import { describe, it, expect } from 'vitest'
import { buildDiffView } from '../src/renderer/src/editor'
import { makeDiff } from '../src/renderer/src/diff'

/** The current-side view of one text pair, plus the map the overlay reads. */
function view(original: string, updated: string): ReturnType<typeof buildDiffView> {
  return buildDiffView(makeDiff('M', original, updated))
}

describe('buildDiffView', () => {
  it('maps an added line to the line it replaced', () => {
    const { lines, peek } = view('a\nold\nb', 'a\nnew\nb')
    expect(lines.map((l) => l.text)).toEqual(['a', 'new', 'b'])
    expect(lines[1].row).toBe('add')
    expect(peek.get(2)).toEqual({ anchor: 2, from: 2, to: 2 })
    expect(lines.every((l) => !l.gap)).toBe(true)
  })

  it('puts a pure deletion on the line that follows it', () => {
    const { lines, peek } = view('a\ngone\nb', 'a\nb')
    expect(lines[1].text).toBe('b')
    expect(lines[1].gap).toBe('above')
    expect(lines[1].row).toBeNull()
    expect(peek.get(2)).toEqual({ anchor: 2, from: 2, to: 2 })
  })

  it('puts a deletion at end of file under the last line', () => {
    const { lines, peek } = view('a\nb\ntail', 'a\nb')
    expect(lines[1].gap).toBe('below')
    expect(peek.get(2)).toEqual({ anchor: 3, from: 3, to: 3 })
  })

  it('anchors an insertion but marks nothing as removed', () => {
    const { lines, peek } = view('a\nb', 'a\nNEW\nb')
    expect(lines[1].row).toBe('add')
    expect(peek.get(2)).toEqual({ anchor: 1, from: null, to: null })
    expect(lines.every((l) => !l.gap)).toBe(true)
  })

  it('leaves an unchanged file without marks or peek targets', () => {
    const { lines, peek } = view('a\nb\n', 'a\nb\n')
    expect(peek.size).toBe(0)
    expect(lines.every((l) => !l.row && !l.gap)).toBe(true)
  })
})