From 9483f2df60d6e08b33610f6e0591b787ef9f4805 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <renault.cle@gmail.com>
Date: Mon, 8 Apr 2019 15:19:57 +0200
Subject: [PATCH] feat: Introduce a custom Error type

---
 meilidb-data/Cargo.toml      |  2 +-
 meilidb-data/src/database.rs | 85 ++++++++++++++++++++++++++++++++----
 2 files changed, 78 insertions(+), 9 deletions(-)

diff --git a/meilidb-data/Cargo.toml b/meilidb-data/Cargo.toml
index 23749631b..a142c0bd5 100644
--- a/meilidb-data/Cargo.toml
+++ b/meilidb-data/Cargo.toml
@@ -12,5 +12,5 @@ meilidb-core = { path = "../meilidb-core", version = "0.1.0" }
 ordered-float = { version = "1.0.2", features = ["serde"] }
 serde = { version = "1.0.88", features = ["derive"] }
 serde_json = { version = "1.0.39", features = ["preserve_order"] }
-sled = "0.20.0"
+sled = "0.21.3"
 toml = { version = "0.5.0", features = ["preserve_order"] }
diff --git a/meilidb-data/src/database.rs b/meilidb-data/src/database.rs
index 7f52dccda..f3a4d1dbd 100644
--- a/meilidb-data/src/database.rs
+++ b/meilidb-data/src/database.rs
@@ -1,21 +1,90 @@
-use std::path::Path;
 use std::sync::Arc;
+use std::path::Path;
+
+use crate::schema::Schema;
+
+#[derive(Debug)]
+pub enum Error {
+    SchemaNotFound,
+    SledError(sled::Error),
+    BincodeError(bincode::Error),
+}
+
+impl From<sled::Error> for Error {
+    fn from(error: sled::Error) -> Error {
+        Error::SledError(error)
+    }
+}
+
+impl From<bincode::Error> for Error {
+    fn from(error: bincode::Error) -> Error {
+        Error::BincodeError(error)
+    }
+}
+
+fn index_name(name: &str) -> Vec<u8> {
+    format!("index-{}", name).into_bytes()
+}
 
 #[derive(Clone)]
 pub struct Database(sled::Db);
 
 impl Database {
-    pub fn start_default<P: AsRef<Path>>(path: P) -> sled::Result<Database> {
-        sled::Db::start_default(path).map(Database)
+    pub fn start_default<P: AsRef<Path>>(path: P) -> Result<Database, Error> {
+        sled::Db::start_default(path).map(Database).map_err(Into::into)
     }
 
-    pub fn open_index(&self, name: &str) -> sled::Result<Index> {
-        let name = format!("index-{}", name);
-        let bytes = name.into_bytes();
+    pub fn open_index(&self, name: &str) -> Result<Option<Index>, Error> {
+        let name = index_name(name);
 
-        self.0.open_tree(bytes).map(Index)
+        if self.0.tree_names().into_iter().any(|tn| tn == name) {
+            let tree = self.0.open_tree(name)?;
+            let index = Index::from_raw(tree)?;
+            return Ok(Some(index))
+        }
+
+        Ok(None)
+    }
+
+    pub fn create_index(&self, name: &str, schema: Schema) -> Result<Index, Error> {
+        match self.open_index(name)? {
+            Some(index) => {
+                // TODO check if the schema is the same
+                Ok(index)
+            },
+            None => {
+                let name = index_name(name);
+                let tree = self.0.open_tree(name)?;
+                let index = Index::new_from_raw(tree, schema)?;
+                Ok(index)
+            },
+        }
     }
 }
 
 #[derive(Debug, Clone)]
-pub struct Index(Arc<sled::Tree>);
+pub struct Index {
+    schema: Schema,
+    inner: Arc<sled::Tree>,
+}
+
+impl Index {
+    fn from_raw(inner: Arc<sled::Tree>) -> Result<Index, Error> {
+        let bytes = inner.get("schema")?;
+        let bytes = bytes.ok_or(Error::SchemaNotFound)?;
+
+        let schema = Schema::read_from_bin(bytes.as_ref())?;
+        Ok(Index { schema, inner })
+    }
+
+    fn new_from_raw(inner: Arc<sled::Tree>, schema: Schema) -> Result<Index, Error> {
+        let mut schema_bytes = Vec::new();
+        schema.write_to_bin(&mut schema_bytes);
+        inner.set("schema", schema_bytes)?;
+        Ok(Index { schema, inner })
+    }
+
+    pub fn schema(&self) -> &Schema {
+        &self.schema
+    }
+}