ama-team / voxengine-sdk

 * @module logger/_common

 */

/**

 * @enum

 * @readonly

 */

var Level = {

  All: 'ALL',

  Trace: 'TRACE',

  Debug: 'DEBUG',

  Notice: 'NOTICE',

  Info: 'INFO',

  Warn: 'WARN',

  Error: 'ERROR',

  Off: 'OFF'

}

/**

 * @enum

 * @readonly

 */

var Threshold = {

  ALL: 1,

  TRACE: 2,

  DEBUG: 3,

  INFO: 4,

  NOTICE: 5,

  WARN: 6,

  ERROR: 7,

  OFF: 8

}

/**

 * Converts input to appropriate level

 *

 * @param {Level|Threshold|string} level

 * @return {Level}

 */

function level (level) {

  return Object.keys(Threshold).reduce(function (carrier, key) {

    if (level && (Threshold[key] === level || level.toString().toUpperCase() === key)) {

      return key

    }

    return carrier

  })

}

/**

 * Converts unknown input into threshold

 *

 * @param {Level|Threshold|string} lvl

 * @return {Threshold}

 */

function threshold (lvl) {

  return Threshold[level(lvl)]

}

/**

 * This class represents basic tree branch consisting of a node and (optionally)

 * child nodes. It is created with sole purpose to provide easy support for

 * package hierarchy tooling, so `ama-team.voxengine` would be presented as node

 * (root) -> (ama-team) -> (voxengine), and it's properties would be stored as

 * trees, allowing easy and configurable overlapping.

 *

 * @class

 *

 * @template {V} Wrapped value type

 *

 * @param {V|null} value Initial value

 */

function TreeNode (value) {

  var self = this

  /**

   * @template {V}

   * @typedef {Object.<string, TreeNode<V>>}

   */

  var children = {}

  /**

   * Adds new child to current node.

   *

   * @param {string} name Child name

   * @param {TreeNode<V>} child Child value

   * @return {TreeNode<V>} Returns added child

   */

  this.addChild = function (name, child) {

    children[name] = child

    return child

  }

  /**

   * Removes child

   *

   * @param {string} name Child name

   * @return {TreeNode<V>|null} Removed child value

   */

  this.removeChild = function (name) {

    var value = children[name]

    delete children[name]

    return value || null

  }

  /**

   * Fetches current node child by it's name.

   *

   * @param {string} name Child name.

   *

   * @return {TreeNode.<V>|null} Existing node or nothing.

   */

  this.child = function (name) { return children[name] || null }

  /**

   * Sets value for current node.

   *

   * @param {V} v

   * @return {TreeNode} Returns current instance.

   */

  this.set = function (v) {

    value = v

    return self

  }

  /**

   * Returns current node value.

   *

   * @return {V}

   */

  this.get = function () { return typeof value === 'undefined' ? null : value }

  /**

   * Retrieves node at path

   *

   * @param {string[]} path

   * @return {TreeNode<V>|null}

   */

  this.traverse = function (path) {

    if (path.length === 0) {

      return this

    }

    var name = path.shift()

    var cursor = this

    while (name && cursor) {

      cursor = cursor.child(name)

      name = path.shift()

    }

    return cursor || null

  }

  /**

   * Picks branch as a list of nodes (starting from the root) that match

   * requested path the most. In the best case, branch would contain root and

   * all requested nodes, in the worst - branch would consist of root only.

   *

   * @param {string[]} path Branch path as list of child names.

   * @return {[TreeNode<V>]} Picked branch.

   */

  this.branch = function (path) {

    var branch = [self]

    var cursor = self

    var name = path.shift()

    while (name) {

      cursor = cursor.child(name)

      if (!cursor) {

        break

      }

      branch.push(cursor)

      name = path.shift()

    }

    return branch

  }

  /**

   * Puts provided value at designated path down the tree.

   *

   * @param {string[]} path Path at which value has to be set.

   * @param {V} value Value to be set.

   * @return {TreeNode<V>} Created or updated node.

   */

  this.put = function (path, value) {

    var cursor = self

    var name = path.shift()

    while (name) {

      if (!cursor.child(name)) {

        cursor.addChild(name, new TreeNode(null))

      }

      cursor = cursor.child(name)

      name = path.shift()

    }

    return cursor.set(value)

  }

  /**

   * Fetches value closest to provided path. If node contains falsey value, it

   * is skipped.

   *

   * @param {string[]} path Path to pick the branch.

   * @return {V|null} Target value or null

   */

  this.retrieve = function (path) {

    return self.branch(path).reverse().reduce(function (carrier, node) {

      return carrier || node.get()

    }, null)

  }

  /**

   * Removes node at path and returns it's value

   * @param {string[]} path

   * @return {V|undefined}

   */

  this.remove = function (path) {

    if (path.length === 0) {

      throw new Error('You can\'t remove root node')

    }

    var segment = path.pop()

    var node = this.traverse(path)

    var child = node ? node.removeChild(segment) : null

    return child ? child.get() : null

  }

}

/**

 * This class acts as a structured closure in which logger may operate.

 *

 * It encloses logger settings - currently writer and threshold - for every

 * specified package, so loggers refer to context they were associated in to

 * find their settings, and end user may configure any logger he wants without

 * knowing about those loggers (unless particular level has been associated

 * with particular logger - in that case end user has to override it directly).

 *

 * @class

 * @template T

 * @implements ILoggerContext.<T>

 *

 * @param {Level} [lvl] Root threshold, {@see Level.Info} by default

 * @param {IWritable} [writer]

 */

function Context (lvl, writer) {

  var self = this

  var writers

  var levels

  function reset (lvl, writer) {

    writers = new TreeNode(writer || Logger)

    levels = new TreeNode(level(lvl) || Level.Info)

  }

  reset(lvl, writer)

  this.reset = reset

  this.path = path

  /**

   * Retrieves level for provided logger

   *

   * @param {string} name

   * @return {Level}

   */

  this.getLevel = function (name) { return levels.retrieve(path(name)) }

  /**

   * Retrieves level for provided logger

   *

   * @deprecated

   *

   * @param {string} name

   * @return {Level}

   */

  this.getThreshold = this.getLevel

  /**

   * Sets level for specified logger

   *

   * @param {string} [name]

   * @param {Level} lvl

   */

  this.setLevel = function (name, lvl) {

    if (!lvl) {

      lvl = name

      name = null

    }

    levels.put(path(name), level(lvl))

    return self

  }

  /**

   * Sets level for specified logger

   *

   * @deprecated

   *

   * @param {string} [name]

   * @param {Level} level

   */

  this.setThreshold = this.setLevel

  /**

   * Removes and returns level at provided path

   *

   * @param {string} name

   * @return {Level|undefined}

   */

  this.removeLevel = function (name) {

    var segments = path(name)

    if (segments.length === 0) {

      throw new Error('You can\'t remove default writer')

    }

    return levels.remove(segments)

  }

  /**

   * @param {string} name

   *

   * @return {IWritable}

   */

  this.getWriter = function (name) { return writers.retrieve(path(name)) }

  /**

   * @param {string} [name] Logger name

   * @param {IWritable} writer

   */

  this.setWriter = function (name, writer) {

    if (!writer) {

      writer = name

      name = null

    }

    writers.put(path(name), writer)

    return self

  }

  /**

   * Removes and returns writer under provided path

   *

   * @throws If attempted to remove root writer

   *

   * @param {string} name

   * @return {IWritable|undefined}

   */

  this.removeWriter = function (name) {

    var segments = path(name)

    if (segments.length === 0) {

      throw new Error('You can\'t remove default writer')

    }

    return writers.remove(segments)

  }

  /**

   * @abstract

   * @function Context#create

   * @param {string} name

   * @param {Level} [threshold]

   * @param {IWritable} [writer]

   * @return {T}

   */

}

/**

 * @namespace

 */

module.exports = {

  Level: Level,

  Threshold: Threshold,

  level: level,

  threshold: threshold,

  Context: Context,

  TreeNode: TreeNode

}