feat: add amazon oncreate function to expo plugin

[christianEconify]

Resolves issue #2861

[hyochan]

@christianEconify Thank you for this! I have a question here. Does Expo support Amazon SDK?

[christianEconify]

Hey, it does and Amazon even recommend using expo.
https://developer.amazon.com/apps-and-games/blogs/2024/08/react-native-for-fire-os

I have been using this patch in my codebase already, and have confirmed IAP working on Fire TV with this plugin.

[hyochan]

Thank you for the update!

Could you kindly check the codereview done by code-review-gpt below? You may ignore tests for now if it is too burden but I hope you can cover code refactoring.

1. Consolidating addToBuildGradle and addToMainActivity Logic

The logic for adding lines to files is duplicated in addToBuildGradle and addToMainActivity. We can refactor these into a single reusable function addLineToFile to reduce redundancy and increase maintainability.

Refactored addLineToFile:

const addLineToFile = (
  newLine: string,
  anchor: RegExp | string,
  offset: number,
  fileContents: string
) => {
  const lines = fileContents.split('\n');
  const lineIndex = lines.findIndex((line) => line.match(anchor));
  
  if (lineIndex === -1) {
    console.warn(`Anchor "${anchor}" not found, skipping modification.`);
    return fileContents;
  }

  lines.splice(lineIndex + offset, 0, newLine);
  return lines.join('\n');
};

Both addToBuildGradle and addToMainActivity can then reuse this function, like so:

const addToBuildGradle = (newLine: string, anchor: RegExp | string, offset: number, buildGradle: string) => {
  return addLineToFile(newLine, anchor, offset, buildGradle);
};

const addToMainActivity = (newLine: string, anchor: RegExp | string, offset: number, mainActivity: string) => {
  return addLineToFile(newLine, anchor, offset, mainActivity);
};

2. Handling the both Case in modifyAppBuildGradle

The both case needs to handle the addition of flavor dimensions for both Play Store and Amazon AppStore. Here's the updated version of modifyAppBuildGradle:

Updated modifyAppBuildGradle:

export const modifyAppBuildGradle = (
  buildGradle: string,
  paymentProvider: PaymentProvider
): string => {
  switch (paymentProvider) {
    case 'Amazon AppStore':
      return handleAmazonAppStore(buildGradle);
    
    case 'Play Store':
      return handlePlayStore(buildGradle);

    case 'both':
      // Ensure flavor dimensions for both stores are added
      if (!buildGradle.includes(`flavorDimensions "appstore"`)) {
        const anchor = 'defaultConfig';  // Place to add the new lines
        return addToBuildGradle(linesToAdd['both'], anchor, -1, buildGradle);
      }
      return buildGradle;  // If already present, return as-is

    default:
      throw new Error(`Unsupported payment provider: ${paymentProvider}`);
  }
};

3. Isolating Logic for Testability

To improve testability, I’ve isolated the key logic (finding line indices, adding lines) into smaller functions, which can now be easily tested independently. Here’s how you can organize them for unit testing:

Example Unit Tests:

For addLineToFile:

describe('addLineToFile', () => {
  it('should add a line at the correct position', () => {
    const fileContents = 'line1\nline2\nline3';
    const result = addLineToFile('newLine', 'line2', 1, fileContents);
    expect(result).toContain('newLine');
  });

  it('should skip if anchor is not found', () => {
    const fileContents = 'line1\nline2\nline3';
    const result = addLineToFile('newLine', 'nonexistent', 1, fileContents);
    expect(result).toBe(fileContents);  // No change
  });
});

For modifyAppBuildGradle:

describe('modifyAppBuildGradle', () => {
  it('should add both Amazon and Play Store flavors when paymentProvider is "both"', () => {
    const buildGradle = `android {
      defaultConfig {
        // Some config here
      }
    }`;

    const result = modifyAppBuildGradle(buildGradle, 'both');
    expect(result).toContain('flavorDimensions "appstore"');
    expect(result).toContain('missingDimensionStrategy "store", "amazon"');
    expect(result).toContain('missingDimensionStrategy "store", "play"');
  });

  it('should return unchanged build.gradle if flavorDimensions is already present', () => {
    const buildGradle = `android {
      flavorDimensions "appstore"
      defaultConfig {
        // Some config here
      }
    }`;

    const result = modifyAppBuildGradle(buildGradle, 'both');
    expect(result).toBe(buildGradle);  // No modification needed
  });
});

[christianEconify]

I have updated to the 1st suggestion, but don't really get the 2nd suggestion. Seems unnecessary to me