1 files changed, 360 insertions, 0 deletions
diff --git a/lib/wallet/query.ts b/lib/wallet/query.ts
new file mode 100644
index 000000000..62411dab3
--- /dev/null
+++ b/lib/wallet/query.ts
@@ -0,0 +1,360 @@
+/*
+ This file is part of TALER
+ (C) 2016 GNUnet e.V.
+
+ TALER is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+ */
+
+
+/**
+ * Database query abstractions.
+ * @module Query
+ * @author Florian Dold
+ */
+
+"use strict";
+
+
+export function Query(db) {
+  return new QueryRoot(db);
+}
+
+/**
+ * Stream that can be filtered, reduced or joined
+ * with indices.
+ */
+export interface QueryStream<T> {
+  indexJoin<S>(storeName: string,
+               indexName: string,
+               keyFn: (obj: any) => any): QueryStream<[T,S]>;
+  filter(f: (any) => boolean): QueryStream<T>;
+  reduce<S>(f: (v: T, acc: S) => S, start?: S): Promise<S>;
+}
+
+
+/**
+ * Get an unresolved promise together with its extracted resolve / reject
+ * function.
+ *
+ * @returns {{resolve: any, reject: any, promise: Promise<T>}}
+ */
+function openPromise<T>() {
+  let resolve, reject;
+  const promise = new Promise<T>((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  return {resolve, reject, promise};
+}
+
+
+abstract class QueryStreamBase<T> implements QueryStream<T> {
+  abstract subscribe(f: (isDone: boolean,
+                         value: any,
+                         tx: IDBTransaction) => void);
+
+  root: QueryRoot;
+
+  constructor(root: QueryRoot) {
+    this.root = root;
+  }
+
+  indexJoin<S>(storeName: string,
+               indexName: string,
+               key: any): QueryStream<[T,S]> {
+    this.root.addWork(null, storeName, false);
+    return new QueryStreamIndexJoin(this, storeName, indexName, key);
+  }
+
+  filter(f: (any) => boolean): QueryStream<T> {
+    return new QueryStreamFilter(this, f);
+  }
+
+  reduce(f, acc?): Promise<any> {
+    let leakedResolve;
+    let p = new Promise((resolve, reject) => {
+      leakedResolve = resolve;
+    });
+
+    this.subscribe((isDone, value) => {
+      if (isDone) {
+        leakedResolve(acc);
+        return;
+      }
+      acc = f(value, acc);
+    });
+
+    return Promise.resolve()
+                  .then(() => this.root.finish())
+                  .then(() => p);
+  }
+}
+
+
+class QueryStreamFilter<T> extends QueryStreamBase<T> {
+  s: QueryStreamBase<T>;
+  filterFn;
+
+  constructor(s: QueryStreamBase<T>, filterFn) {
+    super(s.root);
+    this.s = s;
+    this.filterFn = filterFn;
+  }
+
+  subscribe(f) {
+    this.s.subscribe((isDone, value, tx) => {
+      if (isDone) {
+        f(true, undefined, tx);
+        return;
+      }
+      if (this.filterFn(value)) {
+        f(false, value, tx)
+      }
+    });
+  }
+}
+
+
+class QueryStreamIndexJoin<T> extends QueryStreamBase<T> {
+  s: QueryStreamBase<T>;
+  storeName;
+  key;
+  indexName;
+
+  constructor(s, storeName: string, indexName: string, key: any) {
+    super(s.root);
+    this.s = s;
+    this.storeName = storeName;
+    this.key = key;
+    this.indexName = indexName;
+  }
+
+  subscribe(f) {
+    this.s.subscribe((isDone, value, tx) => {
+      if (isDone) {
+        f(true, undefined, tx);
+        return;
+      }
+      let s = tx.objectStore(this.storeName).index(this.indexName);
+      let req = s.openCursor(IDBKeyRange.only(this.key(value)));
+      req.onsuccess = () => {
+        let cursor = req.result;
+        if (cursor) {
+          f(false, [value, cursor.value], tx);
+          cursor.continue();
+        } else {
+          f(true, undefined, tx);
+        }
+      }
+    });
+  }
+}
+
+
+class IterQueryStream<T> extends QueryStreamBase<T> {
+  private storeName;
+  private options;
+
+  constructor(qr, storeName, options) {
+    super(qr);
+    this.options = options;
+    this.storeName = storeName;
+  }
+
+  subscribe(f) {
+    let doIt = (tx) => {
+      const {indexName = void 0, only = void 0} = this.options;
+      let s;
+      if (indexName !== void 0) {
+        s = tx.objectStore(this.storeName)
+              .index(this.options.indexName);
+      } else {
+        s = tx.objectStore(this.storeName);
+      }
+      let kr = undefined;
+      if (only !== void 0) {
+        kr = IDBKeyRange.only(this.options.only);
+      }
+      let req = s.openCursor(kr);
+      req.onsuccess = (e) => {
+        let cursor: IDBCursorWithValue = req.result;
+        if (cursor) {
+          f(false, cursor.value, tx);
+          cursor.continue();
+        } else {
+          f(true, undefined, tx);
+        }
+      }
+    };
+
+    this.root.addWork(doIt, null, false);
+  }
+}
+
+
+class QueryRoot {
+  private work = [];
+  private db: IDBDatabase;
+  private stores = new Set();
+  private kickoffPromise;
+
+  /**
+   * Some operations is a write operation,
+   * and we need to do a "readwrite" transaction/
+   */
+  private hasWrite;
+
+  constructor(db) {
+    this.db = db;
+  }
+
+  iter<T>(storeName, {only = void 0, indexName = void 0} = {}): QueryStream<T> {
+    this.stores.add(storeName);
+    return new IterQueryStream(this, storeName, {only, indexName});
+  }
+
+  /**
+   * Put an object into the given object store.
+   * Overrides if an existing object with the same key exists
+   * in the store.
+   */
+  put(storeName, val): QueryRoot {
+    let doPut = (tx: IDBTransaction) => {
+      tx.objectStore(storeName).put(val);
+    };
+    this.addWork(doPut, storeName, true);
+    return this;
+  }
+
+
+  /**
+   * Add all object from an iterable to the given object store.
+   * Fails if the object's key is already present
+   * in the object store.
+   */
+  putAll(storeName, iterable): QueryRoot {
+    const doPutAll = (tx: IDBTransaction) => {
+      for (const obj of iterable) {
+        tx.objectStore(storeName).put(obj);
+      }
+    };
+    this.addWork(doPutAll, storeName, true);
+    return this;
+  }
+
+  /**
+   * Add an object to the given object store.
+   * Fails if the object's key is already present
+   * in the object store.
+   */
+  add(storeName, val): QueryRoot {
+    const doAdd = (tx: IDBTransaction) => {
+      tx.objectStore(storeName).add(val);
+    };
+    this.addWork(doAdd, storeName, true);
+    return this;
+  }
+
+  /**
+   * Get one object from a store by its key.
+   */
+  get(storeName, key): Promise<any> {
+    if (key === void 0) {
+      throw Error("key must not be undefined");
+    }
+
+    const {resolve, promise} = openPromise();
+
+    const doGet = (tx) => {
+      const req = tx.objectStore(storeName).get(key);
+      req.onsuccess = (r) => {
+        resolve(req.result);
+      };
+    };
+
+    this.addWork(doGet, storeName, false);
+    return Promise.resolve()
+                  .then(() => this.finish())
+                  .then(() => promise);
+  }
+
+  /**
+   * Get one object from a store by its key.
+   */
+  getIndexed(storeName, indexName, key): Promise<any> {
+    if (key === void 0) {
+      throw Error("key must not be undefined");
+    }
+
+    const {resolve, promise} = openPromise();
+
+    const doGetIndexed = (tx) => {
+      const req = tx.objectStore(storeName).index(indexName).get(key);
+      req.onsuccess = (r) => {
+        resolve(req.result);
+      };
+    };
+
+    this.addWork(doGetIndexed, storeName, false);
+    return Promise.resolve()
+                  .then(() => this.finish())
+                  .then(() => promise);
+  }
+
+  /**
+   * Finish the query, and start the query in the first place if necessary.
+   */
+  finish(): Promise<void> {
+    if (this.kickoffPromise) {
+      return this.kickoffPromise;
+    }
+    this.kickoffPromise = new Promise((resolve, reject) => {
+      const mode = this.hasWrite ? "readwrite" : "readonly";
+      const tx = this.db.transaction(Array.from(this.stores), mode);
+      tx.oncomplete = () => {
+        resolve();
+      };
+      for (let w of this.work) {
+        w(tx);
+      }
+    });
+    return this.kickoffPromise;
+  }
+
+  /**
+   * Delete an object by from the given object store.
+   */
+  delete(storeName: string, key): QueryRoot {
+    const doDelete = (tx) => {
+      tx.objectStore(storeName).delete(key);
+    };
+    this.addWork(doDelete, storeName, true);
+    return this;
+  }
+
+  /**
+   * Low-level function to add a task to the internal work queue.
+   */
+  addWork(workFn: (IDBTransaction) => void,
+          storeName: string,
+          isWrite: boolean) {
+    if (storeName) {
+      this.stores.add(storeName);
+    }
+    if (isWrite) {
+      this.hasWrite = true;
+    }
+    if (workFn) {
+      this.work.push(workFn);
+    }
+  }
+}
+\ No newline at end of file