namespace ts.projectSystem {
    describe("unittests:: tsserver:: cancellationToken", () => {
        // Disable sourcemap support for the duration of the test, as sourcemapping the errors generated during this test is slow and not something we care to test
        let oldPrepare: AnyFunction;
        before(() => {
            oldPrepare = (Error as any).prepareStackTrace;
            delete (Error as any).prepareStackTrace;
        });

        after(() => {
            (Error as any).prepareStackTrace = oldPrepare;
        });

        it("is attached to request", () => {
            const f1 = {
                path: "/a/b/app.ts",
                content: "let xyz = 1;"
            };
            const host = createServerHost([f1]);
            let expectedRequestId: number;
            const cancellationToken: server.ServerCancellationToken = {
                isCancellationRequested: () => false,
                setRequest: requestId => {
                    if (expectedRequestId === undefined) {
                        assert.isTrue(false, "unexpected call");
                    }
                    assert.equal(requestId, expectedRequestId);
                },
                resetRequest: noop
            };

            const session = createSession(host, { cancellationToken });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.OpenRequest>{
                command: "open",
                arguments: { file: f1.path }
            });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.GeterrRequest>{
                command: "geterr",
                arguments: { files: [f1.path] }
            });

            expectedRequestId = session.getNextSeq();
            session.executeCommandSeq(<server.protocol.OccurrencesRequest>{
                command: "occurrences",
                arguments: { file: f1.path, line: 1, offset: 6 }
            });

            expectedRequestId = 2;
            host.runQueuedImmediateCallbacks();
            expectedRequestId = 2;
            host.runQueuedImmediateCallbacks();
        });

        it("Geterr is cancellable", () => {
            const f1 = {
                path: "/a/app.ts",
                content: "let x = 1"
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {}
                })
            };

            const cancellationToken = new TestServerCancellationToken();
            const host = createServerHost([f1, config]);
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: noop,
                cancellationToken
            });
            {
                session.executeCommandSeq(<protocol.OpenRequest>{
                    command: "open",
                    arguments: { file: f1.path }
                });
                // send geterr for missing file
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: ["/a/missing"] }
                });
                // no files - expect 'completed' event
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(session.getSeq(), 0);
            }
            {
                const getErrId = session.getNextSeq();
                // send geterr for a valid file
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });

                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run new request
                session.executeCommandSeq(<protocol.ProjectInfoRequest>{
                    command: "projectInfo",
                    arguments: { file: f1.path }
                });
                session.clearMessages();

                // cancel previously issued Geterr
                cancellationToken.setRequestToCancel(getErrId);
                host.runQueuedTimeoutCallbacks();

                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(getErrId, 0);

                cancellationToken.resetToken();
            }
            {
                const getErrId = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                cancellationToken.setRequestToCancel(getErrId);
                host.runQueuedImmediateCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                verifyRequestCompleted(getErrId, 0);

                cancellationToken.resetToken();
            }
            {
                const getErrId = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");

                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                // the semanticDiag message
                host.runQueuedImmediateCallbacks();
                assert.equal(host.getOutput().length, 1);
                const e2 = <protocol.Event>getMessage(0);
                assert.equal(e2.event, "semanticDiag");
                session.clearMessages();

                host.runQueuedImmediateCallbacks(1);
                assert.equal(host.getOutput().length, 2);
                const e3 = <protocol.Event>getMessage(0);
                assert.equal(e3.event, "suggestionDiag");
                verifyRequestCompleted(getErrId, 1);

                cancellationToken.resetToken();
            }
            {
                const getErr1 = session.getNextSeq();
                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                assert.equal(host.getOutput().length, 0, "expect 0 messages");
                // run first step
                host.runQueuedTimeoutCallbacks();
                assert.equal(host.getOutput().length, 1, "expect 1 message");
                const e1 = <protocol.Event>getMessage(0);
                assert.equal(e1.event, "syntaxDiag");
                session.clearMessages();

                session.executeCommandSeq(<protocol.GeterrRequest>{
                    command: "geterr",
                    arguments: { files: [f1.path] }
                });
                // make sure that getErr1 is completed
                verifyRequestCompleted(getErr1, 0);
            }

            function verifyRequestCompleted(expectedSeq: number, n: number) {
                const event = <protocol.RequestCompletedEvent>getMessage(n);
                assert.equal(event.event, "requestCompleted");
                assert.equal(event.body.request_seq, expectedSeq, "expectedSeq");
                session.clearMessages();
            }

            function getMessage(n: number) {
                return JSON.parse(server.extractMessage(host.getOutput()[n]));
            }
        });

        it("Lower priority tasks are cancellable", () => {
            const f1 = {
                path: "/a/app.ts",
                content: `{ let x = 1; } var foo = "foo"; var bar = "bar"; var fooBar = "fooBar";`
            };
            const config = {
                path: "/a/tsconfig.json",
                content: JSON.stringify({
                    compilerOptions: {}
                })
            };
            const cancellationToken = new TestServerCancellationToken(/*cancelAfterRequest*/ 3);
            const host = createServerHost([f1, config]);
            const session = createSession(host, {
                canUseEvents: true,
                eventHandler: noop,
                cancellationToken,
                throttleWaitMilliseconds: 0
            });
            {
                session.executeCommandSeq(<protocol.OpenRequest>{
                    command: "open",
                    arguments: { file: f1.path }
                });

                // send navbar request (normal priority)
                session.executeCommandSeq(<protocol.NavBarRequest>{
                    command: "navbar",
                    arguments: { file: f1.path }
                });

                // ensure the nav bar request can be canceled
                verifyExecuteCommandSeqIsCancellable(<protocol.NavBarRequest>{
                    command: "navbar",
                    arguments: { file: f1.path }
                });

                // send outlining spans request (normal priority)
                session.executeCommandSeq(<protocol.OutliningSpansRequestFull>{
                    command: "outliningSpans",
                    arguments: { file: f1.path }
                });

                // ensure the outlining spans request can be canceled
                verifyExecuteCommandSeqIsCancellable(<protocol.OutliningSpansRequestFull>{
                    command: "outliningSpans",
                    arguments: { file: f1.path }
                });
            }

            function verifyExecuteCommandSeqIsCancellable<T extends server.protocol.Request>(request: Partial<T>) {
                // Set the next request to be cancellable
                // The cancellation token will cancel the request the third time
                // isCancellationRequested() is called.
                cancellationToken.setRequestToCancel(session.getNextSeq());
                let operationCanceledExceptionThrown = false;

                try {
                    session.executeCommandSeq(request);
                }
                catch (e) {
                    assert(e instanceof OperationCanceledException);
                    operationCanceledExceptionThrown = true;
                }
                assert(operationCanceledExceptionThrown, "Operation Canceled Exception not thrown for request: " + JSON.stringify(request));
            }
        });
    });
}
