root/luci/trunk/libs/web/luasrc/cbi.lua @ 6608

--[[
LuCI - Configuration Bind Interface

Description:
Offers an interface for binding configuration values to certain
data types. Supports value and range validation and basic dependencies.

FileId:
$Id$

License:
Copyright 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

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

]]--
module("luci.cbi", package.seeall)

require("luci.template")
local util = require("luci.util")
require("luci.http")


--local event      = require "luci.sys.event"
local fs         = require("nixio.fs")
local uci        = require("luci.model.uci")
local datatypes  = require("luci.cbi.datatypes")
local class      = util.class
local instanceof = util.instanceof

FORM_NODATA  =  0
FORM_PROCEED =  0
FORM_VALID   =  1
FORM_DONE    =  1
FORM_INVALID = -1
FORM_CHANGED =  2
FORM_SKIP    =  4

AUTO = true

CREATE_PREFIX = "cbi.cts."
REMOVE_PREFIX = "cbi.rts."

-- Loads a CBI map from given file, creating an environment and returns it
function load(cbimap, ...)
    local fs   = require "nixio.fs"
    local i18n = require "luci.i18n"
    require("luci.config")
    require("luci.util")

    local upldir = "/lib/uci/upload/"
    local cbidir = luci.util.libpath() .. "/model/cbi/"
    local func, err

    if fs.access(cbidir..cbimap..".lua") then
        func, err = loadfile(cbidir..cbimap..".lua")
    elseif fs.access(cbimap) then
        func, err = loadfile(cbimap)
    else
        func, err = nil, "Model '" .. cbimap .. "' not found!"
    end

    assert(func, err)

    luci.i18n.loadc("base")

    local env = {
        translate=i18n.translate,
        translatef=i18n.translatef,
        arg={...}
    }

    setfenv(func, setmetatable(env, {__index =
        function(tbl, key)
            return rawget(tbl, key) or _M[key] or _G[key]
        end}))

    local maps       = { func() }
    local uploads    = { }
    local has_upload = false

    for i, map in ipairs(maps) do
        if not instanceof(map, Node) then
            error("CBI map returns no valid map object!")
            return nil
        else
            map:prepare()
            if map.upload_fields then
                has_upload = true
                for _, field in ipairs(map.upload_fields) do
                    uploads[
                        field.config .. '.' ..
                        field.section.sectiontype .. '.' ..
                        field.option
                    ] = true
                end
            end
        end
    end

    if has_upload then
        local uci = luci.model.uci.cursor()
        local prm = luci.http.context.request.message.params
        local fd, cbid

        luci.http.setfilehandler(
            function( field, chunk, eof )
                if not field then return end
                if field.name and not cbid then
                    local c, s, o = field.name:gmatch(
                        "cbid%.([^%.]+)%.([^%.]+)%.([^%.]+)"
                    )()

                    if c and s and o then
                        local t = uci:get( c, s )
                        if t and uploads[c.."."..t.."."..o] then
                            local path = upldir .. field.name
                            fd = io.open(path, "w")
                            if fd then
                                cbid = field.name
                                prm[cbid] = path
                            end
                        end
                    end
                end

                if field.name == cbid and fd then
                    fd:write(chunk)
                end

                if eof and fd then
                    fd:close()
                    fd   = nil
                    cbid = nil
                end
            end
        )
    end

    return maps
end


-- Node pseudo abstract class
Node = class()

function Node.__init__(self, title, description)
    self.children = {}
    self.title = title or ""
    self.description = description or ""
    self.template = "cbi/node"
end

-- hook helper
function Node._run_hook(self, hook)
    if type(self[hook]) == "function" then
        return self[hook](self)
    end
end

function Node._run_hooks(self, ...)
    local f
    local r = false
    for _, f in ipairs(arg) do
        if type(self[f]) == "function" then
            self[f](self)
            r = true
        end
    end
    return r
end

-- Prepare nodes
function Node.prepare(self, ...)
    for k, child in ipairs(self.children) do
        child:prepare(...)
    end
end

-- Append child nodes
function Node.append(self, obj)
    table.insert(self.children, obj)
end

-- Parse this node and its children
function Node.parse(self, ...)
    for k, child in ipairs(self.children) do
        child:parse(...)
    end
end

-- Render this node
function Node.render(self, scope)
    scope = scope or {}
    scope.self = self

    luci.template.render(self.template, scope)
end

-- Render the children
function Node.render_children(self, ...)
    for k, node in ipairs(self.children) do
        node:render(...)
    end
end


--[[
A simple template element
]]--
Template = class(Node)

function Template.__init__(self, template)
    Node.__init__(self)
    self.template = template
end

function Template.render(self)
    luci.template.render(self.template, {self=self})
end

function Template.parse(self, readinput)
    self.readinput = (readinput ~= false)
    return Map.formvalue(self, "cbi.submit") and FORM_DONE or FORM_NODATA
end


--[[
Map - A map describing a configuration file
]]--
Map = class(Node)

function Map.__init__(self, config, ...)
    Node.__init__(self, ...)

    self.config = config
    self.parsechain = {self.config}
    self.template = "cbi/map"
    self.apply_on_parse = nil
    self.readinput = true
    self.proceed = false
    self.flow = {}

    self.uci = uci.cursor()
    self.save = true

    self.changed = false

    if not self.uci:load(self.config) then
        error("Unable to read UCI data: " .. self.config)
    end
end

function Map.formvalue(self, key)
    return self.readinput and luci.http.formvalue(key)
end

function Map.formvaluetable(self, key)
    return self.readinput and luci.http.formvaluetable(key) or {}
end

function Map.get_scheme(self, sectiontype, option)
    if not option then
        return self.scheme and self.scheme.sections[sectiontype]
    else
        return self.scheme and self.scheme.variables[sectiontype]
         and self.scheme.variables[sectiontype][option]
    end
end

function Map.submitstate(self)
    return self:formvalue("cbi.submit")
end

-- Chain foreign config
function Map.chain(self, config)
    table.insert(self.parsechain, config)
end

function Map.state_handler(self, state)
    return state
end

-- Use optimized UCI writing
function Map.parse(self, readinput, ...)
    self.readinput = (readinput ~= false)
    self:_run_hooks("on_parse")

    if self:formvalue("cbi.skip") then
        self.state = FORM_SKIP
        return self:state_handler(self.state)
    end

    Node.parse(self, ...)

    if self.save then
        self:_run_hooks("on_save", "on_before_save")
        for i, config in ipairs(self.parsechain) do
            self.uci:save(config)
        end
        self:_run_hooks("on_after_save")
        if self:submitstate() and ((not self.proceed and self.flow.autoapply) or luci.http.formvalue("cbi.apply")) then
            self:_run_hooks("on_before_commit")
            for i, config in ipairs(self.parsechain) do
                self.uci:commit(config)

                -- Refresh data because commit changes section names
                self.uci:load(config)
            end
            self:_run_hooks("on_commit", "on_after_commit", "on_before_apply")
            if self.apply_on_parse then
                self.uci:apply(self.parsechain)
                self:_run_hooks("on_apply", "on_after_apply")
            else
                -- This is evaluated by the dispatcher and delegated to the
                -- template which in turn fires XHR to perform the actual
                -- apply actions.
                self.apply_needed = true
            end

            -- Reparse sections
            Node.parse(self, true)

        end
        for i, config in ipairs(self.parsechain) do
            self.uci:unload(config)
        end
        if type(self.commit_handler) == "function" then
            self:commit_handler(self:submitstate())
        end
    end

    if self:submitstate() then
        if not self.save then
            self.state = FORM_INVALID
        elseif self.proceed then
            self.state = FORM_PROCEED
        else
            self.state = self.changed and FORM_CHANGED or FORM_VALID
        end
    else
        self.state = FORM_NODATA
    end

    return self:state_handler(self.state)
end

function Map.render(self, ...)
    self:_run_hooks("on_init")
    Node.render(self, ...)
end

-- Creates a child section
function Map.section(self, class, ...)
    if instanceof(class, AbstractSection) then
        local obj  = class(self, ...)
        self:append(obj)
        return obj
    else
        error("class must be a descendent of AbstractSection")
    end
end

-- UCI add
function Map.add(self, sectiontype)
    return self.uci:add(self.config, sectiontype)
end

-- UCI set
function Map.set(self, section, option, value)
    if type(value) ~= "table" or #value > 0 then
        if option then
            return self.uci:set(self.config, section, option, value)
        else
            return self.uci:set(self.config, section, value)
        end
    else
        return Map.del(self, section, option)
    end
end

-- UCI del
function Map.del(self, section, option)
    if option then
        return self.uci:delete(self.config, section, option)
    else
        return self.uci:delete(self.config, section)
    end
end

-- UCI get
function Map.get(self, section, option)
    if not section then
        return self.uci:get_all(self.config)
    elseif option then
        return self.uci:get(self.config, section, option)
    else
        return self.uci:get_all(self.config, section)
    end
end

--[[
Compound - Container
]]--
Compound = class(Node)

function Compound.__init__(self, ...)
    Node.__init__(self)
    self.template = "cbi/compound"
    self.children = {...}
end

function Compound.populate_delegator(self, delegator)
    for _, v in ipairs(self.children) do
        v.delegator = delegator
    end
end

function Compound.parse(self, ...)
    local cstate, state = 0

    for k, child in ipairs(self.children) do
        cstate = child:parse(...)
        state = (not state or cstate < state) and cstate or state
    end

    return state
end


--[[
Delegator - Node controller
]]--
Delegator = class(Node)
function Delegator.__init__(self, ...)
    Node.__init__(self, ...)
    self.nodes = {}
    self.defaultpath = {}
    self.pageaction = false
    self.readinput = true
    self.allow_reset = false
    self.allow_cancel = false
    self.allow_back = false
    self.allow_finish = false
    self.template = "cbi/delegator"
end

function Delegator.set(self, name, node)
    assert(not self.nodes[name], "Duplicate entry")

    self.nodes[name] = node
end

function Delegator.add(self, name, node)
    node = self:set(name, node)
    self.defaultpath[#self.defaultpath+1] = name
end

function Delegator.insert_after(self, name, after)
    local n = #self.chain + 1
    for k, v in ipairs(self.chain) do
        if v == after then
            n = k + 1
            break
        end
    end
    table.insert(self.chain, n, name)
end

function Delegator.set_route(self, ...)
    local n, chain, route = 0, self.chain, {...}
    for i = 1, #chain do
        if chain[i] == self.current then
            n = i
            break
        end
    end
    for i = 1, #route do
        n = n + 1
        chain[n] = route[i]
    end
    for i = n + 1, #chain do
        chain[i] = nil
    end
end

function Delegator.get(self, name)
    local node = self.nodes[name]

    if type(node) == "string" then
        node = load(node, name)
    end

    if type(node) == "table" and getmetatable(node) == nil then
        node = Compound(unpack(node))
    end

    return node
end

function Delegator.parse(self, ...)
    if self.allow_cancel and Map.formvalue(self, "cbi.cancel") then
        if self:_run_hooks("on_cancel") then
            return FORM_DONE
        end
    end

    if not Map.formvalue(self, "cbi.delg.current") then
        self:_run_hooks("on_init")
    end

    local newcurrent
    self.chain = self.chain or self:get_chain()
    self.current = self.current or self:get_active()
    self.active = self.active or self:get(self.current)
    assert(self.active, "Invalid state")

    local stat = FORM_DONE
    if type(self.active) ~= "function" then
        self.active:populate_delegator(self)
        stat = self.active:parse()
    else
        self:active()
    end

    if stat > FORM_PROCEED then
        if Map.formvalue(self, "cbi.delg.back") then
            newcurrent = self:get_prev(self.current)
        else
            newcurrent = self:get_next(self.current)
        end
    elseif stat < FORM_PROCEED then
        return stat
    end


    if not Map.formvalue(self, "cbi.submit") then
        return FORM_NODATA
    elseif stat > FORM_PROCEED
    and (not newcurrent or not self:get(newcurrent)) then
        return self:_run_hook("on_done") or FORM_DONE
    else
        self.current = newcurrent or self.current
        self.active = self:get(self.current)
        if type(self.active) ~= "function" then
            self.active:populate_delegator(self)
            local stat = self.active:parse(false)
            if stat == FORM_SKIP then
                return self:parse(...)
            else
                return FORM_PROCEED
            end
        else
            return self:parse(...)
        end
    end
end

function Delegator.get_next(self, state)
    for k, v in ipairs(self.chain) do
        if v == state then
            return self.chain[k+1]
        end
    end
end

function Delegator.get_prev(self, state)
    for k, v in ipairs(self.chain) do
        if v == state then
            return self.chain[k-1]
        end
    end
end

function Delegator.get_chain(self)
    local x = Map.formvalue(self, "cbi.delg.path") or self.defaultpath
    return type(x) == "table" and x or {x}
end

function Delegator.get_active(self)
    return Map.formvalue(self, "cbi.delg.current") or self.chain[1]
end

--[[
Page - A simple node
]]--

Page = class(Node)
Page.__init__ = Node.__init__
Page.parse    = function() end


--[[
SimpleForm - A Simple non-UCI form
]]--
SimpleForm = class(Node)

function SimpleForm.__init__(self, config, title, description, data)
    Node.__init__(self, title, description)
    self.config = config
    self.data = data or {}
    self.template = "cbi/simpleform"
    self.dorender = true
    self.pageaction = false
    self.readinput = true
end

SimpleForm.formvalue = Map.formvalue
SimpleForm.formvaluetable = Map.formvaluetable

function SimpleForm.parse(self, readinput, ...)
    self.readinput = (readinput ~= false)

    if self:formvalue("cbi.skip") then
        return FORM_SKIP
    end

    if self:formvalue("cbi.cancel") and self:_run_hooks("on_cancel") then
        return FORM_DONE
    end

    if self:submitstate() then
        Node.parse(self, 1, ...)
    end

    local valid = true
    for k, j in ipairs(self.children) do
        for i, v in ipairs(j.children) do
            valid = valid
             and (not v.tag_missing or not v.tag_missing[1])
             and (not v.tag_invalid or not v.tag_invalid[1])
             and (not v.error)
        end
    end

    local state =
        not self:submitstate() and FORM_NODATA
        or valid and FORM_VALID
        or FORM_INVALID

    self.dorender = not self.handle
    if self.handle then
        local nrender, nstate = self:handle(state, self.data)
        self.dorender = self.dorender or (nrender ~= false)
        state = nstate or state
    end
    return state
end

function SimpleForm.render(self, ...)
    if self.dorender then
        Node.render(self, ...)
    end
end

function SimpleForm.submitstate(self)
    return self:formvalue("cbi.submit")
end

function SimpleForm.section(self, class, ...)
    if instanceof(class, AbstractSection) then
        local obj  = class(self, ...)
        self:append(obj)
        return obj
    else
        error("class must be a descendent of AbstractSection")
    end
end

-- Creates a child field
function SimpleForm.field(self, class, ...)
    local section
    for k, v in ipairs(self.children) do
        if instanceof(v, SimpleSection) then
            section = v
            break
        end
    end
    if not section then
        section = self:section(SimpleSection)
    end

    if instanceof(class, AbstractValue) then
        local obj  = class(self, section, ...)
        obj.track_missing = true
        section:append(obj)
        return obj
    else
        error("class must be a descendent of AbstractValue")
    end
end

function SimpleForm.set(self, section, option, value)
    self.data[option] = value
end


function SimpleForm.del(self, section, option)
    self.data[option] = nil
end


function SimpleForm.get(self, section, option)
    return self.data[option]
end


function SimpleForm.get_scheme()
    return nil
end


Form = class(SimpleForm)

function Form.__init__(self, ...)
    SimpleForm.__init__(self, ...)
    self.embedded = true
end


--[[
AbstractSection
]]--
AbstractSection = class(Node)

function AbstractSection.__init__(self, map, sectiontype, ...)
    Node.__init__(self, ...)
    self.sectiontype = sectiontype
    self.map = map
    self.config = map.config
    self.optionals = {}
    self.defaults = {}
    self.fields = {}
    self.tag_error = {}
    self.tag_invalid = {}
    self.tag_deperror = {}
    self.changed = false

    self.optional = true
    self.addremove = false
    self.dynamic = false
end

-- Define a tab for the section
function AbstractSection.tab(self, tab, title, desc)
    self.tabs      = self.tabs      or { }
    self.tab_names = self.tab_names or { }

    self.tab_names[#self.tab_names+1] = tab
    self.tabs[tab] = {
        title       = title,
        description = desc,
        childs      = { }
    }
end

-- Check whether the section has tabs
function AbstractSection.has_tabs(self)
    return (self.tabs ~= nil) and (next(self.tabs) ~= nil)
end

-- Appends a new option
function AbstractSection.option(self, class, option, ...)
    if instanceof(class, AbstractValue) then
        local obj  = class(self.map, self, option, ...)
        self:append(obj)
        self.fields[option] = obj
        return obj
    elseif class == true then
        error("No valid class was given and autodetection failed.")
    else
        error("class must be a descendant of AbstractValue")
    end
end

-- Appends a new tabbed option
function AbstractSection.taboption(self, tab, ...)

    assert(tab and self.tabs and self.tabs[tab],
        "Cannot assign option to not existing tab %q" % tostring(tab))

    local l = self.tabs[tab].childs
    local o = AbstractSection.option(self, ...)

    if o then l[#l+1] = o end

    return o
end

-- Render a single tab
function AbstractSection.render_tab(self, tab, ...)

    assert(tab and self.tabs and self.tabs[tab],
        "Cannot render not existing tab %q" % tostring(tab))

    for _, node in ipairs(self.tabs[tab].childs) do
        node:render(...)
    end
end

-- Parse optional options
function AbstractSection.parse_optionals(self, section)
    if not self.optional then
        return
    end

    self.optionals[section] = {}

    local field = self.map:formvalue("cbi.opt."..self.config.."."..section)
    for k,v in ipairs(self.children) do
        if v.optional and not v:cfgvalue(section) and not self:has_tabs() then
            if field == v.option then
                field = nil
                self.map.proceed = true
            else
                table.insert(self.optionals[section], v)
            end
        end
    end

    if field and #field > 0 and self.dynamic then
        self:add_dynamic(field)
    end
end

-- Add a dynamic option
function AbstractSection.add_dynamic(self, field, optional)
    local o = self:option(Value, field, field)
    o.optional = optional
end

-- Parse all dynamic options
function AbstractSection.parse_dynamic(self, section)
    if not self.dynamic then
        return
    end

    local arr  = luci.util.clone(self:cfgvalue(section))
    local form = self.map:formvaluetable("cbid."..self.config.."."..section)
    for k, v in pairs(form) do
        arr[k] = v
    end

    for key,val in pairs(arr) do
        local create = true

        for i,c in ipairs(self.children) do
            if c.option == key then
                create = false
            end
        end

        if create and key:sub(1, 1) ~= "." then
            self.map.proceed = true
            self:add_dynamic(key, true)
        end
    end
end

-- Returns the section's UCI table
function AbstractSection.cfgvalue(self, section)
    return self.map:get(section)
end

-- Push events
function AbstractSection.push_events(self)
    --luci.util.append(self.map.events, self.events)
    self.map.changed = true
end

-- Removes the section
function AbstractSection.remove(self, section)
    self.map.proceed = true
    return self.map:del(section)
end

-- Creates the section
function AbstractSection.create(self, section)
    local stat

    if section then
        stat = section:match("^[%w_]+$") and self.map:set(section, nil, self.sectiontype)
    else
        section = self.map:add(self.sectiontype)
        stat = section
    end

    if stat then
        for k,v in pairs(self.children) do
            if v.default then
                self.map:set(section, v.option, v.default)
            end
        end

        for k,v in pairs(self.defaults) do
            self.map:set(section, k, v)
        end
    end

    self.map.proceed = true

    return stat
end


SimpleSection = class(AbstractSection)

function SimpleSection.__init__(self, form, ...)
    AbstractSection.__init__(self, form, nil, ...)
    self.template = "cbi/nullsection"
end


Table = class(AbstractSection)

function Table.__init__(self, form, data, ...)
    local datasource = {}
    local tself = self
    datasource.config = "table"
    self.data = data or {}

    datasource.formvalue = Map.formvalue
    datasource.formvaluetable = Map.formvaluetable
    datasource.readinput = true

    function datasource.get(self, section, option)
        return tself.data[section] and tself.data[section][option]
    end

    function datasource.submitstate(self)
        return Map.formvalue(self, "cbi.submit")
    end

    function datasource.del(...)
        return true
    end

    function datasource.get_scheme()
        return nil
    end

    AbstractSection.__init__(self, datasource, "table", ...)
    self.template = "cbi/tblsection"
    self.rowcolors = true
    self.anonymous = true
end

function Table.parse(self, readinput)
    self.map.readinput = (readinput ~= false)
    for i, k in ipairs(self:cfgsections()) do
        if self.map:submitstate() then
            Node.parse(self, k)
        end
    end
end

function Table.cfgsections(self)
    local sections = {}

    for i, v in luci.util.kspairs(self.data) do
        table.insert(sections, i)
    end

    return sections
end

function Table.update(self, data)
    self.data = data
end



--[[
NamedSection - A fixed configuration section defined by its name
]]--
NamedSection = class(AbstractSection)

function NamedSection.__init__(self, map, section, stype, ...)
    AbstractSection.__init__(self, map, stype, ...)

    -- Defaults
    self.addremove = false
    self.template = "cbi/nsection"
    self.section = section
end

function NamedSection.parse(self, novld)
    local s = self.section
    local active = self:cfgvalue(s)

    if self.addremove then
        local path = self.config.."."..s
        if active then -- Remove the section
            if self.map:formvalue("cbi.rns."..path) and self:remove(s) then
                self:push_events()
                return
            end
        else           -- Create and apply default values
            if self.map:formvalue("cbi.cns."..path) then
                self:create(s)
                return
            end
        end
    end

    if active then
        AbstractSection.parse_dynamic(self, s)
        if self.map:submitstate() then
            Node.parse(self, s)
        end
        AbstractSection.parse_optionals(self, s)

        if self.changed then
            self:push_events()
        end
    end
end


--[[
TypedSection - A (set of) configuration section(s) defined by the type
    addremove:  Defines whether the user can add/remove sections of this type
    anonymous:  Allow creating anonymous sections
    validate:   a validation function returning nil if the section is invalid
]]--
TypedSection = class(AbstractSection)

function TypedSection.__init__(self, map, type, ...)
    AbstractSection.__init__(self, map, type, ...)

    self.template = "cbi/tsection"
    self.deps = {}
    self.anonymous = false
end

-- Return all matching UCI sections for this TypedSection
function TypedSection.cfgsections(self)
    local sections = {}
    self.map.uci:foreach(self.map.config, self.sectiontype,
        function (section)
            if self:checkscope(section[".name"]) then
                table.insert(sections, section[".name"])
            end
        end)

    return sections
end

-- Limits scope to sections that have certain option => value pairs
function TypedSection.depends(self, option, value)
    table.insert(self.deps, {option=option, value=value})
end

function TypedSection.parse(self, novld)
    if self.addremove then
        -- Remove
        local crval = REMOVE_PREFIX .. self.config
        local name = self.map:formvaluetable(crval)
        for k,v in pairs(name) do
            if k:sub(-2) == ".x" then
                k = k:sub(1, #k - 2)
            end
            if self:cfgvalue(k) and self:checkscope(k) then
                self:remove(k)
            end
        end
    end

    local co
    for i, k in ipairs(self:cfgsections()) do
        AbstractSection.parse_dynamic(self, k)
        if self.map:submitstate() then
            Node.parse(self, k, novld)
        end
        AbstractSection.parse_optionals(self, k)
    end

    if self.addremove then
        -- Create
        local created
        local crval = CREATE_PREFIX .. self.config .. "." .. self.sectiontype
        local name  = self.map:formvalue(crval)
        if self.anonymous then
            if name then
                created = self:create()
            end
        else
            if name then
                -- Ignore if it already exists
                if self:cfgvalue(name) then
                    name = nil;
                end

                name = self:checkscope(name)

                if not name then
                    self.err_invalid = true
                end

                if name and #name > 0 then
                    created = self:create(name) and name
                    if not created then
                        self.invalid_cts = true
                    end
                end
            end
        end

        if created then
            AbstractSection.parse_optionals(self, created)
        end
    end

    if created or self.changed then
        self:push_events()
    end
end

-- Verifies scope of sections
function TypedSection.checkscope(self, section)
    -- Check if we are not excluded
    if self.filter and not self:filter(section) then
        return nil
    end

    -- Check if at least one dependency is met
    if #self.deps > 0 and self:cfgvalue(section) then
        local stat = false

        for k, v in ipairs(self.deps) do
            if self:cfgvalue(section)[v.option] == v.value then
                stat = true
            end
        end

        if not stat then
            return nil
        end
    end

    return self:validate(section)
end


-- Dummy validate function
function TypedSection.validate(self, section)
    return section
end


--[[
AbstractValue - An abstract Value Type
    null:       Value can be empty
    valid:      A function returning the value if it is valid otherwise nil
    depends:    A table of option => value pairs of which one must be true
    default:    The default value
    size:       The size of the input fields
    rmempty:    Unset value if empty
    optional:   This value is optional (see AbstractSection.optionals)
]]--
AbstractValue = class(Node)

function AbstractValue.__init__(self, map, section, option, ...)
    Node.__init__(self, ...)
    self.section = section
    self.option  = option
    self.map     = map
    self.config  = map.config
    self.tag_invalid = {}
    self.tag_missing = {}
    self.tag_reqerror = {}
    self.tag_error = {}
    self.deps = {}
    self.subdeps = {}
    --self.cast = "string"

    self.track_missing = false
    self.rmempty   = true
    self.default   = nil
    self.size      = nil
    self.optional  = false
end

function AbstractValue.prepare(self)
    self.cast = self.cast or "string"
end

-- Add a dependencie to another section field
function AbstractValue.depends(self, field, value)
    local deps
    if type(field) == "string" then
        deps = {}
        deps[field] = value
    else
        deps = field
    end

    table.insert(self.deps, {deps=deps, add=""})
end

-- Generates the unique CBID
function AbstractValue.cbid(self, section)
    return "cbid."..self.map.config.."."..section.."."..self.option
end

-- Return whether this object should be created
function AbstractValue.formcreated(self, section)
    local key = "cbi.opt."..self.config.."."..section
    return (self.map:formvalue(key) == self.option)
end

-- Returns the formvalue for this object
function AbstractValue.formvalue(self, section)
    return self.map:formvalue(self:cbid(section))
end

function AbstractValue.additional(self, value)
    self.optional = value
end

function AbstractValue.mandatory(self, value)
    self.rmempty = not value
end

function AbstractValue.add_error(self, section, type, msg)
    self.error = self.error or { }
    self.error[section] = msg or type

    self.section.error = self.section.error or { }
    self.section.error[section] = self.section.error[section] or { }
    table.insert(self.section.error[section], msg or type)

    if type == "invalid" then
        self.tag_invalid[section] = true
    elseif type == "missing" then
        self.tag_missing[section] = true
    end

    self.tag_error[section] = true
    self.map.save = false
end

function AbstractValue.parse(self, section, novld)
    local fvalue = self:formvalue(section)
    local cvalue = self:cfgvalue(section)

    -- If favlue and cvalue are both tables and have the same content
    -- make them identical
    if type(fvalue) == "table" and type(cvalue) == "table" then
        local equal = #fvalue == #cvalue
        if equal then
            for i=1, #fvalue do
                if cvalue[i] ~= fvalue[i] then
                    equal = false
                end
            end
        end
        if equal then
            fvalue = cvalue
        end
    end

    if fvalue and #fvalue > 0 then -- If we have a form value, write it to UCI
        local val_err
        fvalue, val_err = self:validate(fvalue, section)
        fvalue = self:transform(fvalue)

        if not fvalue and not novld then
            self:add_error(section, "invalid", val_err)
        end

        if fvalue and (self.forcewrite or not (fvalue == cvalue)) then
            if self:write(section, fvalue) then
                -- Push events
                self.section.changed = true
                --luci.util.append(self.map.events, self.events)
            end
        end
    else                            -- Unset the UCI or error
        if self.rmempty or self.optional then
            if self:remove(section) then
                -- Push events
                self.section.changed = true
                --luci.util.append(self.map.events, self.events)
            end
        elseif cvalue ~= fvalue and not novld then
            -- trigger validator with nil value to get custom user error msg.
            local _, val_err = self:validate(nil, section)
            self:add_error(section, "missing", val_err)
        end
    end
end

-- Render if this value exists or if it is mandatory
function AbstractValue.render(self, s, scope)
    if not self.optional or self.section:has_tabs() or self:cfgvalue(s) or self:formcreated(s) then
        scope = scope or {}
        scope.section   = s
        scope.cbid      = self:cbid(s)
        scope.striptags = luci.util.striptags
        scope.pcdata    = luci.util.pcdata

        scope.ifattr = function(cond,key,val)
            if cond then
                return string.format(
                    ' %s="%s"', tostring(key),
                    luci.util.pcdata(tostring( val
                     or scope[key]
                     or (type(self[key]) ~= "function" and self[key])
                     or "" ))
                )
            else
                return ''
            end
        end

        scope.attr = function(...)
            return scope.ifattr( true, ... )
        end

        Node.render(self, scope)
    end
end

-- Return the UCI value of this object
function AbstractValue.cfgvalue(self, section)
    local value
    if self.tag_error[section] then
        value = self:formvalue(section)
    else
        value = self.map:get(section, self.option)
    end

    if not value then
        return nil
    elseif not self.cast or self.cast == type(value) then
        return value
    elseif self.cast == "string" then
        if type(value) == "table" then
            return value[1]
        end
    elseif self.cast == "table" then
        return { value }
    end
end

-- Validate the form value
function AbstractValue.validate(self, value)
    if self.datatype and value then
        local args = { }
        local dt, ar = self.datatype:match("^(%w+)%(([^%(%)]+)%)")

        if dt and ar then
            local a
            for a in ar:gmatch("[^%s,]+") do
                args[#args+1] = a
            end
        else
            dt = self.datatype
        end

        if dt and datatypes[dt] then
            if type(value) == "table" then
                local v
                for _, v in ipairs(value) do
                    if v and #v > 0 and not datatypes[dt](v, unpack(args)) then
                        return nil
                    end
                end
            else
                if not datatypes[dt](value, unpack(args)) then
                    return nil
                end
            end
        end
    end

    return value
end

AbstractValue.transform = AbstractValue.validate


-- Write to UCI
function AbstractValue.write(self, section, value)
    return self.map:set(section, self.option, value)
end

-- Remove from UCI
function AbstractValue.remove(self, section)
    return self.map:del(section, self.option)
end




--[[
Value - A one-line value
    maxlength:  The maximum length
]]--
Value = class(AbstractValue)

function Value.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/value"
    self.keylist = {}
    self.vallist = {}
end

function Value.reset_values(self)
    self.keylist = {}
    self.vallist = {}
end

function Value.value(self, key, val)
    val = val or key
    table.insert(self.keylist, tostring(key))
    table.insert(self.vallist, tostring(val))
end


-- DummyValue - This does nothing except being there
DummyValue = class(AbstractValue)

function DummyValue.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template = "cbi/dvalue"
    self.value = nil
end

function DummyValue.cfgvalue(self, section)
    local value
    if self.value then
        if type(self.value) == "function" then
            value = self:value(section)
        else
            value = self.value
        end
    else
        value = AbstractValue.cfgvalue(self, section)
    end
    return value
end

function DummyValue.parse(self)

end


--[[
Flag - A flag being enabled or disabled
]]--
Flag = class(AbstractValue)

function Flag.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/fvalue"

    self.enabled = "1"
    self.disabled = "0"
end

-- A flag can only have two states: set or unset
function Flag.parse(self, section)
    local fvalue = self:formvalue(section)

    if fvalue then
        fvalue = self.enabled
    else
        fvalue = self.disabled
    end

    if fvalue == self.enabled or (not self.optional and not self.rmempty) then
        if not(fvalue == self:cfgvalue(section)) then
            self:write(section, fvalue)
        end
    else
        self:remove(section)
    end
end



--[[
ListValue - A one-line value predefined in a list
    widget: The widget that will be used (select, radio)
]]--
ListValue = class(AbstractValue)

function ListValue.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/lvalue"

    self.keylist = {}
    self.vallist = {}
    self.size   = 1
    self.widget = "select"
end

function ListValue.reset_values(self)
    self.keylist = {}
    self.vallist = {}
end

function ListValue.value(self, key, val, ...)
    if luci.util.contains(self.keylist, key) then
        return
    end

    val = val or key
    table.insert(self.keylist, tostring(key))
    table.insert(self.vallist, tostring(val))

    for i, deps in ipairs({...}) do
        self.subdeps[#self.subdeps + 1] = {add = "-"..key, deps=deps}
    end
end

function ListValue.validate(self, val)
    if luci.util.contains(self.keylist, val) then
        return val
    else
        return nil
    end
end



--[[
MultiValue - Multiple delimited values
    widget: The widget that will be used (select, checkbox)
    delimiter: The delimiter that will separate the values (default: " ")
]]--
MultiValue = class(AbstractValue)

function MultiValue.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template = "cbi/mvalue"

    self.keylist = {}
    self.vallist = {}

    self.widget = "checkbox"
    self.delimiter = " "
end

function MultiValue.render(self, ...)
    if self.widget == "select" and not self.size then
        self.size = #self.vallist
    end

    AbstractValue.render(self, ...)
end

function MultiValue.reset_values(self)
    self.keylist = {}
    self.vallist = {}
end

function MultiValue.value(self, key, val)
    if luci.util.contains(self.keylist, key) then
        return
    end

    val = val or key
    table.insert(self.keylist, tostring(key))
    table.insert(self.vallist, tostring(val))
end

function MultiValue.valuelist(self, section)
    local val = self:cfgvalue(section)

    if not(type(val) == "string") then
        return {}
    end

    return luci.util.split(val, self.delimiter)
end

function MultiValue.validate(self, val)
    val = (type(val) == "table") and val or {val}

    local result

    for i, value in ipairs(val) do
        if luci.util.contains(self.keylist, value) then
            result = result and (result .. self.delimiter .. value) or value
        end
    end

    return result
end


StaticList = class(MultiValue)

function StaticList.__init__(self, ...)
    MultiValue.__init__(self, ...)
    self.cast = "table"
    self.valuelist = self.cfgvalue

    if not self.override_scheme
     and self.map:get_scheme(self.section.sectiontype, self.option) then
        local vs = self.map:get_scheme(self.section.sectiontype, self.option)
        if self.value and vs.values and not self.override_values then
            for k, v in pairs(vs.values) do
                self:value(k, v)
            end
        end
    end
end

function StaticList.validate(self, value)
    value = (type(value) == "table") and value or {value}

    local valid = {}
    for i, v in ipairs(value) do
        if luci.util.contains(self.keylist, v) then
            table.insert(valid, v)
        end
    end
    return valid
end


DynamicList = class(AbstractValue)

function DynamicList.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/dynlist"
    self.cast = "table"
    self.keylist = {}
    self.vallist = {}
end

function DynamicList.reset_values(self)
    self.keylist = {}
    self.vallist = {}
end

function DynamicList.value(self, key, val)
    val = val or key
    table.insert(self.keylist, tostring(key))
    table.insert(self.vallist, tostring(val))
end

function DynamicList.write(self, section, value)
    local t = { }

    if type(value) == "table" then
        local x
        for _, x in ipairs(value) do
            if x and #x > 0 then
                t[#t+1] = x
            end
        end
    else
        t = { value }
    end

    if self.cast == "string" then
        value = table.concat(t, " ")
    else
        value = t
    end

    return AbstractValue.write(self, section, value)
end

function DynamicList.cfgvalue(self, section)
    local value = AbstractValue.cfgvalue(self, section)

    if type(value) == "string" then
        local x
        local t = { }
        for x in value:gmatch("%S+") do
            if #x > 0 then
                t[#t+1] = x
            end
        end
        value = t
    end

    return value
end

function DynamicList.formvalue(self, section)
    local value = AbstractValue.formvalue(self, section)

    if type(value) == "string" then
        if self.cast == "string" then
            local x
            local t = { }
            for x in value:gmatch("%S+") do
                t[#t+1] = x
            end
            value = t
        else
            value = { value }
        end
    end

    return value
end


--[[
TextValue - A multi-line value
    rows:   Rows
]]--
TextValue = class(AbstractValue)

function TextValue.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/tvalue"
end

--[[
Button
]]--
Button = class(AbstractValue)

function Button.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template  = "cbi/button"
    self.inputstyle = nil
    self.rmempty = true
end


FileUpload = class(AbstractValue)

function FileUpload.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template = "cbi/upload"
    if not self.map.upload_fields then
        self.map.upload_fields = { self }
    else
        self.map.upload_fields[#self.map.upload_fields+1] = self
    end
end

function FileUpload.formcreated(self, section)
    return AbstractValue.formcreated(self, section) or
        self.map:formvalue("cbi.rlf."..section.."."..self.option) or
        self.map:formvalue("cbi.rlf."..section.."."..self.option..".x")
end

function FileUpload.cfgvalue(self, section)
    local val = AbstractValue.cfgvalue(self, section)
    if val and fs.access(val) then
        return val
    end
    return nil
end

function FileUpload.formvalue(self, section)
    local val = AbstractValue.formvalue(self, section)
    if val then
        if not self.map:formvalue("cbi.rlf."..section.."."..self.option) and
           not self.map:formvalue("cbi.rlf."..section.."."..self.option..".x")
        then
            return val
        end
        fs.unlink(val)
        self.value = nil
    end
    return nil
end

function FileUpload.remove(self, section)
    local val = AbstractValue.formvalue(self, section)
    if val and fs.access(val) then fs.unlink(val) end
    return AbstractValue.remove(self, section)
end


FileBrowser = class(AbstractValue)

function FileBrowser.__init__(self, ...)
    AbstractValue.__init__(self, ...)
    self.template = "cbi/browser"
end