From 41bad17be71cb98c390aaf60ac049a9c6a8872fd Mon Sep 17 00:00:00 2001
From: Roman Kashitsyn <roman@dfinity.org>
Date: Tue, 24 May 2022 22:51:38 +0200
Subject: [PATCH] feat: fetch ledger block example

This change introduces a new Rust canister example that demonstrates how
to fetch a block from the ICP ledger.
---
 rust/fetch_block/.gitignore                   |  18 +
 rust/fetch_block/Cargo.lock                   | 983 ++++++++++++++++++
 rust/fetch_block/Cargo.toml                   |   4 +
 rust/fetch_block/README.md                    |  58 ++
 rust/fetch_block/dfx.json                     |  23 +
 rust/fetch_block/src/fetch_block/Cargo.toml   |  17 +
 .../src/fetch_block/fetch_block.did           |  23 +
 rust/fetch_block/src/fetch_block/src/main.rs  |  38 +
 8 files changed, 1164 insertions(+)
 create mode 100644 rust/fetch_block/.gitignore
 create mode 100644 rust/fetch_block/Cargo.lock
 create mode 100644 rust/fetch_block/Cargo.toml
 create mode 100644 rust/fetch_block/README.md
 create mode 100644 rust/fetch_block/dfx.json
 create mode 100644 rust/fetch_block/src/fetch_block/Cargo.toml
 create mode 100644 rust/fetch_block/src/fetch_block/fetch_block.did
 create mode 100644 rust/fetch_block/src/fetch_block/src/main.rs

diff --git a/rust/fetch_block/.gitignore b/rust/fetch_block/.gitignore
new file mode 100644
index 000000000..d459d1e6a
--- /dev/null
+++ b/rust/fetch_block/.gitignore
@@ -0,0 +1,18 @@
+# Various IDEs and Editors
+.vscode/
+.idea/
+**/*~
+
+# Mac OSX temporary files
+.DS_Store
+**/.DS_Store
+
+# dfx temporary files
+.dfx/
+
+# rust
+target/
+
+# frontend code
+node_modules/
+dist/
diff --git a/rust/fetch_block/Cargo.lock b/rust/fetch_block/Cargo.lock
new file mode 100644
index 000000000..2a869794e
--- /dev/null
+++ b/rust/fetch_block/Cargo.lock
@@ -0,0 +1,983 @@
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diff --git a/rust/fetch_block/Cargo.toml b/rust/fetch_block/Cargo.toml
new file mode 100644
index 000000000..f10b0d2a8
--- /dev/null
+++ b/rust/fetch_block/Cargo.toml
@@ -0,0 +1,4 @@
+[workspace]
+members = [
+    "src/fetch_block",
+]
diff --git a/rust/fetch_block/README.md b/rust/fetch_block/README.md
new file mode 100644
index 000000000..2095c48e8
--- /dev/null
+++ b/rust/fetch_block/README.md
@@ -0,0 +1,58 @@
+# Fetch ICP block
+
+This example demonstrates querying ICP ledger blocks.
+
+## Introduction
+
+The application provides an interface exposes a single method, `fetch_block`.
+This method fetches a single ledger block with the specified index on the mainnet.
+
+## Prerequisites
+
+Verify the following before running this demo:
+
+*  You have downloaded and installed the [DFINITY Canister
+   SDK](https://sdk.dfinity.org).
+
+*  You have a wallet and enough cycles to deploy the canister on the mainnet.
+
+## Demo
+
+1. Reserve an identifier for your canister.
+
+   ```text
+   dfx canister --network ic create fetch_block
+   ```
+
+1. Deploy your canister.
+
+   ```text
+   dfx deploy --network ic fetch_block
+   ```
+
+1. Fetch a ledger block.
+
+   ```text
+    dfx canister --network ic call fetch_block fetch_block '(3_671_055)'
+    (
+      opt record {
+        transaction = record {
+          memo = 1_347_768_404 : nat64;
+          operation = opt variant {
+            Transfer = record {
+              to = blob ";\a0\c7\9c\ee.Sn\85\c3t\da\16\a9\f1\f9\16\dc\e4\9d\11\f0[\17:\bfJ\1c\9e\fan\c3";
+              fee = record { e8s = 10_000 : nat64 };
+              from = blob "\9bgg\93b\98\8a\d8\9bYQ\22E\d8\15G\15y\a8q \cdK\27D\99\e3\ae\fal\a8\eb";
+              amount = record { e8s = 100_000_000 : nat64 };
+            }
+          };
+          created_at_time = record {
+            timestamp_nanos = 1_653_423_511_396_865_000 : nat64;
+          };
+        };
+        timestamp = record { timestamp_nanos = 1_653_423_514_702_069_961 : nat64 };
+        parent_hash = opt blob "\d2\e3\cd\cav\e5\90\e5.q\0d)$+\fd\919:pj\f0he\a5J\d9\d9[P\cc\dc\dc";
+      },
+     )
+    ```
+
diff --git a/rust/fetch_block/dfx.json b/rust/fetch_block/dfx.json
new file mode 100644
index 000000000..1b0d759a2
--- /dev/null
+++ b/rust/fetch_block/dfx.json
@@ -0,0 +1,23 @@
+{
+  "version": 1,
+  "dfx": "0.10.0",
+  "canisters": {
+    "fetch_block": {
+      "type": "rust",
+      "package": "fetch_block",
+      "candid": "src/fetch_block/fetch_block.did"
+    }
+  },
+  "defaults": {
+    "build": {
+      "packtool": "",
+      "args": ""
+    }
+  },
+  "networks": {
+    "local": {
+      "bind": "127.0.0.1:8000",
+      "type": "ephemeral"
+    }
+  }
+}
diff --git a/rust/fetch_block/src/fetch_block/Cargo.toml b/rust/fetch_block/src/fetch_block/Cargo.toml
new file mode 100644
index 000000000..c799e5e2a
--- /dev/null
+++ b/rust/fetch_block/src/fetch_block/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "fetch_block"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+candid = "0.7.10"
+ic-cdk = "0.5"
+ic-cdk-macros = "0.5"
+ic-ledger-types = { git = "https://github.com/dfinity/cdk-rs", rev = "7d461057a24eacd48c5afd628c951693227c6257" }
+
+[profile.release]
+lto = true
+opt-level = 'z'
+panic = 'abort'
diff --git a/rust/fetch_block/src/fetch_block/fetch_block.did b/rust/fetch_block/src/fetch_block/fetch_block.did
new file mode 100644
index 000000000..c135ff5d3
--- /dev/null
+++ b/rust/fetch_block/src/fetch_block/fetch_block.did
@@ -0,0 +1,23 @@
+type Block = record {
+  transaction : Transaction;
+  timestamp : Timestamp;
+  parent_hash : opt vec nat8;
+};
+type Operation = variant {
+  Burn : record { from : vec nat8; amount : Tokens };
+  Mint : record { to : vec nat8; amount : Tokens };
+  Transfer : record {
+    to : vec nat8;
+    fee : Tokens;
+    from : vec nat8;
+    amount : Tokens;
+  };
+};
+type Timestamp = record { timestamp_nanos : nat64 };
+type Tokens = record { e8s : nat64 };
+type Transaction = record {
+  memo : nat64;
+  operation : opt Operation;
+  created_at_time : Timestamp;
+};
+service : { fetch_block : (nat64) -> (opt Block) }
diff --git a/rust/fetch_block/src/fetch_block/src/main.rs b/rust/fetch_block/src/fetch_block/src/main.rs
new file mode 100644
index 000000000..161f2b882
--- /dev/null
+++ b/rust/fetch_block/src/fetch_block/src/main.rs
@@ -0,0 +1,38 @@
+use candid::candid_method;
+use ic_cdk_macros::update;
+use ic_ledger_types::{
+    query_archived_blocks, query_blocks, Block, BlockIndex, GetBlocksArgs,
+    MAINNET_LEDGER_CANISTER_ID,
+};
+
+#[update]
+#[candid_method]
+async fn fetch_block(block_index: BlockIndex) -> Option<Block> {
+    let args = GetBlocksArgs {
+        start: block_index,
+        length: 1,
+    };
+
+    let blocks_result = query_blocks(MAINNET_LEDGER_CANISTER_ID, args.clone())
+        .await
+        .expect("failed to query ledger");
+
+    if blocks_result.blocks.len() >= 1 {
+        return blocks_result.blocks.into_iter().next();
+    }
+
+    if let Some(func) = blocks_result.archived_blocks.into_iter().find_map(|b| {
+        (b.start <= block_index && (block_index - b.start) < b.length).then(|| b.callback)
+    }) {
+        match query_archived_blocks(&func, args)
+            .await
+            .expect("failed to query archive")
+        {
+            Ok(range) => return range.blocks.into_iter().next(),
+            _ => (),
+        }
+    }
+    None
+}
+
+fn main() {}