import { describe, expect, it } from 'vitest'
import { decideBaseUpdate, isEfCoreConflict, buildConflictGuidance } from '../update-policy.js'

describe('decideBaseUpdate — pure decision for updating a branch from its base', () => {
  it('returns none when there is nothing to take from the base', () => {
    expect(decideBaseUpdate({ ahead: 0, behind: 0, strategy: 'merge' })).toBe('none')
    // ahead-only must NEVER touch the branch (regardless of strategy)
    expect(decideBaseUpdate({ ahead: 5, behind: 0, strategy: 'merge' })).toBe('none')
    expect(decideBaseUpdate({ ahead: 5, behind: 0, strategy: 'rebase' })).toBe('none')
  })

  it('fast-forwards when behind with no own commits — ff wins over BOTH strategies', () => {
    expect(decideBaseUpdate({ ahead: 0, behind: 3, strategy: 'merge' })).toBe('ff')
    expect(decideBaseUpdate({ ahead: 0, behind: 3, strategy: 'rebase' })).toBe('ff')
  })

  it('falls back to the chosen strategy only when genuinely diverged', () => {
    expect(decideBaseUpdate({ ahead: 2, behind: 3, strategy: 'merge' })).toBe('merge')
    expect(decideBaseUpdate({ ahead: 2, behind: 3, strategy: 'rebase' })).toBe('rebase')
  })
})

describe('isEfCoreConflict — EF Core artifacts in a conflict list', () => {
  it('detects files under a Migrations/ directory', () => {
    expect(isEfCoreConflict(['Migrations/20260101_Init.cs'])).toBe(true)
    expect(isEfCoreConflict(['src/Data/Migrations/20260101_Init.cs'])).toBe(true)
  })

  it('detects model snapshots anywhere, case-insensitively', () => {
    expect(isEfCoreConflict(['src/Persistence/FooModelSnapshot.cs'])).toBe(true)
    expect(isEfCoreConflict(['src/Persistence/foomodelsnapshot.CS'])).toBe(true)
  })

  it('does not match a file merely NAMED Migrations (not a directory segment)', () => {
    expect(isEfCoreConflict(['src/components/Migrations.tsx'])).toBe(false)
    expect(isEfCoreConflict(['src/MigrationsHelper.cs'])).toBe(false)
  })

  it('returns false for unrelated files and empty lists', () => {
    expect(isEfCoreConflict(['src/Program.cs', 'web/src/App.tsx'])).toBe(false)
    expect(isEfCoreConflict([])).toBe(false)
  })
})

describe('buildConflictGuidance — human guidance after a rolled-back conflict', () => {
  it('states the abort + untouched guarantee and names the operation and base ref', () => {
    const g = buildConflictGuidance({
      operation: 'merge',
      baseRef: 'origin/develop',
      branch: 'feature/x',
      conflictFiles: ['src/a.ts', 'src/b.ts'],
    })
    expect(g).toContain('aborted')
    expect(g).toContain('untouched')
    expect(g).toContain('merge')
    expect(g).toContain('origin/develop')
    expect(g).toContain('2 file(s)')
  })

  it('points at /efcore rebase-snapshot when EF Core files conflict', () => {
    const g = buildConflictGuidance({
      operation: 'rebase',
      baseRef: 'origin/develop',
      branch: 'feature/x',
      conflictFiles: ['src/Persistence/Migrations/AppModelSnapshot.cs'],
    })
    expect(g).toContain('/efcore rebase-snapshot')
  })

  it('does NOT mention efcore for non-EF conflicts', () => {
    const g = buildConflictGuidance({
      operation: 'merge',
      baseRef: 'origin/develop',
      branch: 'feature/x',
      conflictFiles: ['src/a.ts'],
    })
    expect(g).not.toContain('/efcore')
  })
})