/* @flow */

import { decodeHTML } from 'entities'
import { parseHTML } from './html-parser'
import { parseText } from './text-parser'
import { cached, no } from 'shared/util'
import {
  pluckModuleFunction,
  getAndRemoveAttr,
  addProp,
  addAttr,
  addStaticAttr,
  addHandler,
  addDirective,
  getBindingAttr,
  baseWarn
} from '../helpers'

export const dirRE = /^v-|^@|^:/
export const forAliasRE = /(.*)\s+(?:in|of)\s+(.*)/
export const forIteratorRE = /\(([^,]*),([^,]*)(?:,([^,]*))?\)/
const bindRE = /^:|^v-bind:/
const onRE = /^@|^v-on:/
const argRE = /:(.*)$/
const modifierRE = /\.[^\.]+/g

const decodeHTMLCached = cached(decodeHTML)

// configurable state
let warn
let platformGetTagNamespace
let platformMustUseProp
let transforms
let delimiters

/**
 * Convert HTML string to AST.
 */
export function parse (
  template: string,
  options: CompilerOptions
): ASTElement | void {
  warn = options.warn || baseWarn
  platformGetTagNamespace = options.getTagNamespace || no
  platformMustUseProp = options.mustUseProp || no
  transforms = pluckModuleFunction(options.modules, 'transformNode')
  delimiters = options.delimiters
  const stack = []
  const preserveWhitespace = options.preserveWhitespace !== false
  let root
  let currentParent
  let inPre = false
  let warned = false
  parseHTML(template, {
    expectHTML: options.expectHTML,
    isUnaryTag: options.isUnaryTag,
    start (tag, attrs, unary) {
      // check namespace.
      // inherit parent ns if there is one
      const ns = (currentParent && currentParent.ns) || platformGetTagNamespace(tag)

      // handle IE svg bug
      /* istanbul ignore if */
      if (options.isIE && ns === 'svg') {
        attrs = guardIESVGBug(attrs)
      }

      const element: ASTElement = {
        type: 1,
        tag,
        attrsList: attrs,
        attrsMap: makeAttrsMap(attrs),
        parent: currentParent,
        children: []
      }
      if (ns) {
        element.ns = ns
      }

      if (isForbiddenTag(element)) {
        element.forbidden = true
        process.env.NODE_ENV !== 'production' && warn(
          'Templates should only be responsbile for mapping the state to the ' +
          'UI. Avoid placing tags with side-effects in your templates, such as ' +
          `<${tag}>.`
        )
      }

      if (!inPre) {
        processPre(element)
        if (element.pre) {
          inPre = true
        }
      }
      if (inPre) {
        processRawAttrs(element)
      } else {
        processFor(element)
        processIf(element)
        processOnce(element)

        // determine whether this is a plain element after
        // removing structural attributes
        element.plain = !element.key && !attrs.length

        processKey(element)
        processRef(element)
        processSlot(element)
        processComponent(element)
        for (let i = 0; i < transforms.length; i++) {
          transforms[i](element, options)
        }
        processAttrs(element)
      }

      // tree management
      if (!root) {
        root = element
        // check root element constraints
        if (process.env.NODE_ENV !== 'production') {
          if (tag === 'slot' || tag === 'template') {
            warn(
              `Cannot use <${tag}> as component root element because it may ` +
              'contain multiple nodes:\n' + template
            )
          }
          if (element.attrsMap.hasOwnProperty('v-for')) {
            warn(
              'Cannot use v-for on stateful component root element because ' +
              'it renders multiple elements:\n' + template
            )
          }
        }
      } else if (process.env.NODE_ENV !== 'production' && !stack.length && !warned) {
        warned = true
        warn(
          `Component template should contain exactly one root element:\n\n${template}`
        )
      }
      if (currentParent && !element.forbidden) {
        if (element.else) {
          processElse(element, currentParent)
        } else {
          currentParent.children.push(element)
          element.parent = currentParent
        }
      }
      if (!unary) {
        currentParent = element
        stack.push(element)
      }
    },

    end () {
      // remove trailing whitespace
      const element = stack[stack.length - 1]
      const lastNode = element.children[element.children.length - 1]
      if (lastNode && lastNode.type === 3 && lastNode.text === ' ') {
        element.children.pop()
      }
      // pop stack
      stack.length -= 1
      currentParent = stack[stack.length - 1]
      // check pre state
      if (element.pre) {
        inPre = false
      }
    },

    chars (text: string) {
      if (!currentParent) {
        if (process.env.NODE_ENV !== 'production' && !warned) {
          warned = true
          warn(
            'Component template should contain exactly one root element:\n\n' + template
          )
        }
        return
      }
      text = currentParent.tag === 'pre' || text.trim()
        ? decodeHTMLCached(text)
        // only preserve whitespace if its not right after a starting tag
        : preserveWhitespace && currentParent.children.length ? ' ' : ''
      if (text) {
        let expression
        if (!inPre && text !== ' ' && (expression = parseText(text, delimiters))) {
          currentParent.children.push({
            type: 2,
            expression,
            text
          })
        } else {
          currentParent.children.push({
            type: 3,
            text
          })
        }
      }
    }
  })
  return root
}

function processPre (el) {
  if (getAndRemoveAttr(el, 'v-pre') != null) {
    el.pre = true
  }
}

function processRawAttrs (el) {
  const l = el.attrsList.length
  if (l) {
    const attrs = el.staticAttrs = new Array(l)
    for (let i = 0; i < l; i++) {
      attrs[i] = {
        name: el.attrsList[i].name,
        value: JSON.stringify(el.attrsList[i].value)
      }
    }
  } else if (!el.pre) {
    // non root node in pre blocks with no attributes
    el.plain = true
  }
}

function processKey (el) {
  const exp = getBindingAttr(el, 'key')
  if (exp) {
    el.key = exp
  }
}

function processRef (el) {
  const ref = getBindingAttr(el, 'ref')
  if (ref) {
    el.ref = ref
    let parent = el
    while (parent) {
      if (parent.for !== undefined) {
        el.refInFor = true
        break
      }
      parent = parent.parent
    }
  }
}

function processFor (el) {
  let exp
  if ((exp = getAndRemoveAttr(el, 'v-for'))) {
    const inMatch = exp.match(forAliasRE)
    if (!inMatch) {
      process.env.NODE_ENV !== 'production' && warn(
        `Invalid v-for expression: ${exp}`
      )
      return
    }
    el.for = inMatch[2].trim()
    const alias = inMatch[1].trim()
    const iteratorMatch = alias.match(forIteratorRE)
    if (iteratorMatch) {
      el.alias = iteratorMatch[1].trim()
      el.iterator1 = iteratorMatch[2].trim()
      if (iteratorMatch[3]) {
        el.iterator2 = iteratorMatch[3].trim()
      }
    } else {
      el.alias = alias
    }
  }
}

function processIf (el) {
  const exp = getAndRemoveAttr(el, 'v-if')
  if (exp) {
    el.if = exp
  }
  if (getAndRemoveAttr(el, 'v-else') != null) {
    el.else = true
  }
}

function processElse (el, parent) {
  const prev = findPrevElement(parent.children)
  if (prev && prev.if) {
    prev.elseBlock = el
  } else if (process.env.NODE_ENV !== 'production') {
    warn(
      `v-else used on element <${el.tag}> without corresponding v-if.`
    )
  }
}

function processOnce (el) {
  const once = getAndRemoveAttr(el, 'v-once')
  if (once != null) {
    el.once = true
  }
}

function processSlot (el) {
  if (el.tag === 'slot') {
    el.slotName = getBindingAttr(el, 'name')
  } else {
    const slotTarget = getBindingAttr(el, 'slot')
    if (slotTarget) {
      el.slotTarget = slotTarget
    }
  }
}

function processComponent (el) {
  let binding
  if ((binding = getBindingAttr(el, 'is'))) {
    el.component = binding
  }
  if (getAndRemoveAttr(el, 'keep-alive') != null) {
    el.keepAlive = true
  }
  if (getAndRemoveAttr(el, 'inline-template') != null) {
    el.inlineTemplate = true
  }
}

function processAttrs (el) {
  const list = el.attrsList
  let i, l, name, value, arg, modifiers
  for (i = 0, l = list.length; i < l; i++) {
    name = list[i].name
    value = list[i].value
    if (dirRE.test(name)) {
      // modifiers
      modifiers = parseModifiers(name)
      if (modifiers) {
        name = name.replace(modifierRE, '')
      }
      if (bindRE.test(name)) { // v-bind
        name = name.replace(bindRE, '')
        if (platformMustUseProp(name)) {
          addProp(el, name, value)
        } else {
          addAttr(el, name, value)
        }
      } else if (onRE.test(name)) { // v-on
        name = name.replace(onRE, '')
        addHandler(el, name, value, modifiers)
      } else { // normal directives
        name = name.replace(dirRE, '')
        // parse arg
        const argMatch = name.match(argRE)
        if (argMatch && (arg = argMatch[1])) {
          name = name.slice(0, -(arg.length + 1))
        }
        addDirective(el, name, value, arg, modifiers)
      }
    } else {
      // literal attribute
      if (process.env.NODE_ENV !== 'production') {
        const expression = parseText(value, delimiters)
        if (expression) {
          warn(
            `${name}="${value}": ` +
            'Interpolation inside attributes has been deprecated. ' +
            'Use v-bind or the colon shorthand instead.'
          )
        }
      }
      addStaticAttr(el, name, JSON.stringify(value))
    }
  }
}

function parseModifiers (name: string): Object | void {
  const match = name.match(modifierRE)
  if (match) {
    const ret = {}
    match.forEach(m => { ret[m.slice(1)] = true })
    return ret
  }
}

function makeAttrsMap (attrs: Array<Object>): Object {
  const map = {}
  for (let i = 0, l = attrs.length; i < l; i++) {
    if (process.env.NODE_ENV !== 'production' && map[attrs[i].name]) {
      warn('duplicate attribute: ' + attrs[i].name)
    }
    map[attrs[i].name] = attrs[i].value
  }
  return map
}

function findPrevElement (children: Array<any>): ASTElement | void {
  let i = children.length
  while (i--) {
    if (children[i].tag) return children[i]
  }
}

function isForbiddenTag (el): boolean {
  return (
    el.tag === 'style' ||
    (el.tag === 'script' && (
      !el.attrsMap.type ||
      el.attrsMap.type === 'text/javascript'
    ))
  )
}

const ieNSBug = /^xmlns:NS\d+/
const ieNSPrefix = /^NS\d+:/

/* istanbul ignore next */
function guardIESVGBug (attrs) {
  const res = []
  for (let i = 0; i < attrs.length; i++) {
    const attr = attrs[i]
    if (!ieNSBug.test(attr.name)) {
      attr.name = attr.name.replace(ieNSPrefix, '')
      res.push(attr)
    }
  }
  return res
}