-- The top bar, painted by the firmware once a second in every app. It draws in panel
-- coordinates (the firmware drops the app viewport around the call), so gui.width()
-- here is the whole screen.

local ui = require("ui")

local PAD = 6

-- The firmware reads both: `height` is the strip it keeps apps out of, `interval` is how
-- often it calls draw().
local M = {height = 22, interval = 1000}
local BAR_H = M.height

local function clock()
  return sys.clockSynced() and os.date("%H:%M") or "--:--"
end

-- Bars rather than glyphs: there is no icon font, and signal strength is a scale.
local function drawSignal(x, y, color, muted)
  local status = wifi.status()
  local bars = 0
  if status.state == "connected" then
    bars = status.rssi >= -60 and 3 or status.rssi >= -75 and 2 or 1
  end
  for i = 1, 3 do
    local h = i * 3
    gui.fillRect(x + (i - 1) * 4, y + 9 - h, 3, h, i <= bars and color or muted)
  end
end

-- Fills the leading square of the bar, which is the rect the firmware treats as home.
-- Drawn as a button rather than left as a hidden hit region: a target nobody can see is
-- one nobody finds.
local function drawHome(theme)
  local inset = 3
  local side = BAR_H - 1 - inset * 2
  gui.roundRect(inset, inset, side, side, 4, theme.bg, theme.face[1], theme.face[2], theme.muted)
  local x, y = inset + side // 2 + 1, inset + side // 2
  for offset = 0, 1 do  -- two passes, because a one pixel chevron reads as a speck
    gui.drawLine(x + offset, y - 4, x + offset - 4, y, theme.fg)
    gui.drawLine(x + offset - 4, y, x + offset, y + 4, theme.fg)
  end
end

function M.draw(home)
  local theme = ui.theme
  gui.setTextSize(1)  -- panel state: the app may have left it scaled up
  local w = gui.width()
  gui.fillRect(0, 0, w, BAR_H, theme.bg)
  gui.fillRect(0, BAR_H - 1, w, 1, theme.muted)  -- a rule, so the bar reads as chrome

  local textY = math.floor((BAR_H - 1 - gui.fontHeight()) / 2)
  local nameX = PAD
  if home then
    drawHome(theme)
    nameX = BAR_H + PAD
  end
  gui.drawText(sys.appName(), nameX, textY, theme.fg, theme.bg)

  local time = clock()
  gui.drawText(time, w - PAD - gui.textWidth(time), textY, theme.muted, theme.bg)
  drawSignal(w - PAD - gui.textWidth(time) - 8 - 11, textY, theme.fg, theme.muted)
end

return M