//! Advanced Replace-By-Fee (RBF) operations
//!
//! Provides advanced RBF functionality including batch fee bumping
//! and RBF with payment consolidation for fee optimization.

use bitcoin::hashes::Hash;
use bitcoin::{FeeRate, Txid};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

use crate::client::BitcoinClient;
use crate::error::{BitcoinError, Result};
use crate::rbf::RbfConfig;

/// Batch RBF operation for multiple transactions
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BatchRbfOperation {
    /// Transactions to be replaced
    pub original_txids: Vec<Txid>,
    /// New fee rate
    pub new_fee_rate: FeeRate,
    /// Whether to consolidate payments
    pub consolidate: bool,
}

/// Batch RBF result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BatchRbfResult {
    /// New transaction ID(s)
    pub new_txids: Vec<Txid>,
    /// Total fee saved by batching
    pub fee_saved: u64,
    /// Number of original transactions
    pub original_count: usize,
    /// Number of new transactions
    pub new_count: usize,
}

/// Payment consolidation during RBF
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConsolidatedPayment {
    /// Original transaction IDs being consolidated
    pub original_txids: Vec<Txid>,
    /// Destination address
    pub address: String,
    /// Total amount (sum of all payments to this address)
    pub total_amount: u64,
}

/// Advanced RBF manager
pub struct AdvancedRbfManager {
    #[allow(dead_code)]
    rbf_config: RbfConfig,
    client: BitcoinClient,
}

impl AdvancedRbfManager {
    /// Create a new advanced RBF manager
    pub fn new(rbf_config: RbfConfig, client: BitcoinClient) -> Self {
        Self { rbf_config, client }
    }

    /// Perform batch RBF on multiple transactions
    pub fn batch_rbf(&self, operations: Vec<BatchRbfOperation>) -> Result<Vec<BatchRbfResult>> {
        let mut results = Vec::new();

        for op in operations {
            let result = self.execute_batch_rbf(op)?;
            results.push(result);
        }

        Ok(results)
    }

    /// Execute a single batch RBF operation
    fn execute_batch_rbf(&self, operation: BatchRbfOperation) -> Result<BatchRbfResult> {
        if operation.original_txids.is_empty() {
            return Err(BitcoinError::Validation(
                "No transactions to replace".to_string(),
            ));
        }

        // Analyze the original transactions
        let payments = self.analyze_original_transactions(&operation.original_txids)?;

        // Calculate fee savings from batching
        let original_fee_total = self.estimate_individual_fees(&operation.original_txids)?;
        let batch_fee = self.estimate_batch_fee(&payments, operation.new_fee_rate)?;
        let fee_saved = original_fee_total.saturating_sub(batch_fee);

        // If consolidating, group payments by address
        let new_txids = if operation.consolidate {
            self.create_consolidated_transactions(&payments, operation.new_fee_rate)?
        } else {
            self.create_batch_transaction(&payments, operation.new_fee_rate)?
        };

        tracing::info!(
            original_count = operation.original_txids.len(),
            new_count = new_txids.len(),
            fee_saved = fee_saved,
            "Completed batch RBF operation"
        );

        Ok(BatchRbfResult {
            new_txids,
            fee_saved,
            original_count: operation.original_txids.len(),
            new_count: 1, // Typically one new transaction
        })
    }

    /// Analyze original transactions to extract payments
    fn analyze_original_transactions(&self, txids: &[Txid]) -> Result<Vec<(String, u64)>> {
        let mut payments = Vec::new();

        for txid in txids {
            // Get transaction details
            let tx_result = self.client.get_raw_transaction(txid)?;

            // Extract outputs (payments) from transaction field
            let tx = tx_result.transaction()?;
            for output in &tx.output {
                if output.value.to_sat() > 0 {
                    // Convert script to address (simplified)
                    let address = format!("address_{}", payments.len());
                    payments.push((address, output.value.to_sat()));
                }
            }
        }

        Ok(payments)
    }

    /// Estimate fees for individual transactions
    fn estimate_individual_fees(&self, txids: &[Txid]) -> Result<u64> {
        let mut total_fee = 0u64;

        for txid in txids {
            let _tx_info = self.client.get_transaction(txid)?;
            // In production, calculate actual fee from inputs - outputs
            total_fee += 1000; // Placeholder
        }

        Ok(total_fee)
    }

    /// Estimate fee for batched transaction
    fn estimate_batch_fee(&self, payments: &[(String, u64)], fee_rate: FeeRate) -> Result<u64> {
        // Estimate transaction size: inputs + outputs + overhead
        let num_inputs = 1; // Simplified - would calculate based on UTXOs needed
        let num_outputs = payments.len();

        // Rough estimate: 180 bytes per input, 34 bytes per output, 10 bytes overhead
        let estimated_vsize = (num_inputs * 180) + (num_outputs * 34) + 10;

        let fee = fee_rate.to_sat_per_vb_ceil() * estimated_vsize as u64;

        Ok(fee)
    }

    /// Create consolidated transactions (group payments by address)
    fn create_consolidated_transactions(
        &self,
        payments: &[(String, u64)],
        fee_rate: FeeRate,
    ) -> Result<Vec<Txid>> {
        // Group payments by address
        let mut consolidated: HashMap<String, u64> = HashMap::new();
        for (address, amount) in payments {
            *consolidated.entry(address.clone()).or_insert(0) += amount;
        }

        tracing::info!(
            original_payments = payments.len(),
            consolidated_payments = consolidated.len(),
            "Consolidated payments"
        );

        // Create single transaction with consolidated outputs
        self.create_batch_transaction(&consolidated.into_iter().collect::<Vec<_>>(), fee_rate)
    }

    /// Create a batch transaction
    fn create_batch_transaction(
        &self,
        payments: &[(String, u64)],
        _fee_rate: FeeRate,
    ) -> Result<Vec<Txid>> {
        // In production, this would:
        // 1. Select UTXOs to fund the transaction
        // 2. Build PSBT with all payments as outputs
        // 3. Sign and broadcast

        // For now, return placeholder
        tracing::info!(num_payments = payments.len(), "Created batch transaction");

        Ok(vec![Txid::all_zeros(); 1])
    }

    /// Calculate savings from consolidation
    pub fn calculate_consolidation_savings(
        &self,
        original_txids: &[Txid],
        fee_rate: FeeRate,
    ) -> Result<ConsolidationSavings> {
        let payments = self.analyze_original_transactions(original_txids)?;

        // Calculate before and after
        let individual_fee = self.estimate_individual_fees(original_txids)?;
        let batch_fee = self.estimate_batch_fee(&payments, fee_rate)?;

        // Count unique addresses
        let mut unique_addresses = HashMap::new();
        for (addr, amt) in &payments {
            *unique_addresses.entry(addr.clone()).or_insert(0) += amt;
        }

        Ok(ConsolidationSavings {
            original_tx_count: original_txids.len(),
            consolidated_tx_count: 1,
            original_payment_count: payments.len(),
            consolidated_payment_count: unique_addresses.len(),
            individual_fee,
            batch_fee,
            fee_saved: individual_fee.saturating_sub(batch_fee),
            savings_percentage: if individual_fee > 0 {
                ((individual_fee - batch_fee) as f64 / individual_fee as f64) * 100.0
            } else {
                0.0
            },
        })
    }

    /// Get RBF recommendations for pending transactions
    pub fn get_rbf_recommendations(
        &self,
        pending_txids: &[Txid],
    ) -> Result<Vec<RbfRecommendation>> {
        let mut recommendations = Vec::new();

        for txid in pending_txids {
            let tx_info = self.client.get_transaction(txid)?;

            // Check if transaction is stuck (no confirmations for a while)
            let confirmations = tx_info.info.confirmations;

            if confirmations == 0 {
                // Recommend RBF
                recommendations.push(RbfRecommendation {
                    txid: *txid,                                                  // Copy the Txid value
                    current_fee_rate: FeeRate::from_sat_per_vb_unchecked(1),      // Placeholder
                    recommended_fee_rate: FeeRate::from_sat_per_vb_unchecked(10), // Placeholder
                    reason: RecommendationReason::Stuck,
                    urgency: RecommendationUrgency::High,
                });
            }
        }

        Ok(recommendations)
    }
}

/// Consolidation savings analysis
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConsolidationSavings {
    /// Number of original transactions
    pub original_tx_count: usize,
    /// Number of consolidated transactions
    pub consolidated_tx_count: usize,
    /// Number of original payments
    pub original_payment_count: usize,
    /// Number of consolidated payments
    pub consolidated_payment_count: usize,
    /// Total fee for individual transactions
    pub individual_fee: u64,
    /// Total fee for batch transaction
    pub batch_fee: u64,
    /// Fee saved by consolidation
    pub fee_saved: u64,
    /// Savings as percentage
    pub savings_percentage: f64,
}

/// RBF recommendation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RbfRecommendation {
    /// Transaction ID
    pub txid: Txid,
    /// Current fee rate
    pub current_fee_rate: FeeRate,
    /// Recommended new fee rate
    pub recommended_fee_rate: FeeRate,
    /// Reason for recommendation
    pub reason: RecommendationReason,
    /// Urgency level
    pub urgency: RecommendationUrgency,
}

/// Reason for RBF recommendation
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum RecommendationReason {
    /// Transaction is stuck (low fee)
    Stuck,
    /// Mempool is congested
    Congestion,
    /// Time-sensitive payment
    Urgent,
    /// Opportunity to consolidate
    Consolidation,
}

/// Urgency level for RBF
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum RecommendationUrgency {
    /// Low urgency, no immediate action required
    Low,
    /// Moderate urgency, consider bumping fee soon
    Medium,
    /// High urgency, fee bump recommended promptly
    High,
    /// Critical urgency, immediate fee bump required
    Critical,
}

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

    #[test]
    fn test_batch_rbf_operation_creation() {
        let op = BatchRbfOperation {
            original_txids: vec![Txid::all_zeros(); 1],
            new_fee_rate: FeeRate::from_sat_per_vb_unchecked(10),
            consolidate: true,
        };

        assert_eq!(op.original_txids.len(), 1);
        assert!(op.consolidate);
    }

    #[test]
    fn test_consolidation_savings() {
        let savings = ConsolidationSavings {
            original_tx_count: 5,
            consolidated_tx_count: 1,
            original_payment_count: 10,
            consolidated_payment_count: 5,
            individual_fee: 5000,
            batch_fee: 2000,
            fee_saved: 3000,
            savings_percentage: 60.0,
        };

        assert_eq!(savings.original_tx_count, 5);
        assert_eq!(savings.consolidated_tx_count, 1);
        assert_eq!(savings.fee_saved, 3000);
        assert_eq!(savings.savings_percentage, 60.0);
    }

    #[test]
    fn test_rbf_recommendation() {
        let txid = Txid::all_zeros();
        let rec = RbfRecommendation {
            txid,
            current_fee_rate: FeeRate::from_sat_per_vb_unchecked(1),
            recommended_fee_rate: FeeRate::from_sat_per_vb_unchecked(10),
            reason: RecommendationReason::Stuck,
            urgency: RecommendationUrgency::High,
        };

        assert_eq!(rec.reason, RecommendationReason::Stuck);
        assert_eq!(rec.urgency, RecommendationUrgency::High);
    }

    #[test]
    fn test_recommendation_urgency_levels() {
        assert_ne!(RecommendationUrgency::Low, RecommendationUrgency::High);
        assert_eq!(
            RecommendationUrgency::Critical,
            RecommendationUrgency::Critical
        );
    }
}
