local utf8 = require 'utf8'

require 'app'
require 'test'

require 'keychord'
require 'file'
require 'button'
local Text = require 'text'
local Drawing = require 'drawing'
local geom = require 'geom'
require 'help'
require 'icons'

-- run in both tests and a real run
function App.initialize_globals()
-- a line is either text or a drawing
-- a text is a table with:
--    mode = 'text',
--    string data,
--    a (y) coord in pixels (updated while painting screen),
--    some cached data that's blown away and recomputed when data changes:
--      fragments: snippets of rendered love.graphics.Text, guaranteed to not wrap
--      screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line
-- a drawing is a table with:
--    mode = 'drawing'
--    a (y) coord in pixels (updated while painting screen),
--    a (h)eight,
--    an array of points, and
--    an array of shapes
-- a shape is a table containing:
--    a mode
--    an array points for mode 'freehand' (raw x,y coords; freehand drawings don't pollute the points array of a drawing)
--    an array vertices for mode 'polygon', 'rectangle', 'square'
--    p1, p2 for mode 'line'
--    center, radius for mode 'circle'
--    center, radius, start_angle, end_angle for mode 'arc'
-- Unless otherwise specified, coord fields are normalized; a drawing is always 256 units wide
-- The field names are carefully chosen so that switching modes in midstream
-- remembers previously entered points where that makes sense.
Lines = {{mode='text', data=''}}

-- Lines can be too long to fit on screen, in which case they _wrap_ into
-- multiple _screen lines_.
--
-- Therefore, any potential location for the cursor can be described in two ways:
-- * schema 1: As a combination of line index and position within a line (in utf8 codepoint units)
-- * schema 2: As a combination of line index, screen line index within the line, and a position within the screen line.
--
-- Most of the time we'll only persist positions in schema 1, translating to
-- schema 2 when that's convenient.
Screen_top1 = {line=1, pos=1}  -- position of start of screen line at top of screen
Cursor1 = {line=1, pos=1}  -- position of cursor
Screen_bottom1 = {line=1, pos=1}  -- position of start of screen line at bottom of screen

Selection1 = {}
Old_cursor1, Old_selection1, Mousepress_shift = nil  -- some extra state to compute selection between mouse press and release
Recent_mouse = {}  -- when selecting text, avoid recomputing some state on every single frame

Cursor_x, Cursor_y = 0, 0  -- in pixels

Current_drawing_mode = 'line'
Previous_drawing_mode = nil

-- values for tests
Font_height = 14
Line_height = 15
-- widest possible character width
Em = App.newText(love.graphics.getFont(), 'm')

Margin_top = 15
Margin_left = 25

Drawing_padding_top = 10
Drawing_padding_bottom = 10
Drawing_padding_height = Drawing_padding_top + Drawing_padding_bottom

Filename = love.filesystem.getUserDirectory()..'/lines.txt'
Next_save = nil

-- undo
History = {}
Next_history = 1

-- search
Search_term = nil
Search_text = nil
Search_backup = nil  -- stuff to restore when cancelling search

-- resize
Last_resize_time = nil

-- blinking cursor
Cursor_time = 0

end  -- App.initialize_globals

function App.initialize(arg)
  love.keyboard.setTextInput(true)  -- bring up keyboard on touch screen
  love.keyboard.setKeyRepeat(true)

  if arg[1] == '-geometry' then
    initialize_window_geometry(arg[2])
    table.remove(arg, 2)
    table.remove(arg, 1)
  else
    initialize_window_geometry()
  end

  initialize_font_settings(20)
--?   Line_width = 80

  if #arg > 0 then
    Filename = arg[1]
  end
  Lines = load_from_disk(Filename)
  for i,line in ipairs(Lines) do
    if line.mode == 'text' then
      Cursor1.line = i
      break
    end
  end
  love.window.setTitle('lines.love - '..Filename)

  if #arg > 1 then
    print('ignoring commandline args after '..arg[1])
  end

  if rawget(_G, 'jit') then
    jit.off()
    jit.flush()
  end
end  -- App.initialize

function initialize_window_geometry(geometry_spec)
  local geometry_initialized
  if geometry_spec then
    geometry_initialized = parse_geometry_spec(geometry_spec)
  end
  if not geometry_initialized then
    -- maximize window
    love.window.setMode(0, 0)  -- maximize
    App.screen.width, App.screen.height, App.screen.flags = love.window.getMode()
    -- shrink slightly to account for window decoration
    App.screen.width = App.screen.width-100
    App.screen.height = App.screen.height-100
  end
  App.screen.flags.resizable = true
  App.screen.flags.minwidth = math.min(App.screen.width, 200)
  App.screen.flags.minheight = math.min(App.screen.width, 200)
  love.window.updateMode(App.screen.width, App.screen.height, App.screen.flags)
end

function parse_geometry_spec(geometry_spec)
  local width, height, x, y = geometry_spec:match('(%d+)x(%d+)%+(%d+)%+(%d+)')
  if width == nil then
    print('invalid geometry spec: '..geometry_spec)
    print('expected format: {width}x{height}+{x}+{y}')
    return false
  end
  App.screen.width = math.floor(tonumber(width))
  App.screen.height = math.floor(tonumber(height))
  App.screen.flags = {x=math.floor(tonumber(x)), y=math.floor(tonumber(y))}
  return true
end

function love.resize(w, h)
--?   print(("Window resized to width: %d and height: %d."):format(w, h))
  App.screen.width, App.screen.height = w, h
  Line_width = math.min(40*App.width(Em), App.screen.width-50)
  Text.redraw_all()
  Last_resize_time = App.getTime()
end

function initialize_font_settings(font_height)
  Font_height = font_height
  love.graphics.setFont(love.graphics.newFont(Font_height))
  Line_height = math.floor(font_height*1.3)

  Em = App.newText(love.graphics.getFont(), 'm')

  -- maximum width available to either text or drawings, in pixels
  -- readable text width is 50-75 chars
  Line_width = math.min(40*App.width(Em), App.screen.width-50)
end

function App.filedropped(file)
  App.initialize_globals()  -- in particular, forget all undo history
  Filename = file:getFilename()
  file:open('r')
  Lines = load_from_file(file)
  file:close()
  for i,line in ipairs(Lines) do
    if line.mode == 'text' then
      Cursor1.line = i
      break
    end
  end
  love.window.setTitle('Text with Lines - '..Filename)
end

function App.draw()
  Button_handlers = {}
  love.graphics.setColor(1, 1, 1)
  love.graphics.rectangle('fill', 0, 0, App.screen.width-1, App.screen.height-1)
--?   love.graphics.setColor(0, 1, 0)
--?   love.graphics.line(Line_width,0, Line_width,App.screen.height)
  love.graphics.setColor(0, 0, 0)

  -- some hysteresis while resizing
  if Last_resize_time then
    if App.getTime() - Last_resize_time < 0.1 then
      return
    else
      Last_resize_time = nil
    end
  end

  assert(Text.le1(Screen_top1, Cursor1))
  Cursor_y = -1
  local y = Margin_top
--?   print('== draw')
  for line_index,line in ipairs(Lines) do
--?     print('draw:', y, line_index, line)
    if y + Line_height > App.screen.height then break end
--?     print('a')
    if line_index >= Screen_top1.line then
      Screen_bottom1.line = line_index
      if line.mode == 'text' and line.data == '' then
        line.y = y
        button('draw', {x=4,y=y+4, w=12,h=12, color={1,1,0},
          icon = icon.insert_drawing,
          onpress1 = function()
                       Drawing.before = snapshot(line_index-1, line_index)
                       table.insert(Lines, line_index, {mode='drawing', y=y, h=256/2, points={}, shapes={}, pending={}})
                       if Cursor1.line >= line_index then
                         Cursor1.line = Cursor1.line+1
                       end
                       schedule_save()
                       record_undo_event({before=Drawing.before, after=snapshot(line_index-1, line_index+1)})
                     end})
          if Search_term == nil then
            if line_index == Cursor1.line then
              Text.draw_cursor(Margin_left, y)
            end
          end
        Screen_bottom1.pos = Screen_top1.pos
        y = y + Line_height
      elseif line.mode == 'drawing' then
        y = y+Drawing_padding_top
        line.y = y
        Drawing.draw(line)
        y = y + Drawing.pixels(line.h) + Drawing_padding_bottom
      else
--?         print('text')
        line.y = y
        y, Screen_bottom1.pos = Text.draw(line, Line_width, line_index)
        y = y + Line_height
--?         print('=> y', y)
      end
    end
  end
  if Cursor_y == -1 then
    Cursor_y = App.screen.height
  end
--?   print('screen bottom: '..tostring(Screen_bottom1.pos)..' in '..tostring(Lines[Screen_bottom1.line].data))
  if Search_term then
    Text.draw_search_bar()
  end
end

function App.update(dt)
  Cursor_time = Cursor_time + dt
  -- some hysteresis while resizing
  if Last_resize_time then
    if App.getTime() - Last_resize_time < 0.1 then
      return
    else
      Last_resize_time = nil
    end
  end
  Drawing.update(dt)
  if Next_save and Next_save < App.getTime() then
    save_to_disk(Lines, Filename)
    Next_save = nil
  end
end

function schedule_save()
  if Next_save == nil then
    Next_save = App.getTime() + 3  -- short enough that you're likely to still remember what you did
  end
end

function App.mousepressed(x,y, mouse_button)
  if Search_term then return end
  propagate_to_button_handlers(x,y, mouse_button)

  for line_index,line in ipairs(Lines) do
    if line.mode == 'text' then
      if Text.in_line(line_index,line, x,y) then
        -- delicate dance between cursor, selection and old cursor
        -- manual tests:
        --  regular press+release: sets cursor, clears selection
        --  shift press+release:
        --    sets selection to old cursor if not set otherwise leaves it untouched
        --    sets cursor
        --  press and hold to start a selection: sets selection on press, cursor on release
        --  press and hold, then press shift: ignore shift
        --    i.e. mousereleased should never look at shift state
        Old_cursor1 = Cursor1
        Old_selection1 = Selection1
        Mousepress_shift = App.shift_down()
        Selection1 = {line=line_index, pos=Text.to_pos_on_line(line, x, y)}
      end
    elseif line.mode == 'drawing' then
      if Drawing.in_drawing(line, x, y) then
        Lines.current_drawing_index = line_index
        Lines.current_drawing = line
        Drawing.before = snapshot(line_index)
        Drawing.mouse_pressed(line, x,y, button)
      end
    end
  end
end

function App.mousereleased(x,y, button)
  if Search_term then return end
  if Lines.current_drawing then
    Drawing.mouse_released(x,y, button)
    schedule_save()
    if Drawing.before then
      record_undo_event({before=Drawing.before, after=snapshot(Lines.current_drawing_index)})
      Drawing.before = nil
    end
  else
    for line_index,line in ipairs(Lines) do
      if line.mode == 'text' then
        if Text.in_line(line_index,line, x,y) then
          Cursor1 = {line=line_index, pos=Text.to_pos_on_line(line, x, y)}
--?           print(Cursor1.line, Cursor1.pos)
          if Mousepress_shift then
            if Old_selection1.line == nil then
              Selection1 = Old_cursor1
            else
              Selection1 = Old_selection1
            end
          end
          Old_cursor1, Old_selection1, Mousepress_shift = nil
        end
      end
    end
--?     print('select:', Selection1.line, Selection1.pos)
  end
end

function App.textinput(t)
  for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
  if Search_term then
    Search_term = Search_term..t
    Search_text = nil
    Text.search_next()
  elseif Current_drawing_mode == 'name' then
    local before = snapshot(Lines.current_drawing_index)
    local drawing = Lines.current_drawing
    local p = drawing.points[drawing.pending.target_point]
    p.name = p.name..t
    record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
  else
    Text.textinput(t)
  end
  schedule_save()
end

function App.keychord_pressed(chord)
  if Search_term then
    if chord == 'escape' then
      Search_term = nil
      Search_text = nil
      Cursor1 = Search_backup.cursor
      Screen_top1 = Search_backup.screen_top
      Search_backup = nil
      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
    elseif chord == 'return' then
      Search_term = nil
      Search_text = nil
      Search_backup = nil
    elseif chord == 'backspace' then
      local len = utf8.len(Search_term)
      local byte_offset = utf8.offset(Search_term, len)
      Search_term = string.sub(Search_term, 1, byte_offset-1)
      Search_text = nil
    elseif chord == 'down' then
      Cursor1.pos = Cursor1.pos+1
      Text.search_next()
    elseif chord == 'up' then
      Text.search_previous()
    end
    return
  elseif chord == 'C-f' then
    Search_term = ''
    Search_backup = {cursor={line=Cursor1.line, pos=Cursor1.pos}, screen_top={line=Screen_top1.line, pos=Screen_top1.pos}}
    assert(Search_text == nil)
  elseif chord == 'C-=' then
    initialize_font_settings(Font_height+2)
    Text.redraw_all()
  elseif chord == 'C--' then
    initialize_font_settings(Font_height-2)
    Text.redraw_all()
  elseif chord == 'C-0' then
    initialize_font_settings(20)
    Text.redraw_all()
  elseif chord == 'C-z' then
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    local event = undo_event()
    if event then
      local src = event.before
      Screen_top1 = deepcopy(src.screen_top)
      Cursor1 = deepcopy(src.cursor)
      Selection1 = deepcopy(src.selection)
      patch(Lines, event.after, event.before)
      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
      schedule_save()
    end
  elseif chord == 'C-y' then
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    local event = redo_event()
    if event then
      local src = event.after
      Screen_top1 = deepcopy(src.screen_top)
      Cursor1 = deepcopy(src.cursor)
      Selection1 = deepcopy(src.selection)
      patch(Lines, event.before, event.after)
      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
      schedule_save()
    end
  -- clipboard
  elseif chord == 'C-c' then
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    local s = Text.selection()
    if s then
      App.setClipboardText(s)
    end
  elseif chord == 'C-x' then
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    local s = Text.cut_selection()
    if s then
      App.setClipboardText(s)
    end
    schedule_save()
  elseif chord == 'C-v' then
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    -- We don't have a good sense of when to scroll, so we'll be conservative
    -- and sometimes scroll when we didn't quite need to.
    local before_line = Cursor1.line
    local before = snapshot(before_line)
    local clipboard_data = App.getClipboardText()
    for _,code in utf8.codes(clipboard_data) do
      local c = utf8.char(code)
      if c == '\n' then
        Text.insert_return()
      else
        Text.insert_at_cursor(c)
      end
    end
    App.draw()
    if Cursor_y >= App.screen.height - Line_height then
      Text.snap_cursor_to_bottom_of_screen()
    end
    schedule_save()
    record_undo_event({before=before, after=snapshot(before_line, Cursor1.line)})
  -- dispatch to drawing or text
  elseif App.mouse_down(1) or chord:sub(1,2) == 'C-' then
    -- DON'T reset line.y here
    local drawing_index, drawing = Drawing.current_drawing()
    if drawing_index then
      local before = snapshot(drawing_index)
      Drawing.keychord_pressed(chord)
      record_undo_event({before=before, after=snapshot(drawing_index)})
      schedule_save()
    end
  elseif chord == 'escape' and App.mouse_down(1) then
    local _,drawing = Drawing.current_drawing()
    if drawing then
      drawing.pending = {}
    end
  elseif chord == 'escape' and not App.mouse_down(1) then
    for _,line in ipairs(Lines) do
      if line.mode == 'drawing' then
        line.show_help = false
      end
    end
  elseif Current_drawing_mode == 'name' then
    if chord == 'return' then
      Current_drawing_mode = Previous_drawing_mode
      Previous_drawing_mode = nil
    else
      local before = snapshot(Lines.current_drawing_index)
      local drawing = Lines.current_drawing
      local p = drawing.points[drawing.pending.target_point]
      if chord == 'escape' then
        p.name = nil
      elseif chord == 'backspace' then
        local len = utf8.len(p.name)
        local byte_offset = utf8.offset(p.name, len-1)
        p.name = string.sub(p.name, 1, byte_offset)
      end
      record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
    end
    schedule_save()
  else
    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
    Text.keychord_pressed(chord)
  end
end

function App.keyreleased(key, scancode)
end