import { copyObj, createObj } from "./util/misc.js"

// Known modes, by name and by MIME
export let modes = {}, mimeModes = {}

// Extra arguments are stored as the mode's dependencies, which is
// used by (legacy) mechanisms like loadmode.js to automatically
// load a mode. (Preferred mechanism is the require/define calls.)
export function defineMode(name, mode) {
  if (arguments.length > 2)
    mode.dependencies = Array.prototype.slice.call(arguments, 2)
  modes[name] = mode
}

export function defineMIME(mime, spec) {
  mimeModes[mime] = spec
}

// Given a MIME type, a {name, ...options} config object, or a name
// string, return a mode config object.
export function resolveMode(spec) {
  if (typeof spec == "string" && mimeModes.hasOwnProperty(spec)) {
    spec = mimeModes[spec]
  } else if (spec && typeof spec.name == "string" && mimeModes.hasOwnProperty(spec.name)) {
    let found = mimeModes[spec.name]
    if (typeof found == "string") found = {name: found}
    spec = createObj(found, spec)
    spec.name = found.name
  } else if (typeof spec == "string" && /^[\w\-]+\/[\w\-]+\+xml$/.test(spec)) {
    return resolveMode("application/xml")
  } else if (typeof spec == "string" && /^[\w\-]+\/[\w\-]+\+json$/.test(spec)) {
    return resolveMode("application/json")
  }
  if (typeof spec == "string") return {name: spec}
  else return spec || {name: "null"}
}

// Given a mode spec (anything that resolveMode accepts), find and
// initialize an actual mode object.
export function getMode(options, spec) {
  spec = resolveMode(spec)
  let mfactory = modes[spec.name]
  if (!mfactory) return getMode(options, "text/plain")
  let modeObj = mfactory(options, spec)
  if (modeExtensions.hasOwnProperty(spec.name)) {
    let exts = modeExtensions[spec.name]
    for (let prop in exts) {
      if (!exts.hasOwnProperty(prop)) continue
      if (modeObj.hasOwnProperty(prop)) modeObj["_" + prop] = modeObj[prop]
      modeObj[prop] = exts[prop]
    }
  }
  modeObj.name = spec.name
  if (spec.helperType) modeObj.helperType = spec.helperType
  if (spec.modeProps) for (let prop in spec.modeProps)
    modeObj[prop] = spec.modeProps[prop]

  return modeObj
}

// This can be used to attach properties to mode objects from
// outside the actual mode definition.
export let modeExtensions = {}
export function extendMode(mode, properties) {
  let exts = modeExtensions.hasOwnProperty(mode) ? modeExtensions[mode] : (modeExtensions[mode] = {})
  copyObj(properties, exts)
}

export function copyState(mode, state) {
  if (state === true) return state
  if (mode.copyState) return mode.copyState(state)
  let nstate = {}
  for (let n in state) {
    let val = state[n]
    if (val instanceof Array) val = val.concat([])
    nstate[n] = val
  }
  return nstate
}

// Given a mode and a state (for that mode), find the inner mode and
// state at the position that the state refers to.
export function innerMode(mode, state) {
  let info
  while (mode.innerMode) {
    info = mode.innerMode(state)
    if (!info || info.mode == mode) break
    state = info.state
    mode = info.mode
  }
  return info || {mode: mode, state: state}
}

export function startState(mode, a1, a2) {
  return mode.startState ? mode.startState(a1, a2) : true
}