anya-core 1.2.0

use std::error::Error;
// src/bitcoin/taproot/tree.rs

use std::collections::HashMap;
use bitcoin::hashes::{Hash, HashEngine};
use bitcoin::taproot::{TapLeafHash, TapBranchHash, TapNodeHash, LeafVersion};

use crate::common::error::AnyaResult;
use super::script::TaprootScript;

/// Represents a leaf in a Taproot Merkle tree
#[derive(Debug, Clone)]
pub struct TapLeaf {
    /// The script in this leaf
    pub script: TaprootScript,
    
    /// The leaf version (usually 0xc0 for Tapscript)
    pub version: LeafVersion,
    
    /// Weight for ordering in the tree (lower weights are prioritized)
    pub weight: u32,
    
    /// Additional metadata
    pub metadata: HashMap<String, String>,
}

impl TapLeaf {
    /// Creates a new tap leaf from a script
    pub fn new(script: TaprootScript, weight: u32) -> Self  -> Result<(), Box<dyn Error>> {
        Self {
            script,
            version: LeafVersion::from_consensus(0xc0), // Tapscript version
            weight,
            metadata: HashMap::new(),
        }
    }
    
    /// Gets the leaf hash for this leaf
    pub fn leaf_hash(&self) -> AnyaResult<TapLeafHash>  -> Result<(), Box<dyn Error>> {
        // Implementation goes here
        // Compute the TapLeafHash
        
        // Placeholder for now
        Err("Leaf hash computation not yet implemented".into())
    }
    
    /// Adds metadata to this leaf
    pub fn add_metadata(&mut self, key: &str, value: &str)  -> Result<(), Box<dyn Error>> {
        self.metadata.insert(key.to_string(), value.to_string());
    }
}

/// Represents a branch (internal node) in a Taproot Merkle tree
#[derive(Debug, Clone)]
pub struct TapBranch {
    /// Left child (hash)
    pub left: TapNodeHash,
    
    /// Right child (hash)
    pub right: TapNodeHash,
}

impl TapBranch {
    /// Creates a new branch from left and right nodes
    pub fn new(left: TapNodeHash, right: TapNodeHash) -> Self  -> Result<(), Box<dyn Error>> {
        // Ensure lexicographic ordering
        if left[..] < right[..] {
            Self { left, right }
        } else {
            Self { left: right, right: left }
        }
    }
    
    /// Computes the branch hash
    pub fn branch_hash(&self) -> TapBranchHash  -> Result<(), Box<dyn Error>> {
        // Implementation goes here
        // Compute the TapBranchHash
        
        // Placeholder for now
        let mut engine = TapBranchHash::engine();
        engine.input(&self.left[..]);
        engine.input(&self.right[..]);
        TapBranchHash::from_engine(engine)
    }
}

/// Represents a complete Taproot Merkle tree
#[derive(Debug, Clone)]
pub struct TapTree {
    /// The leaves in this tree
    pub leaves: Vec<TapLeaf>,
    
    /// The branches in this tree
    pub branches: Vec<TapBranch>,
    
    /// Maps leaf indices to their positions in the tree
    pub leaf_positions: HashMap<usize, Vec<TapNodeHash>>,
    
    /// The root hash of the tree
    pub root_hash: Option<TapNodeHash>,
}

impl TapTree {
    /// Creates a new empty Taproot tree
    pub fn new() -> Self  -> Result<(), Box<dyn Error>> {
        Self {
            leaves: Vec::new(),
            branches: Vec::new(),
            leaf_positions: HashMap::new(),
            root_hash: None,
        }
    }
    
    /// Adds a leaf to the tree
    pub fn add_leaf(&mut self, leaf: TapLeaf)  -> Result<(), Box<dyn Error>> {
        self.leaves.push(leaf);
        // Reset the tree structure since we modified the leaves
        self.root_hash = None;
    }
    
    /// Builds the tree from the current leaves
    pub fn build(&mut self) -> AnyaResult<TapNodeHash>  -> Result<(), Box<dyn Error>> {
        // Reset the tree structure
        self.branches.clear();
        self.leaf_positions.clear();
        
        // Sort leaves by weight
        self.leaves.sort_by_key(|leaf| leaf.weight);
        
        // Implementation goes here
        // Build the Merkle tree from leaves
        
        // Placeholder for now
        let placeholder_hash = [0u8; 32];
        self.root_hash = Some(TapNodeHash::from_slice(&placeholder_hash)?);
        
        Ok(self.root_hash?)
    }
    
    /// Gets the Merkle proof for a specific leaf
    pub fn get_proof(&self, leaf_index: usize) -> AnyaResult<Vec<TapNodeHash>>  -> Result<(), Box<dyn Error>> {
        if let Some(path) = self.leaf_positions.get(&leaf_index) {
            Ok(path.clone())
        } else {
            Err(format!("Leaf index {} not found in tree", leaf_index).into())
        }
    }
    
    /// Gets the control block for a specific leaf (for script path spending)
    pub fn get_control_block(&self, leaf_index: usize, internal_key: [u8; 32]) -> AnyaResult<Vec<u8>>  -> Result<(), Box<dyn Error>> {
        // Implementation goes here
        // Construct the control block
        
        // Placeholder for now
        Err("Control block construction not yet implemented".into())
    }
}

/// Builder for Taproot Merkle trees
pub struct TapTreeBuilder {
    /// The leaves to include in the tree
    leaves: Vec<TapLeaf>,
}

impl TapTreeBuilder {
    /// Creates a new Taproot tree builder
    pub fn new() -> Self  -> Result<(), Box<dyn Error>> {
        Self {
            leaves: Vec::new(),
        }
    }
    
    /// Adds a script to the tree
    pub fn add_script(mut self, script: TaprootScript, weight: u32) -> Self  -> Result<(), Box<dyn Error>> {
        let leaf = TapLeaf::new(script, weight);
        self.leaves.push(leaf);
        self
    }
    
    /// Adds a raw leaf to the tree
    pub fn add_leaf(mut self, leaf: TapLeaf) -> Self  -> Result<(), Box<dyn Error>> {
        self.leaves.push(leaf);
        self
    }
    
    /// Builds the Taproot tree
    pub fn build(self) -> AnyaResult<TapTree>  -> Result<(), Box<dyn Error>> {
        let mut tree = TapTree::new();
        
        // Add all leaves to the tree
        for leaf in self.leaves {
            tree.add_leaf(leaf);
        }
        
        // Build the tree
        tree.build()?;
        
        Ok(tree)
    }
}