--[[
	Auctioneer Addon for World of Warcraft(tm).
	Version: <%version%> (<%codename%>)
	Revision: $Id: AucSnapshotDB.lua 1260 2006-12-27 16:49:51Z norganna $

	SnapshotDB - the AH snapshot database

	License:
		This program is free software; you can redistribute it and/or
		modify it under the terms of the GNU General Public License
		as published by the Free Software Foundation; either version 2
		of the License, or (at your option) any later version.

		This program is distributed in the hope that it will be useful,
		but WITHOUT ANY WARRANTY; without even the implied warranty of
		MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
		GNU General Public License for more details.

		You should have received a copy of the GNU General Public License
		along with this program(see GPL.txt); if not, write to the Free Software
		Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

	Note:
		This AddOn's source code is specifically designed to work with
		World of Warcraft's interpreted AddOn system.
		You have an implicit licence to use this AddOn with these facilities
		since that is it's designated purpose as per:
		http://www.fsf.org/licensing/licenses/gpl-faq.html#InterpreterIncompat
]]

-------------------------------------------------------------------------------
-- Function Imports
-------------------------------------------------------------------------------
local tonumber = tonumber;

local chatPrint = Auctioneer.Util.ChatPrint;
local nilSafe = Auctioneer.Database.NilSafeStringFromString;
local stringFromBoolean = Auctioneer.Database.StringFromBoolean;
local booleanFromString = Auctioneer.Database.BooleanFromString;
local stringFromNumber = Auctioneer.Database.StringFromNumber;
local nilSafeStringFromString = Auctioneer.Database.NilSafeStringFromString;
local stringFromNilSafeString = Auctioneer.Database.StringFromNilSafeString;

-------------------------------------------------------------------------------
-- Function Prototypes
-------------------------------------------------------------------------------
local load;

local loadDatabase;
local createDatabase;
local createAHDatabase;
local upgradeAHDatabase;
local getAHDatabase;
local clear;

local updateForQuery;
local updateForSignature;
local updateAuction;
local addAuction;
local removeAuction;
local query;
local queryWithItemKey;
local getAuctionsForItem;
local getAuctionById;
local getCurrentBid;
local doesItemKeyMatchQuery;
local reconcileAuctionsForSignature;
local reconcileAuction;
local getTimeLeft;
local getMaxBids;
local getNextAuctionId;
local getAuctionIdsForItemKey;
local addAuctionToSnapshot;
local updateAuctionInSnapshot;
local removeAuctionFromSnapshot;
local packAuction;
local unpackAuction;
local isValidAuction;

local createAuctionSignatureFromAuction;
local breakAuctionSignature;
local createItemKeyFromAuctionSignature;

local addUpdate;
local removeSubsetUpdates;
local getLastUpdate;
local isUpdateSubsetOfUpdate;
local createUpdateFromQuery;
local packUpdate;
local unpackUpdate;

local debugPrint;

-------------------------------------------------------------------------------
-- Data Members
-------------------------------------------------------------------------------
-- The Auctioneer snapshot database saved on disk. Nobody should access this
-- variable outside of the loadDatabase() method. Instead the LoadedSnapshotDB
-- variable should be used.
AuctioneerSnapshotDB = nil;

-- The current Auctioneer history database as determined in the load() method.
-- This is either the database on disk or a temporary database if the user
-- chose not to upgrade their database.
local LoadedSnapshotDB;

-------------------------------------------------------------------------------
-- Constants
-------------------------------------------------------------------------------

-- The current version of the snapshot database. This number must be incremented
-- anytime a change is made to the database schema.
local CURRENT_SNAPSHOTDB_VERSION = 1; -- Auctioneer 4.0

-- Map of time left index to time left seconds.
local TimeLeftInSeconds = Auctioneer.Core.Constants.TimeLeft.Seconds

-- Schema for records in the auctions table of the snapshot database.
local AuctionMetaData = {
	{
		fieldName = "itemId";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "suffixId";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "enchantId";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "uniqueId";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "count";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "minBid";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "buyoutPrice";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "owner";
		fromStringFunc = stringFromNilSafeString;
		toStringFunc = nilSafeStringFromString;
	},
	{
		fieldName = "bidAmount";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "highBidder";
		fromStringFunc = booleanFromString;
		toStringFunc = stringFromBoolean;
	},
	{
		fieldName = "timeLeft";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "lastSeen";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "expiration";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
};

-- Schema for records in the update history table of the snapshot database.
local UpdateMetaData = {
	{
		fieldName = "date";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "name";
		fromStringFunc = stringFromNilSafeString;
		toStringFunc = nilSafeStringFromString;
	},
	{
		fieldName = "minLevel";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "maxLevel";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "invTypeIndex";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "classIndex";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "subclassIndex";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
	{
		fieldName = "qualityIndex";
		fromStringFunc = tonumber;
		toStringFunc = stringFromNumber;
	},
};

-------------------------------------------------------------------------------
-- Loads this module.
-------------------------------------------------------------------------------
function load(usePersistentDatabase)
	-- Decide what database to use. If the user has an older database and they
	-- choose not to upgrade, we cannot use it. Insetad we'll use a temporary
	-- empty database that will not be saved.
	if (usePersistentDatabase) then
		loadDatabase();
	else
		debugPrint("Using temporary AuctioneerSnapshotDB");
		LoadedSnapshotDB = createDatabase();
	end

end

--=============================================================================
-- Database management functions
--=============================================================================

-------------------------------------------------------------------------------
-- Upgrades the AuctioneerSnapshotDB database. If the table does not exist
-- it creates a new one.
-------------------------------------------------------------------------------
function loadDatabase()
	-- Create the root AuctioneerSnapshotDB table, if needed.
	if (not AuctioneerSnapshotDB) then
		AuctioneerSnapshotDB = createDatabase();
		debugPrint("Created AuctioneerSnapshotDB database");
	end

	-- Upgrade each realm-faction database, if needed.
	for ahKey in pairs(AuctioneerSnapshotDB) do
		if (not upgradeAHDatabase(AuctioneerSnapshotDB[ahKey])) then
			debugPrint("WARNING: Snapshot database corrupted for", ahKey, "! Creating new database.");
			AuctioneerSnapshotDB[ahKey] = createAHDatabase(ahKey);
		end
	end

	-- Make AuctioneerSnapshotDB the loaded database!
	LoadedSnapshotDB = AuctioneerSnapshotDB;
end

-------------------------------------------------------------------------------
-- Creates a new database.
-------------------------------------------------------------------------------
function createDatabase()
	return {};
end

-------------------------------------------------------------------------------
-- Create a brand new database for an auction house key (realm-faction).
-------------------------------------------------------------------------------
function createAHDatabase(ahKey)
	return {
		version = CURRENT_SNAPSHOTDB_VERSION;
		ahKey = ahKey;
		nextAuctionId = 1;
		auctions = {};
		auctionIdsByItemKey = {};
		updates = {};
	}
end

-------------------------------------------------------------------------------
-- Upgrades the specified database. Returns true if the database was upgraded
-- successfully.
-------------------------------------------------------------------------------
function upgradeAHDatabase(ah)
	-- Check that we have a valid database.
	if (not (ah.version and ah.ahKey)) then
		return false
	end

	-- Check if we need upgrading.
	if (ah.version == CURRENT_SNAPSHOTDB_VERSION) then
		return true;
	end

	-- Future DB upgrade code goes here...
	debugPrint("Upgrading snapshot database for", ah.ahKey);

	-- Return the result of the upgrade!
	return (ah.version == CURRENT_SNAPSHOTDB_VERSION);
end

-------------------------------------------------------------------------------
-- Gets the Auctioneer snapshot database for the specified auction house.
-------------------------------------------------------------------------------
function getAHDatabase(ahKey, create)
	-- If no auction house key was provided use the default key for the
	-- current zone.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();
	local ah = LoadedSnapshotDB[ahKey];
	if (ah == nil and create) then
		ah = createAHDatabase(ahKey);
		LoadedSnapshotDB[ahKey] = ah;
		debugPrint("Created LoadedSnapshotDB["..ahKey.."]");
	end
	return ah;
end

-------------------------------------------------------------------------------
-- Removes the specified item from the snapshot. Removes all items if itemKey
-- is nil.
-------------------------------------------------------------------------------
function clear(itemKey, ahKey)
	local ah = getAHDatabase(ahKey, false);
	if (ah) then
		if (itemKey) then
			-- Remove the specified item from the database.
			local auctionIdsForItemKey = ah.auctionIdsByItemKey[itemKey];
			if (auctionIdsForItemKey) then
				for _, auctionId in ipairs(auctionIdsForItemKey) do
					ah.auctions[auctionId] = nil;
				end
			end
			ah.auctionIdsByItemKey[itemKey] = nil;
			debugPrint("Removed", itemKey, "from snapshot database", ah.ahKey);
		else
			-- Toss the entire database by recreating it.
			LoadedSnapshotDB[ah.ahKey] = createAHDatabase(ah.ahKey);
			ah.updates = {};
			debugPrint("Cleared snapshot database for", ah.ahKey);
		end
	end
end


--=============================================================================
-- Snapshot functions
--=============================================================================

-------------------------------------------------------------------------------
-- Updates the snapshot with the results from the specified query.
-------------------------------------------------------------------------------
function updateForQuery(ahKey, query, auctions, partial)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();
	local ah = getAHDatabase(ahKey, true);

	debugPrint("Updating snapshot", ahKey, "for query: ");
	debugPrint("    name", query.name);
	debugPrint("    minLevel", query.minLevel);
	debugPrint("    maxLevel", query.maxLevel);
	debugPrint("    invTypeIndex", query.invTypeIndex);
	debugPrint("    classIndex", query.classIndex);
	debugPrint("    subclassIndex", query.subclassIndex);
	debugPrint("    qualityIndex", query.qualityIndex);

	-- Convert the pages into a list of auctions. Auctions get filed first under
	-- itemKey, then under auctionSignature. We do this so all auctions of the same
	-- item are grouped together when doing the reconciling. This allows us to take
	-- advantage of caching in other modules.
	--
	-- auctionsInUpdateByItemKey as follows:
	-- auctionsInUpdateByItemKey[itemKey][auctionSignature] = {
	--     [1] = <auction>
	--     ...
	-- }
	local auctionsInUpdateByItemKey = {};
	for _, auction in ipairs(auctions) do
		if (isValidAuction(auction)) then
			-- Get the list of auctions in the update for this signature and
			-- add this auction to the list.
			local itemKey = Auctioneer.ItemDB.CreateItemKeyFromAuction(auction);
			local auctionSignature = createAuctionSignatureFromAuction(auction);
			local auctionsInUpdateBySignature = auctionsInUpdateByItemKey[itemKey];
			if (not auctionsInUpdateBySignature) then
				auctionsInUpdateBySignature = {};
				auctionsInUpdateByItemKey[itemKey] = auctionsInUpdateBySignature;
			end
			local auctionsInUpdate = auctionsInUpdateBySignature[auctionSignature];
			if (not auctionsInUpdate) then
				auctionsInUpdate = {};
				auctionsInUpdateBySignature[auctionSignature] = auctionsInUpdate;
			end
			table.insert(auctionsInUpdate, auction);
		else
			debugPrint("Ignoring invalid auction");
		end
	end

	-- Get the matching auctions from the snapshot. Auctions get filed first under
	-- itemKey, then under auctionSignature. We do this so all auctions of the same
	-- item are grouped together when doing the reconciling. This allows us to take
	-- advantage of caching in other modules.
	--
	-- auctionsInSnapshotByItemKey[itemKey][auctionSignature] = {
	--     [1] = <auction>
	--     ...
	-- }
	local auctionsInSnapshotByItemKey = {};
	for itemKey, auctionIdsForItemKey in pairs(ah.auctionIdsByItemKey) do
		if ((not query) or doesItemKeyMatchQuery(itemKey, query)) then
			local auctionsInSnapshotBySignature = {};
			auctionsInSnapshotByItemKey[itemKey] = auctionsInSnapshotBySignature;
			for _, auctionId in ipairs(auctionIdsForItemKey) do
				local packedAuction = ah.auctions[auctionId];
				if (packedAuction) then
					local auction = unpackAuction(ahKey, auctionId, packedAuction);
					local auctionSignature = createAuctionSignatureFromAuction(auction);
					local auctionsInSnapshot = auctionsInSnapshotBySignature[auctionSignature];
					if (not auctionsInSnapshot) then
						auctionsInSnapshot = {};
						auctionsInSnapshotBySignature[auctionSignature] = auctionsInSnapshot;
					end
					table.insert(auctionsInSnapshot, auction);
				else
					debugPrint("WARNING: AuctionIdsForItemKey table corrupted!");
				end
			end
		end
	end

	-- Now for each signature in the update list, reconcile it against
	-- the snapshot list for the same signature.
	for itemKey, auctionsInUpdateBySignature in pairs(auctionsInUpdateByItemKey) do
		for auctionSignature, auctionsInUpdate in pairs(auctionsInUpdateBySignature) do
			-- Get the list of corresponding auctions in the snapshot.
			local auctionsInSnapshot;
			local auctionsInSnapshotBySignature = auctionsInSnapshotByItemKey[itemKey];
			if (auctionsInSnapshotBySignature) then
				auctionsInSnapshot = auctionsInSnapshotBySignature[auctionSignature];
			end
			if (auctionsInSnapshot) then
				-- Reconcile the auctions in the update against the auctions
				-- in the snapshot.
				reconcileAuctionsForSignature(ah, auctionSignature, auctionsInUpdate, auctionsInSnapshot, partial);
				-- Remove these auctions from the snapshot list so we don't remove
				-- them later.
				auctionsInSnapshotBySignature[auctionSignature] = nil;
			else
				-- No auctions for this item in the snapshot. Just add
				-- all the auctions from the update.
				for index, auction in ipairs(auctionsInUpdate) do
					addAuctionToSnapshot(ah, auction);
				end
			end
		end
	end

	-- If this isn't a partial update, remove any auctions that didn't match.
	if (not partial) then
		for itemKey, auctionsInSnapshotBySignature in pairs(auctionsInSnapshotByItemKey) do
			for auctionSignature, auctionsInSnapshot in pairs(auctionsInSnapshotBySignature) do
				-- Check for  auctionsInUpdateByItemKey[itemKey][auctionSignature].
				-- If it doesn't exist then we need to remove all auctions in the
				-- snapshot for the signature.
				local auctionsInUpdateBySignature = auctionsInUpdateByItemKey[itemKey];
				if (not (auctionsInUpdateBySignature and auctionsInUpdateBySignature[auctionSignature])) then
					for _, auction in ipairs(auctionsInSnapshot) do
						removeAuctionFromSnapshot(ah, auction);
					end
				end
			end
		end

		-- Note the update in the database.
		addUpdate(ah, query);
		Auctioneer.EventManager.FireEvent("AUCTIONEER_SNAPSHOT_UPDATE", query);
	end
end

-------------------------------------------------------------------------------
-- Updates the snapshot with the results from the specified query.
-------------------------------------------------------------------------------
function updateForSignature(ahKey, auctionSignature, auctions, partial)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();
	local ah = getAHDatabase(ahKey, true);
	debugPrint("Updating snapshot", ahKey, "for signature:", auctionSignature);

	-- Get the matching auctions from the snapshot.
	local auctionsInSnapshot = {};
	local itemKey = createItemKeyFromAuctionSignature(auctionSignature);
	local auctionIdsForItemKey = ah.auctionIdsByItemKey[itemKey];
	if (auctionIdsForItemKey) then
		for _, auctionId in ipairs(auctionIdsForItemKey) do
			local packedAuction = ah.auctions[auctionId];
			if (packedAuction) then
				local auction = unpackAuction(ahKey, auctionId, packedAuction);
				if (auctionSignature == createAuctionSignatureFromAuction(auction)) then
					table.insert(auctionsInSnapshot, auction);
				end
			else
				debugPrint("WARNING: AuctionIdsForItemKey table corrupted!");
			end
		end
	end

	-- Reconcile the auctions in the update against the auctions
	-- in the snapshot.
	reconcileAuctionsForSignature(ah, auctionSignature, auctions, auctionsInSnapshot, partial);
end

-------------------------------------------------------------------------------
-- Updates the auction in the snapshot.
-------------------------------------------------------------------------------
function updateAuction(auction)
	-- Use the default auction house for the zone if none was provided.
	local ah = getAHDatabase(auction.ahKey, true);
	debugPrint("Updating snapshot", auction.ahKey, "for auction:", auction.auctionId);

	-- Update the auction in the database if its valid.
	if (Auctioneer.QueryManager.IsAuctionValid(auction)) then
		local auctionInSnapshot = getAuctionById(auction.ahKey, auction.auctionId);
		if (auctionInSnapshot) then
			updateAuctionInSnapshot(ah, auctionInSnapshot, auction);
		else
			debugPrint("WARNING: Auction", auction.auctionId, "not in snapshot");
		end
	else
		debugPrint("WARNING: Auction", auction.auctionId, "is not valid");
	end
end

-------------------------------------------------------------------------------
-- Adds the auction to the snapshot.
-------------------------------------------------------------------------------
function addAuction(auction)
	-- Use the default auction house for the zone if none was provided.
	local ah = getAHDatabase(auction.ahKey, true);
	debugPrint("Adding auction to snapshot", auction.ahKey);

	-- Add the auction to the database if its valid.
	if (Auctioneer.QueryManager.IsAuctionValid(auction)) then
		addAuctionToSnapshot(ah, auction);
	else
		debugPrint("WARNING: Auction to add is not valid");
	end
end


-------------------------------------------------------------------------------
-- Removes the auction from the snapshot.
-------------------------------------------------------------------------------
function removeAuction(auction)
	-- Use the default auction house for the zone if none was provided.
	local ah = getAHDatabase(auction.ahKey, true);
	debugPrint("Updating snapshot", auction.ahKey, "for auction:", auction.auctionId);

	-- Update the auction in the database.
	local auctionInSnapshot = getAuctionById(auction.ahKey, auction.auctionId);
	if (auctionInSnapshot) then
		removeAuctionFromSnapshot(ah, auctionInSnapshot);
	else
		debugPrint("WARNING: Auction", auction.auctionId, "not in snapshot");
	end
end

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
function query(ahKey, query, filterFunc, filterArg)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();

	-- Iterate over the list of auctions and find the matching ones.
	local matchingAuctions = {};
	local ah = getAHDatabase(ahKey, true);
	for itemKey, auctionIdsForItemKey in pairs(ah.auctionIdsByItemKey) do
		if ((not query) or doesItemKeyMatchQuery(itemKey, query)) then
			for _, auctionId in ipairs(auctionIdsForItemKey) do
				local packedAuction = ah.auctions[auctionId];
				if (packedAuction) then
					local auction = unpackAuction(ahKey, auctionId, packedAuction);
					if ((not filterFunc) or filterFunc(auction, filterArg)) then
						table.insert(matchingAuctions, auction);
					end
				else
					debugPrint("WARNING: AuctionIdsForItemKey table corrupted!");
				end
			end
		end
	end
	return matchingAuctions;
end

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
function queryWithItemKey(itemKey, ahKey, filterFunc, filterArg)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();

	-- Iterate over the list of auctions and find the matching ones.
	local matchingAuctions = {};
	local ah = getAHDatabase(ahKey, true);
	local auctionIdsForItemKey = getAuctionIdsForItemKey(ah, itemKey, false);
	if (auctionIdsForItemKey) then
		for _, auctionId in ipairs(auctionIdsForItemKey) do
			local packedAuction = ah.auctions[auctionId];
			if (packedAuction) then
				local auction = unpackAuction(ahKey, auctionId, packedAuction);
				if ((not filterFunc) or filterFunc(auction, filterArg)) then
					table.insert(matchingAuctions, auction);
				end
			else
				debugPrint("WARNING: AuctionIdsForItemKey table corrupted!");
			end
		end
	end
	return matchingAuctions;
end

-------------------------------------------------------------------------------
-- Gets a list of auction ids for auctions of the specified item.
-------------------------------------------------------------------------------
function getAuctionsForItem(itemKey, ahKey)
	return queryWithItemKey(itemKey, ahKey);
end

-------------------------------------------------------------------------------
-- Gets an auction (unpacked) from the snapshot.
-------------------------------------------------------------------------------
function getAuctionById(ahKey, auctionId)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();
	local ah = getAHDatabase(ahKey, true);

	-- Lookup the auction for the corresponding id.
	if (auctionId) then
		local packedAuction = ah.auctions[auctionId];
		if (packedAuction) then
			return unpackAuction(ahKey, auctionId, packedAuction);
		end
	end
end

-------------------------------------------------------------------------------
-- Returns the current bid, or if none, the min bid.
-------------------------------------------------------------------------------
function getCurrentBid(auction)
	if (auction.bidAmount and auction.bidAmount > 0) then
		return auction.bidAmount;
	else
		return auction.minBid;
	end
end
-------------------------------------------------------------------------------
-- Checks if the specified item matches the query.
-------------------------------------------------------------------------------
function doesItemKeyMatchQuery(itemKey, query)
	-- Get the information about the item.
	local itemInfo = Auctioneer.ItemDB.GetItemInfo(itemKey);
	if (not itemInfo) then
		debugPrint("WARNING: Unable to get item info for itemKey", itemKey);
		return false;
	end
	local equipLoc= itemInfo.equipLocName
	if (equipLoc== "INVTYPE_ROBE") then equipLoc = "INVTYPE_CHEST" end

	-- Check if the item info matches the query constraints.
	if (query.name and not Auctioneer.Database.DoesNameMatch(itemInfo.name, query.name, false)) then return false end;
	if (query.minLevel and itemInfo.useLevel < (tonumber(query.minLevel) or 0)) then return false end;			--Default to a minLevel of 0 if not present
	if (query.maxLevel and itemInfo.useLevel > (tonumber(query.maxLevel) or math.huge)) then return false end;	--Default to a maxLevel of infinite (math.huge) if not present
	if (query.qualityIndex and itemInfo.quality < (tonumber(query.qualityIndex) or 0)) then return false end;	--Default to a qualityIndex of 0 (Poor) if not present

	-- Check the inventory type, sub class and class.
	if (query.classIndex and
		itemInfo.categoryName ~= Auctioneer.ItemDB.GetCategoryName(query.classIndex)) then return false end;
	if (query.subclassIndex and
		itemInfo.subCategoryName ~= Auctioneer.ItemDB.GetSubCategoryName(query.classIndex, query.subclassIndex)) then return false end;
	if (query.invTypeIndex and
		equipLoc ~= Auctioneer.ItemDB.GetInventoryTypeName(query.classIndex, query.subclassIndex, query.invTypeIndex)) then return false end;

	-- %todo: Check if its usable...

	return true;
end

-------------------------------------------------------------------------------
-- Reconciles auctions in an update against auctions in the snapshot.
-------------------------------------------------------------------------------
function reconcileAuctionsForSignature(ah, auctionSignature, auctionsInUpdate, auctionsInSnapshot, partial)
	debugPrint("Reconcling auctions:", auctionSignature, "(", #auctionsInUpdate, "in update;", #auctionsInSnapshot, " in snapshot)");

	-- Sort the auctions in the update by time left and bid amount.
	table.sort(
		auctionsInUpdate,
		function(a, b)
			if (a.dup == b.dup) then
				if (a.timeLeft == b.timeLeft) then
					return (a.bidAmount < b.bidAmount);
				end
				return (a.timeLeft < b.timeLeft);
			end
			return (not a.dup)
		end
	);

	-- Sort the auctions in the snapshot by expiration time and bid amount.
	table.sort(
		auctionsInSnapshot,
		function(a, b)
			if (a.expiration == b.expiration) then
				return (a.bidAmount < b.bidAmount);
			end
			return (a.expiration < b.expiration);
		end);

	-- Reconcile each auction in the update against the auctions in the snapshot.
	for _, auctionInUpdate in ipairs(auctionsInUpdate) do
		-- Ignore invalid auctions so we can keep the database clean.
		if (Auctioneer.QueryManager.IsAuctionValid(auctionInUpdate)) then
			reconcileAuction(ah, auctionInUpdate, auctionsInSnapshot);
		else
			debugPrint("reconcileAuctionsForSignature() - ignoring invalid auction");
		end
	end

	-- Remove any auctions that remain in the snapshot list.
	if (not partial) then
		for _, auctionInSnapshot in ipairs(auctionsInSnapshot) do
			removeAuctionFromSnapshot(ah, auctionInSnapshot);
		end
		auctionInSnapshot = {};
	end
end

-------------------------------------------------------------------------------
-- Reconciles an auction against the snapshot. If the auction is matched with
-- an auction in the snapshot auction list, the snapshot auction is removed
-- from the list.
-------------------------------------------------------------------------------
function reconcileAuction(ah, auctionInUpdate, auctionsInSnapshot)
	local bestSnapshotMatchIndex;
	for auctionInSnapshotIndex, auctionInSnapshot in ipairs(auctionsInSnapshot) do
		-- The bid amount of the updated auction must be greater than or equal to the bid
		-- amount of the snapshot auction in order to match.
		if (auctionInUpdate.bidAmount >= auctionInSnapshot.bidAmount) then
			-- Calculate the maximum number of times the auction could have been bidded.
			local maxBids = getMaxBids(auctionInSnapshot, auctionInUpdate);

			-- Calculate the maximum and minimum time left for the snapshot
			-- auction based on the update auction.
			local timeElapsed = auctionInUpdate.lastSeen - auctionInSnapshot.lastSeen;
			local minTimeLeft = getTimeLeft(TimeLeftInSeconds[auctionInSnapshot.timeLeft - 1] - timeElapsed);
			local timeUntilExpiration = auctionInSnapshot.expiration - auctionInSnapshot.lastSeen;
			local maxTimeLeft = getTimeLeft(timeUntilExpiration - timeElapsed + (300 * maxBids));
			debugPrint("timeUntilExpiration", timeUntilExpiration, "timeElapsed", timeElapsed, "minTimeLeft", minTimeLeft, "timeLeft", auctionInUpdate.timeLeft, "maxTimeLeft", maxTimeLeft);

			-- Check if we have a possible match based on time left.
			if (minTimeLeft <= auctionInUpdate.timeLeft and auctionInUpdate.timeLeft <= maxTimeLeft) then
				-- Yep, check for an exact match. We always prefer exact matches
				-- inexact matches.
				if (auctionInUpdate.auctionId and auctionInUpdate.auctionId == auctionInSnapshot.auctionId) then
					bestSnapshotMatchIndex = auctionInSnapshotIndex;
					debugPrint("Found an exact match (AuctionId)!");
					break;
				elseif ((not auctionInUpdate.auctionId) and auctionInUpdate.bidAmount == auctionInSnapshot.bidAmount) then
					bestSnapshotMatchIndex = auctionInSnapshotIndex;
					debugPrint("Found an exact match (BidAmount)!");
					break;
				end

				-- No exact match, but is it a better match than what we have already?
				if (not bestSnapshotMatchIndex) then
					debugPrint("Found inexact match!");
					bestSnapshotMatchIndex = auctionInSnapshotIndex
				else
					-- If this snapshot auction has a lower bid amount than the one
					-- we already matched, use this one instead.
					bestSnapshotMatch = auctionsInSnapshot[bestSnapshotMatchIndex];
					if (auctionInSnapshot.bidAmount < bestSnapshotMatch.bidAmount) then
						debugPrint("Found better inexact match!");
						bestSnapshotMatchIndex = auctionInSnapshotIndex;
					end
				end
			else
				debugPrint("No match due to time left");
			end
		else
			debugPrint("No match due to bid amount");
		end
	end

	-- If we found a match, update the auction. Otherwise add a new auction to the snapshot.
	if (bestSnapshotMatchIndex) then
		updateAuctionInSnapshot(ah, auctionsInSnapshot[bestSnapshotMatchIndex], auctionInUpdate);
		table.remove(auctionsInSnapshot, bestSnapshotMatchIndex);
	elseif (not auctionInUpdate.dup) then
		addAuctionToSnapshot(ah, auctionInUpdate);
	else
		debugPrint("Omitting auction from snapshot because it might be a dup");
	end
end

-------------------------------------------------------------------------------
-- Converts from seconds to timeLeft (0 to 4)
-------------------------------------------------------------------------------
function getTimeLeft(seconds)
	for timeLeft = 0, 3 do
		if (seconds <= TimeLeftInSeconds[timeLeft]) then
			return timeLeft;
		end
	end
	return 4;
end

-------------------------------------------------------------------------------
-- Calculates the number of times an auction could have been bidded.
-------------------------------------------------------------------------------
function getMaxBids(auctionInSnapshot, auctionInUpdate)
	-- %todo: The speed of this calculation could be improved?
	local maxBids = 0;
	if (auctionInSnapshot.bidAmount ~= auctionInUpdate.bidAmount) then
		local bidAmount = auctionInSnapshot.bidAmount;
		if (bidAmount == 0) then
			bidAmount = auctionInSnapshot.minBid;
			maxBids = 1;
		end
		while (bidAmount < auctionInUpdate.bidAmount) do
			bidAmount = bidAmount * 1.05;
			maxBids = maxBids + 1;
		end
	end
	--debugPrint("Calculated maxBids to be "..maxBids);
	return maxBids;
end

-------------------------------------------------------------------------------
-- Gets the next auction id.
-------------------------------------------------------------------------------
function getNextAuctionId(ah)
	local auctionId = ah.nextAuctionId;
	ah.nextAuctionId = auctionId + 1;
	return auctionId;
end

-------------------------------------------------------------------------------
-- Gets the auctionId table for the specified itemKey from the database.
-------------------------------------------------------------------------------
function getAuctionIdsForItemKey(ah, itemKey, create)
	local auctionIdsForItemKey = ah.auctionIdsByItemKey[itemKey];
	if ((not auctionIdsForItemKey) and create) then
		debugPrint("Creating auctionIdsForItemKey["..itemKey.."]");
		auctionIdsForItemKey = {};
		ah.auctionIdsByItemKey[itemKey] = auctionIdsForItemKey;
	end
	return auctionIdsForItemKey;
end

-------------------------------------------------------------------------------
-- Adds the specified auction to the snapshot.
-------------------------------------------------------------------------------
function addAuctionToSnapshot(ah, auction)
	-- Add the auction.
	auction.auctionId = getNextAuctionId(ah);
	auction.expiration = auction.lastSeen + TimeLeftInSeconds[auction.timeLeft];
	local packedAuction = packAuction(auction);
	ah.auctions[auction.auctionId] = packedAuction;

	-- Add the auction id to the itemKey index table.
	local itemKey = Auctioneer.ItemDB.CreateItemKeyFromAuction(auction);
	local auctionIdsForItemKey = getAuctionIdsForItemKey(ah, itemKey, true);
	table.insert(auctionIdsForItemKey, auction.auctionId);

	-- Fire the auction added event.
	debugPrint("Added auction", auction.auctionId, ":", packedAuction);
	Auctioneer.EventManager.FireEvent("AUCTIONEER_AUCTION_ADDED", auction);
end

-------------------------------------------------------------------------------
-- Updates the specified auction in the snapshot.
-------------------------------------------------------------------------------
function updateAuctionInSnapshot(ah, oldAuction, newAuction)
	-- Update the auction.
	newAuction.auctionId = oldAuction.auctionId;
	if (newAuction.timeLeft == oldAuction.timeLeft and newAuction.bidAmount == oldAuction.bidAmount) then
		-- Add 5 minutes to the expiration for each possible bid.
		local maxAddedTime = getMaxBids(oldAuction, newAuction) * 300;
		newAuction.expiration = oldAuction.expiration + maxAddedTime;
		-- Check that we didn't add too much time.
		if (TimeLeftInSeconds[newAuction.timeLeft] < (newAuction.expiration - newAuction.lastSeen)) then
			newAuction.expiration = newAuction.lastSeen + TimeLeftInSeconds[newAuction.timeLeft];
		end
	else
		-- TimeLeft has changed, so just use the timeLeft to calculate the
		-- estimated expiration.
		newAuction.expiration = newAuction.lastSeen + TimeLeftInSeconds[newAuction.timeLeft];
	end
	local packedAuction = packAuction(newAuction);
	ah.auctions[newAuction.auctionId] = packedAuction;

	-- Fire the auction updated event if the bidAmount or timeLeft changed.
	if (newAuction.bidAmount ~= oldAuction.bidAmount or
		newAuction.highBidder ~= oldAuction.highBidder or
		newAuction.timeLeft ~= oldAuction.timeLeft) then
		debugPrint("Updated auction "..newAuction.auctionId.. ": "..packedAuction);
		Auctioneer.EventManager.FireEvent("AUCTIONEER_AUCTION_UPDATED", newAuction, oldAuction);
	else
		debugPrint("Unchanged auction", newAuction.auctionId, ":", packedAuction);
	end
end

-------------------------------------------------------------------------------
-- Removes the specified auction from the snapshot.
-------------------------------------------------------------------------------
function removeAuctionFromSnapshot(ah, auction)
	-- Remove the auction.
	ah.auctions[auction.auctionId] = nil;

	-- Remove the auction id from the itemKey index table.
	local itemKey = Auctioneer.ItemDB.CreateItemKeyFromAuction(auction);
	local auctionIdsForItemKey = getAuctionIdsForItemKey(ah, itemKey, false);
	if (auctionIdsForItemKey) then
		for index, auctionId in ipairs(auctionIdsForItemKey) do
			if (auctionId == auction.auctionId) then
				table.remove(auctionIdsForItemKey, index);
				break;
			end
		end
	end

	-- Fire the auction removed event.
	debugPrint("Removed auction", auction.auctionId, ":", packAuction(auction));
	Auctioneer.EventManager.FireEvent("AUCTIONEER_AUCTION_REMOVED", auction);
end

-------------------------------------------------------------------------------
-- Converts an auction into a ';' delimited string.
-------------------------------------------------------------------------------
function packAuction(auction)
	return Auctioneer.Database.PackRecord(auction, AuctionMetaData);
end

-------------------------------------------------------------------------------
-- Converts a ';' delimited string into an auction using the AuctionMetaData
-- table.
-------------------------------------------------------------------------------
function unpackAuction(ahKey, auctionId, packedAuction)
	local auction = Auctioneer.Database.UnpackRecord(packedAuction, AuctionMetaData);
	auction.ahKey = ahKey;
	auction.auctionId = auctionId;
	return auction;
end

-------------------------------------------------------------------------------
-- Checks if an auction is valid.
-------------------------------------------------------------------------------
function isValidAuction(auction)
	return (
		auction.itemId and auction.suffixId and	auction.enchantId and
		auction.uniqueId and auction.count and auction.minBid and
		auction.owner and auction.timeLeft
	)
end

-------------------------------------------------------------------------------
-- Creates an auction signature (itemId:suffixId:enchantId:uniqueId:count:minBid:buyoutPrice:owner)
-------------------------------------------------------------------------------
function createAuctionSignatureFromAuction(auction)
	return strjoin(
		":", auction.itemId, auction.suffixId, auction.enchantId,
		auction.uniqueId, auction.count, auction.minBid,
		auction.buyoutPrice, auction.owner
	);
end

-------------------------------------------------------------------------------
-- Breaks an auction signature (itemId:suffixId:enchantId:uniqueId:count:minBid:buyoutPrice:owner)
-------------------------------------------------------------------------------
function breakAuctionSignature(auctionSignature)
	itemId, suffixId, enchantId, uniqueId, count, minBid, buyoutPrice, owner = strsplit(":", auctionSignature);
	return tonumber(itemId), tonumber(suffixId), tonumber(enchantId), tonumber(uniqueId), tonumber(count), tonumber(minBid), tonumber(buyoutPrice), owner;
end

-------------------------------------------------------------------------------
-- Creates an item key from an auction signature (itemId:suffixId:enchantId)
-------------------------------------------------------------------------------
function createItemKeyFromAuctionSignature(auctionSignature)
	return Auctioneer.ItemDB.CreateItemKey(breakAuctionSignature(auctionSignature));
end

--=============================================================================
-- Update history methods.
--=============================================================================

-------------------------------------------------------------------------------
-- Adds an update and removes any updates that are a subset.
-------------------------------------------------------------------------------
function addUpdate(ah, query)
	-- First remove updates that are a subset of this query.
	removeSubsetUpdates(ah, query);

	-- Add the new update to the end of the table.
	local update = createUpdateFromQuery(query);
	update.date = time();
	table.insert(ah.updates, packUpdate(update));
	debugPrint("Added update at index", #ah.updates);
end

-------------------------------------------------------------------------------
-- Removes updates that are a subset of the specified query.
-------------------------------------------------------------------------------
function removeSubsetUpdates(ah, query)
	-- Remove the old updates that are a subset of the new update.
	local update = createUpdateFromQuery(query);
	for index = #ah.updates, 1, -1 do
		local updateAtIndex = unpackUpdate(ah.updates[index]);
		if (updateAtIndex.date + (24 * 60 * 60) < time()) then
			debugPrint("Removed update at index", index, "(age)");
			table.remove(ah.updates, index);
		elseif (isUpdateSubsetOfUpdate(updateAtIndex, update)) then
			debugPrint("Removed update at index", index, "(subset)");
			table.remove(ah.updates, index);
		end
	end
end

-------------------------------------------------------------------------------
-- Gets the time of the last update for the specified query.
-------------------------------------------------------------------------------
function getLastUpdate(ahKey, query)
	-- Use the default auction house for the zone if none was provided.
	ahKey = ahKey or Auctioneer.Util.GetAuctionKey();
	local ah = getAHDatabase(ahKey, true);

	-- Look for the last update for which the query is a subset.
	local update = createUpdateFromQuery(query);
	for index = #ah.updates, 1, -1 do
		local updateAtIndex = unpackUpdate(ah.updates[index]);
		if (isUpdateSubsetOfUpdate(update, updateAtIndex)) then
			return updateAtIndex.date;
		end
	end

	return 0;
end

-------------------------------------------------------------------------------
-- Checks if one update is a subset of another update.
-------------------------------------------------------------------------------
function isUpdateSubsetOfUpdate(subset, set)
	-- Check the name.
	if (set.name ~= "" and not Auctioneer.Database.DoesNameMatch(subset.name, set.name)) then
		return false;
	end

	local setMin = tonumber(set.minLevel) or 0
	local setMax = tonumber(set.maxLevel) or 0
	local subMin = tonumber(subset.minLevel) or 0
	local subMax = tonumber(subset.maxLevel) or 0

	-- Check the min level.
	if (setMin ~= 0 and setMin > subMin) then
		return false;
	end

	-- Check the max level.
	if (setMax ~= 0 and setMax < subMax) then
		return false;
	end

	-- Check the classIndex index.
	if (set.classIndex ~= 0 and set.classIndex ~= subset.classIndex) then
		return false;
	end

	-- Check the subclass index.
	if (set.subclassIndex ~= 0 and set.subclassIndex ~= subset.subclassIndex) then
		return false;
	end

	-- Check the invTypeIndex index.
	if (set.invTypeIndex ~= 0 and set.invTypeIndex ~= subset.invTypeIndex) then
		return false;
	end

	-- Check the quality.
	if (set.qualityIndex ~= 0 and set.qualityIndex > subset.qualityIndex) then
		return false;
	end

	-- If we make it this far then it subset really is a subset.
	return true;
end

-------------------------------------------------------------------------------
-- Creates an update record from a query.
-------------------------------------------------------------------------------
function createUpdateFromQuery(query)
	-- Create the new update.
	return {
		name = query.name or "";
		minLevel = query.minLevel or 0;
		maxLevel = query.maxLevel or 0;
		invTypeIndex = query.invTypeIndex or 0;
		classIndex = query.classIndex or 0;
		subclassIndex = query.subclassIndex or 0;
		qualityIndex = query.qualityIndex or 0;
	};
end

-------------------------------------------------------------------------------
-- Converts an update into a ';' delimited string.
-------------------------------------------------------------------------------
function packUpdate(update)
	return Auctioneer.Database.PackRecord(update, UpdateMetaData);
end

-------------------------------------------------------------------------------
-- Converts a ';' delimited string into an auction using the AuctionMetaData
-- table.
-------------------------------------------------------------------------------
function unpackUpdate(packedUpdate)
	return Auctioneer.Database.UnpackRecord(packedUpdate, UpdateMetaData);
end

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
function debugPrint(...)
	EnhTooltip.DebugPrint("[Auc.SnapshotDB]", ...);
end

--=============================================================================
-- Initialization
--=============================================================================
if (Auctioneer.SnapshotDB) then return end;
debugPrint("AucSnapshotDB.lua loaded");

-------------------------------------------------------------------------------
-- Public API
-------------------------------------------------------------------------------
Auctioneer.SnapshotDB = {
	Load = load;
	Clear = clear;
	UpdateForQuery = updateForQuery;
	UpdateForSignature = updateForSignature;
	UpdateAuction = updateAuction;
	AddAuction = addAuction;
	RemoveAuction = removeAuction;
	Query = query;
	QueryWithItemKey = queryWithItemKey;
	DoesItemKeyMatchQuery = doesItemKeyMatchQuery;
	GetAuctionsForItem = getAuctionsForItem;
	GetAuctionById = getAuctionById;
	GetCurrentBid = getCurrentBid;
	CreateAuctionSignatureFromAuction = createAuctionSignatureFromAuction;
	GetLastUpdate = getLastUpdate;
}

-------------------------------------------------------------------------------
-- Create an empty database to use before any upgrading is performed.
-------------------------------------------------------------------------------
AuctioneerSnapshotDB = createDatabase();
LoadedSnapshotDB = AuctioneerSnapshotDB;
