From caf2cbbcfed75a4682df6ef22c55b6ef506ba34f Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Mon, 1 Sep 2014 00:19:47 +0200
Subject: [PATCH] Introduced non standard HSPATIAL hash first second which
 performs a spatial query between coords first and second. TODO: Implement in
 backends. Write documentation.

---
 backend.go    | 10 ++++++++++
 connection.go | 37 +++++++++++++++++++++++++++++++------
 leveldb.go    |  5 +++++
 parser.go     | 16 ++++++++++++++++
 sqlite.go     |  5 +++++
 5 files changed, 67 insertions(+), 6 deletions(-)

diff --git a/backend.go b/backend.go
index 0f4f2e2..ac4e507 100644
--- a/backend.go
+++ b/backend.go
@@ -4,12 +4,22 @@
 
 package main
 
+import "errors"
+
+var ErrNotImplemented = errors.New("Not implemented")
+
 type (
+	Block struct {
+		Key  []byte
+		Data []byte
+	}
+
 	Session interface {
 		Fetch(hash, key []byte) ([]byte, error)
 		InTransaction() bool
 		Store(hash, key, value []byte) (bool, error)
 		AllKeys(hash []byte, done chan struct{}) (chan []byte, int, error)
+		SpatialQuery(hash, first, second []byte, done chan struct{}) (chan Block, error)
 		BeginTransaction() error
 		CommitTransaction() error
 		Close() error
diff --git a/connection.go b/connection.go
index accb9b4..b834030 100644
--- a/connection.go
+++ b/connection.go
@@ -112,10 +112,6 @@ func (c *Connection) Hkeys(hash []byte) bool {
 		return c.writeError(err)
 	}
 
-	if err != nil {
-		return c.writeError(err)
-	}
-
 	if n == 0 {
 		return c.writeEmptyArray()
 	}
@@ -126,15 +122,44 @@ func (c *Connection) Hkeys(hash []byte) bool {
 	}
 
 	for key := range keys {
-		if err := c.writeBulkString(key); err != nil {
+		if err = c.writeBulkString(key); err != nil {
 			logError(err)
-			close(keys)
 			return false
 		}
 	}
 	return true
 }
 
+func (c *Connection) HSpatial(hash, first, second []byte) bool {
+	var (
+		err    error
+		blocks chan Block
+		done   = make(chan struct{})
+	)
+	defer close(done)
+
+	if blocks, err = c.session.SpatialQuery(hash, first, second, done); err != nil {
+		return c.writeError(err)
+	}
+
+	for block := range blocks {
+		if err = c.writeBulkString(block.Key); err != nil {
+			logError(err)
+			return false
+		}
+		if err = c.writeBulkString(block.Data); err != nil {
+			logError(err)
+			return false
+		}
+	}
+
+	if err = c.writeBulkString(nil); err != nil {
+		logError(err)
+		return false
+	}
+	return true
+}
+
 func (c *Connection) writeError(err error) bool {
 	logError(err)
 	if _, err = c.conn.Write(redisError); err != nil {
diff --git a/leveldb.go b/leveldb.go
index 47fa8b1..7143386 100644
--- a/leveldb.go
+++ b/leveldb.go
@@ -222,3 +222,8 @@ func (ldbs *LevelDBSession) AllKeys(hash []byte, done chan struct{}) (keys chan
 
 	return
 }
+
+func (ldbs *LevelDBSession) SpatialQuery(hash, first, second []byte, done chan struct{}) (blocks chan Block, err error) {
+	err = ErrNotImplemented
+	return
+}
diff --git a/parser.go b/parser.go
index 45921ca..1bb9e74 100644
--- a/parser.go
+++ b/parser.go
@@ -127,6 +127,7 @@ type RedisCommands interface {
 	Multi() bool
 	Exec() bool
 	Hkeys(hash []byte) bool
+	HSpatial(hash, first, second []byte) bool
 }
 
 type RedisCommandExecutor struct {
@@ -217,6 +218,21 @@ func (rce *RedisCommandExecutor) execute() bool {
 			return false
 		}
 		return rce.commands.Hkeys(hash)
+
+	case "HSPATIAL":
+		if l < 4 {
+			log.Println("WARN: Missing argments for HSPATIAL.")
+			return false
+		}
+		hash, ok1 := rce.args[1].([]byte)
+		first, ok2 := rce.args[2].([]byte)
+		second, ok3 := rce.args[3].([]byte)
+
+		if !ok1 || !ok2 || !ok3 {
+			log.Println("WARN: HSET data are not byte slices.")
+			return false
+		}
+		return rce.commands.HSpatial(hash, first, second)
 	}
 	log.Printf("WARN: unknown command: '%s'\n", cmd)
 	return false
diff --git a/sqlite.go b/sqlite.go
index d27bc0a..1dd7f97 100644
--- a/sqlite.go
+++ b/sqlite.go
@@ -274,3 +274,8 @@ func (ss *SqliteSession) AllKeys(hash []byte, done chan struct{}) (keys chan []b
 
 	return
 }
+
+func (ss *SqliteSession) SpatialQuery(hash, first, second []byte, done chan struct{}) (blocks chan Block, err error) {
+	err = ErrNotImplemented
+	return
+}