--[[
Copyright (c) 2012-2013 Kaarle Ritvanen
See LICENSE file for license details
--]]

module(..., package.seeall)

local err = require('acf.error')
local raise = err.raise

local node = require('acf.model.node')

local object = require('acf.object')
local class = object.class
local super = object.super

local map = require('acf.util').map


local function contains(list, value)
   for k, v in ipairs(list) do if v == value then return true end end
   return false
end

local function auto_ui_name(name)
   if not name then return end
   return string.gsub(string.upper(string.sub(name, 1, 1))..string.sub(name, 2),
		      '_', ' ')
end


Field = class()

function Field:init(params)
   for k, v in pairs(params or {}) do
      if self[k] == nil then self[k] = v end
   end

   if self.choice and not self['ui-choice'] then
      self['ui-choice'] = map(auto_ui_name, self.choice)
   end

   if not self.widget then
      self.widget = self.choice and 'combobox' or 'field'
   end
end

function Field:meta(context)
   assert(self.dtype)
   return {
      name=self.name,
      type=self.dtype,
      required=self.required,
      default=self.default,
      choice=self.choice,
      description=self.description,
      ['ui-name']=self['ui-name'] or auto_ui_name(self.name),
      widget=self.widget,
      ['ui-choice']=self['ui-choice']
   }
end

function Field:load(context)
   local value = context.txn:get(context.addr)
   if value == nil then return self.default end
   return value
end

function Field:_validate(context, value)
   if self.required and value == nil then
      raise(context.path, 'Required value not set')
   end
   if self.choice and value ~= nil and not contains(self.choice, value) then
      raise(context.path, 'Invalid value')
   end
   if value ~= nil then self:validate(context, value) end
   return value
end

function Field:validate(context, value) end

function Field:save(context, value)
   -- 2nd argument currenly not much used by backends
   context.txn:set(context.addr, self.dtype, self:_validate(context, value))
end

function Field:validate_saved(context)
   self:save(context, self:load(context))
end


TreeNode = class(Field)

function TreeNode:save(context, value)
   local path = context.path

   -- TODO hack, allow preserving old instance on parent update
   if value == path then return end

   if object.isinstance(value, node.TreeNode) then
      -- TODO clone if TreeNode has wrong path
      if node.path(value) ~= path then
	 raise(path, 'Attempted to assign foreign object as value')
      end
      return
   end

   context.txn:set(context.addr)

   if value then
      if type(value) ~= 'table' then
	 raise(path, 'Cannot assign primitive value')
      end

      context.txn:set(context.addr, 'table')
      local new = self:load(context, true)

      local errors = err.ErrorDict()
      for k, v in pairs(value) do
	 errors:collect(self.save_member, new, k, v)
      end
      errors:raise()
   end
end

function TreeNode.save_member(node, k, v) node[k] = v end


Model = class(TreeNode)

function Model:init(params)
   super(self, Model):init(params)
   assert(self.model)
   self.dtype = 'model'
   self.widget = self.dtype
end

function Model:load(context, create)
   if not create and not context.txn:get(context.addr) then return end
   return self.model(context)
end