#!/usr/bin/env lua

--
-- Yoink
-- This script wraps around the compiler command to handle the creation of
-- dependency files.  It works with GCC.  The script is based off of Emile
-- van Bergen's `ccdeps-gcc' script.
--


-- Get the next argument passed to the script.
function shift()
	var = arg[1]
	table.remove(arg, 1)
	arguments = string.format("%s %q", tostring(arguments), tostring(var))
	return var
end


-- The compiler command is the first argument.
compiler	= shift()
arguments	= ""
paths		= {}


-- Consume each compiler argument, appending it to the arguments variable.
while 0 < #arg do
	local v = shift()
	if v == "-o" then
		product = shift()
	elseif v:match("%-[xubV]$") then
		shift()		-- Shift an extra one for the option's payload.
	else
		path = v:match("([^-].*)/")
		if path then paths[path] = true end
	end
end
if not product then print("No output file specified.") os.exit(1) end


-- Now try the actual compile WITH dependency generation.
if os.execute(compiler.." -MD"..arguments) ~= 0 then
	-- Try it without dependency generation.
	if os.execute(compiler..arguments) ~= 0 then
		print("The compile failed.  :-(")
		os.exit(1)
	end
	print("The compile succeeded without dependency generation.")
	os.exit(0)
end


-- Remove the old dependency file.
dep = product..".d"
os.remove(dep)


-- GCC outputs file.d for a product named file.o, either in the current
-- directory or in the directory where the source is.
depname = product:gsub("^.*/(.*)%.o$", "%1.d")
depfiles = {}
table.insert(depfiles, depname)
for path in pairs(paths) do table.insert(depfiles, path.."/"..depname) end

for _,gccdep in ipairs(depfiles) do
	tmpname = gccdep..".tmp"
	-- Fix up the dependency file with correct paths.
	if os.execute("test -f "..gccdep) == 0 and os.rename(gccdep, tmpname) then
		os.execute(string.format("sed -e 's|.*:|%s %s:|' <%s >>%s", product, dep, tmpname, dep))
		os.execute(string.format("sed -e 's/^.*://' -e 's/^ *//' -e 's/ *\\\\$//' -e 's/$/:/' <%s >>%s", tmpname, dep))
		os.remove(tmpname)
		os.exit()
	end
end

print("Couldn't find the dependency file.")
os.exit(1)