Implement check method

repository/src/lib.rs

@@ -231,13 +231,139 @@ impl<T: RawRepository> DistributedRepository<T> {
     /// Checks the validity of the repository, starting from the given height.
     ///
     /// It checks
-    /// 1. all the reserved branches and tags
-    /// 2. the finalization proof in the `fp` branch.
-    /// 3. the existence of merge commits
-    /// 4. the canonical history of the `finalized` branch.
+    /// 1. all the reserved branches and tags,
+    /// 2. the finalization proof in the `fp` branch,
+    /// 3. the existence of merge commits,
+    /// 4. the canonical history of the `finalized` branch,
     /// 5. the reserved state in a valid format.
-    pub async fn check(&self, _starting_height: BlockHeight) -> Result<bool, Error> {
-        unimplemented!()
+    pub async fn check(&self, starting_height: BlockHeight) -> Result<bool, Error> {
+        let last_header = self.get_last_finalized_block_header().await?;
+        if last_header.height < starting_height {
+            return Err(anyhow!(
+                "starting height {} is higher than the last finalized block height {}",
+                starting_height,
+                last_header.height
+            ));
+        }
+
+        // Construct a commit list starting from the block commit of the `starting_height`
+        // to the `last_header_commit`(the most recent commit of the `finalized` branch)
+        let inital_commit_hash = self.raw.get_initial_commit().await?;
+        let last_header_commit = self.raw.locate_branch(FINALIZED_BRANCH_NAME.into()).await?;
+        let all_commits = read_commits(self, inital_commit_hash, last_header_commit).await?;
+        let starting_block_commit_position = all_commits
+            .iter()
+            .position(|(commit, _)| {
+                if let Commit::Block(block_header) = commit {
+                    block_header.height == starting_height
+                } else {
+                    false
+                }
+            })
+            .ok_or_else(|| {
+                anyhow!(
+                    "cannot find the commit of the block at height {}",
+                    starting_height
+                )
+            })?;
+        let commits = all_commits
+            .into_iter()
+            .skip(starting_block_commit_position)
+            .collect::<Vec<_>>();
+
+        // TODO: Get the reserved state of the `starting_height` block and verify.
+        // to check the canonical history of the `finalized` branch
+        // Note that whether the reserved state in a valid format is also checked
+        // by the `CommitSequenceVerifier`. (See #166)
+        // TODO: Check the existence of merge commits
+        for (commit, commit_hash) in commits {
+            // Check all the reserved branches
+            let branches = self.raw.get_branches(commit_hash).await?;
+            for branch in branches {
+                match commit {
+                    Commit::Agenda(_) => {
+                        if branch
+                            != format!(
+                                "a-{:?}",
+                                commit
+                                    .to_hash256()
+                                    .to_string()
+                                    .truncate(TAG_NAME_HASH_DIGITS)
+                            )
+                        {
+                            return Ok(false);
+                        }
+                    }
+                    Commit::AgendaProof(_) => {
+                        if branch
+                            != format!(
+                                "a-{:?}",
+                                commit
+                                    .to_hash256()
+                                    .to_string()
+                                    .truncate(TAG_NAME_HASH_DIGITS)
+                            )
+                        {
+                            return Ok(false);
+                        }
+                    }
+                    Commit::Block(_) => {
+                        if branch
+                            != format!(
+                                "b-{:?}",
+                                commit
+                                    .to_hash256()
+                                    .to_string()
+                                    .truncate(TAG_NAME_HASH_DIGITS)
+                            )
+                        {
+                            return Ok(false);
+                        }
+                    }
+                    _ => {
+                        return Ok(false);
+                    }
+                }
+            }
+
+            // Check all the reserved tags
+            let tags = self.raw.get_tag(commit_hash).await?;
+            for tag in tags {
+                match commit {
+                    Commit::Agenda(_) => {
+                        if tag
+                            != format!(
+                                "vote-{:?}",
+                                commit
+                                    .to_hash256()
+                                    .to_string()
+                                    .truncate(TAG_NAME_HASH_DIGITS)
+                            )
+                        {
+                            return Ok(false);
+                        }
+                    }
+                    Commit::Block(_) => {
+                        if tag
+                            != format!(
+                                "veto-{:?}",
+                                commit
+                                    .to_hash256()
+                                    .to_string()
+                                    .truncate(TAG_NAME_HASH_DIGITS)
+                            )
+                        {
+                            return Ok(false);
+                        }
+                    }
+                    _ => {
+                        return Ok(false);
+                    }
+                }
+            }
+        }
+
+        Ok(true)
     }
 
     /// Synchronizes the `finalized` branch to the given commit.