« get me outta code hell

playlist-utils.js - mtui - Music Text User Interface - user-friendly command line music player
about summary refs log tree commit diff
path: root/playlist-utils.js
blob: 92e62b159f63faa27c831ecbcd1f537521ca964a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
'use strict'

const path = require('path')
const fs = require('fs')

const { promisify } = require('util')
const unlink = promisify(fs.unlink)

const parentSymbol = Symbol('Parent group')

function updatePlaylistFormat(playlist) {
  const defaultPlaylist = {
    options: [],
    items: []
  }

  let playlistObj = {}

  // Playlists can be in two formats...
  if (Array.isArray(playlist)) {
    // ..the first, a simple array of tracks and groups;

    playlistObj = {items: playlist}
  } else {
    // ..or an object including metadata and configuration as well as the
    // array described in the first.

    playlistObj = playlist

    // The 'tracks' property was used for a while, but it doesn't really make
    // sense, since we also store groups in the 'tracks' property. So it was
    // renamed to 'items'.
    if ('tracks' in playlistObj) {
      playlistObj.items = playlistObj.tracks
      delete playlistObj.tracks
    }
  }

  const fullPlaylistObj = Object.assign(defaultPlaylist, playlistObj)

  return updateGroupFormat(fullPlaylistObj)
}

function updateGroupFormat(group) {
  const defaultGroup = {
    name: '',
    items: []
  }

  let groupObj = {}

  if (Array.isArray(group[1])) {
    groupObj = {name: group[0], items: group[1]}
  } else {
    groupObj = group
  }

  groupObj = Object.assign(defaultGroup, groupObj)

  groupObj.items = groupObj.items.map(item => {
    // Check if it's a group; if not, it's probably a track.
    if (typeof item[1] === 'array' || item.items) {
      item = updateGroupFormat(item)
    } else {
      item = updateTrackFormat(item)

      // TODO: Should this also apply to groups? Is recursion good? Probably
      // not!
      //
      // TODO: How should saving/serializing handle this? For now it just saves
      // the result, after applying. (I.e., "apply": {"foo": "baz"} will save
      // child tracks with {"foo": "baz"}.)
      if (groupObj.apply) {
        Object.assign(item, groupObj.apply)
      }
    }

    item[parentSymbol] = groupObj

    return item
  })

  return groupObj
}

function updateTrackFormat(track) {
  const defaultTrack = {
    name: '',
    downloaderArg: ''
  }

  let trackObj = {}

  if (Array.isArray(track)) {
    if (track.length === 2) {
      trackObj = {name: track[0], downloaderArg: track[1]}
    } else {
      throw new Error("Unexpected non-length 2 array-format track")
    }
  } else {
    trackObj = track
  }

  return Object.assign(defaultTrack, trackObj)
}

function filterTracks(grouplike, handleTrack) {
  // Recursively filters every track in the passed grouplike. The track-handler
  // function passed should either return true (to keep a track) or false (to
  // remove the track). After tracks are filtered, groups which contain no
  // items are removed.

  if (typeof handleTrack !== 'function') {
    throw new Error("Missing track handler function")
  }

  return Object.assign({}, grouplike, {
    items: grouplike.items.filter(item => {
      if (isTrack(item)) {
        return handleTrack(item)
      } else {
        return true
      }
    }).map(item => {
      if (isGroup(item)) {
        return filterTracks(item, handleTrack)
      } else {
        return item
      }
    }).filter(item => {
      if (isGroup(item)) {
        return item.items.length > 0
      } else {
        return true
      }
    })
  })
}

function flattenGrouplike(grouplike) {
  // Flattens a group-like, taking all of the non-group items (tracks) at all
  // levels in the group tree and returns them as a new group containing those
  // tracks.

  return {
    items: grouplike.items.map(item => {
      if (isGroup(item)) {
        return flattenGrouplike(item).items
      } else {
        return [item]
      }
    }).reduce((a, b) => a.concat(b), [])
  }
}

function collectGrouplikeChildren(grouplike, filter = null) {
  // Collects all descendants of a grouplike into a single flat array.
  // Can be passed a filter function, which will decide whether or not to add
  // an item to the return array. However, note that all descendants will be
  // checked against this function; a group will be descended through even if
  // the filter function checks false against it.
  // Returns an array, not a grouplike.

  const items = []

  for (const item of grouplike.items) {
    if (filter === null || filter(item) === true) {
      items.push(item)
    }

    if (isGroup(item)) {
      items.push(...collectGrouplikeChildren(item, filter))
    }
  }

  return items
}

function partiallyFlattenGrouplike(grouplike, resultDepth) {
  // Flattens a grouplike so that it is never more than a given number of
  // groups deep, INCLUDING the "top" group -- e.g. a resultDepth of 2
  // means that there can be one level of groups remaining in the resulting
  // grouplike, plus the top group.

  if (resultDepth <= 1) {
    return flattenGrouplike(grouplike)
  }

  const items = grouplike.items.map(item => {
    if (isGroup(item)) {
      return {items: partiallyFlattenGrouplike(item, resultDepth - 1).items}
    } else {
      return item
    }
  })

  return {items}
}

function collapseGrouplike(grouplike) {
  // Similar to partiallyFlattenGrouplike, but doesn't discard the individual
  // ordering of tracks; rather, it just collapses them all to one level.

  // Gather the groups. The result is an array of groups.
  // Collapsing [Kar/Baz/Foo, Kar/Baz/Lar] results in [Foo, Lar].
  // Aha! Just collect the top levels.
  // Only trouble is what to do with groups that contain both groups and
  // tracks. Maybe give them their own separate group (e.g. Baz).

  const subgroups = grouplike.items.filter(x => isGroup(x))
  const nonGroups = grouplike.items.filter(x => !isGroup(x))

  // Get each group's own collapsed groups, and store them all in one big
  // array.
  const ret = subgroups.map(group => {
    return collapseGrouplike(group).items
  }).reduce((a, b) => a.concat(b), [])

  if (nonGroups.length) {
    ret.unshift({name: grouplike.name, items: nonGroups})
  }

  return {items: ret}
}

function filterGrouplikeByProperty(grouplike, property, value) {
  // Returns a copy of the original grouplike, only keeping tracks with the
  // given property-value pair. (If the track's value for the given property
  // is an array, this will check if that array includes the given value.)

  return Object.assign({}, grouplike, {
    items: grouplike.items.map(item => {
      if (isGroup(item)) {
        const newGroup = filterGrouplikeByProperty(item, property, value)
        if (newGroup.items.length) {
          return newGroup
        } else {
          return false
        }
      } else if (isTrack(item)) {
        const itemValue = item[property]
        if (Array.isArray(itemValue) && itemValue.includes(value)) {
          return item
        } else if (item[property] === value) {
          return item
        } else {
          return false
        }
      } else {
        return item
      }
    }).filter(item => item !== false)
  })
}

function filterPlaylistByPathString(playlist, pathString) {
  // Calls filterGroupContentsByPath, taking an unparsed path string.

  return filterGrouplikeByPath(playlist, parsePathString(pathString))
}

function filterGrouplikeByPath(grouplike, pathParts) {
  // Finds a group by following the given group path and returns it. If the
  // function encounters an item in the group path that is not found, it logs
  // a warning message and returns the group found up to that point. If the
  // pathParts array is empty, it returns the group given to the function.

  if (pathParts.length === 0) {
    return grouplike
  }

  let firstPart = pathParts[0]
  let possibleMatches

  if (firstPart.startsWith('?')) {
    possibleMatches = collectGrouplikeChildren(grouplike)
    firstPart = firstPart.slice(1)
  } else {
    possibleMatches = grouplike.items
  }

  const titleMatch = (group, caseInsensitive = false) => {
    let a = group.name
    let b = firstPart

    if (caseInsensitive) {
      a = a.toLowerCase()
      b = b.toLowerCase()
    }

    return a === b || a === b + '/'
  }

  let match = possibleMatches.find(g => titleMatch(g, false))

  if (!match) {
    match = possibleMatches.find(g => titleMatch(g, true))
  }

  if (match) {
    if (pathParts.length > 1) {
      const rest = pathParts.slice(1)
      return filterGrouplikeByPath(match, rest)
    } else {
      return match
    }
  } else {
    console.warn(`Not found: "${firstPart}"`)
    return null
  }
}

function removeGroupByPathString(playlist, pathString) {
  // Calls removeGroupByPath, taking a path string, rather than a parsed path.

  return removeGroupByPath(playlist, parsePathString(pathString))
}

function removeGroupByPath(playlist, pathParts) {
  // Removes the group at the given path from the given playlist.

  const groupToRemove = filterGrouplikeByPath(playlist, pathParts)

  if (groupToRemove === null) {
    return
  }

  if (playlist === groupToRemove) {
    console.error(
      'You can\'t remove the playlist from itself! Instead, try --clear' +
      ' (shorthand -c).'
    )

    return
  }

  if (!(parentSymbol in groupToRemove)) {
    console.error(
      `Group ${pathParts.join('/')} doesn't have a parent, so we can't` +
      ' remove it from the playlist.'
    )

    return
  }

  const parent = groupToRemove[parentSymbol]

  const index = parent.items.indexOf(groupToRemove)

  if (index >= 0) {
    parent.items.splice(index, 1)
  } else {
    console.error(
      `Group ${pathParts.join('/')} doesn't exist, so we can't explicitly ` +
      'ignore it.'
    )
  }
}

function getPlaylistTreeString(playlist, showTracks = false) {
  function recursive(group) {
    const groups = group.items.filter(x => isGroup(x))
    const nonGroups = group.items.filter(x => !isGroup(x))

    const childrenString = groups.map(group => {
      const name = group.name
      const groupString = recursive(group)

      if (groupString) {
        const indented = groupString.split('\n').map(l => '| ' + l).join('\n')
        return '\n' + name + '\n' + indented
      } else {
        return name
      }
    }).join('\n')

    let tracksString = ''
    if (showTracks) {
      tracksString = nonGroups.map(g => g.name).join('\n')
    }

    if (tracksString && childrenString) {
      return tracksString + '\n' + childrenString
    } else if (childrenString) {
      return childrenString
    } else if (tracksString) {
      return tracksString
    } else {
      return ''
    }
  }

  return recursive(playlist)
}

function getItemPath(item) {
  if (item[parentSymbol]) {
    return [...getItemPath(item[parentSymbol]), item]
  } else {
    return [item]
  }
}

function getItemPathString(item) {
  // Gets the playlist path of an item by following its parent chain.
  //
  // Returns a string in format Foo/Bar/Baz, where Foo and Bar are group
  // names, and Baz is the name of the item.
  //
  // Unnamed parents are given the name '(Unnamed)'.
  // Always ignores the root (top) group.
  //
  // Requires that the given item be from a playlist processed by
  // updateGroupFormat.

  // Check if the parent is not the top level group.
  // The top-level group is included in the return path as '/'.
  if (item[parentSymbol]) {
    const displayName = item.name || '(Unnamed)'

    if (item[parentSymbol][parentSymbol]) {
      return getItemPathString(item[parentSymbol]) + '/' + displayName
    } else {
      return '/' + displayName
    }
  } else {
    return '/'
  }
}

function parsePathString(pathString) {
  const pathParts = pathString.split('/').filter(item => item.length)
  return pathParts
}

function getTrackIndexInParent(track) {
  if (parentSymbol in track === false) {
    throw new Error(
      'getTrackIndexInParent called with a track that has no parent!'
    )
  }

  const parent = track[parentSymbol]

  let i = 0, foundTrack = false;
  for (; i < parent.items.length; i++) {
    if (isSameTrack(track, parent.items[i])) {
      foundTrack = true
      break
    }
  }

  if (foundTrack === false) {
    return [-1, parent.items.length]
  } else {
    return [i, parent.items.length]
  }
}

function isGroup(obj) {
  return !!(obj && obj.items)
}

function isTrack(obj) {
  return !!(obj && obj.downloaderArg)
}

module.exports = {
  parentSymbol,
  updatePlaylistFormat, updateGroupFormat, updateTrackFormat,
  filterTracks,
  flattenGrouplike,
  partiallyFlattenGrouplike, collapseGrouplike,
  filterGrouplikeByProperty,
  filterPlaylistByPathString, filterGrouplikeByPath,
  removeGroupByPathString, removeGroupByPath,
  getPlaylistTreeString,
  getItemPath, getItemPathString,
  parsePathString,
  getTrackIndexInParent,
  isGroup, isTrack
}