factor taskdb into multiple modules

taskchampion/src/taskdb/ops.rs

@@ -0,0 +1,37 @@
+use crate::errors::Error;
+use crate::storage::{Operation, StorageTxn};
+
+pub(super) fn apply_op(txn: &mut dyn StorageTxn, op: &Operation) -> anyhow::Result<()> {
+    match op {
+        Operation::Create { uuid } => {
+            // insert if the task does not already exist
+            if !txn.create_task(*uuid)? {
+                return Err(Error::Database(format!("Task {} already exists", uuid)).into());
+            }
+        }
+        Operation::Delete { ref uuid } => {
+            if !txn.delete_task(*uuid)? {
+                return Err(Error::Database(format!("Task {} does not exist", uuid)).into());
+            }
+        }
+        Operation::Update {
+            ref uuid,
+            ref property,
+            ref value,
+            timestamp: _,
+        } => {
+            // update if this task exists, otherwise ignore
+            if let Some(mut task) = txn.get_task(*uuid)? {
+                match value {
+                    Some(ref val) => task.insert(property.to_string(), val.clone()),
+                    None => task.remove(property),
+                };
+                txn.set_task(*uuid, task)?;
+            } else {
+                return Err(Error::Database(format!("Task {} does not exist", uuid)).into());
+            }
+        }
+    }
+
+    Ok(())
+}