refactor: organize prompt generation to its own file

src/utils/prompt.ts

@@ -0,0 +1,48 @@
+import type { CommitType } from './config.js';
+
+const commitTypeFormats: Record<CommitType, string> = {
+	'': '<commit message>',
+	conventional: '<type>(<optional scope>): <commit message>',
+};
+const specifyCommitFormat = (type: CommitType) => `The output response must be in format:\n${commitTypeFormats[type]}`;
+
+const commitTypes: Record<CommitType, string> = {
+	'': '',
+
+	/**
+	 * References:
+	 * Commitlint:
+	 * https://github.com/conventional-changelog/commitlint/blob/18fbed7ea86ac0ec9d5449b4979b762ec4305a92/%40commitlint/config-conventional/index.js#L40-L100
+	 *
+	 * Conventional Changelog:
+	 * https://github.com/conventional-changelog/conventional-changelog/blob/d0e5d5926c8addba74bc962553dd8bcfba90e228/packages/conventional-changelog-conventionalcommits/writer-opts.js#L182-L193
+	 */
+	conventional: `Choose a type from the type-to-description JSON below that best describes the git diff:\n${
+		JSON.stringify({
+			docs: 'Documentation only changes',
+			style: 'Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)',
+			refactor: 'A code change that neither fixes a bug nor adds a feature',
+			perf: 'A code change that improves performance',
+			test: 'Adding missing tests or correcting existing tests',
+			build: 'Changes that affect the build system or external dependencies',
+			ci: 'Changes to our CI configuration files and scripts',
+			chore: "Other changes that don't modify src or test files",
+			revert: 'Reverts a previous commit',
+			feat: 'A new feature',
+			fix: 'A bug fix',
+		}, null, 2)
+	}`,
+};
+
+export const generatePrompt = (
+	locale: string,
+	maxLength: number,
+	type: CommitType,
+) => [
+	'Generate a concise git commit message written in present tense for the following code diff with the given specifications below:',
+	`Message language: ${locale}`,
+	`Commit message must be a maximum of ${maxLength} characters.`,
+	'Exclude anything unnecessary such as translation. Your entire response will be passed directly into git commit.',
+	commitTypes[type],
+	specifyCommitFormat(type),
+].filter(Boolean).join('\n');