/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "istream.h"
#include "dsync-mail.h"
#include "dsync-mailbox.h"
#include "dsync-mailbox-state.h"
#include "dsync-mailbox-tree.h"
#include "dsync-ibc-private.h"

enum item_type {
	ITEM_END_OF_LIST,
	ITEM_HANDSHAKE,
	ITEM_MAILBOX_STATE,
	ITEM_MAILBOX_TREE_NODE,
	ITEM_MAILBOX_DELETE,
	ITEM_MAILBOX,
	ITEM_MAILBOX_ATTRIBUTE,
	ITEM_MAIL_CHANGE,
	ITEM_MAIL_REQUEST,
	ITEM_MAIL,
	ITEM_FINISH
};

struct item {
	enum item_type type;
	pool_t pool;

	union {
		struct dsync_ibc_settings set;
		struct dsync_mailbox_state state;
		struct dsync_mailbox_node node;
		guid_128_t mailbox_guid;
		struct dsync_mailbox dsync_box;
		struct dsync_mailbox_attribute attr;
		struct dsync_mail_change change;
		struct dsync_mail_request request;
		struct dsync_mail mail;
		struct {
			const struct dsync_mailbox_delete *deletes;
			unsigned int count;
			char hierarchy_sep;
			char escape_char;
		} mailbox_delete;
		struct {
			const char *error;
			enum mail_error mail_error;
			bool require_full_resync;
		} finish;
	} u;
};

struct dsync_ibc_pipe {
	struct dsync_ibc ibc;

	ARRAY(pool_t) pools;
	ARRAY(struct item) item_queue;
	struct dsync_ibc_pipe *remote;

	pool_t pop_pool;
	struct item pop_item;
};

static pool_t dsync_ibc_pipe_get_pool(struct dsync_ibc_pipe *pipe)
{
	pool_t *pools, ret;
	unsigned int count;

	pools = array_get_modifiable(&pipe->pools, &count);
	if (count == 0)
		return pool_alloconly_create(MEMPOOL_GROWING"pipe item pool", 1024);

	ret = pools[count-1];
	array_delete(&pipe->pools, count-1, 1);
	p_clear(ret);
	return ret;
}

static struct item * ATTR_NOWARN_UNUSED_RESULT
dsync_ibc_pipe_push_item(struct dsync_ibc_pipe *pipe, enum item_type type)
{
	struct item *item;

	item = array_append_space(&pipe->item_queue);
	item->type = type;

	switch (type) {
	case ITEM_END_OF_LIST:
	case ITEM_MAILBOX_STATE:
	case ITEM_MAILBOX_DELETE:
		break;
	case ITEM_HANDSHAKE:
	case ITEM_MAILBOX:
	case ITEM_MAILBOX_TREE_NODE:
	case ITEM_MAILBOX_ATTRIBUTE:
	case ITEM_MAIL_CHANGE:
	case ITEM_MAIL_REQUEST:
	case ITEM_MAIL:
	case ITEM_FINISH:
		item->pool = dsync_ibc_pipe_get_pool(pipe);
		break;
	}
	return item;
}

static struct item *
dsync_ibc_pipe_pop_item(struct dsync_ibc_pipe *pipe, enum item_type type)
{
	struct item *item;

	if (array_count(&pipe->item_queue) == 0)
		return NULL;

	item = array_front_modifiable(&pipe->item_queue);
	i_assert(item->type == type);
	pipe->pop_item = *item;
	array_pop_front(&pipe->item_queue);
	item = NULL;

	pool_unref(&pipe->pop_pool);
	pipe->pop_pool = pipe->pop_item.pool;
	return &pipe->pop_item;
}

static bool dsync_ibc_pipe_try_pop_eol(struct dsync_ibc_pipe *pipe)
{
	const struct item *item;

	if (array_count(&pipe->item_queue) == 0)
		return FALSE;

	item = array_front(&pipe->item_queue);
	if (item->type != ITEM_END_OF_LIST)
		return FALSE;

	array_pop_front(&pipe->item_queue);
	return TRUE;
}

static void dsync_ibc_pipe_deinit(struct dsync_ibc *ibc)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;
	pool_t pool;

	if (pipe->remote != NULL) {
		i_assert(pipe->remote->remote == pipe);
		pipe->remote->remote = NULL;
	}

	pool_unref(&pipe->pop_pool);
	array_foreach_modifiable(&pipe->item_queue, item) {
		pool_unref(&item->pool);
	}
	array_foreach_elem(&pipe->pools, pool)
		pool_unref(&pool);
	array_free(&pipe->pools);
	array_free(&pipe->item_queue);
	i_free(pipe);
}

static void
dsync_ibc_pipe_send_handshake(struct dsync_ibc *ibc,
			      const struct dsync_ibc_settings *set)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_HANDSHAKE);
	item->u.set = *set;
	item->u.set.sync_ns_prefixes =
		p_strdup(item->pool, set->sync_ns_prefixes);
	item->u.set.sync_box = p_strdup(item->pool, set->sync_box);
	item->u.set.virtual_all_box = p_strdup(item->pool, set->virtual_all_box);
	item->u.set.exclude_mailboxes = set->exclude_mailboxes == NULL ? NULL :
		p_strarray_dup(item->pool, set->exclude_mailboxes);
	memcpy(item->u.set.sync_box_guid, set->sync_box_guid,
	       sizeof(item->u.set.sync_box_guid));
	item->u.set.sync_since_timestamp = set->sync_since_timestamp;
	item->u.set.sync_until_timestamp = set->sync_until_timestamp;
	item->u.set.sync_max_size = set->sync_max_size;
	item->u.set.sync_flags = p_strdup(item->pool, set->sync_flags);
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_handshake(struct dsync_ibc *ibc,
			      const struct dsync_ibc_settings **set_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_HANDSHAKE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*set_r = &item->u.set;
	return DSYNC_IBC_RECV_RET_OK;
}

static bool dsync_ibc_pipe_is_send_queue_full(struct dsync_ibc *ibc)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;

	return array_count(&pipe->remote->item_queue) > 0;
}

static bool dsync_ibc_pipe_has_pending_data(struct dsync_ibc *ibc)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;

	return array_count(&pipe->item_queue) > 0;
}

static void
dsync_ibc_pipe_send_end_of_list(struct dsync_ibc *ibc,
				enum dsync_ibc_eol_type type ATTR_UNUSED)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;

	dsync_ibc_pipe_push_item(pipe->remote, ITEM_END_OF_LIST);
}

static void
dsync_ibc_pipe_send_mailbox_state(struct dsync_ibc *ibc,
				  const struct dsync_mailbox_state *state)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAILBOX_STATE);
	item->u.state = *state;
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mailbox_state(struct dsync_ibc *ibc,
				  struct dsync_mailbox_state *state_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAILBOX_STATE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*state_r = item->u.state;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mailbox_tree_node(struct dsync_ibc *ibc,
				      const char *const *name,
				      const struct dsync_mailbox_node *node)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAILBOX_TREE_NODE);

	/* a little bit kludgy way to send it */
	item->u.node.name = (void *)p_strarray_dup(item->pool, name);
	dsync_mailbox_node_copy_data(&item->u.node, node);
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mailbox_tree_node(struct dsync_ibc *ibc,
				      const char *const **name_r,
				      const struct dsync_mailbox_node **node_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAILBOX_TREE_NODE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*name_r = (const void *)item->u.node.name;
	item->u.node.name = NULL;

	*node_r = &item->u.node;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mailbox_deletes(struct dsync_ibc *ibc,
				    const struct dsync_mailbox_delete *deletes,
				    unsigned int count, char hierarchy_sep,
				    char escape_char)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAILBOX_DELETE);

	/* we'll assume that the deletes are permanent. this works for now.. */
	/* a little bit kludgy way to send it */
	item->u.mailbox_delete.deletes = deletes;
	item->u.mailbox_delete.count = count;
	item->u.mailbox_delete.hierarchy_sep = hierarchy_sep;
	item->u.mailbox_delete.escape_char = escape_char;
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mailbox_deletes(struct dsync_ibc *ibc,
				    const struct dsync_mailbox_delete **deletes_r,
				    unsigned int *count_r,
				    char *hierarchy_sep_r,
				    char *escape_char_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAILBOX_DELETE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*deletes_r = item->u.mailbox_delete.deletes;
	*count_r = item->u.mailbox_delete.count;
	*hierarchy_sep_r = item->u.mailbox_delete.hierarchy_sep;
	*escape_char_r = item->u.mailbox_delete.escape_char;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mailbox(struct dsync_ibc *ibc,
			    const struct dsync_mailbox *dsync_box)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;
	const struct mailbox_cache_field *cf;
	struct mailbox_cache_field *ncf;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAILBOX);
	item->u.dsync_box = *dsync_box;
	p_array_init(&item->u.dsync_box.cache_fields, item->pool,
		     array_count(&dsync_box->cache_fields));
	array_foreach(&dsync_box->cache_fields, cf) {
		ncf = array_append_space(&item->u.dsync_box.cache_fields);
		ncf->name = p_strdup(item->pool, cf->name);
		ncf->decision = cf->decision;
		ncf->last_used = cf->last_used;
	}
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mailbox(struct dsync_ibc *ibc,
			    const struct dsync_mailbox **dsync_box_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAILBOX);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*dsync_box_r = &item->u.dsync_box;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mailbox_attribute(struct dsync_ibc *ibc,
				      const struct dsync_mailbox_attribute *attr)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAILBOX_ATTRIBUTE);
	dsync_mailbox_attribute_dup(item->pool, attr, &item->u.attr);
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mailbox_attribute(struct dsync_ibc *ibc,
				      const struct dsync_mailbox_attribute **attr_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAILBOX_ATTRIBUTE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*attr_r = &item->u.attr;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_change(struct dsync_ibc *ibc,
			   const struct dsync_mail_change *change)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAIL_CHANGE);
	dsync_mail_change_dup(item->pool, change, &item->u.change);
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_change(struct dsync_ibc *ibc,
			   const struct dsync_mail_change **change_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAIL_CHANGE);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*change_r = &item->u.change;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mail_request(struct dsync_ibc *ibc,
				 const struct dsync_mail_request *request)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAIL_REQUEST);
	item->u.request.guid = p_strdup(item->pool, request->guid);
	item->u.request.uid = request->uid;
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mail_request(struct dsync_ibc *ibc,
				 const struct dsync_mail_request **request_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAIL_REQUEST);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*request_r = &item->u.request;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_mail(struct dsync_ibc *ibc, const struct dsync_mail *mail)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_MAIL);
	item->u.mail.guid = p_strdup(item->pool, mail->guid);
	item->u.mail.uid = mail->uid;
	item->u.mail.pop3_uidl = p_strdup(item->pool, mail->pop3_uidl);
	item->u.mail.pop3_order = mail->pop3_order;
	item->u.mail.received_date = mail->received_date;
	if (mail->input != NULL) {
		item->u.mail.input = mail->input;
		i_stream_ref(mail->input);
	}
	item->u.mail.input_mail = mail->input_mail;
	item->u.mail.input_mail_uid = mail->input_mail_uid;
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_mail(struct dsync_ibc *ibc, struct dsync_mail **mail_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	if (dsync_ibc_pipe_try_pop_eol(pipe))
		return DSYNC_IBC_RECV_RET_FINISHED;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_MAIL);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*mail_r = &item->u.mail;
	return DSYNC_IBC_RECV_RET_OK;
}

static void
dsync_ibc_pipe_send_finish(struct dsync_ibc *ibc, const char *error,
			   enum mail_error mail_error,
			   bool require_full_resync)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_push_item(pipe->remote, ITEM_FINISH);
	item->u.finish.error = p_strdup(item->pool, error);
	item->u.finish.mail_error = mail_error;
	item->u.finish.require_full_resync = require_full_resync;
}

static enum dsync_ibc_recv_ret
dsync_ibc_pipe_recv_finish(struct dsync_ibc *ibc, const char **error_r,
			   enum mail_error *mail_error_r,
			   bool *require_full_resync_r)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;
	struct item *item;

	item = dsync_ibc_pipe_pop_item(pipe, ITEM_FINISH);
	if (item == NULL)
		return DSYNC_IBC_RECV_RET_TRYAGAIN;

	*error_r = item->u.finish.error;
	*mail_error_r = item->u.finish.mail_error;
	*require_full_resync_r = item->u.finish.require_full_resync;
	return DSYNC_IBC_RECV_RET_OK;
}

static void pipe_close_mail_streams(struct dsync_ibc_pipe *pipe)
{
	struct item *item;

	if (array_count(&pipe->item_queue) > 0) {
		item = array_front_modifiable(&pipe->item_queue);
		if (item->type == ITEM_MAIL &&
		    item->u.mail.input != NULL)
			i_stream_unref(&item->u.mail.input);
	}
}

static void dsync_ibc_pipe_close_mail_streams(struct dsync_ibc *ibc)
{
	struct dsync_ibc_pipe *pipe = (struct dsync_ibc_pipe *)ibc;

	pipe_close_mail_streams(pipe);
	pipe_close_mail_streams(pipe->remote);
}

static const struct dsync_ibc_vfuncs dsync_ibc_pipe_vfuncs = {
	dsync_ibc_pipe_deinit,
	dsync_ibc_pipe_send_handshake,
	dsync_ibc_pipe_recv_handshake,
	dsync_ibc_pipe_send_end_of_list,
	dsync_ibc_pipe_send_mailbox_state,
	dsync_ibc_pipe_recv_mailbox_state,
	dsync_ibc_pipe_send_mailbox_tree_node,
	dsync_ibc_pipe_recv_mailbox_tree_node,
	dsync_ibc_pipe_send_mailbox_deletes,
	dsync_ibc_pipe_recv_mailbox_deletes,
	dsync_ibc_pipe_send_mailbox,
	dsync_ibc_pipe_recv_mailbox,
	dsync_ibc_pipe_send_mailbox_attribute,
	dsync_ibc_pipe_recv_mailbox_attribute,
	dsync_ibc_pipe_send_change,
	dsync_ibc_pipe_recv_change,
	dsync_ibc_pipe_send_mail_request,
	dsync_ibc_pipe_recv_mail_request,
	dsync_ibc_pipe_send_mail,
	dsync_ibc_pipe_recv_mail,
	dsync_ibc_pipe_send_finish,
	dsync_ibc_pipe_recv_finish,
	dsync_ibc_pipe_close_mail_streams,
	dsync_ibc_pipe_is_send_queue_full,
	dsync_ibc_pipe_has_pending_data
};

static struct dsync_ibc_pipe *
dsync_ibc_pipe_alloc(void)
{
	struct dsync_ibc_pipe *pipe;

	pipe = i_new(struct dsync_ibc_pipe, 1);
	pipe->ibc.v = dsync_ibc_pipe_vfuncs;
	i_array_init(&pipe->pools, 4);
	i_array_init(&pipe->item_queue, 4);
	return pipe;
}

void dsync_ibc_init_pipe(struct dsync_ibc **ibc1_r, struct dsync_ibc **ibc2_r)
{
	struct dsync_ibc_pipe *pipe1, *pipe2;

	pipe1 = dsync_ibc_pipe_alloc();
	pipe2 = dsync_ibc_pipe_alloc();
	pipe1->remote = pipe2;
	pipe2->remote = pipe1;
	*ibc1_r = &pipe1->ibc;
	*ibc2_r = &pipe2->ibc;
}