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
|
/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include "source.hpp"
#include <algorithm>
#include <functional>
#include <memory>
#include <set>
#include <variant>
#include "esp_log.h"
#include "bloom_filter.hpp"
#include "database.hpp"
#include "komihash.h"
#include "random.hpp"
#include "track.hpp"
namespace playlist {
IndexRecordSource::IndexRecordSource(
std::weak_ptr<database::Database> db,
std::shared_ptr<database::Result<database::IndexRecord>> initial)
: db_(db),
initial_page_(initial),
initial_item_(0),
current_page_(initial_page_),
current_item_(initial_item_) {}
IndexRecordSource::IndexRecordSource(
std::weak_ptr<database::Database> db,
std::shared_ptr<database::Result<database::IndexRecord>> initial,
std::size_t initial_index,
std::shared_ptr<database::Result<database::IndexRecord>> current,
std::size_t current_index)
: db_(db),
initial_page_(initial),
initial_item_(initial_index),
current_page_(current),
current_item_(current_index) {}
auto IndexRecordSource::Current() -> std::optional<database::TrackId> {
if (current_page_->values().size() <= current_item_) {
return {};
}
if (current_page_ == initial_page_ && current_item_ < initial_item_) {
return {};
}
return current_page_->values().at(current_item_)->track();
}
auto IndexRecordSource::Advance() -> std::optional<database::TrackId> {
current_item_++;
if (current_item_ >= current_page_->values().size()) {
auto next_page = current_page_->next_page();
if (!next_page) {
current_item_--;
return {};
}
auto db = db_.lock();
if (!db) {
return {};
}
current_page_.reset(db->GetPage(&*next_page).get());
current_item_ = 0;
}
return Current();
}
auto IndexRecordSource::Previous() -> std::optional<database::TrackId> {
if (current_page_ == initial_page_ && current_item_ <= initial_item_) {
return {};
}
current_item_--;
if (current_item_ < 0) {
auto prev_page = current_page_->prev_page();
if (!prev_page) {
return {};
}
auto db = db_.lock();
if (!db) {
return {};
}
current_page_.reset(db->GetPage(&*prev_page).get());
current_item_ = current_page_->values().size() - 1;
}
return Current();
}
auto IndexRecordSource::Peek(std::size_t n, std::vector<database::TrackId>* out)
-> std::size_t {
if (current_page_->values().size() <= current_item_) {
return {};
}
auto db = db_.lock();
if (!db) {
return 0;
}
std::size_t items_added = 0;
std::shared_ptr<database::Result<database::IndexRecord>> working_page =
current_page_;
std::size_t working_item = current_item_ + 1;
while (n > 0) {
if (working_item >= working_page->values().size()) {
auto next_page = current_page_->next_page();
if (!next_page) {
break;
}
// TODO(jacqueline): It would probably be a good idea to hold onto these
// peeked pages, to avoid needing to look them up again later.
working_page.reset(db->GetPage(&*next_page).get());
working_item = 0;
}
out->push_back(working_page->values().at(working_item)->track().value());
n--;
items_added++;
working_item++;
}
return items_added;
}
auto IndexRecordSource::Reset() -> void {
current_page_ = initial_page_;
current_item_ = initial_item_;
}
} // namespace playlist
|
