_sync "VDOM : The Virtual DOM implementation in Ironscript"

  (_include "stdlib")

  [defun h (type props :children) {
    [.props = props]

    [parse-type-string = @{
      var type = args[0];
      var idDelim = args[1];
      var classDelim = args[2];
      if (!idDelim) idDelim = '#';
      if (!classDelim) classDelim = '.';

      function parseClass (str) {
        var tarr = str.split(classDelim);
        var type = "div";
        if (classDelim !== str[0]) type = tarr[0];
        return [type, tarr.slice(1).join(' ')];
      }

      function parseId (str) {
        var tarr = str.split(idDelim);
        if (idDelim === str[0]) return ["div", "", tarr[1]];
        else if (tarr.length > 1) {
          let ret = parseClass(tarr[0]);
          ret.push(tarr[1]);
          return ret;
        }
        else return parseClass(tarr[0]);
      }
      $return (parseId(type));
    }@ ]

    [t = (parse-type-string type) ]
    [if ["object" === (typeof t)]
      then (_begin
        [.type = t.0]
        [props.class = t.1]
        [props.id = t.2]
      )
      else [.type = t]
    ]
    [if children [.children = (_seq :children)] ]
  } ]

  [_rho (H @tag) (h @tag {}) ]
  [_rho (H @tag @props) (h @tag @props) ]
  [_rho (H @tag @props :@children) (h @tag @props :@children) ]
  [_rho (T @tag :@children) (h @tag {} :@children) ]
  [_rho (T @tag) (h @tag {}) ]


  [COMPONENTS = {}]
  [NOOP = (_fn () NIL) ]
  [PORT = (_fn () (_stream NOOP NIL) ) ]


  [defun vnode (node id) (_begin
    [type = node.type]
    [if type
      then (_begin
        [componentfn = (_dot COMPONENTS type)]
        [if componentfn
          then (_begin
            [nd = (componentfn node.props)]
            [if node.props.id then (vnode nd node.props.id) else (vnode nd ".")]
          )
          else {
            [.type = type]
            [.props = node.props]
            [if .props.id then [.id = .props.id] else [.id = "."] ]
            [if node.children
              [.children = (_map node.children (_fn (child index)
                (vnode child (concat .id "." index) )
              ) ) ]
            ]
          }
        ]
      )
      else node
    ]
  )]


  [EVENTS = {
    [init = @{
      var capt = true;
      if (args[0] === "false") capt = false;
      ("keypress keydown keyup click dbclick scroll focus blur change search select submit input invalid".split(" "))
      .forEach (function (e) {
        document.body.addEventListener(e, function (ev) {$yield(ev); ev.stopPropagation();}, capt) ;
      });
    }@ ]

    [.event-stream = (_stream init "true")]

    [listeners = {}]
    [defun .listen (id event port)
      [(_dot listeners (concat id ":" event) ) = port]
    ]
    [defun .mute (id event) [(concat id ":" event) = NIL] ]
    [defun .remove (id) ( @{
      var obj = args[0];
      var id = args[1];
      Object.keys(obj).forEach(function (name) {
        if (name.startsWith(id+'.') || name.startsWith(id+':')) obj[name] = undefined;
      });
    }@ listeners id ) ]

    (_do (_on .event-stream
      (_begin
        [e = (_pull .event-stream)]
        [port = (_dot listeners (concat e.target.id ":" e.type ) ) ]
        [if port (_push port e)]
      )
    ) )
  } ]


  [update-fn-internal = (_fx (
    @{

      function isEventProp (name) { return /^on/.test(name); }
      function extractEventName (name) { return name.slice(2).toLowerCase(); }

      function isCustomProp (name) {
        if (name === "id") return true;
        if (isEventProp(name)) return true;
        return false;
      }

      function setBooleanProp ($target, name, value) {
        if (value) $target.setAttribute(name, value);
        $target[name] = value;
      }

      function setProp ($target, name, value) {
        if (isCustomProp(name)) return;
        else if (typeof value === 'boolean') setBooleanProp ($target, name, value);
        else $target.setAttribute (name, value);
      }

      function setProps ($target, props) {
        if (typeof props === 'object') Object.keys(props).forEach(function (name) {
          setProp($target, name, props[name]);
        });
      }

      function removeBooleanProp ($target, name) {
        $target.removeAttribute (name);
        $target[name] = false;
      }

      function removeProp ($target, name, value) {
        if (isCustomProp(name)) return;
        else if (typeof value === 'boolean') removeBooleanProp ($target, name);
        else $target.removeAttribute (name);
      }

      function updateProp ($target, name, newVal, oldVal) {
        if (!newVal) removeProp ($target, name, oldVal);
        else if (!oldval || newVal !== oldVal) setProp ($target, name, newVal);
        else return;
      }

      function updateProps ($target, newProps, oldProps) {
        if (!oldProps) oldProps = {};
        var props = Object.assign ({}, newProps, oldProps);
        Object.keys(props).forEach (function (name) {
          updateProp ($target, name, newProps[name], oldProps[name]);
        });
      }

      function addEventListeners (id, props) {
        if (typeof props === 'object') Object.keys(props).forEach(function (name) {
          if (isEventProp(name)) addPatch.push({id: id, type: extractEventName(name), port: props[name]});
        });
      }

      function createElement (node) {
        if (typeof node === 'string') return document.createTextNode(node);
        var $el = document.createElement (node.type);
        $el.setAttribute("id", node.id);
        setProps ($el, node.props);
        addEventListeners(node.id, node.props);
        if (node.children) node.children.arr.map(createElement).forEach($el.appendChild.bind($el));
        return $el;
      }

      function changed (node1, node2) {
        return typeof node1 !== typeof node2
          || typeof node1 === 'string' && node1 !== node2
          || node1.type !== node2.type
          || node1.id !== node2.id;
      }

      function Patch () {
        this.arr = [];
        this.push = function (x) {this.arr.push(x); }.bind(this);
      }

      var addPatch = [];
      var removePatch = [];

      function updateElement ($par, newNode, oldNode, index=0) {
        if (!oldNode) {
          $par.appendChild (createElement (newNode));
        }
        else if (!newNode) {
          removePatch.push(oldNode.id);
          $par.removeChild($par.childNodes[index]);
        }
        else if (changed(newNode, oldNode)) {
          removePatch.push(oldNode.id);
          $par.replaceChild(createElement(newNode), $par.childNodes[index]);
        }
        else if (newNode.type) {
          updateProps($par.childNodes[index], newNode.props, oldNode.props);
          var newLen = newNode.children.arr.length;
          var oldLen = oldNode.children.arr.length;

          for (var i=0; i<newLen || i<oldLen; i++) {
            updateElement ($par.childNodes[index], newNode.children.arr[i], oldNode.children.arr[i], i);
          }
        }
      }

      function update (id, newNode, oldNode) {
        var $par = document.getElementById (id);
        addPatch = [];
        removePatch = [];
        updateElement ($par, newNode, oldNode);
        return {add:addPatch, remove:removePatch};
      }
      $return (update);
    }@ ) ) ]


  [defun update (id newNode oldNode)
    (_begin
      [vOldNode = [if oldNode then (vnode oldNode) else NIL]]
      [vNewNode = [if newNode then (vnode newNode) else NIL]]
      [patches = (update-fn-internal id vNewNode vOldNode ) ]
      (_map patches.remove (_fn (item) (EVENTS.remove item) ) )
      (_map patches.add (_fn (item) (EVENTS.listen item.id item.type item.port) ) )
    )
  ]