'use strict'

const fastRedact = require('fast-redact')
const { redactFmtSym, wildcardFirstSym } = require('./symbols')
const { rx, validator } = fastRedact

const validate = validator({
  ERR_PATHS_MUST_BE_STRINGS: () => 'pino – redacted paths must be strings',
  ERR_INVALID_PATH: (s) => `pino – redact paths array contains an invalid path (${s})`
})

const CENSOR = '[Redacted]'
const strict = false // TODO should this be configurable?

function redaction (opts, serialize) {
  const { paths, censor } = handle(opts)

  const shape = paths.reduce((o, str) => {
    rx.lastIndex = 0
    const first = rx.exec(str)
    const next = rx.exec(str)

    // ns is the top-level path segment, brackets + quoting removed.
    let ns = first[1] !== undefined
      ? first[1].replace(/^(?:"|'|`)(.*)(?:"|'|`)$/, '$1')
      : first[0]

    if (ns === '*') {
      ns = wildcardFirstSym
    }

    // top level key:
    if (next === null) {
      o[ns] = null
      return o
    }

    // path with at least two segments:
    // if ns is already redacted at the top level, ignore lower level redactions
    if (o[ns] === null) {
      return o
    }

    const { index } = next
    const nextPath = `${str.substr(index, str.length - 1)}`

    o[ns] = o[ns] || []

    // shape is a mix of paths beginning with literal values and wildcard
    // paths [ "a.b.c", "*.b.z" ] should reduce to a shape of
    // { "a": [ "b.c", "b.z" ], *: [ "b.z" ] }
    // note: "b.z" is in both "a" and * arrays because "a" matches the wildcard.
    // (* entry has wildcardFirstSym as key)
    if (ns !== wildcardFirstSym && o[ns].length === 0) {
      // first time ns's get all '*' redactions so far
      o[ns].push(...(o[wildcardFirstSym] || []))
    }

    if (ns === wildcardFirstSym) {
      // new * path gets added to all previously registered literal ns's.
      Object.keys(o).forEach(function (k) {
        if (o[k]) {
          o[k].push(nextPath)
        }
      })
    }

    o[ns].push(nextPath)
    return o
  }, {})

  // the redactor assigned to the format symbol key
  // provides top level redaction for instances where
  // an object is interpolated into the msg string
  const result = {
    [redactFmtSym]: fastRedact({ paths, censor, serialize, strict })
  }

  const topCensor = (...args) =>
    typeof censor === 'function' ? serialize(censor(...args)) : serialize(censor)

  return [...Object.keys(shape), ...Object.getOwnPropertySymbols(shape)].reduce((o, k) => {
    // top level key:
    if (shape[k] === null) o[k] = topCensor
    else o[k] = fastRedact({ paths: shape[k], censor, serialize, strict })
    return o
  }, result)
}

function handle (opts) {
  if (Array.isArray(opts)) {
    opts = { paths: opts, censor: CENSOR }
    validate(opts)
    return opts
  }
  var { paths, censor = CENSOR, remove } = opts
  if (Array.isArray(paths) === false) { throw Error('pino – redact must contain an array of strings') }
  if (remove === true) censor = undefined
  validate({ paths, censor })

  return { paths, censor }
}

module.exports = redaction