import { describe, it, expect } from 'vitest'
import { mergeLineIntoMarkerBlock, replaceMarkerBlock, spliceDiMarkerBlock } from '../di-markers.js'

const BEGIN = '// <<< BUSINESS-SERVICES-DI BEGIN >>>'
const END = '// <<< BUSINESS-SERVICES-DI END >>>'
const LINE_A = 'services.AddScoped<global::App.Interfaces.IOrderService, global::App.Services.OrderService>();'
const LINE_B = 'services.AddScoped<global::App.Interfaces.IDriverService, global::App.Services.DriverService>();'

const HOST_WITH_MARKERS = `public static IServiceCollection AddInfrastructure(this IServiceCollection services)
{
        // <<< BUSINESS-SERVICES-DI BEGIN >>>
        // services.AddScoped<IOrderService, OrderService>();
        // <<< BUSINESS-SERVICES-DI END >>>

        return services;
}
`

const HOST_WITHOUT_MARKERS = `public static IServiceCollection AddInfrastructure(this IServiceCollection services)
{
        services.AddScoped<ISomethingElse, SomethingElse>();

        return services;
}
`

describe('lib/di-markers — replaceMarkerBlock / spliceDiMarkerBlock (extraction contract)', () => {
  it('replaces an existing marker block content idempotently', () => {
    const block = `        ${BEGIN}\n        ${LINE_A}\n        ${END}`
    const once = spliceDiMarkerBlock(HOST_WITH_MARKERS, BEGIN, END, block)!
    expect(once).toContain(LINE_A)
    // Re-splicing the identical block reports "already up to date".
    expect(spliceDiMarkerBlock(once, BEGIN, END, block)).toBeNull()
  })

  it('falls back to inserting before the last `return services;` when markers are absent', () => {
    const block = `        ${BEGIN}\n        ${LINE_A}\n        ${END}`
    const next = spliceDiMarkerBlock(HOST_WITHOUT_MARKERS, BEGIN, END, block)!
    expect(next.indexOf(LINE_A)).toBeGreaterThan(next.indexOf('ISomethingElse'))
    expect(next.indexOf(LINE_A)).toBeLessThan(next.indexOf('return services;'))
  })

  it('replaceMarkerBlock returns undefined when the markers are missing (caller fallback)', () => {
    expect(replaceMarkerBlock(HOST_WITHOUT_MARKERS, BEGIN, END, 'x')).toBeUndefined()
  })
})

describe('lib/di-markers — mergeLineIntoMarkerBlock', () => {
  it('appends a line into the block, replacing the commented example', () => {
    const r = mergeLineIntoMarkerBlock(HOST_WITH_MARKERS, BEGIN, END, LINE_A)
    expect(r.status).toBe('patched')
    const src = (r as { source: string }).source
    expect(src).toContain(LINE_A)
    // The template's commented example is replaced, not kept alongside.
    expect(src).not.toContain('// services.AddScoped<IOrderService, OrderService>();')
  })

  it('unions lines — a second entity lands under the first, first order preserved', () => {
    const first = mergeLineIntoMarkerBlock(HOST_WITH_MARKERS, BEGIN, END, LINE_A)
    const second = mergeLineIntoMarkerBlock((first as { source: string }).source, BEGIN, END, LINE_B)
    const src = (second as { source: string }).source
    expect(src.indexOf(LINE_A)).toBeLessThan(src.indexOf(LINE_B))
    // One block only — the markers never duplicate.
    expect(src.split(BEGIN).length - 1).toBe(1)
  })

  it('re-merging the same line is a no-op (idempotent re-run)', () => {
    const first = mergeLineIntoMarkerBlock(HOST_WITH_MARKERS, BEGIN, END, LINE_A)
    const again = mergeLineIntoMarkerBlock((first as { source: string }).source, BEGIN, END, LINE_A)
    expect(again).toEqual({ status: 'unchanged', reason: 'line-in-block' })
  })

  it('a line the project already registered OUTSIDE the block is left alone (no double-register)', () => {
    const hand = HOST_WITH_MARKERS.replace(
      'return services;',
      `${LINE_A}\n        return services;`,
    )
    const r = mergeLineIntoMarkerBlock(hand, BEGIN, END, LINE_A)
    expect(r).toEqual({ status: 'unchanged', reason: 'line-outside-block' })
  })

  it('markers absent → creates the block through the return-services fallback (upgrade path)', () => {
    const r = mergeLineIntoMarkerBlock(HOST_WITHOUT_MARKERS, BEGIN, END, LINE_A)
    expect(r.status).toBe('patched')
    const src = (r as { source: string }).source
    expect(src).toContain(BEGIN)
    expect(src.indexOf(LINE_A)).toBeLessThan(src.indexOf('return services;'))
  })

  it('no insertion point at all → failed, never a silent drop', () => {
    const r = mergeLineIntoMarkerBlock('', BEGIN, END, LINE_A)
    expect(r).toEqual({ status: 'failed', reason: 'no-insertion-point' })
  })
})