1  use std::collections::BTreeMap;
 2  
 3  use serde::{Deserialize, Serialize};
 4  
 5  /// Unique identifier for a node in the network
 6  pub type NodeId = u64;
 7  
 8  /// Height of an event in the chain
 9  pub type Height = u64;
10  
11  /// The content of an event (could be any data)
12  pub type EventContent = u64;
13  
14  /// An event in the consensus chain
15  #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
16  pub struct Event {
17      /// The creator of this event
18      pub creator: NodeId,
19      /// The height of this event in the chain
20      pub height: Height,
21      /// Hash of the previous event this one builds on
22      pub prev_hash: Option<String>,
23      /// Content of the event
24      pub content: EventContent,
25      /// Hash of this event (computed when created)
26      pub hash: String,
27  }
28  
29  impl Event {
30      /// Create a new event
31      pub fn new(
32          creator: NodeId,
33          height: Height,
34          prev_hash: Option<String>,
35          content: EventContent,
36      ) -> Self {
37          let mut event = Self {
38              creator,
39              height,
40              prev_hash,
41              content,
42              hash: String::new(),
43          };
44          // Simple hash computation for demonstration purposes
45          event.hash = event.compute_hash();
46          event
47      }
48  
49      /// Compute the hash of this event
50      fn compute_hash(&self) -> String {
51          use std::collections::hash_map::DefaultHasher;
52          use std::hash::{Hash, Hasher};
53  
54          let mut hasher = DefaultHasher::new();
55          self.creator.hash(&mut hasher);
56          self.height.hash(&mut hasher);
57          if let Some(prev) = &self.prev_hash {
58              prev.hash(&mut hasher);
59          }
60          self.content.hash(&mut hasher);
61          format!("{:x}", hasher.finish())
62      }
63  
64      /// Validate that this event is correctly formed
65      pub fn is_valid(&self) -> bool {
66          self.hash == self.compute_hash()
67      }
68  }
69  
70  /// The state of the consensus for a node
71  #[derive(Clone, Debug)]
72  pub struct ConsensusState {
73      /// The node's own ID
74      pub node_id: NodeId,
75      /// The chain of events, indexed by height
76      pub chain: BTreeMap<Height, Event>,
77      /// The maximum number of faulty nodes the system can tolerate
78      pub f: usize,
79      /// Total number of nodes in the system
80      pub n: usize,
81      /// The height of the last event this node has created
82      pub last_created_height: Option<Height>,
83  }