----------------------------------------------------------------------
-- align ipelet
----------------------------------------------------------------------
--[[

    This file is part of the extensible drawing editor Ipe.
    Copyright (c) 1993-2022 Otfried Cheong

    Ipe 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.

    As a special exception, you have permission to link Ipe with the
    CGAL library and distribute executables, as long as you follow the
    requirements of the Gnu General Public License in regard to all of
    the software in the executable aside from CGAL.

    Ipe 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 the GNU General Public
    License for more details.

    You should have received a copy of the GNU General Public License
    along with Ipe; if not, you can find it at
    "http://www.gnu.org/copyleft/gpl.html", or write to the Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

--]]

label = "Align && distribute"

revertOriginal = _G.revertOriginal

about = [[
Several alignment functions.

This ipelet is part of Ipe.
]]

V = ipe.Vector

skip = 0.0

----------------------------------------------------------------------

function set_skip(model)
  local str = model:getString("Enter skip in points")
  if not str or str:match("^%s*$") then return end
  local s = tonumber(str)
  if not s then
    model:warning("Enter distance between consecutive objects in points")
    return
  end
  skip = s
  model.ui:explain("set skip distance to " .. skip .. " points")
end

----------------------------------------------------------------------

function simple_align(model, num)
  local p = model:page()
  if not p:hasSelection() then model.ui:explain("no selection") return end

  local pin = {}
  local selection = {}
  for i, obj, sel, lay in p:objects() do
    if sel == 2 then
      pin[obj:get("pinned")] = true
      selection[#selection + 1] = i
    end
  end
  if #selection == 0 then model.ui:explain("nothing to align") return end

  if (pin.fixed or
      pin.horizontal and methods[num].need_h or
      pin.vertical and methods[num].need_v) then
    model:warning("Cannot align objects",
		  "Some object is pinned and cannot be moved")
    return
  end

  local prim = p:primarySelection()
  local pbox = p:bbox(prim)
  local pref = pbox:bottomLeft()
  local pobj = p[prim]
  if pobj:type() == "text" then pref = pobj:matrix() * pobj:position() end

  local t = { label = "align " .. methods[num].label,
	      pno = model.pno,
	      vno = model.vno,
	      selection = selection,
	      original = p:clone(),
	      undo = revertOriginal,
	      pbox = pbox,
	      pref = pref,
	      fn = num,
	    }

  t.redo = function (t, doc)
	     local p = doc[t.pno]
	     for _,i in ipairs(t.selection) do
	       local box = p:bbox(i)
	       local ref = box:bottomLeft()
	       if (p[i]:type() == "text") then
		 ref = p[i]:matrix() * p[i]:position()
	       end
	       local vx, vy = 0, 0
	       if (t.fn == 1) then        -- top
		 vy = t.pbox:top() - box:top()
	       elseif (t.fn == 2) then    -- bottom
		 vy = t.pbox:bottom() - box:bottom()
	       elseif (t.fn == 3) then    -- left
		 vx = t.pbox:left() - box:left()
	       elseif (t.fn == 4) then    -- right
		 vx = t.pbox:right() - box:right()
	       elseif (t.fn == 5) then    -- center
		 vx = 0.5 * ((t.pbox:left() + t.pbox:right()) -
			   (box:left() + box:right()))
		 vy = 0.5 * ((t.pbox:bottom() + t.pbox:top()) -
			   (box:bottom() + box:top()))
	       elseif (t.fn == 6) then    -- h center
		 vx = 0.5 * ((t.pbox:left() + t.pbox:right()) -
			   (box:left() + box:right()))
	       elseif (t.fn ==  7) then   -- v center
		 vy = 0.5 * ((t.pbox:bottom() + t.pbox:top()) -
			   (box:bottom() + box:top()))
	       elseif (t.fn == 8) then    -- baseline
		 vy = t.pref.y - ref.y
	       end
	       p:transform(i, ipe.Translation(V(vx, vy)))
	     end
	   end
  model:register(t)
end

----------------------------------------------------------------------

function sequence_align_setup(model, num, movement)
  local p = model:page()
  if not p:hasSelection() then model.ui:explain("no selection") return end

  local pin = {}
  for i, obj, sel, lay in p:objects() do
    if sel then pin[obj:get("pinned")] = true end
  end

  if pin.fixed or pin[movement] then
    model:warning("Cannot align objects",
		  "Some object is pinned and cannot be moved")
    return false
  end

  return true
end

----------------------------------------------------------------------

function ltr_skip(p, selection)
  local dx = { 0 }
  local xtarget = p:bbox(selection[1]):right() + skip
  for i = 2,#selection do
    local j = selection[i]
    dx[i] = xtarget - p:bbox(j):left()
    xtarget = xtarget + p:bbox(j):width() + skip
  end
  return dx
end

function ltr_equal_gaps(p, selection)
  local dx = { 0 }
  local total = 0.0
  for _,i in ipairs(selection) do total = total + p:bbox(i):width() end
  local skip = (p:bbox(selection[#selection]):right()
	    - p:bbox(selection[1]):left() - total) / (#selection - 1)

  local xtarget = p:bbox(selection[1]):right() + skip
  for i = 2,#selection-1 do
    local j = selection[i]
    dx[i] = xtarget - p:bbox(j):left()
    xtarget = xtarget + p:bbox(j):width() + skip
  end
  dx[#selection] = 0
  return dx
end

function ltr_centers(p, selection)
  local dx = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local fcenter = (front:left() + front:right()) / 2
  local rcenter = (rear:left() + rear:right()) / 2
  local step = (rcenter - fcenter) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    local center = (box:left() + box:right()) / 2
    dx[i] = (fcenter + (i-1) * step) - center
  end
  dx[#selection] = 0
  return dx
end

function ltr_left(p, selection)
  local dx = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local fleft = front:left()
  local step = (rear:left() - fleft) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    dx[i] = (fleft + (i-1) * step) - box:left()
  end
  dx[#selection] = 0
  return dx
end

function ltr_right(p, selection)
  local dx = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local fright = front:right()
  local step = (rear:right() - fright) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    dx[i] = (fright + (i-1) * step) - box:right()
  end
  dx[#selection] = 0
  return dx
end

function ltr(model, num)
  if not sequence_align_setup(model, num, "horizontal") then return end

  local p = model:page()
  local selection = model:selection()
  table.sort(selection, function (a,b)
			  return (p:bbox(a):left() < p:bbox(b):left())
			end)

  if #selection == 1 or
    #selection == 2 and methods[num].compute ~= ltr_skip then
    model.ui:explain("nothing to distribute")
    return
  end

  local dx = methods[num].compute(p, selection)

  local t = { label = methods[num].label,
	      pno = model.pno,
	      vno = model.vno,
	      selection = selection,
	      original = p:clone(),
	      undo = revertOriginal,
	      dx = dx,
	    }

  t.redo = function (t, doc)
	     local p = doc[t.pno]
	     for i = 1,#t.selection do
	       local j = t.selection[i]
	       local dx = t.dx[i]
	       if dx ~= 0 then p:transform(j, ipe.Translation(V(dx, 0.0))) end
	     end
	   end
  model:register(t)
end

----------------------------------------------------------------------

function ttb_skip(p, selection)
  local dy = { 0 }
  local ytarget = p:bbox(selection[1]):bottom() - skip
  for i = 2,#selection do
    local j = selection[i]
    dy[i] = ytarget - p:bbox(j):top()
    ytarget = ytarget - p:bbox(j):height() - skip
  end
  return dy
end

function ttb_equal_gaps(p, selection)
  local dy = { 0 }
  local total = 0.0
  for _,i in ipairs(selection) do total = total + p:bbox(i):height() end
  local skip = (p:bbox(selection[1]):top()
	    - p:bbox(selection[#selection]):bottom()
	- total) / (#selection - 1)

  local ytarget = p:bbox(selection[1]):bottom() - skip
  for i = 2,#selection-1 do
    local j = selection[i]
    dy[i] = ytarget - p:bbox(j):top()
    ytarget = ytarget - p:bbox(j):height() - skip
  end
  dy[#selection] = 0
  return dy
end

function ttb_centers(p, selection)
  local dy = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local fcenter = (front:top() + front:bottom()) / 2
  local rcenter = (rear:top() + rear:bottom()) / 2
  local step = (fcenter - rcenter) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    local center = (box:top() + box:bottom()) / 2
    dy[i] = (fcenter - (i-1) * step) - center
  end
  dy[#selection] = 0
  return dy
end

function ttb_top(p, selection)
  local dy = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local ftop = front:top()
  local step = (ftop - rear:top()) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    dy[i] = (ftop - (i-1) * step) - box:top()
  end
  dy[#selection] = 0
  return dy
end

function ttb_bottom(p, selection)
  local dy = { 0 }
  local front = p:bbox(selection[1])
  local rear = p:bbox(selection[#selection])
  local fbottom = front:bottom()
  local step = (fbottom - rear:bottom()) / (#selection - 1)
  for i = 2,#selection-1 do
    local box = p:bbox(selection[i])
    dy[i] = (fbottom - (i-1) * step) - box:bottom()
  end
  dy[#selection] = 0
  return dy
end

function ttb(model, num)
  if not sequence_align_setup(model, num, "vertical") then return end

  local p = model:page()
  local selection = model:selection()
  table.sort(selection, function (a,b)
			  return (p:bbox(a):top() > p:bbox(b):top())
			end)

  if #selection == 1 or
    #selection == 2 and methods[num].compute ~= ttb_skip then
    model.ui:explain("nothing to distribute")
    return
  end

  local dy = methods[num].compute(p, selection)

  local t = { label = methods[num].label,
	      pno = model.pno,
	      vno = model.vno,
	      selection = selection,
	      original = p:clone(),
	      undo = revertOriginal,
	      dy = dy,
	    }

  t.redo = function (t, doc)
	     local p = doc[t.pno]
	     for i = 1,#t.selection do
	       local j = t.selection[i]
	       local dy = t.dy[i]
	       if dy ~= 0 then p:transform(j, ipe.Translation(V(0.0, dy))) end
	     end
	   end
  model:register(t)
end

----------------------------------------------------------------------

methods = {
  { label = "align top", run = simple_align, need_v = true },
  { label = "align bottom", run = simple_align, need_v = true },
  { label = "align left", run = simple_align, need_h = true },
  { label = "align right", run = simple_align, need_h = true },
  { label = "align center", run = simple_align, need_v = true, need_h = true },
  { label = "align H center", run = simple_align, need_h = true },
  { label = "align V center", run = simple_align, need_v = true },
  { label = "align baseline", run = simple_align, need_v = true },
  { label = "distribute left to right", run=ltr, compute = ltr_skip },
  { label = "distribute horizontally", run=ltr, compute = ltr_equal_gaps },
  { label = "distribute H centers evenly", run=ltr, compute = ltr_centers },
  { label = "distribute left sides evenly", run=ltr, compute = ltr_left },
  { label = "distribute right sides evenly", run=ltr, compute = ltr_right },
  { label = "distribute top to bottom", run=ttb, compute = ttb_skip },
  { label = "distribute vertically", run=ttb, compute = ttb_equal_gaps },
  { label = "distribute V centers evenly", run=ttb, compute = ttb_centers },
  { label = "distribute top sides evenly", run=ttb, compute = ttb_top },
  { label = "distribute bottom sides evenly", run=ttb, compute = ttb_bottom },
  { label = "set skip...", run = set_skip },
}

shortcuts.ipelet_1_align = "Shift+T"
shortcuts.ipelet_2_align = "Shift+B"
shortcuts.ipelet_3_align = "Shift+L"
shortcuts.ipelet_4_align = "Shift+R"
shortcuts.ipelet_5_align = "Shift+C"
shortcuts.ipelet_6_align = "Shift+H"
shortcuts.ipelet_7_align = "Shift+V"
shortcuts.ipelet_15_align = "Alt+Shift+V"

----------------------------------------------------------------------
