local ui = require("ui")

local PAD, GAP = 12, 8
local CARD_SIZE = 1  -- one scale across every card, regardless of label length

local screen

local function card(name, side)
  return ui.button{
    w = side, h = side,
    justify = "center",
    on_press = function() sys.launch("/apps/" .. name .. "/main.lua") end,
    ui.label(name, {size = CARD_SIZE, fit = side - 16}),
  }
end

function init()
  local names = {}
  for _, name in ipairs(fs.listDirs("/apps")) do
    if name ~= "Home" then names[#names + 1] = name end
  end
  table.sort(names)

  local side, cols = ui.cardSide(math.max(#names, 1), PAD, GAP)

  -- Rows are filled before ui.box() sees them: the constructor moves a spec's array part
  -- into its children, so anything appended afterwards is never laid out.
  local rows = {}
  for _, name in ipairs(names) do
    local row = rows[#rows]
    if not row or #row >= cols then
      row = {}
      rows[#rows + 1] = row
    end
    row[#row + 1] = card(name, side)
  end

  -- Centred left to right as a unit, still top aligned: the gaps inside the grid are
  -- fixed, so the leftover width belongs beside the block, not to its last column.
  local items = {pad = PAD, gap = GAP, w = "fill", align = "center"}
  local gridW = cols * side + (cols - 1) * GAP
  for _, row in ipairs(rows) do
    row.row, row.gap, row.w = true, GAP, gridW
    items[#items + 1] = ui.box(row)
  end
  if #rows == 0 then items[#items + 1] = ui.text("no apps in /apps", {color = ui.theme.muted}) end

  screen = ui.screen(ui.box(items))
  log.info("home ready")
end

function draw() screen:draw() end
function on_touch_down(x, y) screen:down(x, y) end
function on_touch_up(x, y) screen:up(x, y) end