ferrobridge-term 0.1.129

// SPDX-FileCopyrightText: Cadasto B.V.
// SPDX-License-Identifier: BUSL-1.1

//! What each operation answers, as one enum per operation.
//!
//! A negative answer the operation states in its own `out` parameters is a
//! variant here; an answer the server refused is a
//! [`crate::error::Error`] carrying the upstream status and body. Nothing is
//! ever flattened into an empty value.

use crate::concept::{Concept, Designation, Match, Property};
use crate::error::{Outcome, UpstreamError};

/// What `CodeSystem/$lookup` answered.
#[derive(Debug)]
#[non_exhaustive]
pub enum LookupOutcome {
    /// The server knows the code and returned its details.
    Found {
        /// `name`, the code system's name. The operation declares it `1..1`.
        name: String,
        /// `version`, the code system version the answer is from.
        version: Option<String>,
        /// `display`, the preferred display. The operation declares it `1..1`.
        display: String,
        /// Every `designation` the server returned.
        designations: Vec<Designation>,
        /// Every `property` the server returned.
        properties: Vec<Property>,
    },
    /// The server does not know the code, or does not know its system.
    NotFound {
        /// The upstream status and body, with any `tx-issue-type` coding.
        outcome: Box<UpstreamError>,
    },
}

/// What `ConceptMap/$translate` answered.
#[derive(Debug)]
#[non_exhaustive]
pub enum TranslateOutcome {
    /// `result` was `true`: the server found at least one match.
    ///
    /// Every match is carried with its equivalence, including the ones that
    /// are not translations, because the specification asks the caller to
    /// check `match.equivalence` for each one.
    Translated {
        /// The matches, in the order the server sent them.
        matches: Vec<Match>,
        /// `message`, when the server sent one.
        message: Option<String>,
    },
    /// `result` was `false`: the server found no acceptable match.
    NoMatch {
        /// `message`, the server's error detail for a false `result`.
        message: Option<String>,
    },
}

impl TranslateOutcome {
    /// Returns every match that is a translation.
    ///
    /// Only `equivalent` and `equal` matches are yielded
    /// (<https://hl7.org/fhir/R4/valueset-concept-map-equivalence.html>), so a
    /// `wider`, `narrower` or `inexact` match never reaches a target system as
    /// a translation.
    pub fn accepted(&self) -> impl Iterator<Item = &Match> {
        let matches = match self {
            Self::Translated { matches, .. } => matches.as_slice(),
            Self::NoMatch { .. } => &[],
        };
        matches.iter().filter(|found| found.accepted())
    }
}

/// What `ValueSet/$validate-code` answered.
#[derive(Debug)]
#[non_exhaustive]
pub enum ValidateOutcome {
    /// `result` was `true`: the code is a member of the value set.
    Valid {
        /// `display`, "a valid display for the concept if the system wishes to
        /// display this to a user".
        display: Option<String>,
        /// `message`, which carries hints and warnings beside a true `result`.
        message: Option<String>,
    },
    /// `result` was `false`: the code is not a member of the value set.
    Invalid {
        /// `message`, the server's error detail.
        message: Option<String>,
        /// `issues`, the itemised `OperationOutcome` the terminology ecosystem
        /// asks for beside a false `result`
        /// (<https://hl7.org/fhir/uv/tx-ecosystem/requirements.html>).
        outcome: Option<Outcome>,
    },
}

impl ValidateOutcome {
    /// Returns whether the code is a member of the value set.
    #[must_use]
    pub fn is_valid(&self) -> bool {
        matches!(self, Self::Valid { .. })
    }
}

/// One operation to send, for a single call or as a batch entry.
#[derive(Debug, Clone, PartialEq, Eq)]
#[non_exhaustive]
pub enum Request {
    /// `CodeSystem/$lookup`.
    Lookup {
        /// The code system the code is in.
        system: String,
        /// The code to look up.
        code: String,
        /// The code system version, when the source data named one.
        version: Option<String>,
    },
    /// `ConceptMap/$translate`.
    Translate(Translation),
    /// `ValueSet/$validate-code`.
    ValidateCode(Validation),
}

impl Request {
    /// Returns the operation, as `Resource/$code`.
    #[must_use]
    pub const fn operation(&self) -> &'static str {
        match self {
            Self::Lookup { .. } => crate::LOOKUP,
            Self::Translate(_) => crate::TRANSLATE,
            Self::ValidateCode(_) => crate::VALIDATE_CODE,
        }
    }
}

/// One `ConceptMap/$translate` question: what `code` from `system` maps to.
///
/// R4 declares `url`, `targetsystem` and `reverse` each `0..1`
/// (<https://hl7.org/fhir/R4/conceptmap-operation-translate.html>), so each
/// is sent only when it is set here.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Translation {
    /// `system`, the code system the code is in.
    pub system: String,
    /// `code`, the code to translate.
    pub code: String,
    /// `version`, the version of the system, if one was provided in the
    /// source data.
    pub version: Option<String>,
    /// `url`, the canonical URL of the concept map to use, when one is named.
    ///
    /// STU3 `$translate` has no `url` parameter, so an STU3 client refuses a
    /// translation that names one.
    pub concept_map_url: Option<String>,
    /// `targetsystem`, the code system to translate into, when one is named.
    pub target_system: Option<String>,
    /// `reverse`: "if this is true, then the operation should return all the
    /// codes that might be mapped to this code".
    pub reverse: Option<bool>,
}

impl Translation {
    /// Returns the translation of `code` from `system`, naming no concept
    /// map, no target system and no direction yet.
    #[must_use]
    pub fn new(system: impl Into<String>, code: impl Into<String>) -> Self {
        Self {
            system: system.into(),
            code: code.into(),
            version: None,
            concept_map_url: None,
            target_system: None,
            reverse: None,
        }
    }

    /// Names the version of the code system, sent as `version`.
    #[must_use]
    pub fn with_version(mut self, version: impl Into<String>) -> Self {
        self.version = Some(version.into());
        self
    }

    /// Names the concept map, sent as `url`.
    #[must_use]
    pub fn with_concept_map(mut self, url: impl Into<String>) -> Self {
        self.concept_map_url = Some(url.into());
        self
    }

    /// Names the code system to translate into, sent as `targetsystem`.
    #[must_use]
    pub fn with_target_system(mut self, system: impl Into<String>) -> Self {
        self.target_system = Some(system.into());
        self
    }

    /// Sets `reverse`, which asks for the codes that map to this one.
    #[must_use]
    pub const fn with_reverse(mut self, reverse: bool) -> Self {
        self.reverse = Some(reverse);
        self
    }
}

/// One `ValueSet/$validate-code` question: is the coded value a member of
/// the value set.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Validation {
    /// `url`, the canonical URL of the value set, without a version.
    pub value_set_url: String,
    /// `valueSetVersion`, the version of the value set, when the binding
    /// names one.
    ///
    /// STU3 `$validate-code` has no such parameter, so an STU3 client
    /// refuses a validation that names one.
    pub value_set_version: Option<String>,
    /// The coded value, in one of the three forms the operation accepts.
    pub coded: Coded,
}

/// The coded value `ValueSet/$validate-code` tests, in the three input forms
/// the operation declares
/// (<https://hl7.org/fhir/R4/valueset-operation-validate-code.html>).
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[non_exhaustive]
pub enum Coded {
    /// The `code`, `system`, `systemVersion` and `display` parameters. "If a
    /// code is provided, a system or a context must be provided", so the
    /// system is mandatory here.
    Code {
        /// `system`.
        system: String,
        /// `code`.
        code: String,
        /// `systemVersion`, the version of the system, if one was provided in
        /// the source data. STU3 names this parameter `version`.
        version: Option<String>,
        /// `display`, the display associated with the code, if provided.
        display: Option<String>,
    },
    /// The `coding` parameter.
    Coding(Concept),
    /// The `codeableConcept` parameter: "the server returns true if one of the
    /// coding values is in the value set".
    CodeableConcept {
        /// `CodeableConcept.coding`.
        coding: Vec<Concept>,
        /// `CodeableConcept.text`.
        text: Option<String>,
    },
}

/// What one batch entry answered, in the shape of the request that produced
/// it.
#[derive(Debug)]
#[non_exhaustive]
pub enum BatchOutcome {
    /// The answer to a [`Request::Lookup`].
    Lookup(LookupOutcome),
    /// The answer to a [`Request::Translate`].
    Translate(TranslateOutcome),
    /// The answer to a [`Request::ValidateCode`].
    ValidateCode(ValidateOutcome),
}

#[cfg(test)]
mod tests {
    use super::{Request, TranslateOutcome, ValidateOutcome};
    use crate::concept::{Concept, Equivalence, Match};

    fn found(equivalence: &str, code: &str) -> Match {
        Match {
            equivalence: Some(Equivalence::new(equivalence)),
            concept: Some(Concept {
                system: Some("http://example.org/target".to_owned()),
                code: Some(code.to_owned()),
                ..Concept::default()
            }),
            source: None,
        }
    }

    #[test]
    fn accepted_yields_only_the_equivalent_and_equal_matches() {
        let outcome = TranslateOutcome::Translated {
            matches: vec![
                found("wider", "broad"),
                found("equivalent", "same"),
                found("inexact", "close"),
                found("equal", "identical"),
            ],
            message: None,
        };
        let accepted: Vec<Option<String>> = outcome
            .accepted()
            .map(|found| {
                found
                    .concept
                    .as_ref()
                    .and_then(|concept| concept.code.clone())
            })
            .collect();
        assert_eq!(
            vec![Some("same".to_owned()), Some("identical".to_owned())],
            accepted
        );
    }

    #[test]
    fn a_no_match_outcome_accepts_nothing() {
        let outcome = TranslateOutcome::NoMatch {
            message: Some("no map".to_owned()),
        };
        assert_eq!(0, outcome.accepted().count());
    }

    #[test]
    fn an_invalid_outcome_is_not_valid() {
        let outcome = ValidateOutcome::Invalid {
            message: Some("not in the value set".to_owned()),
            outcome: None,
        };
        assert!(!outcome.is_valid());
    }

    #[test]
    fn a_request_names_its_operation() {
        let lookup = Request::Lookup {
            system: "http://example.org/cs".to_owned(),
            code: "a".to_owned(),
            version: None,
        };
        assert_eq!("CodeSystem/$lookup", lookup.operation());
    }
}