--[[
Copyright (c) 2014, Robert 'Bobby' Zenz
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--]]


--- Various utility functions for working with arrays. An array is sub-form of
-- a array, the array is simply indexed with numbers like this:
--
-- local array = { 1 = "a", 2 = "b", 3 = "c" }
-- local array = { "a", "b", "c" }
arrayutil = {}


--- Finds the next matching column.
--
-- @param array The 2D array to search.
-- @param start_index Optional. The index at which to start. Defaults to 1, or
--                    if the direction is reversed, the number of columns in
--                    the array.
-- @param matcher Optional. The function that is used to determine if the column
--                matches or not. Is expected to take one argument, the item,
--                and return a boolean. The column matches if any of its items
--                matches this condition. Defaults to not nil and not empty
--                string.
-- @param reverse Optional. If the array should be serched backwards. Defaults
--                to false.
-- @return The index of the matching column. -1 if none was found.
function arrayutil.next_matching_column(array, start_index, matcher, reverse)
	matcher = matcher or function(item)
		return item ~= nil and item ~= ""
	end
	
	local current_column = 0
	
	if reverse and start_index == nil then
		for row_index = 1, #array, 1 do
			local row = array[row_index]
			
			current_column = math.max(current_column, #row)
		end
	else
		current_column = start_index or 1
	end
	
	local had_column = true
	
	while had_column do
		had_column = false
		
		for row_index = 1, #array, 1 do
			local row = array[row_index]
			
			if current_column >= 1 and current_column <= #row then
				had_column = true
				
				if matcher(row[current_column]) then
					return current_column
				end
			end
		end
		
		if reverse then
			current_column = current_column - 1
		else
			current_column = current_column + 1
		end
	end
	
	return -1
end

--- Finds the next matching row.
--
-- @param array The 2D array to search.
-- @param start_index Optional. The index at which to start. Defaults to 1, or
--                    if the direction is reversed, the number of rows in
--                    the array.
-- @param matcher Optional. The function that is used to determine if the row
--                matches or not. Is expected to take one argument, the item,
--                and return a boolean. The row matches if any of its items
--                matches this condition. Defaults to not nil and not empty
--                string.
-- @param reverse Optional. If the array should be serched backwards. Defaults
--                to false.
-- @return The index of the matching row. -1 if none was found.
function arrayutil.next_matching_row(array, start_index, matcher, reverse)
	matcher = matcher or function(item)
		return item ~= nil and item ~= ""
	end
	
	local to = #array
	local step = 1
	
	if reverse then
		start_index = start_index or #array
		to = 1
		step = -1
	else
		start_index = start_index or 1
	end
	
	for row_index = start_index, to, step do
		local row = array[row_index]
		
		for column_index = 1, #row, 1 do
			if matcher(row[column_index]) then
				return row_index
			end
		end
	end
	
	return -1
end

--- Finds the previous matching column.
--
-- @param array The 2D array to search.
-- @param start_index Optional. The index at which to start. Defaults to
--                    the number columns in the array.
-- @param matcher Optional. The function that is used to determine if the column
--                matches or not. Is expected to take one argument, the item,
--                and return a boolean. The column matches if any of its items
--                matches this condition. Defaults to not nil and not empty
--                string.
-- @return The index of the matching column. -1 if none was found.
function arrayutil.previous_matching_column(array, start_index, matcher)
	return arrayutil.next_matching_column(array, start_index, matcher, true)
end

--- Finds the previous matching row.
--
-- @param array The 2D array to search.
-- @param start_index Optional. The index at which to start. Defaults to
--                    the number rows in the array.
-- @param matcher Optional. The function that is used to determine if the row
--                matches or not. Is expected to take one argument, the item,
--                and return a boolean. The row matches if any of its items
--                matches this condition. Defaults to not nil and not empty
--                string.
-- @return The index of the matching row. -1 if none was found.
function arrayutil.previous_matching_row(array, start_index, matcher)
	return arrayutil.next_matching_row(array, start_index, matcher, true)
end

--- Removes empty rows and columns at the beginning and the end of the given
-- array.
--
-- @param array The array.
-- @param is_empty Optional. The function used for determining if the item is
--                 empty. By default nil and an empty string is considered
--                 empty. Expected is a function that takes one item and returns
--                 a boolean.
function arrayutil.reduce2d(array, is_empty)
	local first_row = arrayutil.next_matching_row(array, nil, is_empty)
	local last_row = arrayutil.previous_matching_row(array, nil, is_empty)
	
	local first_column = arrayutil.next_matching_column(array, nil, is_empty)
	local last_column = arrayutil.previous_matching_column(array, nil, is_empty)
	
	if last_row == -1 then
		last_row = first_row
	end
	
	if last_column == -1 then
		last_column = first_column
	end
	
	local reduced = {}
	
	if first_row ~= -1 and first_column ~= -1 then
		for row_index = first_row, last_row, 1 do
			local row = array[row_index]
			local reduced_row = {}
		
			for column_index = first_column, last_column, 1 do
				reduced_row[column_index - first_column + 1] = row[column_index]
			end
		
			reduced[row_index - first_row + 1] = reduced_row
		end
	end
	
	return reduced
end

--- Reindexes the given 2D array, swapping the two dimensions.
--
-- @param data The array to reindex.
-- @param new_x The new startpoint for the first dimension.
-- @param new_y The new startpoint for the second dimension.
-- @return The reindexed array.
function arrayutil.swapped_reindex2d(data, new_x, new_y)
	local reindexed_data = {}
	
	for old_x = 1, constants.block_size, 1 do
		local index_x = new_x + old_x - 1
		reindexed_data[index_x] = {}
		
		for old_y = 1, constants.block_size, 1 do
			local index_y = new_y + old_y - 1
				
			reindexed_data[index_x][index_y] = data[old_y][old_x]
		end
	end
	
	return reindexed_data
end

--- Reindexes the given 3d array, swapping the two dimensions.
--
-- @param data The array to reindex.
-- @param new_x The new startpoint for the first dimension.
-- @param new_y The new startpoint for the second dimension.
-- @param new_z The new startpoint for the third dimension.
-- @return The reindexed array.
function arrayutil.swapped_reindex3d(data, new_x, new_y, new_z)
	local reindexed_data = {}
	
	for old_x = 1, constants.block_size, 1 do
		local index_x = new_x + old_x - 1
		reindexed_data[index_x] = {}
	
		for old_z = 1, constants.block_size, 1 do
			local index_z = new_z + old_z - 1
			reindexed_data[index_x][index_z] = {}
		
			for old_y = 1, constants.block_size, 1 do
				local index_y = new_y + old_y - 1
			
				reindexed_data[index_x][index_z][index_y] = data[old_z][old_y][old_x]
			end
		end
	end
	
	return reindexed_data
end