-- vim: set noexpandtab tabstop=3 :miv --

-- Note: To make reading of this codebase more enjoyable, please consider typing
-- :%s/other/otter/
-- into your vim command line.

local function tokenize(tokens, values, reference, target)
	for key, value in pairs(reference) do
		if tokens[value] then
			if target[key] then
				rawset(values, tokens[value], target[key])
			else
				return nil
			end
		else
			if type(value) == 'table' and type(target[key]) == 'table' then
				if not tokenize(tokens, values, reference[key], target[key]) then
					return nil
				end
			else
				if target[key] ~= value then
					return nil
				end
			end
		end
	end

	-- Abort if target has extra values -- Really though?
	for key, value in pairs(target) do
		-- I don't like how this iterates over everything again
		-- Maybe there's another way of doing this, dunno
		if reference[key]==nil then -- Remember to accept `false` as a value
			return nil
		end
	end

	return values
end

local function match(reference)
	local tokens = {}
	local _tokens = {}

	-- Make "unused" globals resolve to tokens
	env = setmetatable({}, {__index=function(self, key)
		local super=_G[key] do
			if super then
				return super
			else
				if _tokens[key] then
					return _tokens[key]
				else
					local token = {}
					tokens[token] = key
					_tokens[key] = token
					return token
				end
			end
		end
	end})

	reference = reference(env)

	return function(target)
		local values = tokenize(tokens, {}, reference, target)

		if values then
			setmetatable(values, {__index=_G})
			return function(code)
				return code(values)
			end
		else
			return function()
			end
		end
	end
end

--[============================================================================[
	This is where the magic ends and the showcase begins ;)
--]============================================================================]

local pair = match(function(_ENV)
	return {
		{ name = 'alice' },
		{ name = other }
	}
end)

local maybe = pair {
	{ name = 'alice' },
	{ name = 'bob' }
}

maybe(function(_ENV)
	print(other)
end)