/**
 * Unit tests for GitHub Compare API client (TRUEREF-0021).
 */
import { describe, it, expect, vi, beforeEach } from 'vitest';
import { fetchGitHubChangedFiles } from './github-compare.js';
import { GitHubApiError } from './github-tags.js';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

function mockFetch(status: number, body: unknown): void {
	vi.spyOn(global, 'fetch').mockResolvedValueOnce(
		new Response(JSON.stringify(body), { status })
	);
}

beforeEach(() => {
	vi.restoreAllMocks();
});

// ---------------------------------------------------------------------------
// fetchGitHubChangedFiles
// ---------------------------------------------------------------------------

describe('fetchGitHubChangedFiles', () => {
	it('maps added status correctly', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [{ filename: 'src/new.ts', status: 'added', sha: 'abc123' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result).toHaveLength(1);
		expect(result[0]).toMatchObject({ path: 'src/new.ts', status: 'added', sha: 'abc123' });
	});

	it('maps modified status correctly', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [{ filename: 'src/index.ts', status: 'modified', sha: 'def456' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result[0]).toMatchObject({ path: 'src/index.ts', status: 'modified' });
	});

	it('maps removed status correctly and omits sha', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [{ filename: 'src/old.ts', status: 'removed', sha: '000000' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result[0]).toMatchObject({ path: 'src/old.ts', status: 'removed' });
		expect(result[0].sha).toBeUndefined();
	});

	it('maps renamed status and sets previousPath', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [
				{
					filename: 'src/renamed.ts',
					status: 'renamed',
					sha: 'ghi789',
					previous_filename: 'src/original.ts'
				}
			]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result[0]).toMatchObject({
			path: 'src/renamed.ts',
			status: 'renamed',
			previousPath: 'src/original.ts',
			sha: 'ghi789'
		});
	});

	it('returns empty array when compare status is identical', async () => {
		mockFetch(200, { status: 'identical', files: [] });
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.0.0');
		expect(result).toEqual([]);
	});

	it('returns empty array when compare status is behind', async () => {
		mockFetch(200, {
			status: 'behind',
			files: [{ filename: 'src/index.ts', status: 'modified', sha: 'abc' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.1.0', 'v1.0.0');
		expect(result).toEqual([]);
	});

	it('throws GitHubApiError on 401 unauthorized', async () => {
		mockFetch(401, { message: 'Unauthorized' });
		await expect(
			fetchGitHubChangedFiles('owner', 'private-repo', 'v1.0.0', 'v1.1.0')
		).rejects.toThrow(GitHubApiError);
	});

	it('throws GitHubApiError on 404 not found', async () => {
		mockFetch(404, { message: 'Not Found' });
		await expect(
			fetchGitHubChangedFiles('owner', 'missing-repo', 'v1.0.0', 'v1.1.0')
		).rejects.toThrow(GitHubApiError);
	});

	it('throws GitHubApiError on 422 unprocessable entity', async () => {
		mockFetch(422, { message: 'Unprocessable Entity' });
		await expect(
			fetchGitHubChangedFiles('owner', 'repo', 'bad-ref', 'v1.1.0')
		).rejects.toThrow(GitHubApiError);
	});

	it('returns empty array when files property is missing', async () => {
		mockFetch(200, { status: 'ahead' });
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result).toEqual([]);
	});

	it('returns empty array when files array is empty', async () => {
		mockFetch(200, { status: 'ahead', files: [] });
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result).toEqual([]);
	});

	it('maps copied status to modified', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [{ filename: 'src/copy.ts', status: 'copied', sha: 'jkl012' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result[0]).toMatchObject({ path: 'src/copy.ts', status: 'modified' });
	});

	it('maps changed status to modified', async () => {
		mockFetch(200, {
			status: 'ahead',
			files: [{ filename: 'src/changed.ts', status: 'changed', sha: 'mno345' }]
		});
		const result = await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		expect(result[0]).toMatchObject({ path: 'src/changed.ts', status: 'modified' });
	});

	it('sends Authorization header when token is provided', async () => {
		const fetchSpy = vi.spyOn(global, 'fetch').mockResolvedValueOnce(
			new Response(JSON.stringify({ status: 'ahead', files: [] }), { status: 200 })
		);
		await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0', 'my-token');
		const callArgs = fetchSpy.mock.calls[0];
		const headers = (callArgs[1] as RequestInit).headers as Record<string, string>;
		expect(headers['Authorization']).toBe('Bearer my-token');
	});

	it('does not send Authorization header when no token provided', async () => {
		const fetchSpy = vi.spyOn(global, 'fetch').mockResolvedValueOnce(
			new Response(JSON.stringify({ status: 'ahead', files: [] }), { status: 200 })
		);
		await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
		const callArgs = fetchSpy.mock.calls[0];
		const headers = (callArgs[1] as RequestInit).headers as Record<string, string>;
		expect(headers['Authorization']).toBeUndefined();
	});

	it('throws GitHubApiError with correct status code', async () => {
		mockFetch(403, { message: 'Forbidden' });
		try {
			await fetchGitHubChangedFiles('owner', 'repo', 'v1.0.0', 'v1.1.0');
			expect.fail('should have thrown');
		} catch (e) {
			expect(e).toBeInstanceOf(GitHubApiError);
			expect((e as GitHubApiError).status).toBe(403);
		}
	});
});