document.body.innerHTML = "";

var files = {};
files.prefix = "/papill0n.org/shaders/";
files.current = "spec.txt";

files.builtin = {"spec.txt": `# Spec

- selecting a name from the list loads that file
- built-in files are accessible read-only
    (copy/paste if you want to change them)
- typing a new name and pressing enter (?) creates a new file
- typing an existing name and pressing enter loads that file

File store:

- \`.get(name: string) -> content or false if not existing\`
- \`create(name: string, content: string)\`, throws an error if
    a program with that name already exists (or if it is an
    internal file)
- \`save(name: string, content: string)\`, throws an error if
    there is no program with that name (?)
- \`remove(name: string)\`, for completeness

Some ideas:

- only store custom files in localStorage (obvious in retrospect)
- have a special temporary file that's saved very often (every
    keypress?), to prevent losing stuff.  reopen that file if
    it is present, delete/empty it on save.
- an 'unsaved changes' indicator, to make people save their stuff

Later:

- "forking" would be nice:
    - open existing code
    - say "fork" (or something more understandable)
    - create a new file with the content from the current one
    - edit away!
    - what about new names, though?
`,
             "default.frag": `void main() {
  gl_FragColor = gl_FragCoord;
}`,
             "includes/stdlib.frag": `float sdSphere(vec3 pos) {
  return length(pos) - 1.0;
}

float sdSphere(vec3 pos, float size) {
  return length(pos) - size;
}`,
             "includes/sphere-tracing.frag": `float trace(vec3 origin, vec3 direction) {
  // Uh, ... almost?
  return 0.0;
}`,
             "includes/ray-marching.frag": `// Warning: This is likely to be slower than sphere tracing!
float trace(vec3 origin, vec3 direction) {
  return 0.0;
}`};

files.exists = function(name) {
  return name in files.builtin || (files.prefix + name) in localStorage;
}

files.open = function(name) {
  files.current = name;
  if (name in files.builtin) {
    return {"name": name, "content": files.builtin[name], "readonly": true};
  } else {
    return {"name": name, "content": localStorage[files.prefix + name], "readonly": false};
  }
}

files.create = function(name, content) {
  if (name.trim() == "") { throw new Error("name can't be empty"); }
  if (name in files.builtin) { throw new Error("can't use internal file names"); }
  if (files.exists(name)) { throw new Error("already exists"); }
  
  files.current = name;
  
  var file = { "name": name, "content": content, readonly: false };
  localStorage["/papill0n.org/shaders/" + name] = content;
  return file;
}

files.save = function(name, content) {
  localStorage[files.prefix + name] = content;
}

function setFile(file, nameEl, contentEl) {
  nameEl.value = file.name;
  contentEl.value = file.content;
  contentEl.readOnly = file.readonly;
}

var nameEl = document.createElement("input");
nameEl.value = files.current;
nameEl.maxlength = 20;
nameEl.placeholder = "Name of the shader";
nameEl.setAttribute('list', 'files');

nameEl.onselect = function(ev) {
  setFile(files.open(nameEl.value), nameEl, editorEl);
  editorEl.focus();
}

nameEl.onkeyup = function(ev) {
  if (ev.keyCode == 13 && nameEl.value != files.current) { // Enter
    var file = nameEl.value;
    if (files.exists(file)) {
      setFile(files.open(file), nameEl, editorEl);
    } else {
      setFile(files.create(file, ""), nameEl, editorEl);
      var fileEl = document.createElement("option");
      fileEl.textContent = file;
      filesEl.appendChild(fileEl);
    }
    editorEl.focus();
  }
}

function addFileOption(name) {
  var fileEl = document.createElement("option");
  fileEl.textContent = name;
  filesEl.appendChild(fileEl);
}

var filesEl = document.createElement("datalist");
filesEl.id = "files";
Object.keys(files.builtin).forEach(addFileOption);

Object.keys(localStorage).forEach(function(file) {
  if (file.startsWith(files.prefix)) {
    addFileOption(file.substr(files.prefix.length));
  }
});

var editorEl = document.createElement("textarea");
editorEl.style  = "width: 70ex; height: 40em";
editorEl.onkeydown = function(ev) {
  if (ev.ctrlKey && ev.keyCode == 83) { // Ctrl-s
    ev.preventDefault();
    
    files.save(files.current, editorEl.value);
  }
}

setFile(files.open(files.current), nameEl, editorEl);

document.body.appendChild(filesEl);
document.body.appendChild(nameEl);
document.body.appendChild(editorEl);