ocpi_tariffs/
timezone.rs

1//! Parse an IANA Timezone from JSON or find a timezone in a CDR.
2
3#[cfg(test)]
4pub mod test;
5
6#[cfg(test)]
7mod test_find_or_infer;
8
9use std::{borrow::Cow, fmt};
10
11use chrono_tz::Tz;
12use tracing::{debug, instrument};
13
14use crate::{
15    cdr, country, from_warning_all, json,
16    schema::{self, FromSchema as _, HasElement as _},
17    warning::{self, GatherWarnings as _, WithElement as _},
18    IntoCaveat as _, Verdict,
19};
20
21/// The warnings possible when parsing or linting an IANA timezone.
22#[derive(Debug)]
23pub enum Warning {
24    /// A timezone can't be inferred from the `location`'s `country`.
25    CantInferTimezoneFromCountry(&'static str),
26
27    /// Neither the timezone or country field require char escape codes.
28    ContainsEscapeCodes,
29
30    /// The CDR location is not a valid `ISO 3166-1` alpha-3 code.
31    Country(country::Warning),
32
33    /// The field at the path could not be decoded.
34    Decode(json::decode::Warning),
35
36    /// The CDR location did not contain a valid IANA time-zone.
37    ///
38    /// See: <https://www.iana.org/time-zones>.
39    InvalidTimezone,
40
41    /// The `location.country` field should be an alpha-3 country code.
42    ///
43    /// The alpha-2 code can be converted into an alpha-3 but the caller should be warned.
44    LocationCountryShouldBeAlpha3,
45
46    /// The CDR's `location` has no `country` element and so the timezone can't be inferred.
47    NoLocationCountry,
48
49    /// The CDR has no `location` element and so the timezone can't be found or inferred.
50    NoLocation,
51
52    /// A v221 CDR is given but it contains a `location` field instead of a `cdr_location` as defined in the spec.
53    V221CdrHasLocationField,
54}
55
56from_warning_all!(
57    country::Warning => Warning::Country,
58    json::decode::Warning => Warning::Decode
59);
60
61impl fmt::Display for Warning {
62    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
63        match self {
64            Self::CantInferTimezoneFromCountry(country_code) => write!(f, "Unable to infer timezone from the `location`'s `country`: `{country_code}`"),
65            Self::ContainsEscapeCodes => f.write_str("The CDR location contains needless escape codes."),
66            Self::Country(kind) => fmt::Display::fmt(kind, f),
67            Self::Decode(warning) => fmt::Display::fmt(warning, f),
68            Self::InvalidTimezone => f.write_str("The CDR location did not contain a valid IANA time-zone."),
69            Self::LocationCountryShouldBeAlpha3 => f.write_str("The `location.country` field should be an alpha-3 country code."),
70            Self::NoLocationCountry => {
71                f.write_str("The CDR's `location` has no `country` element and so the timezone can't be inferred.")
72            },
73            Self::NoLocation => {
74                f.write_str("The CDR has no `location` element and so the timezone can't be found or inferred.")                   
75            }
76            Self::V221CdrHasLocationField => f.write_str("the v2.2.1 CDR contains a `location` field but the v2.2.1 spec defines a `cdr_location` field."),
77
78        }
79    }
80}
81
82impl crate::Warning for Warning {
83    fn id(&self) -> warning::Id {
84        match self {
85            Self::CantInferTimezoneFromCountry(_) => {
86                warning::Id::from_static("cant_infer_timezone_from_country")
87            }
88            Self::ContainsEscapeCodes => warning::Id::from_static("contains_escape_codes"),
89            Self::Decode(warning) => warning.id(),
90            Self::Country(warning) => warning.id(),
91            Self::InvalidTimezone => warning::Id::from_static("invalid_timezone"),
92            Self::LocationCountryShouldBeAlpha3 => {
93                warning::Id::from_static("location_country_should_be_alpha3")
94            }
95            Self::NoLocationCountry => warning::Id::from_static("no_location_country"),
96            Self::NoLocation => warning::Id::from_static("no_location"),
97            Self::V221CdrHasLocationField => {
98                warning::Id::from_static("v221_cdr_has_location_field")
99            }
100        }
101    }
102}
103
104/// The source of the timezone.
105#[derive(Copy, Clone, Debug)]
106pub enum Source {
107    /// The timezone was found in the `location` element.
108    Found(Tz),
109
110    /// The timezone is inferred from the `location`'s `country`.
111    Inferred(Tz),
112}
113
114impl Source {
115    /// Return the timezone and disregard where it came from.
116    pub fn into_timezone(self) -> Tz {
117        match self {
118            Source::Found(tz) | Source::Inferred(tz) => tz,
119        }
120    }
121}
122
123/// Try to find or infer the timezone from the `CDR` JSON.
124///
125/// Return `Some` if the timezone can be found or inferred.
126/// Return `None` if the timezone is not found and can't be inferred.
127///
128/// Finding a timezone is an infallible operation. If invalid data is found a `None` is returned
129/// with an appropriate warning.
130///
131/// If the `CDR` contains a `time_zone` in the location object then that is simply returned.
132/// Only pre-`v2.2.1` CDR's have a `time_zone` field in the `Location` object.
133///
134/// Inferring the timezone only works for `CDR`s from European countries.
135///
136pub fn find_or_infer(cdr: &cdr::Versioned<'_>) -> Verdict<Source, Warning> {
137    let mut warnings = warning::Set::new();
138
139    let location = location(cdr)?.gather_warnings_into(&mut warnings);
140
141    debug!("Searching for time-zone in CDR");
142
143    // The `location::time_zone` field is optional in v211 and not part of the v221 spec,
144    // where the schema reports it as a `NonSpecField` and reads it anyway.
145    //
146    // See: <https://github.com/ocpi/ocpi/blob/release-2.2.1-bugfixes/mod_cdrs.asciidoc#mod_cdrs_cdr_location_class>
147    // See: <https://github.com/ocpi/ocpi/blob/release-2.1.1-bugfixes/mod_locations.md#31-location-object>
148    let tz = match &location.time_zone {
149        schema::Integrity::Ok(Some(tz)) => try_parse_location_timezone(tz),
150        // An absent, `null`, or wrongly typed `time_zone` is located by the schema walk.
151        // There may still be a country to infer from, so the search continues.
152        schema::Integrity::Ok(None) | schema::Integrity::Missing(_) | schema::Integrity::Err(_) => {
153            return infer_from_country(&location, warnings)
154        }
155    };
156
157    // A `time_zone` that is present but unusable is not fatal. The failure is deescalated to
158    // a warning and the country is tried instead.
159    let tz = match tz {
160        Ok(tz) => Some(tz.gather_warnings_into(&mut warnings)),
161        Err(err_set) => {
162            warnings.deescalate_error(err_set);
163            None
164        }
165    };
166
167    let Some(tz) = tz else {
168        return infer_from_country(&location, warnings);
169    };
170
171    Ok(Source::Found(tz).into_caveat(warnings))
172}
173
174/// The two fields a timezone can be found or inferred from, borrowed out of whichever
175/// version's location object carries them.
176struct Location<'a, 'buf> {
177    time_zone: &'a schema::Integrity<Option<schema::Str<'buf>>>,
178    country: &'a schema::Integrity<schema::Str<'buf>>,
179}
180
181/// Borrow the location fields out of the CDR's schema IR.
182///
183/// Describes the location that the charge-session took place at. The v211 CDR has a
184/// `location` field while the v221 CDR has a `cdr_location` field. A v221 CDR that still
185/// uses the old name is read from it anyway, because that is the only place its timezone
186/// can be.
187///
188/// * See: <https://github.com/ocpi/ocpi/blob/release-2.2.1-bugfixes/mod_cdrs.asciidoc#131-cdr-object>
189/// * See: <https://github.com/ocpi/ocpi/blob/release-2.1.1-bugfixes/mod_cdrs.md#3-object-description>
190fn location<'a, 'buf>(cdr: &'a cdr::Versioned<'buf>) -> Verdict<Location<'a, 'buf>, Warning> {
191    let mut warnings = warning::Set::new();
192
193    let (time_zone, country) = match cdr.schema() {
194        cdr::Version::V211(ir) => match &ir.location {
195            schema::Integrity::Ok(location) => (&location.time_zone, &location.country),
196            schema::Integrity::Missing(elem) | schema::Integrity::Err(elem) => {
197                return warnings.bail_at(elem.clone(), Warning::NoLocation)
198            }
199        },
200        // A `location` object in a v221 CDR is the v211 field name. It is preferred over
201        // `cdr_location`, because a CDR that carries it put the timezone there.
202        cdr::Version::V221(ir) => match (&ir.location, &ir.cdr_location) {
203            (schema::Integrity::Ok(location), _) => {
204                // Anchored at the document rather than at the field: the schema walk's
205                // `NonSpecField` warning already locates the field itself.
206                warnings.insert(cdr.as_element(), Warning::V221CdrHasLocationField);
207
208                (&location.time_zone, &location.country)
209            }
210            (_, schema::Integrity::Ok(location)) => (&location.time_zone, &location.country),
211            (_, schema::Integrity::Missing(elem) | schema::Integrity::Err(elem)) => {
212                return warnings.bail_at(elem.clone(), Warning::NoLocation)
213            }
214        },
215    };
216
217    Ok(Location { time_zone, country }.into_caveat(warnings))
218}
219
220/// Infer the timezone from the location's `country`, having found no usable `time_zone`.
221fn infer_from_country(
222    location: &Location<'_, '_>,
223    mut warnings: warning::Set<Warning>,
224) -> Verdict<Source, Warning> {
225    debug!("No time-zone found in CDR; trying to infer time-zone from country");
226
227    // `ISO 3166-1 alpha-3` code for the country of this location. The field is required in
228    // both versions.
229    //
230    // See: <https://github.com/ocpi/ocpi/blob/release-2.2.1-bugfixes/mod_cdrs.asciidoc#mod_cdrs_cdr_location_class>
231    // See: <https://github.com/ocpi/ocpi/blob/release-2.1.1-bugfixes/mod_locations.md#31-location-object>
232    let country = match &location.country {
233        schema::Integrity::Ok(country) => country,
234        schema::Integrity::Missing(elem) | schema::Integrity::Err(elem) => {
235            return warnings.bail_at(elem.clone(), Warning::NoLocationCountry)
236        }
237    };
238
239    let tz = infer_timezone_from_location_country(country).gather_warnings_into(&mut warnings)?;
240
241    Ok(Source::Inferred(tz).into_caveat(warnings))
242}
243
244/// Try to parse the location's `time_zone` into a `Tz`.
245fn try_parse_location_timezone(tz: &schema::Str<'_>) -> Verdict<Tz, Warning> {
246    let elem = tz.element();
247    let mut warnings = warning::Set::new();
248
249    // The schema proved the value is a JSON string but keeps it raw, so it is decoded here.
250    let raw = tz.value();
251    let tz = raw
252        .decode_escapes()
253        .with_element(elem)
254        .gather_warnings_into(&mut warnings);
255
256    if matches!(tz, Cow::Owned(_)) {
257        warnings.insert(elem, Warning::ContainsEscapeCodes);
258    }
259
260    debug!(%tz, "Escaped time-zone found in CDR");
261
262    let Ok(tz) = tz.parse::<Tz>() else {
263        return warnings.bail(elem, Warning::InvalidTimezone);
264    };
265
266    Ok(tz.into_caveat(warnings))
267}
268
269/// Try to infer a timezone from the location's `country` field.
270#[instrument(skip_all)]
271fn infer_timezone_from_location_country(country: &schema::Str<'_>) -> Verdict<Tz, Warning> {
272    let elem = country.element();
273    let mut warnings = warning::Set::new();
274    let code_set = country::CodeSet::from_schema(country)?.gather_warnings_into(&mut warnings);
275
276    // The `location.country` field should be an alpha-3 country code.
277    //
278    // The alpha-2 code can be converted into an alpha-3 but the caller should be warned.
279    let country_code = match code_set {
280        country::CodeSet::Alpha2(code) => {
281            warnings.insert(elem, Warning::LocationCountryShouldBeAlpha3);
282            code
283        }
284        country::CodeSet::Alpha3(code) => code,
285    };
286    let Some(tz) = try_detect_timezone(country_code) else {
287        return warnings.bail(
288            elem,
289            Warning::CantInferTimezoneFromCountry(country_code.into_alpha_2_str()),
290        );
291    };
292
293    Ok(tz.into_caveat(warnings))
294}
295
296/// Mapping of European countries to time-zones with geographical naming
297///
298/// This is only possible for countries with a single time-zone and only for countries as they
299/// currently exist (2024). It's a best effort approach to determine a time-zone from just an
300/// ALPHA-3 `ISO 3166-1` country code.
301///
302/// In small edge cases (e.g. Gibraltar) this detection might generate the wrong time-zone.
303#[instrument]
304#[expect(
305    clippy::wildcard_enum_match_arm,
306    reason = "There are many `Code` variants that do not map to a timezone."
307)]
308fn try_detect_timezone(country_code: country::Code) -> Option<Tz> {
309    let tz = match country_code {
310        country::Code::Ad => Tz::Europe__Andorra,
311        country::Code::Al => Tz::Europe__Tirane,
312        country::Code::At => Tz::Europe__Vienna,
313        country::Code::Ba => Tz::Europe__Sarajevo,
314        country::Code::Be => Tz::Europe__Brussels,
315        country::Code::Bg => Tz::Europe__Sofia,
316        country::Code::By => Tz::Europe__Minsk,
317        country::Code::Ch => Tz::Europe__Zurich,
318        country::Code::Cy => Tz::Europe__Nicosia,
319        country::Code::Cz => Tz::Europe__Prague,
320        country::Code::De => Tz::Europe__Berlin,
321        country::Code::Dk => Tz::Europe__Copenhagen,
322        country::Code::Ee => Tz::Europe__Tallinn,
323        country::Code::Es => Tz::Europe__Madrid,
324        country::Code::Fi => Tz::Europe__Helsinki,
325        country::Code::Fr => Tz::Europe__Paris,
326        country::Code::Gb => Tz::Europe__London,
327        country::Code::Gr => Tz::Europe__Athens,
328        country::Code::Hr => Tz::Europe__Zagreb,
329        country::Code::Hu => Tz::Europe__Budapest,
330        country::Code::Ie => Tz::Europe__Dublin,
331        country::Code::Is => Tz::Iceland,
332        country::Code::It => Tz::Europe__Rome,
333        country::Code::Li => Tz::Europe__Vaduz,
334        country::Code::Lt => Tz::Europe__Vilnius,
335        country::Code::Lu => Tz::Europe__Luxembourg,
336        country::Code::Lv => Tz::Europe__Riga,
337        country::Code::Mc => Tz::Europe__Monaco,
338        country::Code::Md => Tz::Europe__Chisinau,
339        country::Code::Me => Tz::Europe__Podgorica,
340        country::Code::Mk => Tz::Europe__Skopje,
341        country::Code::Mt => Tz::Europe__Malta,
342        country::Code::Nl => Tz::Europe__Amsterdam,
343        country::Code::No => Tz::Europe__Oslo,
344        country::Code::Pl => Tz::Europe__Warsaw,
345        country::Code::Pt => Tz::Europe__Lisbon,
346        country::Code::Ro => Tz::Europe__Bucharest,
347        country::Code::Rs => Tz::Europe__Belgrade,
348        country::Code::Ru => Tz::Europe__Moscow,
349        country::Code::Se => Tz::Europe__Stockholm,
350        country::Code::Si => Tz::Europe__Ljubljana,
351        country::Code::Sk => Tz::Europe__Bratislava,
352        country::Code::Sm => Tz::Europe__San_Marino,
353        country::Code::Tr => Tz::Turkey,
354        country::Code::Ua => Tz::Europe__Kiev,
355        _ => return None,
356    };
357
358    debug!(%tz, "time-zone detected");
359
360    Some(tz)
361}
ocpi_tariffs/timezone.rs

ocpi_tariffs/
timezone.rs
