From b0c6399a380addf345622bdea4902d4dea15e797 Mon Sep 17 00:00:00 2001
From: Grisha Kruglov <gkruglov@mozilla.com>
Date: Tue, 30 Jan 2018 19:32:29 -0500
Subject: [PATCH] first pass on transaction read client

---
 tolstoy/Cargo.toml       |   3 +
 tolstoy/src/lib.rs       |   2 +
 tolstoy/src/tx_client.rs | 120 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+)
 create mode 100644 tolstoy/src/tx_client.rs

diff --git a/tolstoy/Cargo.toml b/tolstoy/Cargo.toml
index 03f57bef..827bba94 100644
--- a/tolstoy/Cargo.toml
+++ b/tolstoy/Cargo.toml
@@ -16,6 +16,9 @@ uuid = { version = "0.5", features = ["v4", "serde"] }
 
 error-chain = { git = "https://github.com/rnewman/error-chain", branch = "rnewman/sync" }
 
+[dependencies.mentat_core]
+path = "../core"
+
 [dependencies.mentat_db]
 path = "../db"
 
diff --git a/tolstoy/src/lib.rs b/tolstoy/src/lib.rs
index f7b70e18..38fb4562 100644
--- a/tolstoy/src/lib.rs
+++ b/tolstoy/src/lib.rs
@@ -20,12 +20,14 @@ extern crate futures;
 extern crate serde;
 extern crate serde_json;
 extern crate mentat_db;
+extern crate mentat_core;
 extern crate rusqlite;
 extern crate edn;
 extern crate uuid;
 
 pub mod schema;
 pub mod metadata;
+pub mod tx_client;
 
 error_chain! {
     types {
diff --git a/tolstoy/src/tx_client.rs b/tolstoy/src/tx_client.rs
new file mode 100644
index 00000000..ae874d6d
--- /dev/null
+++ b/tolstoy/src/tx_client.rs
@@ -0,0 +1,120 @@
+// Copyright 2016 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+// read all txs from the database
+// return a list of structures that represent all we need to know about transactions
+
+// so, what do we need here then?
+// we need a "way in"!
+
+// could just query the transactions database directly, read stuff in, and represent
+// it as some data structure on the way out
+
+// will need to weed out transactions as we work through the records
+// -> and then associate with it the "chunks"
+
+// "transaction" then is a meta-concept, it's a label for a collection of concrete changes
+
+// perhaps mentat has useful primitives, but let's begin by just "doing the work"
+
+use rusqlite;
+
+use Result;
+
+use mentat_db::types::{
+    Entid
+};
+
+use mentat_core::{
+    DateTime,
+    Utc,
+    ValueType
+};
+
+use mentat_core::SQLValueType;
+use edn::FromMicros;
+
+struct TxPart {
+    e: Entid,
+    a: i32,
+    v: Vec<u8>,
+    added: i32,
+    value_type_tag: i32
+}
+
+struct Tx {
+    tx: Entid,
+    tx_instant: DateTime<Utc>,
+    parts: Vec<TxPart>
+}
+
+impl Tx {
+    fn new(conn: &rusqlite::Connection, tx: i64, tx_instant: i64) -> Result<Tx> {
+        let mut stmt = conn.prepare("SELECT e,a,v,added,value_type_tag FROM transactions WHERE tx = :tx")?;
+        let mapped_rows = stmt.query_map_named(&[(":tx", &tx)], |row| TxPart {
+            e: row.get(0),
+            a: row.get(1),
+            v: row.get(2),
+            added: row.get(3),
+            value_type_tag: row.get(4)
+        })?;
+
+        let mut parts = Vec::new();
+        for part in mapped_rows {
+            parts.push(part?);
+        }
+
+        Ok(Tx {
+            tx: tx,
+            tx_instant: DateTime::<Utc>::from_micros(tx_instant),
+            parts: parts
+        })
+    }
+}
+
+trait TxReader {
+    fn txs(&self) -> Result<Vec<Tx>>;
+}
+
+struct TxClient {
+    conn: rusqlite::Connection
+}
+
+// TODO This needs to take a mentat connection, as we're making assumptions about
+// what that connection will provide (a transactions table).
+impl TxClient {
+    fn new(conn: rusqlite::Connection) -> Self {
+        TxClient {
+            conn: conn
+        }
+    }
+}
+
+impl TxReader for TxClient {
+    fn txs(&self) -> Result<Vec<Tx>> {
+        let mut stmt = self.conn.prepare("SELECT tx, v FROM transactions GROUP BY tx")?;
+        let mapped_rows = stmt.query_map(&[], |row| Tx::new(&self.conn, row.get(0), row.get(1)))?;
+
+        let mut txes = Vec::new();
+        for tx in mapped_rows {
+            txes.push(match tx? {
+                Err(e) => return Err(e),
+                Ok(v) => v
+            });
+        }
+
+        Ok(txes)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+}