/* Copyright (C) 2003-2004 Timo Sirainen */

#include "lib.h"
#include "array.h"
#include "buffer.h"
#include "mail-index-view-private.h"
#include "mail-transaction-log.h"

void mail_index_view_clone(struct mail_index_view *dest,
			   const struct mail_index_view *src)
{
	memset(dest, 0, sizeof(dest));
	dest->refcount = 1;
	dest->v = src->v;
	dest->index = src->index;
	if (src->log_view != NULL) {
		dest->log_view =
			mail_transaction_log_view_open(src->index->log);
	}

	dest->indexid = src->indexid;
	dest->map = src->map;
	if (dest->map != NULL)
		dest->map->refcount++;

	dest->log_file_expunge_seq = src->log_file_expunge_seq;
	dest->log_file_expunge_offset = src->log_file_expunge_offset;
	dest->log_file_head_seq = src->log_file_head_seq;
	dest->log_file_head_offset = src->log_file_head_offset;

	i_array_init(&dest->module_contexts,
		     I_MIN(5, mail_index_module_register.id));
}

void mail_index_view_ref(struct mail_index_view *view)
{
	view->refcount++;
}

static void _view_close(struct mail_index_view *view)
{
	i_assert(view->refcount == 0);

	/* we're not unlocking the view, because views could be temporarily
	   created and closed and the current map should stay locked
	   (especially syncing) */
	mail_transaction_log_view_close(&view->log_view);

	if (array_is_created(&view->syncs_hidden))
		array_free(&view->syncs_hidden);
	mail_index_unmap(&view->map);
	if (array_is_created(&view->map_refs)) {
		mail_index_view_unref_maps(view);
		array_free(&view->map_refs);
	}
	array_free(&view->module_contexts);
	i_free(view);
}

#ifdef DEBUG
static void mail_index_view_check_nextuid(struct mail_index_view *view)
{
	struct mail_index_record *rec;

	if (view->map->hdr.messages_count == 0)
		return;

	rec = MAIL_INDEX_MAP_IDX(view->map, view->map->hdr.messages_count-1);
	i_assert(rec->uid < view->map->hdr.next_uid);
}
#endif

void mail_index_view_unlock(struct mail_index_view *view __attr_unused__)
{
#ifdef DEBUG
	mail_index_view_check_nextuid(view);
#endif

	/* currently this is a no-op. if we unlock any maps, they might get
	   changed and then it's unspecified what parts of the memory mapping
	   are up-to-date. we could also copy the map to memory always, but
	   that kinds of defeats the purpose of mmaps. */
}

bool mail_index_view_is_inconsistent(struct mail_index_view *view)
{
	if (view->index->indexid != view->indexid)
		view->inconsistent = TRUE;
	return view->inconsistent;
}

struct mail_index *mail_index_view_get_index(struct mail_index_view *view)
{
	return view->index;
}

void mail_index_view_transaction_ref(struct mail_index_view *view)
{
	view->transactions++;
}

void mail_index_view_transaction_unref(struct mail_index_view *view)
{
	i_assert(view->transactions > 0);

	view->transactions--;
}

static void mail_index_view_ref_map(struct mail_index_view *view,
				    struct mail_index_map *map)
{
	struct mail_index_map *const *maps;
	unsigned int i, count;

	if (array_is_created(&view->map_refs)) {
		maps = array_get(&view->map_refs, &count);

		/* if map is already referenced, do nothing */
		for (i = 0; i < count; i++) {
			if (maps[i] == map)
				return;
		}
	} else {
		i_array_init(&view->map_refs, 4);
	}

	/* reference the given mapping. the reference is dropped when the view
	   is synchronized or closed. */
	map->refcount++;
	array_append(&view->map_refs, &map, 1);
}

void mail_index_view_unref_maps(struct mail_index_view *view)
{
	struct mail_index_map **maps;
	unsigned int i, count;

	if (!array_is_created(&view->map_refs))
		return;

	maps = array_get_modifiable(&view->map_refs, &count);
	for (i = 0; i < count; i++)
		mail_index_unmap(&maps[i]);

	array_clear(&view->map_refs);
}

static uint32_t _view_get_messages_count(struct mail_index_view *view)
{
	return view->map->hdr.messages_count;
}

static const struct mail_index_header *
_view_get_header(struct mail_index_view *view)
{
	return &view->map->hdr;
}

static int _view_lookup_full(struct mail_index_view *view, uint32_t seq,
			     struct mail_index_map **map_r,
			     const struct mail_index_record **rec_r)
{
	struct mail_index_map *map;
	const struct mail_index_record *rec, *head_rec;

	i_assert(seq > 0 && seq <= mail_index_view_get_messages_count(view));

	if (mail_index_map_lock(view->map) < 0)
		return -1;

	/* look up the record */
	rec = MAIL_INDEX_MAP_IDX(view->map, seq-1);
	if (rec->uid == 0) {
		mail_index_set_error(view->index, "Corrupted Index file %s: "
			"Record [%u].uid=0", view->index->filepath, seq);
		mail_index_mark_corrupted(view->index);
		return -1;
	}
	if (view->map == view->index->map) {
		/* view's mapping is latest. we can use it directly. */
		*map_r = view->map;
		*rec_r = rec;
		return 1;
	}

	/* look up the record from head mapping. it may contain some changes. */
	if (mail_index_map_lock(view->index->map) < 0)
		return -1;

	/* start looking up from the same sequence as in the old view.
	   if there are no expunges, it's there. otherwise it's somewhere
	   before (since records can't be inserted).

	   usually there are only a few expunges, so just going downwards from
	   our initial sequence position is probably faster than binary
	   search. */
	if (seq > view->index->map->hdr.messages_count)
		seq = view->index->map->hdr.messages_count;
	if (seq == 0) {
		/* everything is expunged from head. use the old record. */
		*map_r = view->map;
		*rec_r = rec;
		return 0;
	}

	map = view->index->map;
	do {
		seq--;
		head_rec = MAIL_INDEX_MAP_IDX(map, seq);
		if (head_rec->uid <= rec->uid)
			break;
	} while (seq > 0);

	if (head_rec->uid == rec->uid) {
		/* found it. use it. reference the index mapping so that the
		   returned record doesn't get invalidated after next sync. */
		mail_index_view_ref_map(view, view->index->map);
		*map_r = view->index->map;
		*rec_r = head_rec;
		return 1;
	} else {
		/* expuned from head. use the old record. */
		*map_r = view->map;
		*rec_r = rec;
		return 0;
	}
}

static int _view_lookup_uid(struct mail_index_view *view, uint32_t seq,
			    uint32_t *uid_r)
{
	i_assert(seq > 0 && seq <= mail_index_view_get_messages_count(view));

	/* UID lookups don't require the view to be locked. only expunges
	   change them, and expunges will recreate the file */
	*uid_r = MAIL_INDEX_MAP_IDX(view->map, seq-1)->uid;
	return 0;
}

static uint32_t mail_index_bsearch_uid(struct mail_index_view *view,
				       uint32_t uid, uint32_t left_idx,
				       int nearest_side)
{
	const struct mail_index_record *rec_base, *rec;
	uint32_t idx, right_idx, record_size;

	i_assert(view->map->hdr.messages_count <=
		 view->map->rec_map->records_count);

	if (uid == 1) {
		/* optimization: the message can be only the first one */
		return 1;
	}
	rec_base = view->map->rec_map->records;
	record_size = view->map->hdr.record_size;

	idx = left_idx;
	right_idx = view->map->hdr.messages_count;

	while (left_idx < right_idx) {
		idx = (left_idx + right_idx) / 2;

                rec = CONST_PTR_OFFSET(rec_base, idx * record_size);
		if (rec->uid < uid)
			left_idx = idx+1;
		else if (rec->uid > uid)
			right_idx = idx;
		else
			break;
	}
	i_assert(idx < view->map->hdr.messages_count);

	rec = CONST_PTR_OFFSET(rec_base, idx * record_size);
	if (rec->uid != uid) {
		if (nearest_side > 0) {
			/* we want uid or larger */
			return rec->uid > uid ? idx+1 :
				(idx == view->map->hdr.messages_count-1 ?
				 0 : idx+2);
		} else {
			/* we want uid or smaller */
			return rec->uid < uid ? idx + 1 : idx;
		}
	}

	return idx+1;
}

static int _view_lookup_uid_range(struct mail_index_view *view,
				  uint32_t first_uid, uint32_t last_uid,
				  uint32_t *first_seq_r, uint32_t *last_seq_r)
{
	i_assert(first_uid > 0);
	i_assert(first_uid <= last_uid);

	/* no locking needed for UIDs, see _view_lookup_uid() */
	if (view->map->hdr.messages_count == 0) {
		*first_seq_r = *last_seq_r = 0;
		return 0;
	}

	*first_seq_r = mail_index_bsearch_uid(view, first_uid, 0, 1);
	if (*first_seq_r == 0 ||
	    MAIL_INDEX_MAP_IDX(view->map, *first_seq_r-1)->uid > last_uid) {
		*first_seq_r = *last_seq_r = 0;
		return 0;
	}

	if (last_uid >= view->map->hdr.next_uid-1) {
		/* we want the last message */
		last_uid = view->map->hdr.next_uid-1;
		if (first_uid > last_uid) {
			*first_seq_r = *last_seq_r = 0;
			return 0;
		}

		*last_seq_r = view->map->hdr.messages_count;
		return 0;
	}

	if (first_uid == last_uid)
		*last_seq_r = *first_seq_r;
	else {
		/* optimization - binary lookup only from right side: */
		*last_seq_r = mail_index_bsearch_uid(view, last_uid,
						     *first_seq_r - 1, -1);
	}
	i_assert(*last_seq_r >= *first_seq_r);
	return 0;
}

static int _view_lookup_first(struct mail_index_view *view,
			      enum mail_flags flags, uint8_t flags_mask,
			      uint32_t *seq_r)
{
#define LOW_UPDATE(x) \
	STMT_START { if ((x) > low_uid) low_uid = x; } STMT_END
	const struct mail_index_record *rec;
	uint32_t seq, low_uid = 1;

	*seq_r = 0;

	if ((flags_mask & MAIL_SEEN) != 0 && (flags & MAIL_SEEN) == 0)
		LOW_UPDATE(view->map->hdr.first_unseen_uid_lowwater);
	if ((flags_mask & MAIL_DELETED) != 0 && (flags & MAIL_DELETED) != 0)
		LOW_UPDATE(view->map->hdr.first_deleted_uid_lowwater);

	if (low_uid == 1)
		seq = 1;
	else {
		if (mail_index_lookup_uid_range(view, low_uid, low_uid,
						&seq, &seq) < 0)
			return -1;

		if (seq == 0)
			return 0;
	}

	i_assert(view->map->hdr.messages_count <=
		 view->map->rec_map->records_count);

	/* we can delay locking until we're looking at the flags */
	if (mail_index_map_lock(view->map) < 0)
		return -1;

	for (; seq <= view->map->hdr.messages_count; seq++) {
		rec = MAIL_INDEX_MAP_IDX(view->map, seq-1);
		if ((rec->flags & flags_mask) == (uint8_t)flags) {
			*seq_r = seq;
			break;
		}
	}

	return 0;
}

static int _view_lookup_ext_full(struct mail_index_view *view, uint32_t seq,
				 uint32_t ext_id, struct mail_index_map **map_r,
				 const void **data_r)
{
	const struct mail_index_ext *ext;
	const struct mail_index_record *rec;
	uint32_t idx, offset;
	int ret;

	if ((ret = mail_index_lookup_full(view, seq, map_r, &rec)) < 0)
		return -1;

	if (rec == NULL || !mail_index_map_get_ext_idx(*map_r, ext_id, &idx)) {
		*data_r = NULL;
		return ret;
	}

	ext = array_idx(&(*map_r)->extensions, idx);
	offset = ext->record_offset;

	*data_r = offset == 0 ? NULL : CONST_PTR_OFFSET(rec, offset);
	return ret;
}

static int _view_get_header_ext(struct mail_index_view *view,
				struct mail_index_map *map, uint32_t ext_id,
				const void **data_r, size_t *data_size_r)
{
	const struct mail_index_ext *ext;
	uint32_t idx;

	if (map == NULL) {
		/* no mapping given, use head mapping */
		map = view->index->map;
	}

	if (mail_index_map_lock(map) < 0)
		return -1;

	if (!mail_index_map_get_ext_idx(map, ext_id, &idx)) {
		/* extension doesn't exist in this index file */
		*data_r = NULL;
		*data_size_r = 0;
		return 0;
	}

	ext = array_idx(&map->extensions, idx);
	*data_r = CONST_PTR_OFFSET(map->hdr_base, ext->hdr_offset);
	*data_size_r = ext->hdr_size;
	return 0;
}

void mail_index_view_close(struct mail_index_view **_view)
{
	struct mail_index_view *view = *_view;

	*_view = NULL;
	if (--view->refcount > 0)
		return;

	i_assert(view->transactions == 0);

	view->v.close(view);
}

uint32_t mail_index_view_get_messages_count(struct mail_index_view *view)
{
	return view->v.get_messages_count(view);
}

const struct mail_index_header *
mail_index_get_header(struct mail_index_view *view)
{
	return view->v.get_header(view);
}

int mail_index_lookup(struct mail_index_view *view, uint32_t seq,
		      const struct mail_index_record **rec_r)
{
	struct mail_index_map *map;

	return mail_index_lookup_full(view, seq, &map, rec_r);
}

int mail_index_lookup_full(struct mail_index_view *view, uint32_t seq,
			   struct mail_index_map **map_r,
			   const struct mail_index_record **rec_r)
{
	return view->v.lookup_full(view, seq, map_r, rec_r);
}

int mail_index_lookup_keywords(struct mail_index_view *view, uint32_t seq,
			       ARRAY_TYPE(keyword_indexes) *keyword_idx)
{
	struct mail_index_map *map;
	const void *data;
	const unsigned char *keyword_data;
	const unsigned int *keyword_idx_map;
	unsigned int i, j, keyword_count, index_idx;
	uint32_t ext_id, idx;
	uint16_t record_size;
	int ret;

	array_clear(keyword_idx);

	/* get the keywords data. */
	ext_id = view->index->keywords_ext_id;
	ret = mail_index_lookup_ext_full(view, seq, ext_id, &map, &data);
	if (ret < 0)
		return -1;

	if (data == NULL) {
		/* no keywords at all in index */
		return ret;
	}

	(void)mail_index_ext_get_size(view, ext_id, map, NULL,
				      &record_size, NULL);

	/* keyword_idx_map[] contains file => index keyword mapping */
	if (!array_is_created(&map->keyword_idx_map)) {
		keyword_idx_map = NULL;
		keyword_count = 0;
	} else {
		keyword_idx_map = array_get(&map->keyword_idx_map,
					    &keyword_count);
	}

        keyword_data = data;
	for (i = 0, idx = 0; i < record_size; i++) {
		/* first do the quick check to see if there's keywords at all */
		if (keyword_data[i] == 0)
			continue;

		idx = i * CHAR_BIT;
		for (j = 0; j < CHAR_BIT; j++, idx++) {
			if ((keyword_data[i] & (1 << j)) == 0)
				continue;

			if (idx >= keyword_count) {
				/* keyword header was updated, parse it again
				   it so we know what this keyword is called */
				if (mail_index_map_parse_keywords(map) < 0)
					return -1;

				if (!array_is_created(&map->keyword_idx_map))
					return ret;

				/* pointer may have changed. update it. */
				keyword_idx_map =
					array_get(&map->keyword_idx_map,
						  &keyword_count);

				if (idx >= keyword_count) {
					/* extra bits set in keyword bytes.
					   shouldn't happen, but just ignore. */
					break;
				}
			}

			index_idx = keyword_idx_map[idx];
			array_append(keyword_idx, &index_idx, 1);
		}
	}
	return ret;
}

int mail_index_lookup_uid(struct mail_index_view *view, uint32_t seq,
			  uint32_t *uid_r)
{
	return view->v.lookup_uid(view, seq, uid_r);
}

int mail_index_lookup_uid_range(struct mail_index_view *view,
				uint32_t first_uid, uint32_t last_uid,
				uint32_t *first_seq_r, uint32_t *last_seq_r)
{
	return view->v.lookup_uid_range(view, first_uid, last_uid,
					first_seq_r, last_seq_r);
}

int mail_index_lookup_first(struct mail_index_view *view, enum mail_flags flags,
			    uint8_t flags_mask, uint32_t *seq_r)
{
	return view->v.lookup_first(view, flags, flags_mask, seq_r);
}

int mail_index_lookup_ext(struct mail_index_view *view, uint32_t seq,
			  uint32_t ext_id, const void **data_r)
{
	struct mail_index_map *map;

	return view->v.lookup_ext_full(view, seq, ext_id, &map, data_r);
}

int mail_index_lookup_ext_full(struct mail_index_view *view, uint32_t seq,
			       uint32_t ext_id, struct mail_index_map **map_r,
			       const void **data_r)
{
	return view->v.lookup_ext_full(view, seq, ext_id, map_r, data_r);
}

int mail_index_get_header_ext(struct mail_index_view *view, uint32_t ext_id,
			      const void **data_r, size_t *data_size_r)
{
	return view->v.get_header_ext(view, NULL, ext_id, data_r, data_size_r);
}

int mail_index_map_get_header_ext(struct mail_index_view *view,
				  struct mail_index_map *map, uint32_t ext_id,
				  const void **data_r, size_t *data_size_r)
{
	return view->v.get_header_ext(view, map, ext_id, data_r, data_size_r);
}

int mail_index_ext_get_size(struct mail_index_view *view __attr_unused__,
			    uint32_t ext_id, struct mail_index_map *map,
			    uint32_t *hdr_size_r, uint16_t *record_size_r,
			    uint16_t *record_align_r)
{
	const struct mail_index_ext *ext;
	uint32_t idx;

	i_assert(map != NULL);

	if (!mail_index_map_get_ext_idx(map, ext_id, &idx)) {
		/* extension doesn't exist in this index file */
		if (hdr_size_r != NULL)
			*hdr_size_r = 0;
		if (record_size_r != NULL)
			*record_size_r = 0;
		if (record_align_r != NULL)
			*record_align_r = 0;
		return 0;
	}

	ext = array_idx(&map->extensions, idx);
	if (hdr_size_r != NULL)
		*hdr_size_r = ext->hdr_size;
	if (record_size_r != NULL)
		*record_size_r = ext->record_size;
	if (record_align_r != NULL)
		*record_align_r = ext->record_align;
	return 0;
}

static struct mail_index_view_vfuncs view_vfuncs = {
	_view_close,
	_view_get_messages_count,
	_view_get_header,
	_view_lookup_full,
	_view_lookup_uid,
	_view_lookup_uid_range,
	_view_lookup_first,
	_view_lookup_ext_full,
	_view_get_header_ext
};

struct mail_index_view *
mail_index_view_open_with_map(struct mail_index *index,
			      struct mail_index_map *map)
{
	struct mail_index_view *view;

	view = i_new(struct mail_index_view, 1);
	view->refcount = 1;
	view->v = view_vfuncs;
	view->index = index;
	view->log_view = mail_transaction_log_view_open(index->log);

	view->indexid = index->indexid;
	view->map = map;
	view->map->refcount++;

	view->log_file_expunge_seq = view->log_file_head_seq =
		view->map->hdr.log_file_seq;
	view->log_file_expunge_offset = view->log_file_head_offset =
		view->map->hdr.log_file_head_offset;

	i_array_init(&view->module_contexts,
		     I_MIN(5, mail_index_module_register.id));
	return view;
}

struct mail_index_view *mail_index_view_open(struct mail_index *index)
{
	return mail_index_view_open_with_map(index, index->map);
}

const struct mail_index_ext *
mail_index_view_get_ext(struct mail_index_view *view, uint32_t ext_id)
{
	uint32_t idx;

	if (!mail_index_map_get_ext_idx(view->map, ext_id, &idx))
		return 0;

	return array_idx(&view->map->extensions, idx);
}