mx20022-validate 0.3.0

//! CBPR+ (Cross-Border Payments and Reporting Plus) scheme validator.
//!
//! Enforces Swift's CBPR+ usage guidelines for pacs.008 and related messages:
//!
//! - Business Application Header (`AppHdr`) is mandatory.
//! - Instructing and instructed agent BICs are required.
//! - Debtor agent and creditor agent BICs are required.
//! - Debtor and creditor names are required.
//! - UETR is mandatory in `PmtId`.
//! - End-to-end ID is mandatory.
//! - Charges bearer (`ChrgBr`) is required and must be one of: CRED, DEBT,
//!   SHAR, SLEV.
//! - Interbank settlement date is required.
//! - All BICs should be 11 characters (8-char BICs generate a warning).
//! - UTF-8 only; no control characters other than LF, CR, TAB.

use std::any::Any;

use super::xml_scan::{extract_all_elements, extract_element, has_element};
use super::SchemeValidator;
use crate::error::{Severity, ValidationError, ValidationResult};

/// CBPR+ scheme validator.
///
/// # Examples
///
/// ```
/// use mx20022_validate::schemes::cbpr::CbprPlusValidator;
/// use mx20022_validate::schemes::SchemeValidator;
///
/// let validator = CbprPlusValidator::new();
/// assert_eq!(validator.name(), "CBPR+");
/// assert!(validator.supported_messages().contains(&"pacs.008"));
/// ```
pub struct CbprPlusValidator;

impl CbprPlusValidator {
    /// Create a new `CbprPlusValidator`.
    pub fn new() -> Self {
        Self
    }
}

impl Default for CbprPlusValidator {
    fn default() -> Self {
        Self::new()
    }
}

/// Valid `ChrgBr` values under CBPR+.
const VALID_CHRGBR: &[&str] = &["CRED", "DEBT", "SHAR", "SLEV"];

impl SchemeValidator for CbprPlusValidator {
    fn name(&self) -> &'static str {
        "CBPR+"
    }

    fn supported_messages(&self) -> &[&str] {
        &[
            "pacs.008", "pacs.009", "pacs.002", "pacs.004", "camt.056", "camt.029",
        ]
    }

    fn validate(&self, xml: &str, message_type: &str) -> ValidationResult {
        let short_type = super::short_message_type(message_type);

        if !self.supported_messages().contains(&short_type.as_str()) {
            return ValidationResult::default();
        }

        let mut errors: Vec<ValidationError> = Vec::new();

        // --- UTF-8 control character check ----------------------------------
        // The XML string is already valid UTF-8 (Rust strings), so we only need
        // to look for disallowed control characters.
        check_control_characters(xml, &mut errors);

        // --- Business Application Header ------------------------------------
        if !has_element(xml, "AppHdr") && !has_element(xml, "BizMsgIdr") {
            errors.push(ValidationError::new(
                "/AppHdr",
                Severity::Error,
                "CBPR_BAH_REQUIRED",
                "CBPR+ requires a Business Application Header (AppHdr / BizMsgIdr)",
            ));
        }

        // Field-level checks are pacs.008-specific.
        if short_type != "pacs.008" {
            return ValidationResult::new(errors);
        }

        // --- Mandatory BICs -------------------------------------------------
        let bic_fields: &[(&str, &str, &str)] = &[
            (
                "InstgAgt",
                "CBPR_INSTG_AGT_BIC",
                "/Document/FIToFICstmrCdtTrf/GrpHdr/InstgAgt/FinInstnId/BICFI",
            ),
            (
                "InstdAgt",
                "CBPR_INSTD_AGT_BIC",
                "/Document/FIToFICstmrCdtTrf/GrpHdr/InstdAgt/FinInstnId/BICFI",
            ),
            (
                "DbtrAgt",
                "CBPR_DBTR_AGT_BIC",
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/DbtrAgt/FinInstnId/BICFI",
            ),
            (
                "CdtrAgt",
                "CBPR_CDTR_AGT_BIC",
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/CdtrAgt/FinInstnId/BICFI",
            ),
        ];
        for (parent, rule_id, path) in bic_fields {
            check_bic_in_parent(xml, parent, path, rule_id, &mut errors);
        }

        // --- Debtor and creditor names required -----------------------------
        check_name_required(xml, "Dbtr", "CBPR_DBTR_NM_REQUIRED", &mut errors);
        check_name_required(xml, "Cdtr", "CBPR_CDTR_NM_REQUIRED", &mut errors);

        // --- UETR required --------------------------------------------------
        if !has_element(xml, "UETR") {
            errors.push(ValidationError::new(
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/PmtId/UETR",
                Severity::Error,
                "CBPR_UETR_REQUIRED",
                "CBPR+ requires a UETR in PmtId",
            ));
        }

        // --- End-to-end ID required -----------------------------------------
        if !has_element(xml, "EndToEndId") {
            errors.push(ValidationError::new(
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/PmtId/EndToEndId",
                Severity::Error,
                "CBPR_E2E_REQUIRED",
                "CBPR+ requires an EndToEndId in PmtId",
            ));
        }

        // --- ChrgBr required and must be valid ------------------------------
        if let Some(chrg_br) = extract_element(xml, "ChrgBr") {
            if !VALID_CHRGBR.contains(&chrg_br) {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/ChrgBr",
                    Severity::Error,
                    "CBPR_CHRGBR_VALUE",
                    format!("ChrgBr must be one of CRED, DEBT, SHAR, SLEV; got \"{chrg_br}\""),
                ));
            }
        } else {
            errors.push(ValidationError::new(
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/ChrgBr",
                Severity::Error,
                "CBPR_CHRGBR_REQUIRED",
                "CBPR+ requires ChrgBr (one of CRED, DEBT, SHAR, SLEV)",
            ));
        }

        // --- Interbank settlement date required -----------------------------
        if !has_element(xml, "IntrBkSttlmDt") {
            errors.push(ValidationError::new(
                "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/IntrBkSttlmDt",
                Severity::Error,
                "CBPR_STTLM_DT_REQUIRED",
                "CBPR+ requires IntrBkSttlmDt",
            ));
        }

        // --- BIC padding check (8-char BICs should be 11) ------------------
        for bic in extract_all_elements(xml, "BICFI") {
            if bic.len() == 8 {
                errors.push(ValidationError::new(
                    "//BICFI",
                    Severity::Warning,
                    "CBPR_BIC_PADDING",
                    format!(
                        "CBPR+ recommends 11-character BICs; \"{bic}\" is 8 characters (pad with XXX)"
                    ),
                ));
            }
        }

        ValidationResult::new(errors)
    }

    fn validate_typed(&self, msg: &dyn Any, message_type: &str) -> Option<ValidationResult> {
        use mx20022_model::generated::pacs::pacs_008_001_13;

        let short_type = super::short_message_type(message_type);
        if !self.supported_messages().contains(&short_type.as_str()) {
            return None;
        }

        if short_type != "pacs.008" {
            return None;
        }

        let doc = msg.downcast_ref::<pacs_008_001_13::Document>()?;

        Some(self.validate_pacs008_typed(doc))
    }
}

impl CbprPlusValidator {
    /// Typed validation for pacs.008 messages under CBPR+ rules.
    #[allow(clippy::unused_self)]
    fn validate_pacs008_typed(
        &self,
        doc: &mx20022_model::generated::pacs::pacs_008_001_13::Document,
    ) -> ValidationResult {
        let mut errors: Vec<ValidationError> = Vec::new();
        let msg = &doc.fi_to_fi_cstmr_cdt_trf;

        // --- Instructing agent BIC required (GrpHdr level) ------------------
        check_bic_typed(
            msg.grp_hdr.instg_agt.as_ref(),
            "InstgAgt",
            "/Document/FIToFICstmrCdtTrf/GrpHdr/InstgAgt/FinInstnId/BICFI",
            "CBPR_INSTG_AGT_BIC",
            &mut errors,
        );

        // --- Instructed agent BIC required (GrpHdr level) -------------------
        check_bic_typed(
            msg.grp_hdr.instd_agt.as_ref(),
            "InstdAgt",
            "/Document/FIToFICstmrCdtTrf/GrpHdr/InstdAgt/FinInstnId/BICFI",
            "CBPR_INSTD_AGT_BIC",
            &mut errors,
        );

        // --- BIC padding check for GrpHdr-level agents ---
        for agent in [
            msg.grp_hdr.instg_agt.as_ref(),
            msg.grp_hdr.instd_agt.as_ref(),
        ]
        .into_iter()
        .flatten()
        {
            if let Some(bic) = &agent.fin_instn_id.bicfi {
                if bic.0.len() == 8 {
                    errors.push(ValidationError::new(
                        "//BICFI",
                        Severity::Warning,
                        "CBPR_BIC_PADDING",
                        format!(
                            "CBPR+ recommends 11-character BICs; \"{}\" is 8 characters (pad with XXX)",
                            bic.0
                        ),
                    ));
                }
            }
        }

        for tx in &msg.cdt_trf_tx_inf {
            // --- Debtor agent BIC required ----------------------------------
            if tx.dbtr_agt.fin_instn_id.bicfi.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/DbtrAgt/FinInstnId/BICFI",
                    Severity::Error,
                    "CBPR_DBTR_AGT_BIC",
                    "DbtrAgt/FinInstnId/BICFI is required for CBPR+",
                ));
            }

            // --- Creditor agent BIC required --------------------------------
            if tx.cdtr_agt.fin_instn_id.bicfi.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/CdtrAgt/FinInstnId/BICFI",
                    Severity::Error,
                    "CBPR_CDTR_AGT_BIC",
                    "CdtrAgt/FinInstnId/BICFI is required for CBPR+",
                ));
            }

            // --- BIC padding check (8-char BICs should be 11) ---------------
            for bic in [
                tx.dbtr_agt.fin_instn_id.bicfi.as_ref(),
                tx.cdtr_agt.fin_instn_id.bicfi.as_ref(),
            ]
            .into_iter()
            .flatten()
            {
                if bic.0.len() == 8 {
                    errors.push(ValidationError::new(
                        "//BICFI",
                        Severity::Warning,
                        "CBPR_BIC_PADDING",
                        format!(
                            "CBPR+ recommends 11-character BICs; \"{}\" is 8 characters (pad with XXX)",
                            bic.0
                        ),
                    ));
                }
            }

            // --- Debtor name required ---------------------------------------
            if tx.dbtr.nm.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/Dbtr/Nm",
                    Severity::Error,
                    "CBPR_DBTR_NM_REQUIRED",
                    "Dbtr/Nm is required for CBPR+",
                ));
            }

            // --- Creditor name required -------------------------------------
            if tx.cdtr.nm.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/Cdtr/Nm",
                    Severity::Error,
                    "CBPR_CDTR_NM_REQUIRED",
                    "Cdtr/Nm is required for CBPR+",
                ));
            }

            // --- UETR required ----------------------------------------------
            if tx.pmt_id.uetr.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/PmtId/UETR",
                    Severity::Error,
                    "CBPR_UETR_REQUIRED",
                    "CBPR+ requires a UETR in PmtId",
                ));
            }

            // --- End-to-end ID is a required field (always present) ----------
            // (Max35Text is required on PaymentIdentification13, nothing to
            // check beyond XSD.)

            // ChrgBr validity is enforced by the ChargeBearerType1Code enum — all
            // variants (Cred, Debt, Shar, Slev) are valid for CBPR+.

            // --- Interbank settlement date required -------------------------
            if tx.intr_bk_sttlm_dt.is_none() {
                errors.push(ValidationError::new(
                    "/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/IntrBkSttlmDt",
                    Severity::Error,
                    "CBPR_STTLM_DT_REQUIRED",
                    "CBPR+ requires IntrBkSttlmDt",
                ));
            }
        }

        // Note: AppHdr check and UTF-8 control character check require raw
        // XML context and are not covered by the typed path.

        ValidationResult::new(errors)
    }
}

/// Check that a `BICFI` element exists inside a parent block (XML scan).
fn check_bic_in_parent(
    xml: &str,
    parent_tag: &str,
    path: &str,
    rule_id: &str,
    errors: &mut Vec<ValidationError>,
) {
    super::common::check_bic_in_parent(xml, parent_tag, path, rule_id, "CBPR+", errors);
}

/// Check that a `Nm` element exists inside a parent block (XML scan).
fn check_name_required(
    xml: &str,
    parent_tag: &str,
    rule_id: &str,
    errors: &mut Vec<ValidationError>,
) {
    let path = format!("/Document/FIToFICstmrCdtTrf/CdtTrfTxInf/{parent_tag}");
    super::common::check_name_in_parent(
        xml, parent_tag, None, &path, rule_id, "CBPR+", errors, true,
    );
}

/// Check that a BIC is present in an optional agent struct (typed).
fn check_bic_typed(
    agent: Option<
        &mx20022_model::generated::pacs::pacs_008_001_13::BranchAndFinancialInstitutionIdentification8,
    >,
    parent_name: &str,
    path: &str,
    rule_id: &str,
    errors: &mut Vec<ValidationError>,
) {
    match agent {
        None => {
            errors.push(ValidationError::new(
                path,
                Severity::Error,
                rule_id,
                format!("{parent_name}/FinInstnId/BICFI is required for CBPR+ but the parent element is missing"),
            ));
        }
        Some(agt) if agt.fin_instn_id.bicfi.is_none() => {
            errors.push(ValidationError::new(
                path,
                Severity::Error,
                rule_id,
                format!("{parent_name}/FinInstnId/BICFI is required for CBPR+"),
            ));
        }
        Some(_) => {}
    }
}

/// Check for disallowed control characters in the XML string.
///
/// CBPR+ requires UTF-8 encoding with no control characters except:
/// - LF (0x0A)
/// - CR (0x0D)
/// - TAB (0x09)
fn check_control_characters(xml: &str, errors: &mut Vec<ValidationError>) {
    for (i, c) in xml.char_indices() {
        if c.is_control() && !matches!(c, '\n' | '\r' | '\t') {
            errors.push(ValidationError::new(
                "/Document",
                Severity::Error,
                "CBPR_CONTROL_CHAR",
                format!(
                    "Disallowed control character U+{:04X} at byte offset {i}",
                    c as u32
                ),
            ));
            // Report only the first occurrence to avoid noise.
            break;
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn name_is_cbpr_plus() {
        assert_eq!(CbprPlusValidator::new().name(), "CBPR+");
    }

    #[test]
    fn supports_pacs008() {
        let v = CbprPlusValidator::new();
        assert!(v.supported_messages().contains(&"pacs.008"));
    }

    #[test]
    fn unsupported_message_returns_empty() {
        let v = CbprPlusValidator::new();
        let result = v.validate("<xml/>", "pain.001.001.09");
        assert!(result.errors.is_empty());
    }

    #[test]
    fn control_character_produces_error() {
        let mut errors = Vec::new();
        check_control_characters("hello\x01world", &mut errors);
        assert_eq!(errors.len(), 1);
        assert_eq!(errors[0].rule_id, "CBPR_CONTROL_CHAR");
    }

    #[test]
    fn allowed_whitespace_is_fine() {
        let mut errors = Vec::new();
        check_control_characters("hello\nworld\r\n\t", &mut errors);
        assert!(errors.is_empty());
    }
}