import { describe, it, expect } from 'vitest';
import { createSmartDiff } from './diff-utils.js';
describe('createSmartDiff', () => {
    it('returns no-change with full content when content is identical', () => {
        const result = createSmartDiff({
            oldContent: 'hello\nworld',
            newContent: 'hello\nworld',
        });
        expect(result.type).toBe('no-change');
        expect(result.content).toBe('hello\nworld');
    });
    it('returns full content when diff would be longer', () => {
        // Small content - diff overhead makes it longer than full content
        const result = createSmartDiff({
            oldContent: 'line1\nline2\nline3\nline4\nline5',
            newContent: 'line1\nline2-modified\nline3\nline4\nline5',
        });
        expect(result.type).toBe('full');
        expect(result.content).toBe('line1\nline2-modified\nline3\nline4\nline5');
    });
    it('returns diff for large content with small changes', () => {
        // Generate large content where diff will be shorter
        const lines = Array.from({ length: 100 }, (_, i) => `line ${i + 1}: some content here`);
        const oldContent = lines.join('\n');
        const newLines = [...lines];
        newLines[50] = 'line 51: MODIFIED content here';
        const newContent = newLines.join('\n');
        const result = createSmartDiff({ oldContent, newContent });
        expect(result.type).toBe('diff');
        expect(result.content).toContain('-line 51: some content here');
        expect(result.content).toContain('+line 51: MODIFIED content here');
    });
    it('returns full content when changes exceed 50% threshold', () => {
        const result = createSmartDiff({
            oldContent: 'a\nb\nc\nd',
            newContent: 'x\ny\nz\nw',
        });
        expect(result.type).toBe('full');
        expect(result.content).toBe('x\ny\nz\nw');
    });
    it('respects custom threshold with large content', () => {
        // Generate content where diff is shorter than full
        const lines = Array.from({ length: 50 }, (_, i) => `line ${i + 1}`);
        const oldContent = lines.join('\n');
        const newLines = [...lines];
        // Change 25 lines = 50%
        for (let i = 0; i < 25; i++) {
            newLines[i * 2] = `CHANGED ${i}`;
        }
        const newContent = newLines.join('\n');
        // With 40% threshold, should return full (50% >= 40%)
        const resultLow = createSmartDiff({
            oldContent,
            newContent,
            threshold: 0.4,
        });
        expect(resultLow.type).toBe('full');
        // With 60% threshold, should return diff (50% < 60%) - but only if diff is shorter
        const resultHigh = createSmartDiff({
            oldContent,
            newContent,
            threshold: 0.6,
        });
        // For this case, even with high threshold, the diff may be longer than full content
        // so it could return 'full' - the key is threshold + length check both apply
        expect(['diff', 'full']).toContain(resultHigh.type);
    });
    it('uses custom label in diff output', () => {
        // Generate large content where diff will be shorter than full
        const lines = Array.from({ length: 100 }, (_, i) => `line ${i + 1}: content`);
        const oldContent = lines.join('\n');
        const newLines = [...lines];
        newLines[50] = 'line 51: MODIFIED';
        const newContent = newLines.join('\n');
        const result = createSmartDiff({
            oldContent,
            newContent,
            label: 'snapshot',
        });
        expect(result.type).toBe('diff');
        expect(result.content).toContain('--- snapshot');
        expect(result.content).toContain('+++ snapshot');
    });
    it('handles empty old content (all additions)', () => {
        const result = createSmartDiff({
            oldContent: '',
            newContent: 'new\ncontent\nhere',
        });
        // 100% new content should trigger full
        expect(result.type).toBe('full');
        expect(result.content).toContain('new\ncontent\nhere');
    });
    it('handles empty new content (all deletions)', () => {
        const result = createSmartDiff({
            oldContent: 'old\ncontent\nhere',
            newContent: '',
        });
        expect(result.type).toBe('full');
        expect(result.content).toBe('');
    });
    it('handles single line changes', () => {
        const result = createSmartDiff({
            oldContent: 'single line',
            newContent: 'modified line',
        });
        // 100% change on single line
        expect(result.type).toBe('full');
    });
    it('returns full content when most lines changed', () => {
        // 4 lines changed out of 5 = 80%
        const result = createSmartDiff({
            oldContent: 'a\nb\nc\nd\ne',
            newContent: 'a\nX\nY\nZ\nW',
        });
        expect(result.type).toBe('full');
        expect(result.content).toBe('a\nX\nY\nZ\nW');
    });
    it('includes context lines in diff output', () => {
        // Generate large content where diff is shorter than full
        const lines = Array.from({ length: 100 }, (_, i) => `line ${i + 1}: some longer content`);
        const oldContent = lines.join('\n');
        const newLines = [...lines];
        newLines[50] = 'line 51: MODIFIED content';
        const newContent = newLines.join('\n');
        const result = createSmartDiff({
            oldContent,
            newContent,
        });
        expect(result.type).toBe('diff');
        // Should have context around the change
        expect(result.content).toContain('line 50');
        expect(result.content).toContain('-line 51: some longer content');
        expect(result.content).toContain('+line 51: MODIFIED content');
        expect(result.content).toContain('line 52');
    });
});
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