Khan · nishasy · Jul 31, 2024 · Jul 30, 2024 · nishasy · Jul 31, 2024
diff --git a/.changeset/eighty-ducks-appear.md b/.changeset/eighty-ducks-appear.md
@@ -0,0 +1,6 @@
+---
+"@khanacademy/perseus": minor
+"@khanacademy/perseus-editor": minor
+---
+
+[Hint Mode: Start Coords] Add start coords UI for sinusoid graphs
diff --git a/packages/perseus-editor/src/__stories__/flags-for-api-options.ts b/packages/perseus-editor/src/__stories__/flags-for-api-options.ts
@@ -19,6 +19,7 @@ export const flags = {
         // Start coords UI flags
         // TODO(LEMS-2228): Remove flags once this is fully released
         "start-coords-ui-phase-1": true,
+        "start-coords-ui-phase-2": true,
     },
 } satisfies APIOptions["flags"];
 

diff --git a/packages/perseus-editor/src/components/__tests__/start-coords-settings.test.tsx b/packages/perseus-editor/src/components/__tests__/start-coords-settings.test.tsx
@@ -391,4 +391,68 @@ describe("StartCoordSettings", () => {
             },
         );
     });
+
+    describe("sinusoid graph", () => {
+        test("shows the start coordinates UI", () => {
+            // Arrange
+
+            // Act
+            render(
+                <StartCoordsSettings
+                    {...defaultProps}
+                    type="sinusoid"
+                    onChange={() => {}}
+                />,
+                {wrapper: RenderStateRoot},
+            );
+
+            // Assert
+            expect(screen.getByText("Start coordinates")).toBeInTheDocument();
+            expect(screen.getByText("Starting equation:")).toBeInTheDocument();
+            expect(
+                // Equation for default start coords
+                screen.getByText("y = 2.000sin(0.524x - 0.000) + 0.000"),
+            ).toBeInTheDocument();
+            expect(screen.getByText("Point 1:")).toBeInTheDocument();
+            expect(screen.getByText("Point 2:")).toBeInTheDocument();
+        });
+
+        test.each`
+            pointIndex | coord
+            ${0}       | ${"x"}
+            ${0}       | ${"y"}
+            ${1}       | ${"x"}
+            ${1}       | ${"y"}
+        `(
+            "calls onChange when $coord coord is changed (line $pointIndex)",
+            async ({pointIndex, coord}) => {
+                // Arrange
+                const onChangeMock = jest.fn();
+
+                // Act
+                render(
+                    <StartCoordsSettings
+                        {...defaultProps}
+                        type="sinusoid"
+                        onChange={onChangeMock}
+                    />,
+                );
+
+                // Assert
+                const input = screen.getAllByRole("spinbutton", {
+                    name: `${coord}`,
+                })[pointIndex];
+                await userEvent.clear(input);
+                await userEvent.type(input, "101");
+
+                const expectedCoords = [
+                    [0, 0],
+                    [3, 2],
+                ];
+                expectedCoords[pointIndex][coord === "x" ? 0 : 1] = 101;
+
+                expect(onChangeMock).toHaveBeenLastCalledWith(expectedCoords);
+            },
+        );
+    });
 });
diff --git a/packages/perseus-editor/src/components/__tests__/util.test.ts b/packages/perseus-editor/src/components/__tests__/util.test.ts
@@ -3,6 +3,7 @@ import {
     getDefaultFigureForType,
     radianToDegree,
     getDefaultGraphStartCoords,
+    getSinusoidEquation,
 } from "../util";
 
 import type {PerseusGraphType, Range} from "@khanacademy/perseus";
@@ -255,3 +256,23 @@ describe("getDefaultGraphStartCoords", () => {
         expect(defaultCoords).toEqual({center: [0, 0], radius: 2});
     });
 });
+
+describe("getSinusoidEquation", () => {
+    test.each`
+        point1      | point2     | expected
+        ${[0, 0]}   | ${[3, 2]}  | ${"y = 2.000sin(0.524x - 0.000) + 0.000"}
+        ${[0, 0]}   | ${[1, 0]}  | ${"y = 0.000sin(1.571x - 0.000) + 0.000"}
+        ${[0, 0]}   | ${[1, 1]}  | ${"y = 1.000sin(1.571x - 0.000) + 0.000"}
+        ${[0, 0]}   | ${[1, -1]} | ${"y = -1.000sin(1.571x - 0.000) + 0.000"}
+        ${[0, 0]}   | ${[-1, 0]} | ${"y = 0.000sin(-1.571x - 0.000) + 0.000"}
+        ${[-1, 0]}  | ${[1, 1]}  | ${"y = 1.000sin(0.785x - -0.785) + 0.000"}
+        ${[0, -1]}  | ${[1, 1]}  | ${"y = 2.000sin(1.571x - 0.000) + -1.000"}
+        ${[-9, -9]} | ${[9, 9]}  | ${"y = 18.000sin(0.087x - -0.785) + -9.000"}
+        ${[3, -4]}  | ${[6, 7]}  | ${"y = 11.000sin(0.524x - 1.571) + -4.000"}
+    `("should return the correct equation", ({point1, point2, expected}) => {
+        // Act
+        const equation = getSinusoidEquation([point1, point2]);
+
+        expect(equation).toBe(expected);
+    });
+});
diff --git a/packages/perseus-editor/src/components/start-coords-settings.tsx b/packages/perseus-editor/src/components/start-coords-settings.tsx
@@ -4,6 +4,7 @@ import {
     getLineCoords,
     getLinearSystemCoords,
     getSegmentCoords,
+    getSinusoidCoords,
 } from "@khanacademy/perseus";
 import Button from "@khanacademy/wonder-blocks-button";
 import {View} from "@khanacademy/wonder-blocks-core";
@@ -16,6 +17,7 @@ import Heading from "./heading";
 import StartCoordsCircle from "./start-coords-circle";
 import StartCoordsLine from "./start-coords-line";
 import StartCoordsMultiline from "./start-coords-multiline";
+import StartCoordsSinusoid from "./start-coords-sinusoid";
 import {getDefaultGraphStartCoords} from "./util";
 
 import type {PerseusGraphType, Range} from "@khanacademy/perseus";
@@ -69,6 +71,15 @@ const StartCoordsSettingsInner = (props: Props) => {
                     onChange={onChange}
                 />
             );
+        case "sinusoid":
+            const sinusoidCoords = getSinusoidCoords(props, range, step);
+            return (
+                <StartCoordsSinusoid
+                    startCoords={sinusoidCoords}
+                    onChange={onChange}
+                />
+            );
+
         default:
             return null;
     }

diff --git a/packages/perseus-editor/src/components/start-coords-sinusoid.tsx b/packages/perseus-editor/src/components/start-coords-sinusoid.tsx
@@ -0,0 +1,80 @@
+import {View} from "@khanacademy/wonder-blocks-core";
+import {Strut} from "@khanacademy/wonder-blocks-layout";
+import {color, font, spacing} from "@khanacademy/wonder-blocks-tokens";
+import {
+    BodyMonospace,
+    LabelLarge,
+    LabelMedium,
+} from "@khanacademy/wonder-blocks-typography";
+import {StyleSheet} from "aphrodite";
+import * as React from "react";
+
+import CoordinatePairInput from "./coordinate-pair-input";
+import {getSinusoidEquation} from "./util";
+
+import type {Coord, PerseusGraphType} from "@khanacademy/perseus";
+
+type Props = {
+    startCoords: [Coord, Coord];
+    onChange: (startCoords: PerseusGraphType["startCoords"]) => void;
+};
+
+const StartCoordsSinusoid = (props: Props) => {
+    const {startCoords, onChange} = props;
+
+    return (
+        <>
+            {/* Current equation */}
+            <View style={styles.equationSection}>
+                <LabelMedium>Starting equation:</LabelMedium>
+                <BodyMonospace style={styles.equationBody}>
+                    {getSinusoidEquation(startCoords)}
+                </BodyMonospace>
+            </View>
+
+            {/* Points UI */}
+            <View style={styles.tile}>
+                <LabelLarge>Point 1:</LabelLarge>
+                <Strut size={spacing.small_12} />
+                <CoordinatePairInput
+                    coord={startCoords[0]}
+                    labels={["x", "y"]}
+                    onChange={(value) => onChange([value, startCoords[1]])}
+                />
+            </View>
+            <View style={styles.tile}>
+                <LabelLarge>Point 2:</LabelLarge>
+                <Strut size={spacing.small_12} />
+                <CoordinatePairInput
+                    coord={startCoords[1]}
+                    labels={["x", "y"]}
+                    onChange={(value) => onChange([startCoords[0], value])}
+                />
+            </View>
+        </>
+    );
+};
+
+const styles = StyleSheet.create({
+    tile: {
+        backgroundColor: color.fadedBlue8,
+        marginTop: spacing.xSmall_8,
+        padding: spacing.small_12,
+        borderRadius: spacing.xSmall_8,
+        flexDirection: "row",
+        alignItems: "center",
+    },
+    equationSection: {
+        marginTop: spacing.small_12,
+    },
+    equationBody: {
+        backgroundColor: color.fadedOffBlack8,
+        border: `1px solid ${color.fadedOffBlack32}`,
+        marginTop: spacing.xSmall_8,
+        paddingLeft: spacing.xSmall_8,
+        paddingRight: spacing.xSmall_8,
+        fontSize: font.size.xSmall,
+    },
+});
+
+export default StartCoordsSinusoid;
diff --git a/packages/perseus-editor/src/components/util.ts b/packages/perseus-editor/src/components/util.ts
@@ -4,6 +4,7 @@
     getLineCoords,
     getLinearSystemCoords,
     getSegmentCoords,
+    getSinusoidCoords,
 } from "@khanacademy/perseus";
 import {UnreachableCaseError} from "@khanacademy/wonder-stuff-core";
 
@@ -18,6 +19,7 @@
     LockedPolygonType,
     LockedFunctionType,
     PerseusGraphType,
+    Coord,
 } from "@khanacademy/perseus";
 
 export function focusWithChromeStickyFocusBugWorkaround(element: Element) {
@@ -178,9 +180,38 @@
             const radius = kvector.length(
                 kvector.subtract(startCoords.radiusPoint, startCoords.center),
             );
-
             return {center: startCoords.center, radius};
+        case "sinusoid":
+            return getSinusoidCoords(
+                {...graph, startCoords: undefined},
+                range,
+                step,
+            );
         default:
             return undefined;
     }
 }
+
+export const getSinusoidEquation = (startCoords: [Coord, Coord]) => {
+    // Get coefficients
+    // It's assumed that p1 is the root and p2 is the first peak
+    const p1 = startCoords[0];
+    const p2 = startCoords[1];
+
+    // Resulting coefficients are canonical for this sine curve
+    const amplitude = p2[1] - p1[1];
+    const angularFrequency = Math.PI / (2 * (p2[0] - p1[0]));
+    const phase = p1[0] * angularFrequency;
+    const verticalOffset = p1[1];
+
+    return (
+        "y = " +
+        amplitude.toFixed(3) +
+        "sin(" +
+        angularFrequency.toFixed(3) +
+        "x - " +
+        phase.toFixed(3) +
+        ") + " +
+        verticalOffset.toFixed(3)
+    );
+};
diff --git a/packages/perseus-editor/src/widgets/__tests__/interactive-graph-editor.test.tsx b/packages/perseus-editor/src/widgets/__tests__/interactive-graph-editor.test.tsx
@@ -701,6 +701,64 @@ describe("InteractiveGraphEditor", () => {
                             mafs: {
                                 ...flags.mafs,
                                 "start-coords-ui-phase-1": shouldRender,
+                                "start-coords-ui-phase-2": false,
+                            },
+                        },
+                    }}
+                    graph={{type}}
+                    correct={{type}}
+                />,
+                {
+                    wrapper: RenderStateRoot,
+                },
+            );
+
+            // Assert
+            if (shouldRender) {
+                expect(
+                    await screen.findByRole("button", {
+                        name: "Use default start coordinates",
+                    }),
+                ).toBeInTheDocument();
+            } else {
+                expect(
+                    screen.queryByRole("button", {
+                        name: "Use default start coordinates",
+                    }),
+                ).toBeNull();
+            }
+        },
+    );
+
+    test.each`
+        type               | shouldRender
+        ${"linear"}        | ${false}
+        ${"ray"}           | ${false}
+        ${"linear-system"} | ${false}
+        ${"segment"}       | ${false}
+        ${"circle"}        | ${false}
+        ${"quadratic"}     | ${false}
+        ${"sinusoid"}      | ${true}
+        ${"polygon"}       | ${false}
+        ${"angle"}         | ${false}
+        ${"point"}         | ${false}
+    `(
+        "should render for $type graphs if phase2 flag is on: $shouldRender",
+        async ({type, shouldRender}) => {
+            // Arrange
+
+            // Act
+            render(
+                <InteractiveGraphEditor
+                    {...baseProps}
+                    apiOptions={{
+                        ...ApiOptions.defaults,
+                        flags: {
+                            ...flags,
+                            mafs: {
+                                ...flags.mafs,
+                                "start-coords-ui-phase-1": false,
+                                "start-coords-ui-phase-2": shouldRender,
                             },
                         },
                     }}

diff --git a/packages/perseus-editor/src/widgets/interactive-graph-editor.tsx b/packages/perseus-editor/src/widgets/interactive-graph-editor.tsx
@@ -70,6 +70,7 @@ const startCoordsUiPhase1Types = [
     "segment",
     "circle",
 ];
+const startCoordsUiPhase2Types = ["sinusoid"];
 
 type Range = [min: number, max: number];
 
@@ -269,6 +270,18 @@ class InteractiveGraphEditor extends React.Component<Props> {
             graph = <div className="perseus-error">{this.props.valid}</div>;
         }
 
+        const startCoordsPhase1 =
+            this.props.apiOptions?.flags?.mafs?.["start-coords-ui-phase-1"];
+        const startCoordsPhase2 =
+            this.props.apiOptions?.flags?.mafs?.["start-coords-ui-phase-2"];
+
+        const displayStartCoordsUI =
+            this.props.graph &&
+            ((startCoordsPhase1 &&
+                startCoordsUiPhase1Types.includes(this.props.graph.type)) ||
+                (startCoordsPhase2 &&
+                    startCoordsUiPhase2Types.includes(this.props.graph.type)));
+
         return (
             <View>
                 <LabeledRow label="Type of Graph:">
@@ -483,12 +496,7 @@ class InteractiveGraphEditor extends React.Component<Props> {
                 )}
                 {this.props.graph?.type &&
                     // TODO(LEMS-2228): Remove flags once this is fully released
-                    this.props.apiOptions?.flags?.mafs?.[
-                        "start-coords-ui-phase-1"
-                    ] &&
-                    startCoordsUiPhase1Types.includes(
-                        this.props.graph.type,
-                    ) && (
+                    displayStartCoordsUI && (
                         <StartCoordsSettings
                             {...this.props.graph}
                             range={this.props.range}

diff --git a/packages/perseus/src/index.ts b/packages/perseus/src/index.ts
@@ -123,6 +123,7 @@ export {
     getLineCoords,
     getLinearSystemCoords,
     getSegmentCoords,
+    getSinusoidCoords,
 } from "./widgets/interactive-graphs/reducer/initialize-graph-state";
 
 /**