/**
 * Web page integration module for the mermaid framework. It uses the mermaidAPI for mermaid functionality and to render
 * the diagrams to svg code.
 */
import he from 'he'

import mermaidAPI from './mermaidAPI'
import { logger } from './logger'

/**
 * ## init
 * Function that goes through the document to find the chart definitions in there and render them.
 *
 * The function tags the processed attributes with the attribute data-processed and ignores found elements with the
 * attribute already set. This way the init function can be triggered several times.
 *
 * Optionally, `init` can accept in the second argument one of the following:
 * - a DOM Node
 * - an array of DOM nodes (as would come from a jQuery selector)
 * - a W3C selector, a la `.mermaid`
 *
 * ```mermaid
 * graph LR;
 *  a(Find elements)-->b{Processed}
 *  b-->|Yes|c(Leave element)
 *  b-->|No |d(Transform)
 * ```
 * Renders the mermaid diagrams
 * @param nodes a css selector or an array of nodes
 */
const init = function () {
  const conf = mermaidAPI.getConfig()
  logger.debug('Starting rendering diagrams')
  let nodes
  if (arguments.length >= 2) {
    /*! sequence config was passed as #1 */
    if (typeof arguments[0] !== 'undefined') {
      mermaid.sequenceConfig = arguments[0]
    }

    nodes = arguments[1]
  } else {
    nodes = arguments[0]
  }

  // if last argument is a function this is the callback function
  let callback
  if (typeof arguments[arguments.length - 1] === 'function') {
    callback = arguments[arguments.length - 1]
    logger.debug('Callback function found')
  } else {
    if (typeof conf.mermaid !== 'undefined') {
      if (typeof conf.mermaid.callback === 'function') {
        callback = conf.mermaid.callback
        logger.debug('Callback function found')
      } else {
        logger.debug('No Callback function found')
      }
    }
  }
  nodes = nodes === undefined ? document.querySelectorAll('.mermaid')
    : typeof nodes === 'string' ? document.querySelectorAll(nodes)
      : nodes instanceof window.Node ? [nodes]
        : nodes // Last case  - sequence config was passed pick next

  logger.debug('Start On Load before: ' + mermaid.startOnLoad)
  if (typeof mermaid.startOnLoad !== 'undefined') {
    logger.debug('Start On Load inner: ' + mermaid.startOnLoad)
    mermaidAPI.initialize({ startOnLoad: mermaid.startOnLoad })
  }

  if (typeof mermaid.ganttConfig !== 'undefined') {
    mermaidAPI.initialize({ gantt: mermaid.ganttConfig })
  }

  let txt

  for (let i = 0; i < nodes.length; i++) {
    const element = nodes[i]

    /*! Check if previously processed */
    if (!element.getAttribute('data-processed')) {
      element.setAttribute('data-processed', true)
    } else {
      continue
    }

    const id = `mermaid-${Date.now()}`

    // Fetch the graph definition including tags
    txt = element.innerHTML

    // transforms the html to pure text
    txt = he.decode(txt).trim().replace(/<br>/ig, '<br/>')

    mermaidAPI.render(id, txt, (svgCode, bindFunctions) => {
      element.innerHTML = svgCode
      if (typeof callback !== 'undefined') {
        callback(id)
      }
      bindFunctions(element)
    }, element)
  }
}

const initialize = function (config) {
  logger.debug('Initializing mermaid')
  if (typeof config.mermaid !== 'undefined') {
    if (typeof config.mermaid.startOnLoad !== 'undefined') {
      mermaid.startOnLoad = config.mermaid.startOnLoad
    }
    if (typeof config.mermaid.htmlLabels !== 'undefined') {
      mermaid.htmlLabels = config.mermaid.htmlLabels
    }
  }
  mermaidAPI.initialize(config)
}

/**
 * ##contentLoaded
 * Callback function that is called when page is loaded. This functions fetches configuration for mermaid rendering and
 * calls init for rendering the mermaid diagrams on the page.
 */
const contentLoaded = function () {
  let config

  if (mermaid.startOnLoad) {
    // No config found, do check API config
    config = mermaidAPI.getConfig()
    if (config.startOnLoad) {
      mermaid.init()
    }
  } else {
    if (typeof mermaid.startOnLoad === 'undefined') {
      logger.debug('In start, no config')
      config = mermaidAPI.getConfig()
      if (config.startOnLoad) {
        mermaid.init()
      }
    }
  }
}

if (typeof document !== 'undefined') {
  /*!
   * Wait for document loaded before starting the execution
   */
  window.addEventListener('load', function () {
    contentLoaded()
  }, false)
}

const mermaid = {
  startOnLoad: true,
  htmlLabels: true,

  mermaidAPI,
  parse: mermaidAPI.parse,
  render: mermaidAPI.render,

  init,
  initialize,

  contentLoaded
}

export default mermaid