) {
		key = *args;

		value = strchr(key, '=');
		if (value != NULL) {
			key = t_strdup_until(key, value++);
			if (strcmp(key, "user") == 0) {
				txn->unsafe_user =
					p_strdup(dtxn->ptxn->pool, value);
			}
		}
	}

	if (txn->unsafe_user == NULL) {
		e_error(dconfig->event, "No user provided in config");
		return FALSE;
	}

	e_debug(dconfig->event, "User (%s)", txn->unsafe_user);

	for (; *events != NULL; events++) {
		if (strcmp(*events, "MessageNew") == 0) {
			config = p_new(
				dtxn->ptxn->pool,
				struct push_notification_event_messagenew_config, 1);
			config->flags = PUSH_NOTIFICATION_MESSAGE_HDR_FROM |
					PUSH_NOTIFICATION_MESSAGE_HDR_SUBJECT |
					PUSH_NOTIFICATION_MESSAGE_BODY_SNIPPET;
			push_notification_event_init(
				dtxn, "MessageNew", config);
			e_debug(dconfig->event, "Handling MessageNew event");
		}
	}

	dtxn->context = txn;

	return TRUE;
}

static void
push_notification_driver_ox_http_callback(
	const struct http_response *response,
	struct push_notification_driver_ox_config *dconfig)
{
	switch (response->status / 100) {
	case 2:
		// Success.
		e_debug(dconfig->event, "Notification sent successfully: %s",
			http_response_get_message(response));
		break;

	default:
		// Error.
		e_error(dconfig->event, "Error when sending notification: %s",
			http_response_get_message(response));
		break;
	}
}

/* Callback needed for i_stream_add_destroy_callback() in
   push_notification_driver_ox_process_msg. */
static void str_free_i(string_t *str)
{
	str_free(&str);
}

static int
push_notification_driver_ox_get_mailbox_status(
	struct push_notification_driver_txn *dtxn,
	struct mailbox_status *r_box_status)
{
	struct push_notification_driver_ox_config *dconfig =
		dtxn->duser->context;
	/* The already opened mailbox. We cannot use or sync it, because we are
	   within a save transaction. */
	struct mailbox *mbox = dtxn->ptxn->mbox;
	struct mailbox *box;
	int ret;

	/* Open and sync new instance of the same mailbox to get most recent
	   status */
	box = mailbox_alloc(mailbox_get_namespace(mbox)->list,
			    mailbox_get_name(mbox), MAILBOX_FLAG_READONLY);
	if (mailbox_sync(box, 0) < 0) {
		e_error(dconfig->event, "mailbox_sync(%s) failed: %s",
			mailbox_get_vname(mbox),
			mailbox_get_last_internal_error(box, NULL));
		ret = -1;
	} else {
		/* only 'unseen' is needed at the moment */
		mailbox_get_open_status(box, STATUS_UNSEEN, r_box_status);
		e_debug(dconfig->event,
			"Got status of mailbox '%s': (unseen: %u)",
			mailbox_get_vname(box), r_box_status->unseen);
		ret = 0;
	}

	mailbox_free(&box);
	return ret;
}


static void
push_notification_driver_ox_process_msg(
	struct push_notification_driver_txn *dtxn,
	struct push_notification_txn_msg *msg)
{
	struct push_notification_driver_ox_config *dconfig =
		(struct push_notification_driver_ox_config *)
			dtxn->duser->context;
	struct http_client_request *http_req;
	struct push_notification_event_messagenew_data *messagenew;
	struct istream *payload;
	string_t *str;
	struct push_notification_driver_ox_txn *txn =
		(struct push_notification_driver_ox_txn *)dtxn->context;
	struct mail_user *user = dtxn->ptxn->muser;
	struct mailbox_status box_status;
	bool status_success = TRUE;

	if (push_notification_driver_ox_get_mailbox_status(
		dtxn, &box_status) < 0) {
		status_success = FALSE;
	}

	messagenew = push_notification_txn_msg_get_eventdata(msg, "MessageNew");
	if (messagenew == NULL)
		return;

	push_notification_driver_ox_init_global(user, dconfig);

	http_req = http_client_request_url(
		ox_global->http_client, "PUT", dconfig->http_url,
		push_notification_driver_ox_http_callback, dconfig);
	http_client_request_set_event(http_req, dtxn->ptxn->event);
	http_client_request_add_header(http_req, "Content-Type",
				       "application/json; charset=utf-8");

	str = str_new(default_pool, 256);
	str_append(str, "{\"user\":\"");
	json_append_escaped(str, dconfig->use_unsafe_username ?
			    txn->unsafe_user : user->username);
	str_append(str, "\",\"event\":\"messageNew\",\"folder\":\"");
	json_append_escaped(str, msg->mailbox);
	str_printfa(str, "\",\"imap-uidvalidity\":%u,\"imap-uid\":%u",
		    msg->uid_validity, msg->uid);
	if (messagenew->from != NULL) {
		str_append(str, ",\"from\":\"");
		json_append_escaped(str, messagenew->from);
		str_append(str, "\"");
	}
	if (messagenew->subject != NULL) {
		str_append(str, ",\"subject\":\"");
		json_append_escaped(str, messagenew->subject);
		str_append(str, "\"");
	}
	if (messagenew->snippet != NULL) {
		str_append(str, ",\"snippet\":\"");
		json_append_escaped(str, messagenew->snippet);
		str_append(str, "\"");
	}
	if (status_success) {
		str_printfa(str, ",\"unseen\":%u", box_status.unseen);
	}
	str_append(str, "}");

	e_debug(dconfig->event, "Sending notification: %s", str_c(str));

	payload = i_stream_create_from_data(str_data(str), str_len(str));
	i_stream_add_destroy_callback(payload, str_free_i, str);
	http_client_request_set_payload(http_req, payload, FALSE);

	http_client_request_submit(http_req);
	i_stream_unref(&payload);
}

static void
push_notification_driver_ox_deinit(
	struct push_notification_driver_user *duser ATTR_UNUSED)
{
	struct push_notification_driver_ox_config *dconfig = duser->context;

	i_free(dconfig->cached_ox_metadata);
	if (ox_global != NULL) {
		if (ox_global->http_client != NULL)
			http_client_wait(ox_global->http_client);
		i_assert(ox_global->refcount > 0);
		--ox_global->refcount;
	}
	event_unref(&dconfig->event);
}

static void push_notification_driver_ox_cleanup(void)
{
	if ((ox_global != NULL) && (ox_global->refcount <= 0)) {
		if (ox_global->http_client != NULL) {
			http_client_deinit(&ox_global->http_client);
		}
		i_free_and_null(ox_global);
	}
}

/* Driver definition */

extern struct push_notification_driver push_notification_driver_ox;

struct push_notification_driver push_notification_driver_ox = {
	.name = "ox",
	.v = {
		.init = push_notification_driver_ox_init,
		.begin_txn = push_notification_driver_ox_begin_txn,
		.process_msg = push_notification_driver_ox_process_msg,
		.deinit = push_notification_driver_ox_deinit,
		.cleanup = push_notification_driver_ox_cleanup,
	},
};