-- This Lua code provides some built-in utilities for writing Lua add-ons
-- It is eval'd automatically once BLLua3 has loaded the TS API and environment
-- It only has access to the sandboxed lua environment, just like user code.

ts = _bllua_ts

-- Provide limited OS functions
os = os or {}
function os.time() return math.floor(tonumber(_bllua_ts.call('getSimTime'))/1000) end
function os.clock() return tonumber(_bllua_ts.call('getSimTime'))/1000 end

-- Virtual file class, emulating a file object as returned by io.open
-- Used to wrap io.open to allow reading from zips (using TS)
-- Not perfect because TS file I/O sucks
--   Can't read nulls, can't distinguish between CRLF and LF.
-- Todo someday: actually read the zip in lua?
local file_meta = {
	read = function(file, mode)
		file:_init()
		if not file or type(file)~='table' or not file._is_file then error('File:read: Not a file', 2) end
		if file._is_open ~= true then error('File:read: File is closed', 2) end
		if mode=='*n' then
			local ws, n = file.data:match('^([ \t\r\n]*)([0-9%.%-e]+)', file.pos)
			if n then
				file.pos = file.pos + #ws + #n
				return n
			else
				return nil
			end
		elseif mode=='*a' then
			local d = file.data:sub(file.pos, #file.data)
			file.pos = #file.data + 1
			return d
		elseif mode=='*l' then
			local l, ws = file.data:match('^([^\r\n]*)(\r?\n)', file.pos)
			if not l then
				l = file.data:match('^([^\r\n]*)$', file.pos); ws = '';
				if l=='' then return nil end
			end
			if l then
				file.pos = file.pos + #l + #ws
				return l
			else
				return nil
			end
		elseif type(mode)=='number' then
			local d = file.data:sub(file.pos, file.pos+mode)
			file.pos = file.pos + #d
			return d
		else
			error('File:read: Invalid mode \''..mode..'\'', 2)
		end
	end,
	lines = function(file)
		file:_init()
		return function()
			return file:read('*l')
		end
	end,
	close = function(file)
		if not file._is_open then error('File:close: File is not open', 2) end
		file._is_open = false
	end,
	__index = function(f, k) return rawget(f, k) or getmetatable(f)[k] end,
	_init = function(f)
		if not f.data then
			f.data = _bllua_ts.call('_bllua_ReadEntireFile', f.filename)
		end
	end,
}
local function new_file_obj(fn)
	local file = {
		_is_file = true,
		_is_open = true,
		pos = 1,
		__index = file_meta.__index,
		filename = fn,
		data = nil,
	}
	setmetatable(file, file_meta)
	return file
end

local function tflip(t) local u = {}; for _, n in ipairs(t) do u[n] = true end; return u; end
local allowed_zip_dirs = tflip{
	'add-ons', 'base', 'config', 'saves', 'screenshots', 'shaders'
}
local function io_open_absolute(fn, mode)
	-- if file exists, use original mode
	local res, err = _bllua_io_open(fn, mode)
	if res then return res
	elseif err and not err:find('No such file or directory$') then return nil, err end
	
	-- otherwise, if TS sees file but Lua doesn't, it must be in a zip, so use TS reader
	local dir = fn:match('^[^/]+')
	if not allowed_zip_dirs[dir:lower()] then return nil, 'Zip is not in one of the allowed directories' end
	local exist = _bllua_ts.call('isFile', fn) == '1'
	if not exist then return nil, err end
	
	if mode~=nil and mode~='r' and mode~='rb' then
		return nil, 'Files in zips can only be opened in read mode' end
	
	-- return a temp lua file object with the data
	local fi = new_file_obj(fn)
	return fi
end

io = io or {}
function io.open(fn, mode, errn)
	errn = errn or 1
	
	-- try to open the file with relative path, otherwise use absolute path
	local curfn = debug.getfilename(errn + 1) or _bllua_ts.getvar('Con::File')
	if curfn == '' then curfn = nil end
	if fn:find('^%.') then
		local relfn = curfn and fn:find('^%./') and
			curfn:gsub('[^/]+$', '')..fn:gsub('^%./', '')
		if relfn then
			local fi, err = io_open_absolute(relfn, mode)
			return fi, err, relfn
		else
			return nil, 'Invalid path', fn
		end
	else
		local fi, err = io_open_absolute(fn, mode)
		return fi, err, fn
	end
end
function io.lines(fn)
	local fi, err, fn2 = io.open(fn, nil, 2)
	if not fi then error('Error opening file \''..fn2..'\': '..err, 2) end
	return fi:lines()
end
function io.type(f)
	if type(f)=='table' and f._is_file then
		return f._is_open and 'file' or 'closed file'
	else
		return _bllua_io_type(f)
	end
end

-- provide dofile
function dofile(fn, errn)
	errn = errn or 1
	
	local fi, err, fn2 = io.open(fn, 'r', errn+1)
	if not fi then error('Error executing file \''..fn2..'\': '..err, errn+1) end
	
	print('Executing '..fn2)
	local text = fi:read('*a')
	fi:close()
	return assert(loadstring('--[['..fn2..']]'..text))()
end

-- provide require (just a wrapper for dofile)
-- searches for ?.lua and ?/init.lua in the following directories:
--   location of current file
--   blockland directory
--   current add-on
local function file_exists(fn, errn)
	local fi, err, fn2 = io.open(fn, 'r', errn+1)
	if fi then
		fi:close()
		return fn2
	else
		return nil
	end
end
local require_memo = {}
function require(mod)
	if require_memo[mod] then return unpack(require_memo[mod]) end
	local fp = mod:gsub('%.', '/')
	local fns = {
		'./'..fp..'.lua',      -- local file
		'./'..fp..'/init.lua', -- local library
		fp..'.lua',            -- global file
		fp..'/init.lua',       -- global library
	}
	if fp:lower():find('^add-ons/') then
		local addonpath = fp:lower():match('^add-ons/[^/]+')..'/'
		table.insert(fns, addonpath..fp..'.lua')      -- add-on file
		table.insert(fns, addonpath..fp..'/init.lua') -- add-on library
	end
	for _,fn in ipairs(fns) do
		local fne = file_exists(fn, 2)
		if fne then
			local res = {dofile(fne, 2)}
			require_memo[mod] = res
			return unpack(res)
		end
	end
	return _bllua_requiresecure(mod)
end

local function isValidCode(code)
	local f,e = loadstring(code)
	return f~=nil
end
function _bllua_smarteval(code)
	if (not code:find('^print%(')) and isValidCode('print('..code..')') then
		code = 'print('..code..')' end
	local f,e = loadstring(code)
	if f then
		return f()
	else
		print(e)
	end
end

function ts.setvar(name, val)
	_bllua_ts.call('_bllua_set_var', name, val)
end

_bllua_ts.call('echo', '  Executed libts-lua.lua')