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//: You guessed right: the '000' prefix means you should start reading here.
//:
//: This project is set up to load all files with a numeric prefix. Just
//: create a new file and start hacking.
//:
//: The first few files (00*) are independent of what this program does, an
//: experimental skeleton that will hopefully make it both easier for others to
//: understand and more malleable, easier to rewrite and remould into radically
//: different shapes without breaking in subtle corner cases. The premise is
//: that understandability and rewrite-friendliness are related in a virtuous
//: cycle. Doing one well makes it easier to do the other.
//:
//: Lower down, this file contains a legal, bare-bones C++ program. It doesn't
//: do anything yet; subsequent files will contain :(...) directives to insert
//: lines into it. For example:
//:   :(after "more events")
//: This directive means: insert the following lines after a line in the
//: program containing the words "more events".
//:
//: A simple tool is included to 'tangle' all the files together in sequence
//: according to their directives into a single source file containing all the
//: code for the project, and then feed the source file to the compiler.
//: (It'll drop these comments starting with a '//:' prefix that only make
//: sense before tangling.)
//:
//: Directives free up the programmer to order code for others to read rather
//: than as forced by the computer or compiler. Each individual feature can be
//: organized in a self-contained 'layer' that adds code to many different data
//: structures and functions all over the program. The right decomposition into
//: layers will let each layer make sense in isolation.
//:
//:   "If I look at any small part of it, I can see what is going on -- I don't
//:   need to refer to other parts to understand what something is doing.
//:
//:   If I look at any large part in overview, I can see what is going on -- I
//:   don't need to know all the details to get it.
//:
//:   Every level of detail is as locally coherent and as well thought-out as
//:   any other level."
//:
//:       -- Richard Gabriel, "The Quality Without A Name"
//:          (http://dreamsongs.com/Files/PatternsOfSoftware.pdf, page 42)
//:
//: Directives are powerful; they permit inserting or modifying any point in
//: the program. Using them tastefully requires mapping out specific lines as
//: waypoints for future layers to hook into. Often such waypoints will be in
//: comments, capitalized to hint that other layers rely on their presence.
//:
//: A single waypoint might have many different code fragments hooking into
//: it from all over the codebase. Use 'before' directives to insert
//: code at a location in order, top to bottom, and 'after' directives to
//: insert code in reverse order. By convention waypoints intended for insertion
//: before begin with 'End'. Notice below how the layers line up above the "End
//: Foo" waypoint.
//:
//:   File 001          File 002                File 003
//:   ============      ===================     ===================
//:   // Foo
//:   ------------
//:              <----  :(before "End Foo")
//:                     ....
//:                     ...
//:   ------------
//:              <----------------------------  :(before "End Foo")
//:                                             ....
//:                                             ...
//:   // End Foo
//:   ============
//:
//: Here's part of a layer in color: http://i.imgur.com/0eONnyX.png. Directives
//: are shaded dark.
//:
//: Layers do more than just shuffle code around. In a well-organized codebase
//: it should be possible to stop loading after any file/layer, build and run
//: the program, and pass all tests for loaded features. (Relevant is
//: http://youtube.com/watch?v=c8N72t7aScY, a scene from "2001: A Space
//: Odyssey".) Get into the habit of running the included script called
//: 'test_layers' before you commit any changes.
//:
//: This 'subsetting guarantee' ensures that this directory contains a
//: cleaned-up narrative of the evolution of this codebase. Organizing
//: autobiographically allows newcomers to rapidly orient themselves, reading
//: the first few files to understand a simple gestalt of a program's core
//: purpose and features, and later gradually working their way through other
//: features as the need arises.
//:
//: Programmers shouldn't need to understand everything about a program to
//: hack on it. But they shouldn't be prevented from a thorough understanding
//: of each aspect either. The goal of layers is to reward curiosity.

// Includes
// End Includes

// Types
// End Types

// Function prototypes are auto-generated in the 'build*' scripts; define your
// functions in any order. Just be sure to declare each function header all on
// one line, ending with the '{'. Our auto-generation scripts are too minimal
// and simple-minded to handle anything else.
#include "function_list"  // by convention, files ending with '_list' are auto-generated

// Globals
//
// All statements in this section should always define a single variable on a
// single line. The 'build*' scripts will simple-mindedly auto-generate extern
// declarations for them. Remember to define (not just declare) constants with
// extern linkage in this section, since C++ global constants have internal
// linkage by default.
//
// End Globals

int main(int argc, char* argv[]) {
  atexit(reset);

  // End One-time Setup

  // Commandline Parsing
  // End Commandline Parsing

  return 0;  // End Main
}

// Unit Tests
// End Unit Tests

//: our first directive; insert the following header at the start of the program
:(before "End Includes")
#include <stdlib.h>

//: Without directives or with the :(code) directive, lines get added at the
//: end.
:(code)
void reset() {
  // End Reset
}
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-- primitives for saving to file and loading from file
function file_exists(filename)
  local infile = App.open_for_reading(filename)
  if infile then
    infile:close()
    return true
  else
    return false
  end
end

function load_from_disk(State)
  local infile = App.open_for_reading(State.filename)
  State.lines = load_from_file(infile)
  if infile then infile:close() end
end

function load_from_file(infile)
  local result = {}
  if infile then
    local infile_next_line = infile:lines()  -- works with both Lua files and LÖVE Files (https://www.love2d.org/wiki/File)
    while true do
      local line = infile_next_line()
      if line == nil then break end
      if line == '```lines' then  -- inflexible with whitespace since these files are always autogenerated
        table.insert(result, load_drawing(infile_next_line))
      else
        table.insert(result, {mode='text', data=line})
      end
    end
  end
  if #result == 0 then
    table.insert(result, {mode='text', data=''})
  end
  return result
end

function save_to_disk(State)
  local outfile = App.open_for_writing(State.filename)
  if not outfile then
    error('failed to write to "'..State.filename..'"')
  end
  for _,line in ipairs(State.lines) do
    if line.mode == 'drawing' then
      store_drawing(outfile, line)
    else
      outfile:write(line.data)
      outfile:write('\n')
    end
  end
  outfile:close()
end

function load_drawing(infile_next_line)
  local drawing = {mode='drawing', h=256/2, points={}, shapes={}, pending={}}
  while true do
    local line = infile_next_line()
    assert(line, 'drawing in file is incomplete')
    if line == '```' then break end
    local shape = json.decode(line)
    if shape.mode == 'freehand' then
      -- no changes needed
    elseif shape.mode == 'line' or shape.mode == 'manhattan' then
      local name = shape.p1.name
      shape.p1 = Drawing.find_or_insert_point(drawing.points, shape.p1.x, shape.p1.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.p1].name = name
      name = shape.p2.name
      shape.p2 = Drawing.find_or_insert_point(drawing.points, shape.p2.x, shape.p2.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.p2].name = name
    elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
      for i,p in ipairs(shape.vertices) do
        local name = p.name
        shape.vertices[i] = Drawing.find_or_insert_point(drawing.points, p.x,p.y, --[[large width to minimize overlap]] 1600)
        drawing.points[shape.vertices[i]].name = name
      end
    elseif shape.mode == 'circle' or shape.mode == 'arc' then
      local name = shape.center.name
      shape.center = Drawing.find_or_insert_point(drawing.points, shape.center.x,shape.center.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.center].name = name
    elseif shape.mode == 'deleted' then
      -- ignore
    else
      assert(false, ('unknown drawing mode %s'):format(shape.mode))
    end
    table.insert(drawing.shapes, shape)
  end
  return drawing
end

function store_drawing(outfile, drawing)
  outfile:write('```lines\n')
  for _,shape in ipairs(drawing.shapes) do
    if shape.mode == 'freehand' then
      outfile:write(json.encode(shape))
      outfile:write('\n')
    elseif shape.mode == 'line' or shape.mode == 'manhattan' then
      local line = json.encode({mode=shape.mode, p1=drawing.points[shape.p1], p2=drawing.points[shape.p2]})
      outfile:write(line)
      outfile:write('\n')
    elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
      local obj = {mode=shape.mode, vertices={}}
      for _,p in ipairs(shape.vertices) do
        table.insert(obj.vertices, drawing.points[p])
      end
      local line = json.encode(obj)
      outfile:write(line)
      outfile:write('\n')
    elseif shape.mode == 'circle' then
      outfile:write(json.encode({mode=shape.mode, center=drawing.points[shape.center], radius=shape.radius}))
      outfile:write('\n')
    elseif shape.mode == 'arc' then
      outfile:write(json.encode({mode=shape.mode, center=drawing.points[shape.center], radius=shape.radius, start_angle=shape.start_angle, end_angle=shape.end_angle}))
      outfile:write('\n')
    elseif shape.mode == 'deleted' then
      -- ignore
    else
      assert(false, ('unknown drawing mode %s'):format(shape.mode))
    end
  end
  outfile:write('```\n')
end

-- for tests
function load_array(a)
  local result = {}
  local next_line = ipairs(a)
  local i,line,drawing = 0, ''
  while true do
    i,line = next_line(a, i)
    if i == nil then break end
--?     print(line)
    if line == '```lines' then  -- inflexible with whitespace since these files are always autogenerated
--?       print('inserting drawing')
      i, drawing = load_drawing_from_array(next_line, a, i)
--?       print('i now', i)
      table.insert(result, drawing)
    else
--?       print('inserting text')
      table.insert(result, {mode='text', data=line})
    end
  end
  if #result == 0 then
    table.insert(result, {mode='text', data=''})
  end
  return result
end

function load_drawing_from_array(iter, a, i)
  local drawing = {mode='drawing', h=256/2, points={}, shapes={}, pending={}}
  local line
  while true do
    i, line = iter(a, i)
    assert(i, 'drawing in array is incomplete')
--?     print(i)
    if line == '```' then break end
    local shape = json.decode(line)
    if shape.mode == 'freehand' then
      -- no changes needed
    elseif shape.mode == 'line' or shape.mode == 'manhattan' then
      local name = shape.p1.name
      shape.p1 = Drawing.find_or_insert_point(drawing.points, shape.p1.x, shape.p1.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.p1].name = name
      name = shape.p2.name
      shape.p2 = Drawing.find_or_insert_point(drawing.points, shape.p2.x, shape.p2.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.p2].name = name
    elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
      for i,p in ipairs(shape.vertices) do
        local name = p.name
        shape.vertices[i] = Drawing.find_or_insert_point(drawing.points, p.x,p.y, --[[large width to minimize overlap]] 1600)
        drawing.points[shape.vertices[i]].name = name
      end
    elseif shape.mode == 'circle' or shape.mode == 'arc' then
      local name = shape.center.name
      shape.center = Drawing.find_or_insert_point(drawing.points, shape.center.x,shape.center.y, --[[large width to minimize overlap]] 1600)
      drawing.points[shape.center].name = name
    elseif shape.mode == 'deleted' then
      -- ignore
    else
      assert(false, ('unknown drawing mode %s'):format(shape.mode))
    end
    table.insert(drawing.shapes, shape)
  end
  return i, drawing
end

function is_absolute_path(path)
  local os_path_separator = package.config:sub(1,1)
  if os_path_separator == '/' then
    -- POSIX systems permit backslashes in filenames
    return path:sub(1,1) == '/'
  elseif os_path_separator == '\\' then
    if path:sub(2,2) == ':' then return true end  -- DOS drive letter followed by volume separator
    local f = path:sub(1,1)
    return f == '/' or f == '\\'
  else
    error('What OS is this? LÖVE reports that the path separator is "'..os_path_separator..'"')
  end
end

function is_relative_path(path)
  return not is_absolute_path(path)
end