import {isObject} from "./utils"
import Dispatcher from "./dispatcher"

export default class Component {
  constructor() {
    this.rootNode = null
    this.props = {}

    // Add dispatcher observers
    if (this.constructor.observers) {
      const observers = this.constructor.observers
      for (let eventName in observers) {
        const methodName = observers[eventName]
        Dispatcher.addObserver(eventName, this, methodName)
      }
    }
  }

  destroy() {
    if (this.rootNode.parentNode) {
      this.rootNode.parentNode.removeChild(this.rootNode)
    }

    // Remove dispatcher observers
    const observers = this.constructor.observers
    if (observers) {
      for (let eventName in observers) {
        Dispatcher.removeObserver(eventName, this)
      }
    }
  }

  // Define an updatable property of the component.
  // Also updates the property if it's already set
  prop(propName, propValue = "") {
    let propNode = this.props[propName]

    if (!propNode) {
      propNode = this.props[propName] = document.createTextNode(propValue)
    }

    if (propValue !== propNode.textContent) {
      propNode.textContent = propValue
    }

    return propNode
  }

  render() {
    if (this.rootNode) {
      throw new Error("already rendered component")
    }
    if (!this.build) {
      throw new Error("unimplemented method build()")
    }

    this.rootNode = this.build()

    // Add DOM event handlers
    const eventHandlers = this.constructor.eventHandlers
    if (eventHandlers) {
      for (let eventName in eventHandlers) {
        const handler = eventHandlers[eventName]
        this.rootNode.addEventListener(eventName, handler.bind(this), true)
      }
    }

    return this.rootNode
  }

  show() {
    this.rootNode.classList.toggle("u-hidden", false)
  }

  hide() {
    this.rootNode.classList.toggle("u-hidden", true)
  }

  toggle() {
    console.warn("hello", this.rootNode)
    this.rootNode.classList.toggle("u-hidden")
  }

  static tag(tagSpec, attributes, children) {
    if (!tagSpec) {
      throw new Error("No tagSpec given")
    }

    attributes = attributes || {}
    children = children || []

    if (!isObject(attributes)) {
      children = attributes
      attributes = {}
    }

    const [tagName, className] = tagSpec.split(".")
    const node = document.createElement(tagName)

    if (className) {
      node.classList.add(className)
    }

    if (!(children instanceof Array)) {
      children = [children]
    }

    for (let attrName in attributes) {
      node.setAttribute(attrName, attributes[attrName])
    }

    for (let child of children) {
      if (typeof child === "object" && "render" in child) {
        // Component children
        child.render()
        node.appendChild(child.rootNode)
      } else if (typeof child === "string") {
        // Text children
        node.appendChild(document.createTextNode(child))
      } else {
        // DOM nodes children
        node.appendChild(child)
      }
    }

    return node
  }
}