var dust = {};

(function(dust) {

dust.cache = {};

dust.register = function(name, tmpl) {
  if (!name) return;
  dust.cache[name] = tmpl;
};

dust.render = function(name, context, callback) {
  var chunk = new Stub(callback).head;
  dust.load(name, chunk, Context.wrap(context)).end();
};

dust.stream = function(name, context) {
  var stream = new Stream();
  dust.nextTick(function() {
    dust.load(name, stream.head, Context.wrap(context)).end();
  });
  return stream;
};

dust.renderSource = function(source, context, callback) {
  return dust.compileFn(source)(context, callback);
};

dust.compileFn = function(source, name) {
  var tmpl = dust.loadSource(dust.compile(source, name));
  return function(context, callback) {
    var master = callback ? new Stub(callback) : new Stream();
    dust.nextTick(function() {
      tmpl(master.head, Context.wrap(context)).end();
    });
    return master;
  }
};

dust.load = function(name, chunk, context) {
  var tmpl = dust.cache[name];
  if (tmpl) {
    return tmpl(chunk, context);
  } else {
    if (dust.onLoad) {
      return chunk.map(function(chunk) {
        dust.onLoad(name, function(err, src) {
          if (err) return chunk.setError(err);
          if (!dust.cache[name]) dust.loadSource(dust.compile(src, name));
          dust.cache[name](chunk, context).end();
        });
      });
    }
    return chunk.setError(new Error("Template Not Found: " + name));
  }
};

dust.loadSource = function(source, path) {
  return eval(source);
};

if (Array.isArray) {
  dust.isArray = Array.isArray;
} else {
  dust.isArray = function(arr) {
    return Object.prototype.toString.call(arr) == "[object Array]";
  };
}

dust.nextTick = function(callback) {
  setTimeout(callback, 0);
}

dust.isEmpty = function(value) {
  if (dust.isArray(value) && !value.length) return true;
  if (value === 0) return false;
  return (!value);
};

dust.filter = function(string, auto, filters) {
  if (filters) {
    for (var i=0, len=filters.length; i<len; i++) {
      var name = filters[i];
      if (name === "s") {
        auto = null;
      } else {
        string = dust.filters[name](string);
      }
    }
  }
  if (auto) {
    string = dust.filters[auto](string);
  }
  return string;
};

dust.filters = {
  h: function(value) { return dust.escapeHtml(value); },
  j: function(value) { return dust.escapeJs(value); },
  u: encodeURI,
  uc: encodeURIComponent
}

function Context(stack, global, blocks) {
  this.stack  = stack;
  this.global = global;
  this.blocks = blocks;
}

dust.makeBase = function(global) {
  return new Context(new Stack(), global);
}

Context.wrap = function(context) {
  if (context instanceof Context) {
    return context;
  }
  return new Context(new Stack(context));
}

Context.prototype.get = function(key) {
  var ctx = this.stack, value;

  while(ctx) {
    if (ctx.isObject) {
      value = ctx.head[key];
      if (!(value === undefined)) {
        return value;
      }
    }
    ctx = ctx.tail;
  }
  return this.global ? this.global[key] : undefined;
};

Context.prototype.getPath = function(cur, down) {
  var ctx = this.stack,
      len = down.length;

  if (cur && len === 0) return ctx.head;
  if (!ctx.isObject) return undefined;
  ctx = ctx.head;
  var i = 0;
  while(ctx && i < len) {
    ctx = ctx[down[i]];
    i++;
  }
  return ctx;
};

Context.prototype.push = function(head, idx, len) {
  return new Context(new Stack(head, this.stack, idx, len), this.global, this.blocks);
};

Context.prototype.rebase = function(head) {
  return new Context(new Stack(head), this.global, this.blocks);
};

Context.prototype.current = function() {
  return this.stack.head;
};

Context.prototype.getBlock = function(key) {
  var blocks = this.blocks;

  if (!blocks) return;
  var len = blocks.length, fn;
  while (len--) {
    fn = blocks[len][key];
    if (fn) return fn;
  }
}

Context.prototype.shiftBlocks = function(locals) {
  var blocks = this.blocks;

  if (locals) {
    if (!blocks) {
      newBlocks = [locals];
    } else {
      newBlocks = blocks.concat([locals]);
    }
    return new Context(this.stack, this.global, newBlocks);
  }
  return this;
}

function Stack(head, tail, idx, len) {
  this.tail = tail;
  this.isObject = !dust.isArray(head) && head && typeof head === "object";
  this.head = head;
  this.index = idx;
  this.of = len;
}

function Stub(callback) {
  this.head = new Chunk(this);
  this.callback = callback;
  this.out = '';
}

Stub.prototype.flush = function() {
  var chunk = this.head;

  while (chunk) {
    if (chunk.flushable) {
      this.out += chunk.data;
    } else if (chunk.error) {
      this.callback(chunk.error);
      this.flush = function() {};
      return;
    } else {
      return;
    }
    chunk = chunk.next;
    this.head = chunk;
  }
  this.callback(null, this.out);
}

function Stream() {
  this.head = new Chunk(this);
}

Stream.prototype.flush = function() {
  var chunk = this.head;

  while(chunk) {
    if (chunk.flushable) {
      this.emit('data', chunk.data);
    } else if (chunk.error) {
      this.emit('error', chunk.error);
      this.flush = function() {};
      return;
    } else {
      return;
    }
    chunk = chunk.next;
    this.head = chunk;
  }
  this.emit('end');
}

Stream.prototype.emit = function(type, data) {
  var events = this.events;

  if (events && events[type]) {
    events[type](data);
  }
}

Stream.prototype.on = function(type, callback) {
  if (!this.events) {
    this.events = {};
  }
  this.events[type] = callback;
  return this;
}

function Chunk(root, next, taps) {
  this.root = root;
  this.next = next;
  this.data = '';
  this.flushable = false;
  this.taps = taps;
}

Chunk.prototype.write = function(data) {
  var taps  = this.taps;

  if (taps) {
    data = taps.go(data);
  }
  this.data += data;
  return this;
}

Chunk.prototype.end = function(data) {
  if (data) {
    this.write(data);
  }
  this.flushable = true;
  this.root.flush();
  return this;
}

Chunk.prototype.map = function(callback) {
  var cursor = new Chunk(this.root, this.next, this.taps),
      branch = new Chunk(this.root, cursor, this.taps);

  this.next = branch;
  this.flushable = true;
  callback(branch);
  return cursor;
}

Chunk.prototype.tap = function(tap) {
  var taps = this.taps;

  if (taps) {
    this.taps = taps.push(tap);
  } else {
    this.taps = new Tap(tap);
  }
  return this;
}

Chunk.prototype.untap = function() {
  this.taps = this.taps.tail;
  return this;
}

Chunk.prototype.render = function(body, context) {
  return body(this, context);
}

Chunk.prototype.reference = function(elem, context, auto, filters) {
  if (typeof elem === "function") {
    elem = elem(this, context, null, {auto: auto, filters: filters});
    if (elem instanceof Chunk) {
      return elem;
    }
  }
  if (!dust.isEmpty(elem)) {
    return this.write(dust.filter(elem, auto, filters));
  } else {
    return this;
  }
};

Chunk.prototype.section = function(elem, context, bodies, params) {
  if (typeof elem === "function") {
    elem = elem(this, context, bodies, params);
    if (elem instanceof Chunk) {
      return elem;
    }
  }

  var body = bodies.block,
      skip = bodies['else'];

  if (params) {
    context = context.push(params);
  }

  if (dust.isArray(elem)) {
    if (body) {
      var len = elem.length, chunk = this;
      for (var i=0; i<len; i++) {
        chunk = body(chunk, context.push(elem[i], i, len));
      }
      return chunk;
    }
  } else if (elem === true) {
    if (body) return body(this, context);
  } else if (elem || elem === 0) {
    if (body) return body(this, context.push(elem));
  } else if (skip) {
    return skip(this, context);
  }
  return this;
};

Chunk.prototype.exists = function(elem, context, bodies) {
  var body = bodies.block,
      skip = bodies['else'];

  if (!dust.isEmpty(elem)) {
    if (body) return body(this, context);
  } else if (skip) {
    return skip(this, context);
  }
  return this;
}

Chunk.prototype.notexists = function(elem, context, bodies) {
  var body = bodies.block,
      skip = bodies['else'];

  if (dust.isEmpty(elem)) {
    if (body) return body(this, context);
  } else if (skip) {
    return skip(this, context);
  }
  return this;
}

Chunk.prototype.block = function(elem, context, bodies) {
  var body = bodies.block;

  if (elem) {
    body = elem;
  }

  if (body) {
    return body(this, context);
  }
  return this;
};

Chunk.prototype.partial = function(elem, context) {
  if (typeof elem === "function") {
    return this.capture(elem, context, function(name, chunk) {
      dust.load(name, chunk, context).end();
    });
  }
  return dust.load(elem, this, context);
};

Chunk.prototype.helper = function(name, context, bodies, params) {
  return dust.helpers[name](this, context, bodies, params);
};

Chunk.prototype.capture = function(body, context, callback) {
  return this.map(function(chunk) {
    var stub = new Stub(function(err, out) {
      if (err) {
        chunk.setError(err);
      } else {
        callback(out, chunk);
      }
    });
    body(stub.head, context).end();
  });
};

Chunk.prototype.setError = function(err) {
  this.error = err;
  this.root.flush();
  return this;
};

dust.helpers = {
  sep: function(chunk, context, bodies) {
    if (context.stack.index === context.stack.of - 1) {
      return chunk;
    }
    return bodies.block(chunk, context);
  },

  idx: function(chunk, context, bodies) {
    return bodies.block(chunk, context.push(context.stack.index));
  }
}

function Tap(head, tail) {
  this.head = head;
  this.tail = tail;
}

Tap.prototype.push = function(tap) {
  return new Tap(tap, this);
};

Tap.prototype.go = function(value) {
  var tap = this;

  while(tap) {
    value = tap.head(value);
    tap = tap.tail;
  }
  return value;
};

var HCHARS = new RegExp(/[&<>\"]/),
    AMP    = /&/g,
    LT     = /</g,
    GT     = />/g,
    QUOT   = /\"/g;

dust.escapeHtml = function(s) {
  if (typeof s === "string") {
    if (!HCHARS.test(s)) {
      return s;
    }
    return s.replace(AMP,'&amp;').replace(LT,'&lt;').replace(GT,'&gt;').replace(QUOT,'&quot;');
  }
  return s;
};

var BS = /\\/g,
    CR = /\r/g,
    LS = /\u2028/g,
    PS = /\u2029/g,
    NL = /\n/g,
    LF = /\f/g,
    SQ = /'/g,
    DQ = /"/g,
    TB = /\t/g;

dust.escapeJs = function(s) {
  if (typeof s === "string") {
    return s
      .replace(BS, '\\\\')
      .replace(DQ, '\\"')
      .replace(SQ, "\\'")
      .replace(CR, '\\r')
      .replace(LS, '\\u2028')
      .replace(PS, '\\u2029')
      .replace(NL, '\\n')
      .replace(LF, '\\f')
      .replace(TB, "\\t");
  }
  return s;
};

})(dust);

if (typeof exports !== "undefined") {
  if (typeof process !== "undefined") {
      require('./server')(dust);
  }
  module.exports = dust;
}