mostro_core/
rating.rs

1//! Encoding of user reputation as Nostr event tags.
2//!
3//! Mostro publishes user reputation as addressable Nostr events of kind
4//! [`NOSTR_RATING_EVENT_KIND`](crate::prelude::NOSTR_RATING_EVENT_KIND). The
5//! [`Rating`] struct in this module mirrors the tag set used on those events
6//! and provides helpers to serialize to / deserialize from both JSON and
7//! `nostr_sdk::Tags`.
8
9use nostr_sdk::prelude::*;
10use serde::{Deserialize, Serialize};
11
12use crate::error::ServiceError;
13
14/// User reputation snapshot, suitable for publishing as Nostr tags.
15///
16/// The fields are the same aggregates stored on [`crate::user::User`], but
17/// typed for transport (unsigned integers for counts, `u8` for rating values).
18#[derive(Debug, Deserialize, Serialize, Clone)]
19pub struct Rating {
20    /// Total number of ratings received.
21    pub total_reviews: u64,
22    /// Weighted rating average across all reviews.
23    pub total_rating: f64,
24    /// Most recent rating, in the `MIN_RATING..=MAX_RATING` range.
25    pub last_rating: u8,
26    /// Highest rating ever received.
27    pub max_rate: u8,
28    /// Lowest rating ever received.
29    pub min_rate: u8,
30}
31
32impl Rating {
33    /// Construct a new [`Rating`] from its individual components.
34    pub fn new(
35        total_reviews: u64,
36        total_rating: f64,
37        last_rating: u8,
38        min_rate: u8,
39        max_rate: u8,
40    ) -> Self {
41        Self {
42            total_reviews,
43            total_rating,
44            last_rating,
45            min_rate,
46            max_rate,
47        }
48    }
49
50    /// Parse a [`Rating`] from its JSON representation.
51    ///
52    /// Returns [`ServiceError::MessageSerializationError`] if `json` is not a
53    /// valid serialization of this type.
54    pub fn from_json(json: &str) -> Result<Self, ServiceError> {
55        serde_json::from_str(json).map_err(|_| ServiceError::MessageSerializationError)
56    }
57
58    /// Serialize the rating to a JSON string.
59    pub fn as_json(&self) -> Result<String, ServiceError> {
60        serde_json::to_string(&self).map_err(|_| ServiceError::MessageSerializationError)
61    }
62
63    /// Encode the rating as a set of Nostr tags, ready to attach to an event.
64    ///
65    /// The returned [`Tags`] value contains one entry per numeric field plus
66    /// a `z` marker tag identifying the payload as a rating.
67    pub fn to_tags(&self) -> Result<Tags> {
68        let tags = vec![
69            Tag::custom(
70                TagKind::Custom(std::borrow::Cow::Borrowed("total_reviews")),
71                vec![self.total_reviews.to_string()],
72            ),
73            Tag::custom(
74                TagKind::Custom(std::borrow::Cow::Borrowed("total_rating")),
75                vec![self.total_rating.to_string()],
76            ),
77            Tag::custom(
78                TagKind::Custom(std::borrow::Cow::Borrowed("last_rating")),
79                vec![self.last_rating.to_string()],
80            ),
81            Tag::custom(
82                TagKind::Custom(std::borrow::Cow::Borrowed("max_rate")),
83                vec![self.max_rate.to_string()],
84            ),
85            Tag::custom(
86                TagKind::Custom(std::borrow::Cow::Borrowed("min_rate")),
87                vec![self.min_rate.to_string()],
88            ),
89            Tag::custom(
90                TagKind::Custom(std::borrow::Cow::Borrowed("z")),
91                vec!["rating".to_string()],
92            ),
93        ];
94
95        let tags = Tags::from_list(tags);
96
97        Ok(tags)
98    }
99
100    /// Rebuild a [`Rating`] from a set of Nostr tags previously produced by
101    /// [`Rating::to_tags`].
102    ///
103    /// Unknown tag keys are ignored so that the function keeps working if the
104    /// server adds new metadata fields. Returns a [`ServiceError`] if a
105    /// required key carries a non-parseable value.
106    pub fn from_tags(tags: Tags) -> Result<Self, ServiceError> {
107        let mut total_reviews = 0;
108        let mut total_rating = 0.0;
109        let mut last_rating = 0;
110        let mut max_rate = 0;
111        let mut min_rate = 0;
112
113        for tag in tags.into_iter() {
114            let t = tag.to_vec();
115            let key = t
116                .first()
117                .ok_or_else(|| ServiceError::NostrError("Missing tag key".to_string()))?;
118            let value = t
119                .get(1)
120                .ok_or_else(|| ServiceError::NostrError("Missing tag value".to_string()))?;
121            match key.as_str() {
122                "total_reviews" => {
123                    total_reviews = value
124                        .parse::<u64>()
125                        .map_err(|_| ServiceError::ParsingNumberError)?
126                }
127                "total_rating" => {
128                    total_rating = value
129                        .parse::<f64>()
130                        .map_err(|_| ServiceError::ParsingNumberError)?
131                }
132                "last_rating" => {
133                    last_rating = value
134                        .parse::<u8>()
135                        .map_err(|_| ServiceError::ParsingNumberError)?
136                }
137                "max_rate" => {
138                    max_rate = value
139                        .parse::<u8>()
140                        .map_err(|_| ServiceError::ParsingNumberError)?
141                }
142                "min_rate" => {
143                    min_rate = value
144                        .parse::<u8>()
145                        .map_err(|_| ServiceError::ParsingNumberError)?
146                }
147                _ => {}
148            }
149        }
150
151        Ok(Self {
152            total_reviews,
153            total_rating,
154            last_rating,
155            max_rate,
156            min_rate,
157        })
158    }
159}
mostro_core/rating.rs

mostro_core/
rating.rs
