datasynth-generators 2.4.0

//! Operational disruption modeling.
//!
//! Models realistic operational disruptions that can be injected into generated data:
//! - System outages (missing data windows)
//! - Migration artifacts (format changes, dual-running periods)
//! - Process changes (workflow shifts, policy changes)
//! - Data recovery patterns (backfill, catch-up processing)

use chrono::NaiveDate;
use datasynth_core::utils::seeded_rng;
use rand::RngExt;
use rand_chacha::ChaCha8Rng;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Types of operational disruptions.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum DisruptionType {
    /// System outage causing missing data
    SystemOutage(OutageConfig),
    /// System migration with format changes
    SystemMigration(MigrationConfig),
    /// Process or policy change
    ProcessChange(ProcessChangeConfig),
    /// Data recovery or backfill
    DataRecovery(RecoveryConfig),
    /// Regulatory compliance change
    RegulatoryChange(RegulatoryConfig),
}

/// Configuration for a system outage.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct OutageConfig {
    /// Start of the outage
    pub start_date: NaiveDate,
    /// End of the outage
    pub end_date: NaiveDate,
    /// Affected systems/modules
    pub affected_systems: Vec<String>,
    /// Whether data was completely lost vs just delayed
    pub data_loss: bool,
    /// Recovery mode (if not complete loss)
    pub recovery_mode: Option<RecoveryMode>,
    /// Outage cause for labeling
    pub cause: OutageCause,
}

/// Cause of an outage.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum OutageCause {
    /// Planned maintenance
    PlannedMaintenance,
    /// Unplanned system failure
    SystemFailure,
    /// Network connectivity issues
    NetworkOutage,
    /// Database issues
    DatabaseFailure,
    /// Third-party service unavailable
    VendorOutage,
    /// Security incident
    SecurityIncident,
    /// Natural disaster
    Disaster,
}

/// How data was recovered after an outage.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum RecoveryMode {
    /// Transactions processed after recovery with original dates
    BackdatedRecovery,
    /// Transactions processed with recovery date
    CurrentDateRecovery,
    /// Mix of both approaches
    MixedRecovery,
    /// Manual journal entries to reconcile
    ManualReconciliation,
}

/// Configuration for a system migration.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub struct MigrationConfig {
    /// Migration go-live date
    pub go_live_date: NaiveDate,
    /// Dual-running period start (before go-live)
    pub dual_run_start: Option<NaiveDate>,
    /// Dual-running period end (after go-live)
    pub dual_run_end: Option<NaiveDate>,
    /// Source system name
    pub source_system: String,
    /// Target system name
    pub target_system: String,
    /// Format changes applied
    pub format_changes: Vec<FormatChange>,
    /// Account mapping changes
    pub account_remapping: HashMap<String, String>,
    /// Data quality issues during migration
    pub migration_issues: Vec<MigrationIssue>,
}

/// Types of format changes during migration.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum FormatChange {
    /// Date format change (e.g., MM/DD/YYYY to YYYY-MM-DD)
    DateFormat {
        old_format: String,
        new_format: String,
    },
    /// Amount precision change
    AmountPrecision { old_decimals: u8, new_decimals: u8 },
    /// Currency code format
    CurrencyCode {
        old_format: String,
        new_format: String,
    },
    /// Account number format
    AccountFormat {
        old_pattern: String,
        new_pattern: String,
    },
    /// Reference number format
    ReferenceFormat {
        old_pattern: String,
        new_pattern: String,
    },
    /// Text encoding change
    TextEncoding {
        old_encoding: String,
        new_encoding: String,
    },
    /// Field length change
    FieldLength {
        field: String,
        old_length: usize,
        new_length: usize,
    },
}

/// Issues that can occur during migration.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum MigrationIssue {
    /// Duplicate records created
    DuplicateRecords { affected_count: usize },
    /// Missing records not migrated
    MissingRecords { affected_count: usize },
    /// Truncated data
    TruncatedData {
        field: String,
        affected_count: usize,
    },
    /// Encoding corruption
    EncodingCorruption { affected_count: usize },
    /// Mismatched balances
    BalanceMismatch { variance: f64 },
    /// Orphaned references
    OrphanedReferences { affected_count: usize },
}

/// Configuration for process changes.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub struct ProcessChangeConfig {
    /// Effective date of the change
    pub effective_date: NaiveDate,
    /// Type of process change
    pub change_type: ProcessChangeType,
    /// Transition period length in days
    pub transition_days: u32,
    /// Whether retroactive changes were applied
    pub retroactive: bool,
}

/// Types of process changes.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum ProcessChangeType {
    /// Approval threshold change
    ApprovalThreshold {
        old_threshold: f64,
        new_threshold: f64,
    },
    /// New approval level added
    NewApprovalLevel { level_name: String, threshold: f64 },
    /// Approval level removed
    RemovedApprovalLevel { level_name: String },
    /// Segregation of duties change
    SodPolicyChange {
        new_conflicts: Vec<(String, String)>,
    },
    /// Account posting rules change
    PostingRuleChange { affected_accounts: Vec<String> },
    /// Vendor management change
    VendorPolicyChange { policy_name: String },
    /// Period close procedure change
    CloseProcessChange {
        old_close_day: u8,
        new_close_day: u8,
    },
    /// Document retention change
    RetentionPolicyChange { old_years: u8, new_years: u8 },
}

/// Configuration for data recovery scenarios.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct RecoveryConfig {
    /// When recovery started
    pub recovery_start: NaiveDate,
    /// When recovery completed
    pub recovery_end: NaiveDate,
    /// Period being recovered
    pub affected_period_start: NaiveDate,
    /// Period being recovered end
    pub affected_period_end: NaiveDate,
    /// Recovery approach
    pub recovery_type: RecoveryType,
    /// Quality of recovered data
    pub data_quality: RecoveredDataQuality,
}

/// Types of data recovery.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum RecoveryType {
    /// Full backup restoration
    BackupRestore,
    /// Reconstruction from source documents
    SourceReconstruction,
    /// Interface file reprocessing
    InterfaceReplay,
    /// Manual entry from paper records
    ManualReentry,
    /// Partial recovery with estimates
    PartialWithEstimates,
}

/// Quality level of recovered data.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum RecoveredDataQuality {
    /// Complete and accurate
    Complete,
    /// Minor discrepancies
    MinorDiscrepancies,
    /// Estimated values used
    EstimatedValues,
    /// Significant gaps remain
    PartialRecovery,
}

/// Configuration for regulatory changes.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct RegulatoryConfig {
    /// Effective date
    pub effective_date: NaiveDate,
    /// Regulation name
    pub regulation_name: String,
    /// Type of regulatory change
    pub change_type: RegulatoryChangeType,
    /// Grace period in days
    pub grace_period_days: u32,
}

/// Types of regulatory changes.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum RegulatoryChangeType {
    /// New reporting requirement
    NewReporting { report_name: String },
    /// Changed chart of accounts structure
    CoaRestructure,
    /// New tax rules
    TaxChange { jurisdiction: String },
    /// Revenue recognition change
    RevenueRecognition,
    /// Lease accounting change
    LeaseAccounting,
    /// Data privacy requirement
    DataPrivacy { regulation: String },
}

/// A disruption event with timing and effects.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisruptionEvent {
    /// Unique identifier
    pub event_id: String,
    /// Type of disruption
    pub disruption_type: DisruptionType,
    /// Detailed description
    pub description: String,
    /// Impact severity (1-5)
    pub severity: u8,
    /// Affected company codes
    pub affected_companies: Vec<String>,
    /// Labels for ML training
    pub labels: HashMap<String, String>,
}

/// Manages disruption scenarios for data generation.
pub struct DisruptionManager {
    /// Active disruption events
    events: Vec<DisruptionEvent>,
    /// Event counter for ID generation
    event_counter: u64,
}

impl DisruptionManager {
    /// Create a new disruption manager.
    pub fn new() -> Self {
        Self {
            events: Vec::new(),
            event_counter: 0,
        }
    }

    /// Add a disruption event.
    pub fn add_event(
        &mut self,
        disruption_type: DisruptionType,
        description: &str,
        severity: u8,
        affected_companies: Vec<String>,
    ) -> String {
        self.event_counter += 1;
        let event_id = format!("DISRUPT-{:06}", self.event_counter);

        let labels = self.generate_labels(&disruption_type);

        let event = DisruptionEvent {
            event_id: event_id.clone(),
            disruption_type,
            description: description.to_string(),
            severity,
            affected_companies,
            labels,
        };

        self.events.push(event);
        event_id
    }

    /// Generate ML labels for a disruption type.
    fn generate_labels(&self, disruption_type: &DisruptionType) -> HashMap<String, String> {
        let mut labels = HashMap::new();

        match disruption_type {
            DisruptionType::SystemOutage(config) => {
                labels.insert("disruption_category".to_string(), "outage".to_string());
                labels.insert("cause".to_string(), format!("{:?}", config.cause));
                labels.insert("data_loss".to_string(), config.data_loss.to_string());
            }
            DisruptionType::SystemMigration(config) => {
                labels.insert("disruption_category".to_string(), "migration".to_string());
                labels.insert("source_system".to_string(), config.source_system.clone());
                labels.insert("target_system".to_string(), config.target_system.clone());
            }
            DisruptionType::ProcessChange(config) => {
                labels.insert(
                    "disruption_category".to_string(),
                    "process_change".to_string(),
                );
                labels.insert(
                    "change_type".to_string(),
                    format!("{:?}", config.change_type),
                );
                labels.insert("retroactive".to_string(), config.retroactive.to_string());
            }
            DisruptionType::DataRecovery(config) => {
                labels.insert("disruption_category".to_string(), "recovery".to_string());
                labels.insert(
                    "recovery_type".to_string(),
                    format!("{:?}", config.recovery_type),
                );
                labels.insert(
                    "data_quality".to_string(),
                    format!("{:?}", config.data_quality),
                );
            }
            DisruptionType::RegulatoryChange(config) => {
                labels.insert("disruption_category".to_string(), "regulatory".to_string());
                labels.insert("regulation".to_string(), config.regulation_name.clone());
                labels.insert(
                    "change_type".to_string(),
                    format!("{:?}", config.change_type),
                );
            }
        }

        labels
    }

    /// Check if a date falls within any outage period.
    pub fn is_in_outage(&self, date: NaiveDate, company_code: &str) -> Option<&DisruptionEvent> {
        self.events.iter().find(|event| {
            if !event.affected_companies.contains(&company_code.to_string())
                && !event.affected_companies.is_empty()
            {
                return false;
            }

            match &event.disruption_type {
                DisruptionType::SystemOutage(config) => {
                    date >= config.start_date && date <= config.end_date
                }
                _ => false,
            }
        })
    }

    /// Check if a date is in a migration dual-run period.
    pub fn is_in_dual_run(&self, date: NaiveDate, company_code: &str) -> Option<&DisruptionEvent> {
        self.events.iter().find(|event| {
            if !event.affected_companies.contains(&company_code.to_string())
                && !event.affected_companies.is_empty()
            {
                return false;
            }

            match &event.disruption_type {
                DisruptionType::SystemMigration(config) => {
                    let start = config.dual_run_start.unwrap_or(config.go_live_date);
                    let end = config.dual_run_end.unwrap_or(config.go_live_date);
                    date >= start && date <= end
                }
                _ => false,
            }
        })
    }

    /// Get format changes applicable to a date.
    pub fn get_format_changes(&self, date: NaiveDate, company_code: &str) -> Vec<&FormatChange> {
        let mut changes = Vec::new();

        for event in &self.events {
            if !event.affected_companies.contains(&company_code.to_string())
                && !event.affected_companies.is_empty()
            {
                continue;
            }

            if let DisruptionType::SystemMigration(config) = &event.disruption_type {
                if date >= config.go_live_date {
                    changes.extend(config.format_changes.iter());
                }
            }
        }

        changes
    }

    /// Get active process changes for a date.
    pub fn get_active_process_changes(
        &self,
        date: NaiveDate,
        company_code: &str,
    ) -> Vec<&ProcessChangeConfig> {
        self.events
            .iter()
            .filter(|event| {
                event.affected_companies.contains(&company_code.to_string())
                    || event.affected_companies.is_empty()
            })
            .filter_map(|event| match &event.disruption_type {
                DisruptionType::ProcessChange(config) if date >= config.effective_date => {
                    Some(config)
                }
                _ => None,
            })
            .collect()
    }

    /// Check if a date is in a recovery period.
    pub fn is_in_recovery(&self, date: NaiveDate, company_code: &str) -> Option<&DisruptionEvent> {
        self.events.iter().find(|event| {
            if !event.affected_companies.contains(&company_code.to_string())
                && !event.affected_companies.is_empty()
            {
                return false;
            }

            match &event.disruption_type {
                DisruptionType::DataRecovery(config) => {
                    date >= config.recovery_start && date <= config.recovery_end
                }
                _ => false,
            }
        })
    }

    /// Get all events.
    pub fn events(&self) -> &[DisruptionEvent] {
        &self.events
    }

    /// Get events affecting a specific company.
    pub fn events_for_company(&self, company_code: &str) -> Vec<&DisruptionEvent> {
        self.events
            .iter()
            .filter(|e| {
                e.affected_companies.contains(&company_code.to_string())
                    || e.affected_companies.is_empty()
            })
            .collect()
    }
}

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

/// Seed discriminator for the disruption generator RNG stream.
const DISRUPTION_SEED_DISCRIMINATOR: u64 = 0xD1_5E;

/// Bulk generator that creates realistic disruption events over a date range.
///
/// Produces approximately 2 events per year, rotating through the five
/// disruption categories: system outage, system migration, process change,
/// data recovery, and regulatory change.
pub struct DisruptionGenerator {
    rng: ChaCha8Rng,
    event_counter: usize,
}

impl DisruptionGenerator {
    /// Create a new disruption generator with the given seed.
    pub fn new(seed: u64) -> Self {
        Self {
            rng: seeded_rng(seed, DISRUPTION_SEED_DISCRIMINATOR),
            event_counter: 0,
        }
    }

    /// Generate disruption events spanning `[start_date, end_date)`.
    ///
    /// Events are returned sorted by their primary date (outage start, go-live,
    /// effective date, recovery start, or regulatory effective date).
    pub fn generate(
        &mut self,
        start_date: NaiveDate,
        end_date: NaiveDate,
        company_codes: &[String],
    ) -> Vec<DisruptionEvent> {
        let total_days = (end_date - start_date).num_days().max(1) as f64;
        let total_years = total_days / 365.25;
        let expected_count = (2.0 * total_years).round().max(1.0) as usize;

        let mut events = Vec::with_capacity(expected_count);

        for i in 0..expected_count {
            // Pick a random date within the range
            let day_offset = self.rng.random_range(0..total_days as i64);
            let event_date = start_date + chrono::Duration::days(day_offset);

            // Pick affected companies (1-N from the provided list, or all if empty)
            let affected = if company_codes.is_empty() {
                Vec::new()
            } else {
                let count = self.rng.random_range(1..=company_codes.len().min(3));
                let mut selected = Vec::with_capacity(count);
                for _ in 0..count {
                    let idx = self.rng.random_range(0..company_codes.len());
                    let code = company_codes[idx].clone();
                    if !selected.contains(&code) {
                        selected.push(code);
                    }
                }
                selected
            };

            let severity: u8 = self.rng.random_range(1..=5);

            // Rotate through disruption categories
            let disruption_type = match i % 5 {
                0 => self.build_outage(event_date),
                1 => self.build_migration(event_date),
                2 => self.build_process_change(event_date),
                3 => self.build_recovery(event_date),
                _ => self.build_regulatory_change(event_date),
            };

            self.event_counter += 1;
            let event_id = format!("DISRUPT-{:06}", self.event_counter);

            let description = match &disruption_type {
                DisruptionType::SystemOutage(c) => {
                    format!(
                        "System outage ({:?}) affecting {:?}",
                        c.cause, c.affected_systems
                    )
                }
                DisruptionType::SystemMigration(c) => {
                    format!(
                        "Migration from {} to {} on {}",
                        c.source_system, c.target_system, c.go_live_date
                    )
                }
                DisruptionType::ProcessChange(c) => {
                    format!(
                        "Process change ({:?}) effective {}",
                        c.change_type, c.effective_date
                    )
                }
                DisruptionType::DataRecovery(c) => {
                    format!(
                        "Data recovery ({:?}) from {} to {}",
                        c.recovery_type, c.recovery_start, c.recovery_end
                    )
                }
                DisruptionType::RegulatoryChange(c) => {
                    format!(
                        "Regulatory change: {} effective {}",
                        c.regulation_name, c.effective_date
                    )
                }
            };

            let mut labels = HashMap::new();
            labels.insert(
                "disruption_category".to_string(),
                match &disruption_type {
                    DisruptionType::SystemOutage(_) => "outage",
                    DisruptionType::SystemMigration(_) => "migration",
                    DisruptionType::ProcessChange(_) => "process_change",
                    DisruptionType::DataRecovery(_) => "recovery",
                    DisruptionType::RegulatoryChange(_) => "regulatory",
                }
                .to_string(),
            );
            labels.insert("severity".to_string(), severity.to_string());

            events.push(DisruptionEvent {
                event_id,
                disruption_type,
                description,
                severity,
                affected_companies: affected,
                labels,
            });
        }

        // Sort by the primary date of each event
        events.sort_by_key(|e| self.primary_date(e));
        events
    }

    /// Extract the primary date from a disruption event for sorting.
    fn primary_date(&self, event: &DisruptionEvent) -> NaiveDate {
        match &event.disruption_type {
            DisruptionType::SystemOutage(c) => c.start_date,
            DisruptionType::SystemMigration(c) => c.go_live_date,
            DisruptionType::ProcessChange(c) => c.effective_date,
            DisruptionType::DataRecovery(c) => c.recovery_start,
            DisruptionType::RegulatoryChange(c) => c.effective_date,
        }
    }

    /// Build a system outage disruption type.
    fn build_outage(&mut self, base_date: NaiveDate) -> DisruptionType {
        let duration_days = self.rng.random_range(1..=5);
        let end_date = base_date + chrono::Duration::days(duration_days);

        let systems = ["GL", "AP", "AR", "MM", "SD", "FI", "CO"];
        let system_count = self.rng.random_range(1..=3);
        let affected_systems: Vec<String> = (0..system_count)
            .map(|_| {
                let idx = self.rng.random_range(0..systems.len());
                systems[idx].to_string()
            })
            .collect();

        let causes = [
            OutageCause::PlannedMaintenance,
            OutageCause::SystemFailure,
            OutageCause::NetworkOutage,
            OutageCause::DatabaseFailure,
            OutageCause::VendorOutage,
            OutageCause::SecurityIncident,
            OutageCause::Disaster,
        ];
        let cause = causes[self.rng.random_range(0..causes.len())].clone();

        let data_loss = self.rng.random_bool(0.2);
        let recovery_mode = if data_loss {
            None
        } else {
            let modes = [
                RecoveryMode::BackdatedRecovery,
                RecoveryMode::CurrentDateRecovery,
                RecoveryMode::MixedRecovery,
                RecoveryMode::ManualReconciliation,
            ];
            Some(modes[self.rng.random_range(0..modes.len())].clone())
        };

        DisruptionType::SystemOutage(OutageConfig {
            start_date: base_date,
            end_date,
            affected_systems,
            data_loss,
            recovery_mode,
            cause,
        })
    }

    /// Build a system migration disruption type.
    fn build_migration(&mut self, base_date: NaiveDate) -> DisruptionType {
        let dual_run_before = self.rng.random_range(7..=30);
        let dual_run_after = self.rng.random_range(7..=30);

        let source_systems = ["Legacy ERP", "SAP ECC", "Oracle 11i", "JDE"];
        let target_systems = ["SAP S/4HANA", "Oracle Cloud", "Workday", "NetSuite"];

        let src_idx = self.rng.random_range(0..source_systems.len());
        let tgt_idx = self.rng.random_range(0..target_systems.len());

        DisruptionType::SystemMigration(MigrationConfig {
            go_live_date: base_date,
            dual_run_start: Some(base_date - chrono::Duration::days(dual_run_before)),
            dual_run_end: Some(base_date + chrono::Duration::days(dual_run_after)),
            source_system: source_systems[src_idx].to_string(),
            target_system: target_systems[tgt_idx].to_string(),
            format_changes: vec![FormatChange::DateFormat {
                old_format: "MM/DD/YYYY".to_string(),
                new_format: "YYYY-MM-DD".to_string(),
            }],
            account_remapping: HashMap::new(),
            migration_issues: Vec::new(),
        })
    }

    /// Build a process change disruption type.
    fn build_process_change(&mut self, base_date: NaiveDate) -> DisruptionType {
        let transition_days = self.rng.random_range(14..=90);
        let retroactive = self.rng.random_bool(0.15);

        let change_type = match self.rng.random_range(0..4) {
            0 => {
                let old_threshold = self.rng.random_range(5000.0..50000.0);
                let new_threshold = old_threshold * self.rng.random_range(0.5..1.5);
                ProcessChangeType::ApprovalThreshold {
                    old_threshold,
                    new_threshold,
                }
            }
            1 => ProcessChangeType::NewApprovalLevel {
                level_name: "Director Review".to_string(),
                threshold: self.rng.random_range(10000.0..100000.0),
            },
            2 => ProcessChangeType::PostingRuleChange {
                affected_accounts: vec!["4100".to_string(), "4200".to_string()],
            },
            _ => {
                let old_day = self.rng.random_range(3..=10);
                let new_day = self.rng.random_range(3..=10);
                ProcessChangeType::CloseProcessChange {
                    old_close_day: old_day,
                    new_close_day: new_day,
                }
            }
        };

        DisruptionType::ProcessChange(ProcessChangeConfig {
            effective_date: base_date,
            change_type,
            transition_days,
            retroactive,
        })
    }

    /// Build a data recovery disruption type.
    fn build_recovery(&mut self, base_date: NaiveDate) -> DisruptionType {
        let affected_duration = self.rng.random_range(3..=14);
        let recovery_duration = self.rng.random_range(2..=10);
        let recovery_start = base_date;
        let recovery_end = base_date + chrono::Duration::days(recovery_duration);
        let affected_period_start = base_date - chrono::Duration::days(affected_duration);
        let affected_period_end = base_date;

        let recovery_types = [
            RecoveryType::BackupRestore,
            RecoveryType::SourceReconstruction,
            RecoveryType::InterfaceReplay,
            RecoveryType::ManualReentry,
            RecoveryType::PartialWithEstimates,
        ];
        let data_qualities = [
            RecoveredDataQuality::Complete,
            RecoveredDataQuality::MinorDiscrepancies,
            RecoveredDataQuality::EstimatedValues,
            RecoveredDataQuality::PartialRecovery,
        ];

        DisruptionType::DataRecovery(RecoveryConfig {
            recovery_start,
            recovery_end,
            affected_period_start,
            affected_period_end,
            recovery_type: recovery_types[self.rng.random_range(0..recovery_types.len())].clone(),
            data_quality: data_qualities[self.rng.random_range(0..data_qualities.len())].clone(),
        })
    }

    /// Build a regulatory change disruption type.
    fn build_regulatory_change(&mut self, base_date: NaiveDate) -> DisruptionType {
        let grace_period_days = self.rng.random_range(30..=180);

        let regulations = [
            ("IFRS 17", RegulatoryChangeType::RevenueRecognition),
            ("ASC 842", RegulatoryChangeType::LeaseAccounting),
            (
                "GDPR Extension",
                RegulatoryChangeType::DataPrivacy {
                    regulation: "GDPR".to_string(),
                },
            ),
            ("SOX Update", RegulatoryChangeType::CoaRestructure),
            (
                "Local Tax Reform",
                RegulatoryChangeType::TaxChange {
                    jurisdiction: "US-Federal".to_string(),
                },
            ),
        ];

        let idx = self.rng.random_range(0..regulations.len());
        let (name, change_type) = regulations[idx].clone();

        DisruptionType::RegulatoryChange(RegulatoryConfig {
            effective_date: base_date,
            regulation_name: name.to_string(),
            change_type,
            grace_period_days,
        })
    }
}

/// Effects that a disruption can have on generated data.
#[derive(Debug, Clone, Default)]
pub struct DisruptionEffect {
    /// Skip generating data for this date
    pub skip_generation: bool,
    /// Apply format transformation
    pub format_transform: Option<FormatChange>,
    /// Add recovery/backfill markers
    pub add_recovery_markers: bool,
    /// Duplicate to secondary system
    pub duplicate_to_system: Option<String>,
    /// Apply process rule changes
    pub process_changes: Vec<ProcessChangeType>,
    /// Labels to add to generated records
    pub labels: HashMap<String, String>,
}

/// Apply disruption effects to determine how data should be generated.
pub fn compute_disruption_effect(
    manager: &DisruptionManager,
    date: NaiveDate,
    company_code: &str,
) -> DisruptionEffect {
    let mut effect = DisruptionEffect::default();

    // Check for outage
    if let Some(outage_event) = manager.is_in_outage(date, company_code) {
        if let DisruptionType::SystemOutage(config) = &outage_event.disruption_type {
            if config.data_loss {
                effect.skip_generation = true;
            } else {
                effect.add_recovery_markers = true;
            }
            effect
                .labels
                .insert("outage_event".to_string(), outage_event.event_id.clone());
        }
    }

    // Check for dual-run
    if let Some(migration_event) = manager.is_in_dual_run(date, company_code) {
        if let DisruptionType::SystemMigration(config) = &migration_event.disruption_type {
            effect.duplicate_to_system = Some(config.target_system.clone());
            effect.labels.insert(
                "migration_event".to_string(),
                migration_event.event_id.clone(),
            );
        }
    }

    // Check for format changes
    let format_changes = manager.get_format_changes(date, company_code);
    if let Some(first_change) = format_changes.first() {
        effect.format_transform = Some((*first_change).clone());
    }

    // Check for process changes
    for process_change in manager.get_active_process_changes(date, company_code) {
        effect
            .process_changes
            .push(process_change.change_type.clone());
    }

    // Check for recovery period
    if let Some(recovery_event) = manager.is_in_recovery(date, company_code) {
        effect.add_recovery_markers = true;
        effect.labels.insert(
            "recovery_event".to_string(),
            recovery_event.event_id.clone(),
        );
    }

    effect
}

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

    #[test]
    fn test_outage_detection() {
        let mut manager = DisruptionManager::new();

        let outage = OutageConfig {
            start_date: NaiveDate::from_ymd_opt(2024, 3, 15).unwrap(),
            end_date: NaiveDate::from_ymd_opt(2024, 3, 17).unwrap(),
            affected_systems: vec!["GL".to_string()],
            data_loss: false,
            recovery_mode: Some(RecoveryMode::BackdatedRecovery),
            cause: OutageCause::SystemFailure,
        };

        manager.add_event(
            DisruptionType::SystemOutage(outage),
            "GL system outage",
            3,
            vec!["1000".to_string()],
        );

        // During outage
        assert!(manager
            .is_in_outage(NaiveDate::from_ymd_opt(2024, 3, 16).unwrap(), "1000")
            .is_some());

        // Before outage
        assert!(manager
            .is_in_outage(NaiveDate::from_ymd_opt(2024, 3, 14).unwrap(), "1000")
            .is_none());

        // Different company
        assert!(manager
            .is_in_outage(NaiveDate::from_ymd_opt(2024, 3, 16).unwrap(), "2000")
            .is_none());
    }

    #[test]
    fn test_migration_dual_run() {
        let mut manager = DisruptionManager::new();

        let migration = MigrationConfig {
            go_live_date: NaiveDate::from_ymd_opt(2024, 7, 1).unwrap(),
            dual_run_start: Some(NaiveDate::from_ymd_opt(2024, 6, 15).unwrap()),
            dual_run_end: Some(NaiveDate::from_ymd_opt(2024, 7, 15).unwrap()),
            source_system: "Legacy".to_string(),
            target_system: "S4HANA".to_string(),
            format_changes: vec![FormatChange::DateFormat {
                old_format: "MM/DD/YYYY".to_string(),
                new_format: "YYYY-MM-DD".to_string(),
            }],
            account_remapping: HashMap::new(),
            migration_issues: Vec::new(),
        };

        manager.add_event(
            DisruptionType::SystemMigration(migration),
            "S/4HANA migration",
            4,
            vec![], // All companies
        );

        // During dual-run
        assert!(manager
            .is_in_dual_run(NaiveDate::from_ymd_opt(2024, 6, 20).unwrap(), "1000")
            .is_some());

        // After dual-run
        assert!(manager
            .is_in_dual_run(NaiveDate::from_ymd_opt(2024, 7, 20).unwrap(), "1000")
            .is_none());
    }

    #[test]
    fn test_process_change() {
        let mut manager = DisruptionManager::new();

        let process_change = ProcessChangeConfig {
            effective_date: NaiveDate::from_ymd_opt(2024, 4, 1).unwrap(),
            change_type: ProcessChangeType::ApprovalThreshold {
                old_threshold: 10000.0,
                new_threshold: 5000.0,
            },
            transition_days: 30,
            retroactive: false,
        };

        manager.add_event(
            DisruptionType::ProcessChange(process_change),
            "Lower approval threshold",
            2,
            vec!["1000".to_string()],
        );

        // After change
        let changes = manager
            .get_active_process_changes(NaiveDate::from_ymd_opt(2024, 5, 1).unwrap(), "1000");
        assert_eq!(changes.len(), 1);

        // Before change
        let changes = manager
            .get_active_process_changes(NaiveDate::from_ymd_opt(2024, 3, 1).unwrap(), "1000");
        assert_eq!(changes.len(), 0);
    }

    #[test]
    fn test_compute_disruption_effect() {
        let mut manager = DisruptionManager::new();

        let outage = OutageConfig {
            start_date: NaiveDate::from_ymd_opt(2024, 3, 15).unwrap(),
            end_date: NaiveDate::from_ymd_opt(2024, 3, 17).unwrap(),
            affected_systems: vec!["GL".to_string()],
            data_loss: true,
            recovery_mode: None,
            cause: OutageCause::SystemFailure,
        };

        manager.add_event(
            DisruptionType::SystemOutage(outage),
            "GL system outage with data loss",
            5,
            vec!["1000".to_string()],
        );

        let effect = compute_disruption_effect(
            &manager,
            NaiveDate::from_ymd_opt(2024, 3, 16).unwrap(),
            "1000",
        );

        assert!(effect.skip_generation);
        assert!(effect.labels.contains_key("outage_event"));
    }

    #[test]
    fn test_disruption_generator_produces_events() {
        let mut gen = DisruptionGenerator::new(42);
        let start = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
        let end = NaiveDate::from_ymd_opt(2025, 12, 31).unwrap();
        let companies = vec!["1000".to_string(), "2000".to_string()];

        let events = gen.generate(start, end, &companies);

        // ~2 events per year over 2 years => ~4 events
        assert!(!events.is_empty());
        assert!(
            events.len() >= 2,
            "expected at least 2 events, got {}",
            events.len()
        );

        // Verify sorted by date
        for window in events.windows(2) {
            let d0 = primary_date_of(&window[0]);
            let d1 = primary_date_of(&window[1]);
            assert!(d0 <= d1, "events should be sorted by date");
        }

        // Verify all events have valid fields
        for event in &events {
            assert!(!event.event_id.is_empty());
            assert!(!event.description.is_empty());
            assert!(event.severity >= 1 && event.severity <= 5);
            assert!(event.labels.contains_key("disruption_category"));
        }
    }

    #[test]
    fn test_disruption_generator_deterministic() {
        let start = NaiveDate::from_ymd_opt(2024, 1, 1).unwrap();
        let end = NaiveDate::from_ymd_opt(2024, 12, 31).unwrap();
        let companies = vec!["C001".to_string()];

        let events1 = DisruptionGenerator::new(99).generate(start, end, &companies);
        let events2 = DisruptionGenerator::new(99).generate(start, end, &companies);

        assert_eq!(events1.len(), events2.len());
        for (a, b) in events1.iter().zip(events2.iter()) {
            assert_eq!(a.event_id, b.event_id);
            assert_eq!(a.severity, b.severity);
        }
    }

    /// Helper to extract primary date without needing access to private method.
    fn primary_date_of(event: &DisruptionEvent) -> NaiveDate {
        match &event.disruption_type {
            DisruptionType::SystemOutage(c) => c.start_date,
            DisruptionType::SystemMigration(c) => c.go_live_date,
            DisruptionType::ProcessChange(c) => c.effective_date,
            DisruptionType::DataRecovery(c) => c.recovery_start,
            DisruptionType::RegulatoryChange(c) => c.effective_date,
        }
    }
}