-- @titre Lettres hors des zones
-- @title Letters off their zones
-- @categorie relire
-- @resume Compare le haut et le bas de chaque lettre latine à sa zone (capitales, hauteur d'x, ascendante, descendante, ligne de base) dans chaque master : signale les lettres qui n'atteignent pas leur zone ou qui la dépassent plus qu'un débordement normal.
-- @summary Compares the top and bottom of each Latin letter with its zone (cap height, x-height, ascender, descender, baseline) in every master: flags letters that fall short of their zone or overshoot it more than a normal overshoot.
-- Fontista · bibliothèque de scripts · https://fontista.thinkspark.dev/scripts.html

local OVERSHOOT = 0.025 -- largest accepted overshoot, as a share of the em (0.025 = 25 units at 1000)
local SHORT = 1         -- a letter that stops more than this many units before its zone is flagged

local en = lang == "en"
local tol = OVERSHOOT * font.upm

-- true outline bounds: straight lines, quadratic and cubic segments sampled; components followed
local function bounds(name, master, depth)
  local l = layer(name, master)
  if not l or (depth or 0) > 5 then return nil end
  local b = nil
  local function add(x, y)
    if not b then b = { x, y, x, y } return end
    if x < b[1] then b[1] = x end
    if y < b[2] then b[2] = y end
    if x > b[3] then b[3] = x end
    if y > b[4] then b[4] = y end
  end
  local function segment(p, offs, q)
    if #offs == 0 then add(q.x, q.y) return end
    for i = 1, 24 do
      local t = i / 24
      local u = 1 - t
      local x, y
      if #offs == 1 then
        local c = offs[1]
        x = u * u * p.x + 2 * u * t * c.x + t * t * q.x
        y = u * u * p.y + 2 * u * t * c.y + t * t * q.y
      else
        local c1, c2 = offs[1], offs[#offs]
        x = u ^ 3 * p.x + 3 * u * u * t * c1.x + 3 * u * t * t * c2.x + t ^ 3 * q.x
        y = u ^ 3 * p.y + 3 * u * u * t * c1.y + 3 * u * t * t * c2.y + t ^ 3 * q.y
      end
      add(x, y)
    end
  end
  for _, c in ipairs(l.contours) do
    local n = #c.nodes
    local first = nil
    for i = 1, n do if c.nodes[i].kind ~= "off" then first = i break end end
    if first then
      local prev, offs = c.nodes[first], {}
      add(prev.x, prev.y)
      local last = c.closed and n or (n - first)
      for k = 1, last do
        local nd = c.nodes[(first - 1 + k) % n + 1]
        if nd.kind == "off" then offs[#offs + 1] = nd
        else segment(prev, offs, nd) prev, offs = nd, {} end
      end
    end
  end
  for _, comp in ipairs(components(name, master)) do
    local cb = bounds(comp.base, master, (depth or 0) + 1)
    if cb then add(cb[1] + comp.dx, cb[2] + comp.dy) add(cb[3] + comp.dx, cb[4] + comp.dy) end
  end
  return b
end

-- the zone each Latin letter should reach (nil: not checked)
local ASC, XH, DESC = "bdfhkl", "acemnorsuvwxz", "gjpqy"
local function zones(ch, m)
  if ch:match("^[A-Z]$") then
    return m.cap_height, (ch ~= "J" and ch ~= "Q") and 0 or nil
  elseif ch:match("^[a-z]$") then
    local top = ASC:find(ch, 1, true) and m.ascender or (XH:find(ch, 1, true) and m.x_height or nil)
    local bottom = DESC:find(ch, 1, true) and m.descender or 0
    return top, bottom
  end
end

local flagged, inked = 0, 0
for _, m in ipairs(font.masters) do
  for _, g in ipairs(font.glyphs) do
    local info = glyph(g)
    local ch = info and info.unicode and info.unicode < 0x80 and string.char(info.unicode) or nil
    local top, bottom = nil, nil
    if ch then top, bottom = zones(ch, m) end
    local l = (top or bottom) and layer(g, m.id) or nil
    -- skeleton layers inked by a brush: their outline only exists once inked, Lua cannot measure it
    local b = nil
    if l and l.ink then inked = inked + 1 elseif l then b = bounds(g, m.id) end
    if b then
      local notes = {}
      if top then
        local d = b[4] - top
        if d < -SHORT then notes[#notes + 1] = string.format(en and "top %.0f below the zone (%.0f)" or "haut %.0f sous la zone (%.0f)", -d, top)
        elseif d > tol then notes[#notes + 1] = string.format(en and "top %.0f above the zone (%.0f)" or "haut %.0f au-dessus de la zone (%.0f)", d, top) end
      end
      if bottom then
        local d = bottom - b[2]
        if d < -SHORT then notes[#notes + 1] = string.format(en and "bottom %.0f above the zone (%.0f)" or "bas %.0f au-dessus de la zone (%.0f)", -d, bottom)
        elseif d > tol then notes[#notes + 1] = string.format(en and "bottom %.0f below the zone (%.0f)" or "bas %.0f sous la zone (%.0f)", d, bottom) end
      end
      if #notes > 0 then
        flagged = flagged + 1
        print(string.format("%-12s %-10s %s", g, m.name, table.concat(notes, " · ")))
      end
    end
  end
end
if inked > 0 then
  print(string.format(en and "%d inked (skeleton) layer(s) not checked: review them in Fontista Control." or "%d calque(s) encré(s) (squelettes) non vérifié(s) : relisez-les dans Fontista Control.", inked))
end
print(flagged == 0 and (en and "Every letter reaches its zones." or "Toutes les lettres atteignent leurs zones.")
  or string.format(en and "%d letter(s) to look at (overshoot accepted up to %.0f units)" or "%d lettre(s) à regarder (débordement accepté jusqu'à %.0f unités)", flagged, tol))