--neccesary to support the widget localisation and autoscaling
local lcd=LCD or lcd
local LCD_W = lcd.W or LCD_W
local LCD_H = lcd.H or LCD_H


--local RIGHT = RIGHT or 0  --fix 2.1 right alignement
--local EVT_MINUS_FIRST = EVT_MINUS_FIRST or EVT_ROT_RIGHT or EVT_DOWN_BREAK
--local EVT_PLUS_FIRST =  EVT_PLUS_FIRST or EVT_ROT_LEFT or EVT_UP_BREAK
--local EVT_ENTER_LONG = EVT_ENTER_LONG or EVT_ROT_LONG

-- Copyright F. Aguerre & M. Ricci.
-- This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License
-- as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
-- This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
-- without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-- See theGNU General Public License for more details.

-- Variable used to manage page and field edition *** do not change

local edit = false      -- true when editing field
local saving = true

local currPage = 1      -- current displayed page
local currField = 0     -- current selected field
local startValue = 0    -- value when start to press plus or minus key

local workIndex, startIndex, workField, workAtt, workValue -- Working variables used in various function.

-- Page title definition *** change to define your own title ***
local pageTitle = {"PredimRC - AILE", "PredimRC - STAB", "PredimRC - FUSELAGE", "PredimRC - REGLAGE", "PredimRC - INFOS"}

-- Page field definition  *** change to define your own page content ***
-- Field structure : {value, column, ligne, attribute, type, state, precision or combobox size, combobox list)
-- > attribute can be DBLSIZE, MIDSIZE, SMLSIZE, XXLSIZE, and also LEFT, PREC1, PREC2 for number (if type = 1)
-- > type can be 0 = text, 1 = number, 2 = combobox, ... can be extend if needed
-- > state can be nil, false = read-only, true = read/write, 0 = selected, 1 = edited
-- > precision (option) is the number of digit after the coma 
--   if 0     -> 100 is displayed 100
--   if PREC1 -> 100 is displayed 10.0
--   if PREC2 -> 100 is displayed 1.00
-- > combobox size (optional) is the size of the combobox 
-- > combobox list (optional) is the item list for the combobox

-- Entête réutilisée dans les pages 1 (aile) et 2 (stab)

local header = {
    -- Entete de colonne
    {"(mm)", 1, 12, 0, 0},
    {"Trap.1", 40, 12, 0, 0}, 
    {"Trap.2", 75, 12, 0, 0}, 
    {"Trap.3", 110, 12, 0, 0}, 
    {"Trap.4", 145, 12, 0, 0}, 
    {"Trap.5", 180, 12, 0, 0},
    -- Entete de ligne
    {"C. Max", 1, 22, 0, 0},
    {"C. Min", 1, 32, 0, 0},
    {"Long.", 1, 42, 0, 0},
    {"Fleche", 1, 52, 0, 0},
}

-- Définition des pages
local pageField = {
  { -- Page 1/5 - Aile
  
    -- Entete de colonne
    header[1],
    header[2],
    header[3],
    header[4],
    header[5],
    header[6],

    -- Entete de ligne
    header[7],
    header[8],
    header[9],
    header[10],

    -- Trapeze 1
    {250, 72, 22, 0, 1, true, 0},  -- corde maxi
    {150, 72, 32, 0, 1, true, 0},  -- corde mini
    {1000, 72, 42, 0, 1, true, 0}, -- longueur
    {100, 72, 52, 0, 1, true, 0},  -- fleche

    -- Trapeze 2
    {0, 107, 22, 0, 1},            -- corde maxi
    {0, 107, 32, 0, 1, true, 0},   -- corde mini
    {0, 107, 42, 0, 1, true, 0},   -- longueur
    {0, 107, 52, 0, 1, true, 0},   -- fleche

    -- Trapeze 3
    {0, 142, 22, 0, 1},            -- corde maxi
    {0, 142, 32, 0, 1, true, 0},   -- corde mini
    {0, 142, 42, 0, 1, true, 0},   -- longueur
    {0, 142, 52, 0, 1, true, 0},   -- fleche

    -- Trapeze 4
    {0, 177, 22, 0, 1},            -- corde maxi
    {0, 177, 32, 0, 1, true, 0},   -- corde mini
    {0, 177, 42, 0, 1, true, 0},   -- longueur
    {0, 177, 52, 0, 1, true, 0},   -- fleche
 
    -- Trapeze 5
    {0, 212, 22, 0, 1},            -- corde maxi
    {0, 212, 32, 0, 1, true, 0},   -- corde mini
    {0, 212, 42, 0, 1, true, 0},   -- longueur
    {0, 212, 52, 0, 1, true, 0}    -- fleche
  },
  { -- Page 2/5 - Stab
  
    -- Entete de colonne
    header[1],
    header[2],
    header[3],
    header[4],
    header[5],
    header[6],

    -- Entete de ligne
    header[7],
    header[8],
    header[9],
    header[10],

    -- Trapeze 1
    {120, 72, 22, 0, 1, true, 0},  -- corde maxi
    {80, 72, 32, 0, 1, true, 0},   -- corde mini
    {270, 72, 42, 0, 1, true, 0},  -- longueur
    {40, 72, 52, 0, 1, true, 0},   -- fleche

    -- Trapeze 2
    {0, 107, 22, 0, 1},            -- corde maxi
    {0, 107, 32, 0, 1, true, 0},   -- corde mini
    {0, 107, 42, 0, 1, true, 0},   -- longueur
    {0, 107, 52, 0, 1, true, 0},   -- fleche

    -- Trapeze 3
    {0, 142, 22, 0, 1},            -- corde maxi
    {0, 142, 32, 0, 1, true, 0},   -- corde mini
    {0, 142, 42, 0, 1, true, 0},   -- longueur
    {0, 142, 52, 0, 1, true, 0},   -- fleche

    -- Trapeze 4
    {0, 177, 22, 0, 1},            -- corde maxi
    {0, 177, 32, 0, 1, true, 0},   -- corde mini
    {0, 177, 42, 0, 1, true, 0},   -- longueur
    {0, 177, 52, 0, 1, true, 0},   -- fleche
 
    -- Trapeze 5
    {0, 212, 22, 0, 1},            -- corde maxi
    {0, 212, 32, 0, 1, true, 0},   -- corde mini
    {0, 212, 42, 0, 1, true, 0},   -- longueur
    {0, 212, 52, 0, 1, true, 0}    -- fleche
  },
  { -- Page 3/5 - Fuselage
    {"STAB", 1, 10, 0 , 0},
    {"Levier :", 40, 10, 0 , 0},
    {700, 145, 10, 0, 1, true, 0},
    {"Ouv. :", 150, 10, 0 , 0},
    {0, 212, 10, 0, 2, true, 30, {180, 120, 115, 110, 105, 90}},
    {"Haut :", 40, 20, 0 , 0},
    {50, 145, 20, 0, 1, true, 0},
    {"FUSO", 1, 30, 0, 0},
    {"Poutre :", 40, 30, 0 , 0},
    {1, 145, 30, 0, 2, true, 54, {"Fine", "Normale", "Epaisse", "Jet"}},
    {"Longueur :", 40, 40, 0 , 0},
    {1070, 145, 40, 0, 1, true, 0},
    {"Nez :", 150, 40, 0 , 0},
    {250, 212, 40, 0, 1, true, 0},
    {"Largeur :", 40, 50, 0 , 0},
    {50, 145, 50, 0, 1, true, 0}
  },
  { -- Page 4/5 - Réglage
    {"Marge", 1, 12, 0 , 0},
    {3, 78, 12, 0, 2, true, 25, {"6%", "5%", "4%", "3%", "2%", "1%"} },
    {"CG", 1, 24, 0 , 0},
    {0, 71, 24, 0, 1, false, PREC1},
    {"%", 72, 24, 0, 0},
    {0, 126, 24, 0, 1, false, PREC1},
    {"mm", 127, 24, 0, 0},
    {"Foyer", 1, 36, 0 , 0},
    {0, 71, 36, 0, 1, false, PREC1},
    {"%", 72, 36, 0, 0},
    {0, 126, 36, 0, 1, false, PREC1},
     {"mm", 127, 36, 0, 0}
  },
  { -- Page 5/5 - Infos
    {"Surf.", 47, 10, 0, 0}, 
    {"C.Moy.", 80, 10, 0,0}, 
    {"Env.", 122, 10, 0, 0}, 
    {"All.", 162, 10, 0, 0}, 
    {"Foyer", 180, 10, 0, 0},
  
    {"AILE", 1, 20, 0, 0},
    {0, 73, 20, 0, 1, false, PREC2},  -- surface aero (dm2)
    {0, 108, 20, 0, 1, false, PREC1}, -- corde moyenne areo
    {0, 143, 20, 0, 1, false, 0},     -- envergure aero
    {0, 178, 20, 0, 1, false, PREC1}, -- allongement aero
    {0, 210, 20, 0, 1, false, PREC1}, -- foyer aero
  
    {"STAB", 1, 32, 0, 0},
    {0, 73, 32, 0, 1, false, PREC2},  -- surface aero (dm2)
    {0, 108, 32, 0, 1, false, PREC1}, -- corde moyenne areo
    {0, 143, 32, 0, 1, false, 0},     -- envergure aero
    {0, 178, 32, 0, 1, false, PREC1}, -- allongement aero
    {0, 210, 32, 0, 1, false, PREC1}, -- foyer aero
  
    {"Levier", 40, 42, 0, 0},         -- Distance Foyer stab - Foyer Aile
    {0, 108, 42, 0, 1, false, 0},     
    {"Vol.", 126, 42, 0, 0},          -- Volume du stab
    {0, 178, 42, 0, 1, false, PREC2}, 
  
    {"FUSO", 1, 54, 0, 0},  
    {"Surf.", 40, 54, 0, 0},          -- Surface projetée du fuselage
    {0, 108, 54, 0, 1, false, PREC1}, 
    {"Foyer", 115, 54, 0, 0},         -- Foyer du fuselage
    {0, 172, 54, 0, 1, false, 0},
    {"%", 173, 54, 0, 0}, 
  }
}

-- Champs réutilisés dans les calculs

local wingMean = pageField[5][8]
local wingSpan = pageField[5][9] 
local wingRatio = pageField[5][10]
local wingCenter = pageField[5][11] 

local stabMean = pageField[5][14]
local stabSpan = pageField[5][15] 
local stabRatio = pageField[5][16]
local stabCenter = pageField[5][17] 

local dist_FS_FA = pageField[5][19]
local stabVol = pageField[5][21]

-- Coefficient liés au combobox

local coeffMarge = {0.06, 0.05, 0.04, 0.03, 0.02, 0.01} -- Marge pour le calcul du centrage
local coeffCenterNormal = {0.15, 0.20, 0.25, 0.45}      -- Coefficient pour le calcul du foyer du fuselage selon la poutre
local coeffCenterCanard = {0.449, 0.35, 0.25, 0.45}     -- Coefficient pour le calcul du foyer du fuselage selon la poutre pour un canard
local coeffPoutre = {0.55, 0.7, 0.85, 1}                -- Coefficient pour le calcul de la surface du fuselage selon la poutre

-- Variable conservée pour les calculs

local wingArea, stabArea, stabProjArea, bodyArea = 0, 0, 0, 0
local wingA, stabA, bodyA = 0, 0, 0

-- Process surface change

local area, span, mean, ratio, center, surfaceA, FlCm, FlCm2, surface
local wrkRoot, wrkSum, wrkArea, wrkMean, wrkOffset

local function surfaceChange()
  area, span, mean, ratio, center, surfaceA = 0, 0, 0, 0, 0, 0
  FlCm, FlCm2, wrkRoot = 0, 0, 0

  surface = pageField[currPage]

  for index = 11, #surface, 4 do
    if surface[index][1] > 0 then
      surface[index][6]     = true
      surface[index + 1][6] = true
      surface[index + 2][6] = true
      surface[index + 3][6] = true
      wrkSum = 3 * (surface[index][1] + surface[index + 1][1])
      if wrkSum > 0 then
        -- calcul de l'envergure et de la surface
        span = span + surface[index + 2][1]
        wrkArea = surface[index + 2][1] * (surface[index][1] + surface[index + 1][1]) / 2
        area = area + wrkArea
        -- calcul de la corde moyenne
        wrkMean = surface[index + 1][1] + (2 * surface[index][1] + surface[index + 1][1]) * (surface[index][1] - surface[index + 1][1]) / wrkSum
        mean = mean + wrkArea * wrkMean
        -- calcul de l'offset du foyer
        wrkOffset = wrkRoot + (surface[index + 3][1] - wrkRoot) * (surface[index][1] + 2 * surface[index + 1][1]) / wrkSum
        center = center + (wrkArea * (wrkOffset + 0.25 * wrkMean))
        wrkRoot = surface[index + 3][1]
      end
    else
      surface[index][6]     = false
      surface[index + 1][6] = false
      surface[index + 2][6] = false
      surface[index + 3][6] = false
    end
  end
  
  if area > 0 then
    mean = mean / area
    center = center / area
    area = 2 * area
    span = 2 * span
    ratio = span * span / area
  
    -- Calcul du facteur A pour la surface
    FlCm = center + 0.25 * mean - pageField[currPage][11][1] / 2
    FlCm2 = math.atan(FlCm / (0.5 * span * 0.53))
    surfaceA = ratio / (math.sqrt((ratio / math.cos(FlCm2))^2 + 4) + 2)
  end

  -- Conserve les calculs pour l'aile ou le stab
  if currPage == 1 then
    wingArea = area
    pageField[5][7][1] = area / 10000   -- surface aero (dm2)
    wingMean[1] = mean
    wingSpan[1] = span
    wingRatio[1] = ratio
    wingCenter[1] = center
    wingA = surfaceA
  else
    stabArea = area
    pageField[5][13][1] = area / 10000   -- surface aero (dm2)
    stabMean[1] = mean
    stabSpan[1] = span
    stabRatio[1] = ratio
    stabCenter[1] = center
    stabA = surfaceA ~= 0 and surfaceA or 0.000001
  end
end

-- Process application changes

local dist_FF_FA, coeffCenter, rx, rh2, racine, eMS, denom
local foyerBrut, corrSillage, corrFuselage, pourcent

local function commonChange()
  -- calcul liés au stab
  dist_FS_FA[1] = 0
  stabVol[1] = 0
  if wingArea > 0 and stabArea > 0 then
    -- calcul de la surface projetee du stab
    stabProjArea = stabArea * math.sin(math.rad(pageField[3][5][8][1 + pageField[3][5][1]]/2))^2
    -- calcul de la distance de foyer aile à foyer stab
    dist_FS_FA[1] = pageField[3][3][1] - wingCenter[1] + stabCenter[1]
    -- calcul du volume du stab
    stabVol[1] = (stabProjArea * dist_FS_FA[1]) / (wingArea * wingMean[1])
  end

  -- effectue le calcul du CG et du foyer seulement si la corde moyenne, l'envergure et l'allongement sont différent de zero
  if wingMean[1] ~= 0 and wingSpan[1] ~= 0 and wingRatio[1] ~= 0 then    
  
  -- calculs liés au fuselage
    coeffCenter = 0
    if stabVol[1] >= 0 then
      coeffCenter = coeffCenterNormal[1 + pageField[3][10][1]]
    else
      coeffCenter = coeffCenterCanard[1 + pageField[3][10][1]]
    end
    pageField[5][26][1] = 100 * coeffCenter
    dist_FF_FA = pageField[3][12][1] * coeffCenter - (pageField[3][14][1] + wingCenter[1])
    bodyA = 0
    if bodyArea > 0 then
      if stabVol[1] > 0.2 then
        bodyA = 0.2 * (1 + wingMean[1] / pageField[3][16][1]) * (stabVol[1] < 10 and wingA or 1)
      elseif stabVol[1] < -0.2 then
        bodyA = 0.2 * stabA * (1 + stabMean[1] / pageField[3][16][1])
      else
        bodyA = 0.1
      end
    end

    -- calcul de la déflexion du sillage (eMS)
    rx = 2 * dist_FS_FA[1] / wingSpan[1]
    rh2 = (2 * pageField[3][7][1] / wingSpan[1])^2
    racine = math.sqrt(math.pi^2 / 16 + rx^2 + rh2)
    eMS = ((racine + rx) / (math.pi^2 / 16 + rh2) + rx / (rx^2 + rh2)) / (racine * (2 + math.sqrt(4 + wingRatio[1]^2)))
  
    -- calcul des corrections
    foyerBrut, corrSillage, corrFuselage = 0, 0, 0
    denom = 0.11 * (wingA * wingArea + (1 - eMS) * stabA * stabProjArea + bodyA * bodyArea)
    if denom ~= 0 then
      foyerBrut = 0.25 + 0.11 * stabA * dist_FS_FA[1] * stabProjArea /(wingMean[1] * denom)
      corrSillage = eMS * dist_FS_FA[1] * 0.11 * stabA * stabProjArea / (wingMean[1] * denom)
      corrFuselage = 0 - (0.11 * dist_FF_FA / wingMean[1]) * bodyA * bodyArea / denom
    end
    
    -- calcul du foyer
    pourcent = foyerBrut - corrSillage - corrFuselage
    pageField[4][9][1] = 100 * pourcent
    pageField[4][11][1] = wingCenter[1] + (pourcent - 0.25) * wingMean[1]

    -- calcul du CG
    pourcent = pourcent - coeffMarge[1 + pageField[4][2][1]]
    pageField[4][4][1] = 100 * pourcent
    pageField[4][6][1] = wingCenter[1] + (pourcent - 0.25) * wingMean[1]
  else
    -- remet à zéro le CG et le foyer
    pageField[4][4][1] = 0
    pageField[4][6][1] = 0
    pageField[4][9][1] = 0
    pageField[4][11][1] = 0
  end  
end

-- Process changes *** function called by the framework when value has change within a page. Include your own page logic
local function onChange()
    if currPage == 1 or currPage == 2 then
      for index = 11, #pageField[currPage], 4 do
        -- contrôle des valeur négatives (corde et longueur)
        if pageField[currPage][index][1] < 0 then pageField[currPage][index][1] = 0 end
        if pageField[currPage][index + 1][1] < 0 then pageField[currPage][index + 1][1] = 0 end
        if pageField[currPage][index + 2][1] < 0 then pageField[currPage][index + 2][1] = 0 end
        -- reporte la corde mini sur le trapèze suivant
        if index > 14 then pageField[currPage][index][1] = pageField[currPage][index - 3][1] end
      end
      -- effectue les calculs lié à la surface
      surfaceChange()
    elseif currPage == 3 then
      -- contrôle des valeur négatives (longueur, nez et largeur)
      if pageField[3][12][1] < 0 then pageField[3][12][1] = 0 end
      if pageField[3][16][1] < 0 then pageField[3][16][1] = 0 end
      -- effectue les calculs liés au fuselage
      bodyArea = pageField[3][12][1] * pageField[3][16][1] * coeffPoutre[1 + pageField[3][10][1]]
      pageField[5][24][1] = bodyArea / 10000
    end
    -- effectue les caluls liés à plusieurs pages
    commonChange()
end

-- Framwork *** DO NOT change the code here under 

-- Add value to current field
local function addField(value)
  if currField > 0 and currField <= #pageField[currPage] then
    workField = pageField[currPage][currField]
    if workField[5] == 1 then         -- Number
      workField[1] = workField[1] + value * (workField[7] == PREC1 and 0.1 or (workField[7] == PREC2 and 0.01 or 1))
    elseif workField[5] == 2 then     -- Combobox
      workField[1] = (workField[1] - (value > 0 and 1 or -1)) % #workField[8]
    end
  end
end

-- Change display attribute to current field
local function changeField(value)
  if currField > 0 and currField <= #pageField[currPage] then
    pageField[currPage][currField][6] = value
  end
end

-- Select the next or previous editable field
local function selectField(step)
  if #pageField[currPage] < 1 then return end   -- empty page
  workIndex = 1 + (currField - 1) % #pageField[currPage]
  startIndex = workIndex
  while true do
    workIndex = 1 + (workIndex + step - 1) % #pageField[currPage]
    if workIndex == startIndex then break end
    if pageField[currPage][workIndex][6] then
      changeField(true)
      currField = workIndex
      changeField(0)
      break
    end
  end
end

-- save entries
local function savePage()
  if io then
    local filename = "/MODELS/" .. model.getInfo().name .. ".predim" .. currPage
    loadfile("/APPS/L/L/TABLE/save.lua")(pageField[currPage],filename)
  end  
end

-- save entries
local function loadPage()
  if io then
    local filename = "/MODELS/" .. model.getInfo().name .. ".predim" .. currPage
    local f=io.open(filename,"r")
    if f then
      io.close(f)
      f=nil
      pageField[currPage]=loadfile("/APPS/L/L/TABLE/load.lua")(filename)()
    end    
  end  
  saving = false
end


-- Select next or previous page
local function selectPage(step)
      savePage()
      saving = true
      if currField > 0 then changeField(true) end
      currPage = 1 + (currPage + step -1) % #pageField
      currField = 0
      selectField(1)
end

-- Redraw the current page
local function redrawPage()
  lcd.clear()
  lcd.drawScreenTitle(pageTitle[currPage], currPage, #pageField)
--  lcd.drawText(1,1,pageTitle[currPage])
--  lcd.drawText(LCD_W,1,  "page " .. currPage .. "/" .. #pageField, RIGHT)
  for index = 1, #pageField[currPage], 1 do
    workField = pageField[currPage][index]
    workAtt = workField[6] == 0 and INVERS or (workField[6] == 1 and INVERS + BLINK or 0) -- determine the display attribut

    -- display text field
    if workField[5] == 0 then
      lcd.drawText(workField[2], workField[3], workField[1], workField[4] + workAtt)

    -- display number field
    elseif workField[5] == 1 then
      workAtt = workAtt + (workField[7] and workField[7] or 0)                          -- change the display attribut based on precision
      workValue = workField[7] == PREC1 and 10 or (workField[7] == PREC2 and 100 or 1)  -- get the multiplication factor based on precision
      workValue = math.floor(workField[1] * workValue + 0.5)                            -- round the value based on the precision
      lcd.drawNumber(workField[2], workField[3], workValue, workField[4]  + workAtt + RIGHT)
    
    -- display combobox except the selected / edited one
    elseif workField[5] == 2 and index ~= currField then -- Combobox
      lcd.drawCombobox(workField[2] - workField[7], workField[3] - 2, workField[7], workField[8], workField[1], workField[4] + workAtt)
    end
  end

  -- finaly if the current field is a combobox, display it 
  if currField > 0 and pageField[currPage][currField][5] == 2 then
    workField = pageField[currPage][currField]
    workAtt = workField[6] == 0 and INVERS or (workField[6] == 1 and INVERS + BLINK or 0)
    lcd.drawCombobox(workField[2] - workField[7], workField[3] - 2, workField[7], workField[8], workField[1], workField[4] + workAtt)
  end
end

-- Init
local function init()
  for index = 1, #pageField, 1 do
    currPage = index
    onChange()
  end
  currPage, currField, edit = 1, 0, false
  selectField(1)
end

-- Main

local function run(event)
  if saving then
    loadPage()
    return 0
  end
  if event == nil then
    error("Cannot be run as a model script!")
    return 2
  elseif event == EVT_ENTER_BREAK then                                          -- toggle editing/selecting current field
    edit = not edit
    changeField(edit and 1 or 0)
    redrawPage()
  elseif event == EVT_EXIT_BREAK then                                           -- exit script
    selectPage(1)
--    return 2
  elseif edit then
    if event == EVT_PLUS_FIRST or event == EVT_MINUS_FIRST then                 -- first in/decrease current field
      startValue = pageField[currPage][currField][1]
      addField(event == EVT_PLUS_FIRST and 1 or -1)
      onChange()                                                             
    elseif event == EVT_PLUS_REPT or event == EVT_MINUS_REPT then               -- repeat in/decrease current field
      if math.abs(pageField[currPage][currField][1] - startValue) > 200 then
        addField(event == EVT_PLUS_REPT and 10 or -10)
      elseif math.abs(pageField[currPage][currField][1] - startValue) > 20 then
        addField(event == EVT_PLUS_REPT and 5 or -5)
      else
        addField(event == EVT_PLUS_REPT and 1 or -1)
      end
      onChange()                             -- process page changes
    end
    redrawPage()
  else
    if event == EVT_MINUS_FIRST then         -- move to next editable field
--    if event == EVT_MINUS_BREAK then         -- move to next editable field
      selectField(1) 
--    elseif event == EVT_PLUS_BREAK then      -- move to previous editable field
    elseif event == EVT_PLUS_FIRST then      -- move to previous editable field
      selectField(-1) 
    elseif event == EVT_PAGE_BREAK then      -- move to next page
      selectPage(1)
    elseif event == EVT_ENTER_LONG then      -- move to next page
      selectPage(1)
    elseif event == EVT_PAGE_LONG then       -- move to previous page
      killEvents(event);
      selectPage(-1)
    end
    redrawPage()
  end

  return 0
end

return { init=init, run=run}