--[[ md
@name lua/tags

Helper methods for cleaning story tags.
Tags are the main way to search smr, a simple `+<tag>` or `-<tag>` will show all
stories that include (+) or do not include (-) a particular tag.

Tags are stored in the {{table_tags}} and are deleted if the story they are
attached to is deleted. If an author is deleted, all their stories are deleted,
and this will cascade to deleting tags on their stories too.
]]
local sql = require("lsqlite3")

local db = require("db")
local queries = require("queries")
local tags = {}

local stmnt_get_tags, stmnt_ins_tag, stmnt_drop_tags

local oldconfigure = configure
function configure(...)
	--Tags for a story
	stmnt_ins_tag = assert(db.conn:prepare(queries.insert_tag))
	stmnt_get_tags = assert(db.conn:prepare(queries.select_tags))
	stmnt_drop_tags = assert(db.conn:prepare(queries.delete_tags))

	return oldconfigure(...)
end


function tags.get(id)
	local ret = {}
	stmnt_get_tags:bind_names{
		id = id
	}
	local err
	repeat
		err = stmnt_get_tags:step()
		if err == sql.BUSY then
			coroutine.yield()
		elseif err == sql.ROW then
			table.insert(ret,stmnt_get_tags:get_value(0))
		elseif err == sql.DONE then
			stmnt_get_tags:reset()
			return ret
		else
			error(string.format("Failed to get tags for story %d : %d", id, err))
		end
	until false
end

function tags.set(storyid,tags_list)
	assert(stmnt_drop_tags:bind_names{postid = storyid} == sql.OK)
	db.do_sql(stmnt_drop_tags)
	stmnt_drop_tags:reset()
	local err
	for _,tag in pairs(tags_list) do
		assert(stmnt_ins_tag:bind(1,storyid) == sql.OK)
		assert(stmnt_ins_tag:bind(2,tag) == sql.OK)
		err = db.do_sql(stmnt_ins_tag)
		stmnt_ins_tag:reset()
	end
	if err ~= sql.DONE then
		log(LOG_CRIT,"Failed to save tags on " .. storyid)
	end

end

return tags