--[[

UCI Validation Layer - Main Library
(c) 2008 Jo-Philipp Wich <xm@leipzig.freifunk.net>
(c) 2008 Steven Barth <steven@midlink.org>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

$Id$

]]--

module( "luci.uvl", package.seeall )

require("luci.fs")
require("luci.util")
require("luci.model.uci")
require("luci.uvl.datatypes")
--require("luci.uvl.validation")
require("luci.uvl.dependencies")

TYPE_SECTION  = 0x01
TYPE_VARIABLE = 0x02
TYPE_ENUM     = 0x03


local default_schemedir = "/etc/scheme"

local function _assert( condition, fmt, ... )
	if not condition then
		return assert( nil, string.format( fmt, ... ) )
	else
		return condition
	end
end

UVL = luci.util.class()

function UVL.__init__( self, schemedir )

	self.schemedir	= schemedir or default_schemedir
	self.packages	= { }
	self.beenthere  = { }
	self.uci		= luci.model.uci
	self.datatypes  = luci.uvl.datatypes
end


function UVL._scheme_section( self, uci, c, s )
	if self.packages[c] and uci[s] then
		return self.packages[c].sections[uci[s][".type"]]
	end
end

function UVL._scheme_option( self, uci, c, s, o )
	if self.packages[c] and uci[s] and uci[s][o] then
		return self.packages[c].variables[uci[s][".type"]][o]
	elseif self.packages[c] and self.packages[c].variables[s] then
		return self.packages[c].variables[s][o]
	end
end

function UVL._keys( self, tbl )
	local keys = { }
	if tbl then
		for k, _ in luci.util.kspairs(tbl) do
			table.insert( keys, k )
		end
	end
	return keys
end


--- Validate given configuration.
-- @param config	Name of the configuration to validate
-- @param scheme	Scheme to validate against (optional)
-- @return			Boolean indicating weather the given config validates
-- @return			String containing the reason for errors (if any)
function UVL.validate( self, config )

	self.uci.set_confdir( self.uci.confdir_default )
	self.uci.load( config )

	local co = self.uci.get_all( config )

	local function _uci_foreach( type, func )
		for k, v in pairs(co) do
			if co[k]['.type'] == type then
				func( k, v )
			end
		end
	end

	luci.util.dumptable(co)



	for k, v in pairs( self.packages[config].sections ) do
		_uci_foreach( k,
			function(s)
				local ok, err = self:validate_section( config, s, co )

				if not ok then
					return ok, err
				end
			end
		)
	end

	return true, nil
end

--- Validate given section of given configuration.
-- @param config	Name of the configuration to validate
-- @param section	Key of the section to validate
-- @param scheme	Scheme to validate against
-- @return			Boolean indicating weather the given config validates
-- @return			String containing the reason for errors (if any)
function UVL.validate_section( self, config, section, co, nodeps )

	if not co then
		self.uci.set_confdir( self.uci.confdir_default )
		self.uci.load( config )
		co = uci.get_all( config )
	end

	local cs     = co[section]
	local scheme = self:_scheme_section( co, config, section )

	if cs then
		--luci.util.dumptable(cs)


		for k, v in pairs(self.packages[config].variables[cs[".type"]]) do
			if k:sub(1,1) ~= "." then
				local ok, err = self:validate_option( config, section, k, co, false, cs[".type"] )

				if not ok then
					print("ERR", err)
					return ok, err
				end
			end
		end

		--local dep_ok = nodeps or luci.uvl.dependencies.check_dependency( self, co, config, section )
		--print( "DEP: ", dep_ok )

		--print( "Validate section: ", config .. '.' .. section, nodeps and '(without depencies)' or '' )

		local ok, err = luci.uvl.dependencies.check_dependency(
			self, co, config, section, nil, true, cs[".type"]
		)

		if ok then
			--print("Validated section!\n\n")
			return true
		else
			print("ERR", "All possible dependencies failed. (Last error was: " .. err .. ")")
			return false, "All possible dependencies failed"
		end
	else
		print( "Error, scheme section '" .. section .. "' not found in data" )
	end

	return true, nil
end

--- Validate given option within section of given configuration.
-- @param config	Name of the configuration to validate
-- @param section	Key of the section to validate
-- @param option	Name of the option to validate
-- @param scheme	Scheme to validate against
-- @return			Boolean indicating weather the given config validates
-- @return			String containing the reason for errors (if any)
function UVL.validate_option( self, config, section, option, co, nodeps, section2 )

	if not co then
		self.uci.set_confdir( self.uci.confdir_default )
		self.uci.load( config )
		co = uci.get_all( config )
	end

	local cs = co[section]
	local sv = self:_scheme_option( co, config, section, option ) or
		self:_scheme_option( co, config, section2, option )

	--print("VOPT", config, section, option )

	if not sv then
		return false, "Requested option '" ..
			config .. '.' .. ( section or section2 ) .. '.' .. option ..
			"' not found in scheme"
	end

	if sv.required and not cs[option] then
		return false, "Mandatory variable '" ..
			config .. '.' .. section .. '.' .. option ..
			"' doesn't have a value"
	end

	if sv.type == "enum" and cs[option] then
		if not sv.values or not sv.values[cs[option]] then
			return false, "Value '" .. ( cs[option] or '<nil>' ) .. "' of given option '" ..
				config .. "." .. section .. "." .. option ..
				"' is not defined in enum { " ..
				table.concat(self:_keys(sv.values),", ") .. " }"
		end
	end

	if sv.datatype and cs[option] then
		if self.datatypes[sv.datatype] then
			if not self.datatypes[sv.datatype]( cs[option] ) then
				return false, "Value '" .. ( cs[option] or '<nil>' ) .. "' of given option '" ..
					config .. "." .. ( section or section2 ) .. "." .. option ..
					"' doesn't validate as datatype '" .. sv.datatype .. "'"
			end
		else
			return false, "Unknown datatype '" .. sv.datatype .. "' encountered"
		end
	end

	if not nodeps then
		return luci.uvl.dependencies.check_dependency(
			self, co, config, section, option, nil, section2
		)
	end

	return true, nil
end

--- Find all parts of given scheme and construct validation tree
-- @param scheme	Name of the scheme to parse
-- @return			Parsed scheme
function UVL.read_scheme( self, scheme )
	local schemes = { }

	for i, file in ipairs( luci.fs.glob(self.schemedir .. '/*/' .. scheme) ) do
		_assert( luci.fs.access(file), "Can't access file '%s'", file )

		self.uci.set_confdir( luci.fs.dirname(file) )
		self.uci.load( luci.fs.basename(file) )

		table.insert( schemes, self.uci.get_all( luci.fs.basename(file) ) )
	end

	return self:_read_scheme_parts( scheme, schemes )
end

-- Process all given parts and construct validation tree
function UVL._read_scheme_parts( self, scheme, schemes )

	-- helper function to construct identifiers for given elements
	local function _id( c, t )
		if c == TYPE_SECTION then
			return string.format(
				"section '%s.%s'",
					scheme, t.name or '?' )
		elseif c == TYPE_VARIABLE then
			return string.format(
				"variable '%s.%s.%s'",
					scheme, t.section or '?.?', t.name or '?' )
		elseif c == TYPE_ENUM then
			return string.format(
				"enum '%s.%s.%s'",
					scheme, t.variable or '?.?.?', t.value or '?' )
		end
	end

	-- helper function to check for required fields
	local function _req( c, t, r )
		for i, v in ipairs(r) do
			_assert( t[v], "Missing required field '%s' in %s", v, _id(c, t) )
		end
	end

	-- helper function to validate references
	local function _ref( c, t )
		local k
		if c == TYPE_SECTION then
			k = "package"
		elseif c == TYPE_VARIABLE then
			k = "section"
		elseif c == TYPE_ENUM then
			k = "variable"
		end

		local r = luci.util.split( t[k], "." )
		r[1] = ( #r[1] > 0 and r[1] or scheme )

		_assert( #r == c, "Malformed %s reference in %s", k, _id(c, t) )

		return r
	end

	-- Step 1: get all sections
	for i, conf in ipairs( schemes ) do
		for k, v in pairs( conf ) do
			if v['.type'] == 'section' then

				_req( TYPE_SECTION, v, { "name", "package" } )

				local r = _ref( TYPE_SECTION, v )

				self.packages[r[1]] =
					self.packages[r[1]] or {
						["sections"]  = { };
						["variables"] = { };
					}

				local p = self.packages[r[1]]
					  p.sections[v.name]  = p.sections[v.name]  or { }
					  p.variables[v.name] = p.variables[v.name] or { }

				local s = p.sections[v.name]

				for k, v2 in pairs(v) do
					if k ~= "name" and k ~= "package" and k:sub(1,1) ~= "." then
						if k:match("^depends") then
							s["depends"] = _assert(
								self:_read_depency( v2, s["depends"] ),
								"Section '%s' in scheme '%s' has malformed " ..
								"depency specification in '%s'",
								v.name or '<nil>', scheme or '<nil>', k
							)
						else
							s[k] = v2
						end
					end
				end
			end
		end
	end

	-- Step 2: get all variables
	for i, conf in ipairs( schemes ) do
		for k, v in pairs( conf ) do
			if v['.type'] == "variable" then

				_req( TYPE_VARIABLE, v, { "name", "section" } )

				local r = _ref( TYPE_VARIABLE, v )

				local p = _assert( self.packages[r[1]],
					"Variable '%s' in scheme '%s' references unknown package '%s'",
					v.name, scheme, r[1] )

				local s = _assert( p.variables[r[2]],
					"Variable '%s' in scheme '%s' references unknown section '%s'",
					v.name, scheme, r[2] )

				s[v.name] = s[v.name] or { }

				local t = s[v.name]

				for k, v in pairs(v) do
					if k ~= "name" and k ~= "section" and k:sub(1,1) ~= "." then
						if k:match("^depends") then
							t["depends"] = _assert(
								self:_read_depency( v, t["depends"] ),
								"Variable '%s' in scheme '%s' has malformed " ..
								"depency specification in '%s'",
								v.name, scheme, k
							)
						elseif k:match("^validator") then
							t["validators"] = _assert(
								self:_read_validator( v, t["validators"] ),
								"Variable '%s' in scheme '%s' has malformed " ..
								"validator specification in '%s'",
								v.name, scheme, k
							)
						else
							t[k] = v
						end
					end
				end
			end
		end
	end

	-- Step 3: get all enums
	for i, conf in ipairs( schemes ) do
		for k, v in pairs( conf ) do
			if v['.type'] == "enum" then

				_req( TYPE_ENUM, v, { "value", "variable" } )

				local r = _ref( TYPE_ENUM, v )

				local p = _assert( self.packages[r[1]],
					"Enum '%s' in scheme '%s' references unknown package '%s'",
					v.value, scheme, r[1] )

				local s = _assert( p.variables[r[2]],
					"Enum '%s' in scheme '%s' references unknown section '%s'",
					v.value, scheme, r[2] )

				local t = _assert( s[r[3]],
					"Enum '%s' in scheme '%s', section '%s' references " ..
					"unknown variable '%s'",
					v.value, scheme, r[2], r[3] )

				_assert( t.type == "enum",
					"Enum '%s' in scheme '%s', section '%s' references " ..
					"variable '%s' with non enum type '%s'",
					v.value, scheme, r[2], r[3], t.type )

				if not t.values then
					t.values = { [v.value] = v.title or v.value }
				else
					t.values[v.value] = v.title or v.value
				end

				if v.default then
					_assert( not t.default,
						"Enum '%s' in scheme '%s', section '%s' redeclares " ..
						"the default value of variable '%s'",
						v.value, scheme, r[2], v.variable )

					t.default = v.value
				end
			end
		end
	end

	return self
end

-- Read a depency specification
function UVL._read_depency( self, value, deps )
	local parts     = luci.util.split( value, "%s*,%s*", nil, true )
	local condition = { }

	for i, val in ipairs(parts) do
		local k, v = unpack(luci.util.split( val, "%s*=%s*", nil, true ))

		if k and (
			k:match("^%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+$") or
			k:match("^%$?[a-zA-Z0-9_]+%.%$?[a-zA-Z0-9_]+$") or
			k:match("^%$?[a-zA-Z0-9_]+$")
		) then
			condition[k] = v or true
		else
			return nil
		end
	end

	if not deps then
		deps = { condition }
	else
		table.insert( deps, condition )
	end

	return deps
end

-- Read a validator specification
function UVL._read_validator( self, value, validators )
	local validator

	if value and value:match("/") and self.datatypes.file(value) then
		validator = value
	else
		validator = self:_resolve_function( value )
	end

	if validator then
		if not validators then
			validators = { validator }
		else
			table.insert( validators, validator )
		end

		return validators
	end
end

-- Resolve given path
function UVL._resolve_function( self, value )
	local path = luci.util.split(value, ".")

	for i=1, #path-1 do
		local stat, mod = pcall(require, table.concat(path, ".", 1, i))
		if stat and mod then
			for j=i+1, #path-1 do
				if not type(mod) == "table" then
					break;
				end
				mod = mod[path[j]]
				if not mod then
					break
				end
			end
			mod = type(mod) == "table" and mod[path[#path]] or nil
			if type(mod) == "function" then
				return mod
			end
		end
	end
end