datasynth-eval 3.0.0

//! Intercompany matching evaluation.
//!
//! Validates that intercompany transactions are properly matched
//! between company pairs.

use crate::error::EvalResult;
use rust_decimal::prelude::ToPrimitive;
use rust_decimal::Decimal;
use serde::{Deserialize, Serialize};

/// Results of intercompany matching evaluation.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ICMatchingEvaluation {
    /// Total company pairs with IC transactions.
    pub total_pairs: usize,
    /// Number of pairs fully matched.
    pub matched_pairs: usize,
    /// Match rate (0.0-1.0).
    pub match_rate: f64,
    /// Total intercompany receivables.
    pub total_receivables: Decimal,
    /// Total intercompany payables.
    pub total_payables: Decimal,
    /// Total unmatched amount.
    pub total_unmatched: Decimal,
    /// Net position (receivables - payables).
    pub net_position: Decimal,
    /// Number of discrepancies (outside tolerance).
    pub discrepancy_count: usize,
    /// Number of unmatched items within tolerance.
    pub within_tolerance_count: usize,
    /// Number of unmatched items outside tolerance.
    pub outside_tolerance_count: usize,
    /// Netting efficiency if applicable.
    pub netting_efficiency: Option<f64>,
}

/// Input for IC matching evaluation.
#[derive(Debug, Clone)]
pub struct ICMatchingData {
    /// Total company pairs.
    pub total_pairs: usize,
    /// Matched company pairs.
    pub matched_pairs: usize,
    /// Total receivables amount.
    pub total_receivables: Decimal,
    /// Total payables amount.
    pub total_payables: Decimal,
    /// Unmatched items details.
    pub unmatched_items: Vec<UnmatchedICItem>,
    /// Gross IC volume (for netting calculation).
    pub gross_volume: Option<Decimal>,
    /// Net settlement amount (for netting calculation).
    pub net_settlement: Option<Decimal>,
}

/// An unmatched IC item.
#[derive(Debug, Clone)]
pub struct UnmatchedICItem {
    /// Company code.
    pub company: String,
    /// Counterparty company code.
    pub counterparty: String,
    /// Amount.
    pub amount: Decimal,
    /// Whether this is a receivable (true) or payable (false).
    pub is_receivable: bool,
}

/// Evaluator for intercompany matching.
pub struct ICMatchingEvaluator {
    /// Tolerance for classifying unmatched items as within/outside tolerance.
    tolerance: Decimal,
}

impl ICMatchingEvaluator {
    /// Create a new evaluator with the specified tolerance.
    pub fn new(tolerance: Decimal) -> Self {
        Self { tolerance }
    }

    /// Evaluate IC matching results.
    pub fn evaluate(&self, data: &ICMatchingData) -> EvalResult<ICMatchingEvaluation> {
        let match_rate = if data.total_pairs > 0 {
            data.matched_pairs as f64 / data.total_pairs as f64
        } else {
            1.0
        };

        let total_unmatched: Decimal = data.unmatched_items.iter().map(|i| i.amount.abs()).sum();
        let net_position = data.total_receivables - data.total_payables;

        // Classify unmatched items by tolerance
        let within_tolerance_count = data
            .unmatched_items
            .iter()
            .filter(|item| item.amount.abs() <= self.tolerance)
            .count();
        let outside_tolerance_count = data.unmatched_items.len() - within_tolerance_count;
        // Only outside-tolerance items count as true discrepancies
        let discrepancy_count = outside_tolerance_count;

        // Calculate netting efficiency if data available
        let netting_efficiency = match (data.gross_volume, data.net_settlement) {
            (Some(gross), Some(net)) if gross > Decimal::ZERO => {
                Some(1.0 - (net / gross).to_f64().unwrap_or(0.0))
            }
            _ => None,
        };

        Ok(ICMatchingEvaluation {
            total_pairs: data.total_pairs,
            matched_pairs: data.matched_pairs,
            match_rate,
            total_receivables: data.total_receivables,
            total_payables: data.total_payables,
            total_unmatched,
            net_position,
            discrepancy_count,
            within_tolerance_count,
            outside_tolerance_count,
            netting_efficiency,
        })
    }
}

impl Default for ICMatchingEvaluator {
    fn default() -> Self {
        Self::new(Decimal::new(1, 2)) // 0.01 tolerance
    }
}

// ---------------------------------------------------------------------------
// IC Net-Zero Reconciliation Validator (v2.5 — fixes consolidation gap)
// ---------------------------------------------------------------------------

/// Input for IC net-zero reconciliation validation.
#[derive(Debug, Clone)]
pub struct ICNetZeroData {
    /// Per-elimination-entry debit/credit totals.
    pub elimination_entries: Vec<ICEliminationLineData>,
    /// IC receivable balance remaining after all eliminations.
    pub post_elimination_ic_receivables: Decimal,
    /// IC payable balance remaining after all eliminations.
    pub post_elimination_ic_payables: Decimal,
}

/// Debit/credit summary for a single elimination entry.
#[derive(Debug, Clone)]
pub struct ICEliminationLineData {
    /// Entry identifier.
    pub entry_id: String,
    /// Elimination type (e.g., "ICBalances", "ICRevenueExpense").
    pub elimination_type: String,
    /// Sum of debit lines in this entry.
    pub total_debits: Decimal,
    /// Sum of credit lines in this entry.
    pub total_credits: Decimal,
}

/// Results of IC net-zero reconciliation validation.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ICNetZeroEvaluation {
    /// Total elimination entries checked.
    pub total_entries: usize,
    /// Number of entries where debits != credits.
    pub unbalanced_entries: usize,
    /// Whether every individual elimination entry is balanced.
    pub all_entries_balanced: bool,
    /// Sum of all elimination debits.
    pub aggregate_debits: Decimal,
    /// Sum of all elimination credits.
    pub aggregate_credits: Decimal,
    /// Aggregate imbalance (debits - credits).
    pub aggregate_imbalance: Decimal,
    /// Residual IC balance after elimination (receivables - payables; should be zero).
    pub residual_ic_balance: Decimal,
    /// Whether IC balances net to zero after elimination.
    pub net_zero_achieved: bool,
    /// Entry IDs that failed the balance check.
    pub failed_entries: Vec<String>,
}

/// Validates that IC elimination entries net to zero (the consolidation principle).
///
/// Checks two levels:
/// 1. **Per-entry**: Each elimination entry's debits must equal its credits.
/// 2. **Aggregate**: After all eliminations, IC receivable and payable balances must net to zero.
pub struct ICNetZeroEvaluator {
    /// Tolerance for floating-point comparison.
    tolerance: Decimal,
}

impl ICNetZeroEvaluator {
    /// Create with a specific tolerance.
    pub fn new(tolerance: Decimal) -> Self {
        Self { tolerance }
    }

    /// Evaluate IC net-zero reconciliation.
    pub fn evaluate(&self, data: &ICNetZeroData) -> EvalResult<ICNetZeroEvaluation> {
        let mut failed_entries = Vec::new();
        let mut aggregate_debits = Decimal::ZERO;
        let mut aggregate_credits = Decimal::ZERO;

        for entry in &data.elimination_entries {
            aggregate_debits += entry.total_debits;
            aggregate_credits += entry.total_credits;

            let diff = (entry.total_debits - entry.total_credits).abs();
            if diff > self.tolerance {
                failed_entries.push(entry.entry_id.clone());
            }
        }

        let aggregate_imbalance = (aggregate_debits - aggregate_credits).abs();
        let all_entries_balanced = failed_entries.is_empty();

        let residual_ic_balance =
            (data.post_elimination_ic_receivables - data.post_elimination_ic_payables).abs();
        let net_zero_achieved =
            residual_ic_balance <= self.tolerance && aggregate_imbalance <= self.tolerance;

        Ok(ICNetZeroEvaluation {
            total_entries: data.elimination_entries.len(),
            unbalanced_entries: failed_entries.len(),
            all_entries_balanced,
            aggregate_debits,
            aggregate_credits,
            aggregate_imbalance,
            residual_ic_balance,
            net_zero_achieved,
            failed_entries,
        })
    }
}

impl Default for ICNetZeroEvaluator {
    fn default() -> Self {
        Self::new(Decimal::new(1, 2)) // 0.01 tolerance
    }
}

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

    #[test]
    fn test_fully_matched_ic() {
        let data = ICMatchingData {
            total_pairs: 5,
            matched_pairs: 5,
            total_receivables: Decimal::new(100000, 2),
            total_payables: Decimal::new(100000, 2),
            unmatched_items: vec![],
            gross_volume: Some(Decimal::new(200000, 2)),
            net_settlement: Some(Decimal::new(20000, 2)),
        };

        let evaluator = ICMatchingEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert_eq!(result.match_rate, 1.0);
        assert_eq!(result.total_unmatched, Decimal::ZERO);
        assert_eq!(result.net_position, Decimal::ZERO);
        assert!(result.netting_efficiency.unwrap() > 0.8);
    }

    #[test]
    fn test_partial_match() {
        let data = ICMatchingData {
            total_pairs: 10,
            matched_pairs: 8,
            total_receivables: Decimal::new(100000, 2),
            total_payables: Decimal::new(95000, 2),
            unmatched_items: vec![UnmatchedICItem {
                company: "1000".to_string(),
                counterparty: "2000".to_string(),
                amount: Decimal::new(5000, 2),
                is_receivable: true,
            }],
            gross_volume: None,
            net_settlement: None,
        };

        let evaluator = ICMatchingEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert_eq!(result.match_rate, 0.8);
        assert_eq!(result.discrepancy_count, 1);
        assert_eq!(result.net_position, Decimal::new(5000, 2));
    }

    #[test]
    fn test_no_ic_transactions() {
        let data = ICMatchingData {
            total_pairs: 0,
            matched_pairs: 0,
            total_receivables: Decimal::ZERO,
            total_payables: Decimal::ZERO,
            unmatched_items: vec![],
            gross_volume: None,
            net_settlement: None,
        };

        let evaluator = ICMatchingEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert_eq!(result.match_rate, 1.0); // No IC = 100% matched
    }

    #[test]
    fn test_ic_net_zero_balanced() {
        let data = ICNetZeroData {
            elimination_entries: vec![
                ICEliminationLineData {
                    entry_id: "ELIM-001".to_string(),
                    elimination_type: "ICBalances".to_string(),
                    total_debits: Decimal::new(500000, 2),
                    total_credits: Decimal::new(500000, 2),
                },
                ICEliminationLineData {
                    entry_id: "ELIM-002".to_string(),
                    elimination_type: "ICRevenueExpense".to_string(),
                    total_debits: Decimal::new(250000, 2),
                    total_credits: Decimal::new(250000, 2),
                },
            ],
            post_elimination_ic_receivables: Decimal::ZERO,
            post_elimination_ic_payables: Decimal::ZERO,
        };

        let evaluator = ICNetZeroEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert!(result.all_entries_balanced);
        assert!(result.net_zero_achieved);
        assert_eq!(result.unbalanced_entries, 0);
        assert_eq!(result.residual_ic_balance, Decimal::ZERO);
    }

    #[test]
    fn test_ic_net_zero_unbalanced_entry() {
        let data = ICNetZeroData {
            elimination_entries: vec![ICEliminationLineData {
                entry_id: "ELIM-BAD".to_string(),
                elimination_type: "ICBalances".to_string(),
                total_debits: Decimal::new(500000, 2),
                total_credits: Decimal::new(495000, 2), // 50.00 difference
            }],
            post_elimination_ic_receivables: Decimal::new(5000, 2),
            post_elimination_ic_payables: Decimal::ZERO,
        };

        let evaluator = ICNetZeroEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert!(!result.all_entries_balanced);
        assert!(!result.net_zero_achieved);
        assert_eq!(result.unbalanced_entries, 1);
    }

    #[test]
    fn test_ic_net_zero_no_eliminations() {
        let data = ICNetZeroData {
            elimination_entries: vec![],
            post_elimination_ic_receivables: Decimal::ZERO,
            post_elimination_ic_payables: Decimal::ZERO,
        };

        let evaluator = ICNetZeroEvaluator::default();
        let result = evaluator.evaluate(&data).unwrap();

        assert!(result.all_entries_balanced);
        assert!(result.net_zero_achieved);
    }
}