/* Copyright (c) 2011-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "llist.h"
#include "hash.h"
#include "indexer-queue.h"

struct indexer_queue {
	indexer_queue_callback_t *callback;
	void (*listen_callback)(struct indexer_queue *);

	/* username+mailbox -> indexer_request */
	HASH_TABLE(struct indexer_request *, struct indexer_request *) requests;
	struct indexer_request *head, *tail;
};

static unsigned int
indexer_request_hash(const struct indexer_request *request)
{
	return str_hash(request->username) ^ str_hash(request->mailbox);
}

static int indexer_request_cmp(const struct indexer_request *r1,
			       const struct indexer_request *r2)
{
	return strcmp(r1->username, r2->username) == 0 &&
		strcmp(r1->mailbox, r2->mailbox) == 0 ? 0 : 1;
}

struct indexer_queue *
indexer_queue_init(indexer_queue_callback_t *callback)
{
	struct indexer_queue *queue;
	
	queue = i_new(struct indexer_queue, 1);
	queue->callback = callback;
	hash_table_create(&queue->requests, default_pool, 0,
			  indexer_request_hash, indexer_request_cmp);
	return queue;
}

void indexer_queue_deinit(struct indexer_queue **_queue)
{
	struct indexer_queue *queue = *_queue;

	*_queue = NULL;

	i_assert(indexer_queue_is_empty(queue));

	hash_table_destroy(&queue->requests);
	i_free(queue);
}

void indexer_queue_set_listen_callback(struct indexer_queue *queue,
				       void (*callback)(struct indexer_queue *))
{
	queue->listen_callback = callback;
}

static struct indexer_request *
indexer_queue_lookup(struct indexer_queue *queue,
		     const char *username, const char *mailbox)
{
	struct indexer_request lookup_request;

	lookup_request.username = (void *)username;
	lookup_request.mailbox = (void *)mailbox;
	return hash_table_lookup(queue->requests, &lookup_request);
}

static void request_add_context(struct indexer_request *request, void *context)
{
	if (context == NULL)
		return;

	if (!array_is_created(&request->contexts))
		i_array_init(&request->contexts, 2);
	array_push_back(&request->contexts, &context);
}

static struct indexer_request *
indexer_queue_append_request(struct indexer_queue *queue, bool append,
			     const char *username, const char *mailbox,
			     const char *session_id,
			     unsigned int max_recent_msgs, void *context)
{
	struct indexer_request *request;

	request = indexer_queue_lookup(queue, username, mailbox);
	if (request == NULL) {
		request = i_new(struct indexer_request, 1);
		request->username = i_strdup(username);
		request->mailbox = i_strdup(mailbox);
		request->session_id = i_strdup(session_id);
		request->max_recent_msgs = max_recent_msgs;
		request_add_context(request, context);
		hash_table_insert(queue->requests, request, request);
	} else {
		if (request->max_recent_msgs > max_recent_msgs)
			request->max_recent_msgs = max_recent_msgs;
		request_add_context(request, context);
		if (request->working) {
			/* we're already indexing this mailbox. */
			if (append)
				request->reindex_tail = TRUE;
			else
				request->reindex_head = TRUE;
			return request;
		}
		if (append) {
			/* keep the request in its old position */
			return request;
		}
		/* move request to beginning of the queue */
		DLLIST2_REMOVE(&queue->head, &queue->tail, request);
	}

	if (append)
		DLLIST2_APPEND(&queue->head, &queue->tail, request);
	else
		DLLIST2_PREPEND(&queue->head, &queue->tail, request);
	return request;
}

static void indexer_queue_append_finish(struct indexer_queue *queue)
{
	if (queue->listen_callback != NULL)
		queue->listen_callback(queue);
	indexer_refresh_proctitle();
}

void indexer_queue_append(struct indexer_queue *queue, bool append,
			  const char *username, const char *mailbox,
			  const char *session_id, unsigned int max_recent_msgs,
			  void *context)
{
	struct indexer_request *request;

	request = indexer_queue_append_request(queue, append, username, mailbox,
					       session_id, max_recent_msgs,
					       context);
	request->index = TRUE;
	indexer_queue_append_finish(queue);
}

void indexer_queue_append_optimize(struct indexer_queue *queue,
				   const char *username, const char *mailbox,
				   void *context)
{
	struct indexer_request *request;

	request = indexer_queue_append_request(queue, TRUE, username, mailbox,
					       NULL, 0, context);
	request->optimize = TRUE;
	indexer_queue_append_finish(queue);
}

struct indexer_request *indexer_queue_request_peek(struct indexer_queue *queue)
{
	return queue->head;
}

void indexer_queue_request_remove(struct indexer_queue *queue)
{
	struct indexer_request *request = queue->head;

	i_assert(request != NULL);

	DLLIST2_REMOVE(&queue->head, &queue->tail, request);
}

static void indexer_queue_request_status_int(struct indexer_queue *queue,
					     struct indexer_request *request,
					     int percentage)
{
	void *context;
	unsigned int i;

	for (i = 0; i < request->working_context_idx; i++) {
		context = array_idx_elem(&request->contexts, i);
		queue->callback(percentage, context);
	}
}

void indexer_queue_request_status(struct indexer_queue *queue,
				  struct indexer_request *request,
				  int percentage)
{
	i_assert(percentage >= 0 && percentage < 100);

	indexer_queue_request_status_int(queue, request, percentage);
}

void indexer_queue_move_head_to_tail(struct indexer_queue *queue)
{
	struct indexer_request *request = queue->head;

	indexer_queue_request_remove(queue);
	DLLIST2_APPEND(&queue->head, &queue->tail, request);
}

void indexer_queue_request_work(struct indexer_request *request)
{
	request->working = TRUE;
	request->working_context_idx =
		!array_is_created(&request->contexts) ? 0 :
		array_count(&request->contexts);
}

void indexer_queue_request_finish(struct indexer_queue *queue,
				  struct indexer_request **_request,
				  bool success)
{
	struct indexer_request *request = *_request;

	*_request = NULL;

	indexer_queue_request_status_int(queue, request, success ? 100 : -1);

	if (request->reindex_head || request->reindex_tail) {
		i_assert(request->working);
		request->working = FALSE;
		request->reindex_head = FALSE;
		request->reindex_tail = FALSE;
		if (request->working_context_idx > 0) {
			array_delete(&request->contexts, 0,
				     request->working_context_idx);
		}
		if (request->reindex_head)
			DLLIST2_PREPEND(&queue->head, &queue->tail, request);
		else
			DLLIST2_APPEND(&queue->head, &queue->tail, request);
		return;
	}

	hash_table_remove(queue->requests, request);
	if (array_is_created(&request->contexts))
		array_free(&request->contexts);
	i_free(request->username);
	i_free(request->mailbox);
	i_free(request->session_id);
	i_free(request);

	indexer_refresh_proctitle();
}

void indexer_queue_cancel_all(struct indexer_queue *queue)
{
	struct indexer_request *request;
	struct hash_iterate_context *iter;

	/* remove all reindex-markers so when the current requests finish
	   (or are cancelled) we don't try to retry them (especially during
	   deinit where it crashes) */
	iter = hash_table_iterate_init(queue->requests);
	while (hash_table_iterate(iter, queue->requests, &request, &request))
		request->reindex_head = request->reindex_tail = FALSE;
	hash_table_iterate_deinit(&iter);

	while ((request = indexer_queue_request_peek(queue)) != NULL) {
		indexer_queue_request_remove(queue);
		indexer_queue_request_finish(queue, &request, FALSE);
	}
}

bool indexer_queue_is_empty(struct indexer_queue *queue)
{
	return queue->head == NULL;
}

unsigned int indexer_queue_count(struct indexer_queue *queue)
{
	return hash_table_count(queue->requests);
}