/* @flow */

// This file contains methods responsible for maintaining a TraversalContext.

import traverse from "../index";

export function call(key): boolean {
  let opts = this.opts;

  this.debug(() => key);

  if (this.node) {
    if (this._call(opts[key])) return true;
  }

  if (this.node) {
    return this._call(opts[this.node.type] && opts[this.node.type][key]);
  }

  return false;
}

export function _call(fns?: Array<Function>): boolean {
  if (!fns) return false;

  for (let fn of fns) {
    if (!fn) continue;

    let node = this.node;
    if (!node) return true;

    let ret = fn.call(this.state, this, this.state);
    if (ret) throw new Error(`Unexpected return value from visitor method ${fn}`);

    // node has been replaced, it will have been requeued
    if (this.node !== node) return true;

    if (this.shouldStop || this.shouldSkip || this.removed) return true;
  }

  return false;
}

export function isBlacklisted(): boolean {
  let blacklist = this.opts.blacklist;
  return blacklist && blacklist.indexOf(this.node.type) > -1;
}

export function visit(): boolean {
  if (!this.node) {
    return false;
  }

  if (this.isBlacklisted()) {
    return false;
  }

  if (this.opts.shouldSkip && this.opts.shouldSkip(this)) {
    return false;
  }

  if (this.call("enter") || this.shouldSkip) {
    this.debug(() => "Skip...");
    return this.shouldStop;
  }

  this.debug(() => "Recursing into...");
  traverse.node(this.node, this.opts, this.scope, this.state, this, this.skipKeys);

  this.call("exit");

  return this.shouldStop;
}

export function skip() {
  this.shouldSkip = true;
}

export function skipKey(key) {
  this.skipKeys[key] = true;
}

export function stop() {
  this.shouldStop = true;
  this.shouldSkip = true;
}

export function setScope() {
  if (this.opts && this.opts.noScope) return;

  let target = this.context && this.context.scope;

  if (!target) {
    let path = this.parentPath;
    while (path && !target) {
      if (path.opts && path.opts.noScope) return;

      target = path.scope;
      path = path.parentPath;
    }
  }

  this.scope = this.getScope(target);
  if (this.scope) this.scope.init();
}

export function setContext(context) {
  this.shouldSkip = false;
  this.shouldStop = false;
  this.removed    = false;
  this.skipKeys   = {};

  if (context) {
    this.context = context;
    this.state   = context.state;
    this.opts    = context.opts;
  }

  this.setScope();

  return this;
}

/**
 * Here we resync the node paths `key` and `container`. If they've changed according
 * to what we have stored internally then we attempt to resync by crawling and looking
 * for the new values.
 */

export function resync() {
  if (this.removed) return;

  this._resyncParent();
  this._resyncList();
  this._resyncKey();
  //this._resyncRemoved();
}

export function _resyncParent() {
  if (this.parentPath) {
    this.parent = this.parentPath.node;
  }
}

export function _resyncKey() {
  if (!this.container) return;

  if (this.node === this.container[this.key]) return;

  // grrr, path key is out of sync. this is likely due to a modification to the AST
  // not done through our path APIs

  if (Array.isArray(this.container)) {
    for (let i = 0; i < this.container.length; i++) {
      if (this.container[i] === this.node) {
        return this.setKey(i);
      }
    }
  } else {
    for (let key in this.container) {
      if (this.container[key] === this.node) {
        return this.setKey(key);
      }
    }
  }

  // ¯\_(ツ)_/¯ who knows where it's gone lol
  this.key = null;
}

export function _resyncList() {
  if (!this.parent || !this.inList) return;

  let newContainer = this.parent[this.listKey];
  if (this.container === newContainer) return;

  // container is out of sync. this is likely the result of it being reassigned
  this.container = newContainer || null;
}

export function _resyncRemoved() {
  if (this.key == null || !this.container || this.container[this.key] !== this.node) {
    this._markRemoved();
  }
}

export function popContext() {
  this.contexts.pop();
  this.setContext(this.contexts[this.contexts.length - 1]);
}

export function pushContext(context) {
  this.contexts.push(context);
  this.setContext(context);
}

export function setup(parentPath, container, listKey, key) {
  this.inList    = !!listKey;
  this.listKey   = listKey;
  this.parentKey = listKey || key;
  this.container = container;

  this.parentPath = parentPath || this.parentPath;
  this.setKey(key);
}

export function setKey(key) {
  this.key  = key;
  this.node = this.container[this.key];
  this.type = this.node && this.node.type;
}

export function requeue(path = this) {
  if (path.removed) return;

  for (let context of this.contexts) {
    context.maybeQueue(path);
  }
}