1. 1
2. 2
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12
13. 13
14. 14
15. 15
16. 16
17. 17
18. 18
19. 19
20. 20
21. 21
22. 22
23. 23
24. 24
25. 25
26. 26
27. 27
28. 28
29. 29
30. 30
31. 31
32. 32
33. 33
34. 34
35. 35
36. 36
37. 37
38. 38
39. 39
40. 40
41. 41
42. 42
43. 43
44. 44
45. 45
46. 46
47. 47
48. 48
49. 49
50. 50
51. 51
52. 52
53. 53
54. 54
55. 55
56. 56
57. 57
58. 58
59. 59
60. 60
61. 61
62. 62
63. 63
64. 64
65. 65
66. 66
67. 67
68. 68
69. 69
70. 70
71. 71
72. 72
73. 73
74. 74
75. 75
76. 76
77. 77
78. 78
79. 79
80. 80
81. 81
82. 82
83. 83
84. 84
85. 85
86. 86
87. 87
88. 88
89. 89
90. 90
91. 91
92. 92
93. 93
94. 94
95. 95
96. 96
97. 97
98. 98
99. 99
100. 100
101. 101
102. 102
103. 103
104. 104
105. 105
106. 106
107. 107
108. 108
109. 109
110. 110
111. 111
112. 112
113. 113
114. 114
115. 115
116. 116
117. 117

package activitypub

// Item struct
type Item = ObjectOrLink

const (
	EmptyIRI IRI = ""
	NilIRI   IRI = "-"

	EmptyID = EmptyIRI
	NilID   = NilIRI
)

// ItemsEqual checks if it and with Items are equal
func ItemsEqual(it, with Item) bool {
	if IsNil(it) || IsNil(with) {
		return with == it
	}
	result := true
	if it.IsCollection() {
		if it.GetType() == CollectionOfItems {
			OnItemCollection(it, func(c *ItemCollection) error {
				result = c.Equals(with)
				return nil
			})
		}
		if it.GetType() == CollectionType {
			OnCollection(it, func(c *Collection) error {
				result = c.Equals(with)
				return nil
			})
		}
		if it.GetType() == OrderedCollectionType {
			OnOrderedCollection(it, func(c *OrderedCollection) error {
				result = c.Equals(with)
				return nil
			})
		}
		if it.GetType() == CollectionPageType {
			OnCollectionPage(it, func(c *CollectionPage) error {
				result = c.Equals(with)
				return nil
			})
		}
		if it.GetType() == OrderedCollectionPageType {
			OnOrderedCollectionPage(it, func(c *OrderedCollectionPage) error {
				result = c.Equals(with)
				return nil
			})
		}
	}
	if it.IsObject() {
		if ActivityTypes.Contains(with.GetType()) {
			OnActivity(it, func(i*Activity) error {
				result = i.Equals(with)
				return nil
			})
		} else if ActorTypes.Contains(with.GetType()) {
			OnActor(it, func(i *Actor) error {
				result = i.Equals(with)
				return nil
			})
		} else {
			OnObject(it, func(i *Object) error {
				result = i.Equals(with)
				return nil
			})
		}
	}
	if with.IsLink() {
		result = with.GetLink().Equals(it.GetLink(), false)
	}
	return result
}

// IsItemCollection returns if the current Item interface holds a Collection
func IsItemCollection(it Item) bool {
	_, ok := it.(ItemCollection)
	_, okP := it.(*ItemCollection)
	return ok || okP
}

// IsIRI returns if the current Item interface holds an IRI
func IsIRI(it Item) bool {
	_, ok := it.(IRI)
	return ok
}

// IsObject returns if the current Item interface holds an IRI
func IsObject(it Item) bool {
	ok := it.IsObject()
	if it.IsLink() {
		_, ok = it.(IRI)
		return !ok
	}
	return ok
}

// IsNil checks if the object matching an ObjectOrLink interface is nil
func IsNil(it Item) bool {
	if it == nil {
		return true
	}
	// This is the default if the argument can't be casted to Object, as is the case for an ItemCollection
	isNil := false
	if IsItemCollection(it) {
		OnItemCollection(it, func(c *ItemCollection) error {
			isNil = c == nil
			return nil
		})
	} else {
		OnObject(it, func(o *Object) error {
			isNil = o == nil
			return nil
		})
	}
	return isNil
}