import { describe, expect, it } from 'vitest'
import { overall, validateReport } from '@extant2000/evidence-record'
import {
  codeOnly,
  toReport,
  compareImplementations,
  extractFunction,
  fingerprint,
  formatDrift,
} from '../src/index.js'

const A = `
// header comment
function evaluateSendRules(c) {
  if (!c.postalAddress) return { ok: false }
  return { ok: true }
}
module.exports = { evaluateSendRules }
`

// Same behaviour, different comments and formatting — must NOT be drift.
const B = `
/* different doc */
function evaluateSendRules(c) {
  // a comment the other copy does not have
  if (!c.postalAddress)    return { ok: false }

  return { ok: true }   // trailing note
}
`

// A real behavioural change — the postal-address check is gone.
const C = `
function evaluateSendRules(c) {
  return { ok: true }
}
`

describe('extractFunction', () => {
  it('extracts a function by brace matching', () => {
    expect(extractFunction(A, 'evaluateSendRules')).toContain('postalAddress')
  })

  it('handles nested braces without stopping early', () => {
    const src = 'function f() { if (x) { g({ a: 1 }) } return 2 }'
    expect(extractFunction(src, 'f')).toBe(src)
  })

  it('finds async and exported declarations', () => {
    expect(extractFunction('async function f() { return 1 }', 'f')).toBeTruthy()
    expect(extractFunction('export function f() { return 1 }', 'f')).toBeTruthy()
  })

  it('returns null when the function is absent', () => {
    expect(extractFunction(A, 'nope')).toBeNull()
  })
})

describe('codeOnly', () => {
  it('ignores comments and whitespace so docs may differ', () => {
    expect(codeOnly(extractFunction(A, 'evaluateSendRules')!))
      .toBe(codeOnly(extractFunction(B, 'evaluateSendRules')!))
  })

  it('does NOT ignore a behavioural change', () => {
    expect(codeOnly(extractFunction(A, 'evaluateSendRules')!))
      .not.toBe(codeOnly(extractFunction(C, 'evaluateSendRules')!))
  })
})

describe('compareImplementations', () => {
  it('reports identical copies as in sync', () => {
    const r = compareImplementations(
      [{ label: 'a', source: A }, { label: 'b', source: B }],
      'evaluateSendRules',
    )
    expect(r.inSync).toBe(true)
    expect(r.groups).toHaveLength(1)
    expect(r.vacuous).toBe(false)
  })

  it('catches the one-sided fix — the failure this exists for', () => {
    // A CAN-SPAM guard removed in one repo only.
    const r = compareImplementations(
      [{ label: 'hosting', source: A }, { label: 'crm', source: C }],
      'evaluateSendRules',
    )
    expect(r.inSync).toBe(false)
    expect(r.groups).toHaveLength(2)
    expect(formatDrift(r)).toContain('has drifted across')
  })

  it('groups three copies as 2-vs-1 and names which side is odd', () => {
    const r = compareImplementations(
      [{ label: 'a', source: A }, { label: 'b', source: B }, { label: 'c', source: C }],
      'evaluateSendRules',
    )
    // Majority group first.
    expect(r.groups[0]!.labels).toEqual(['a', 'b'])
    expect(r.groups[1]!.labels).toEqual(['c'])
  })

  it('treats a MISSING function as not-found, never as passing', () => {
    // Renamed or deleted is not "no drift" — a guard that cannot find its
    // subject is not passing.
    const r = compareImplementations(
      [{ label: 'a', source: A }, { label: 'gone', source: 'function other() {}' }],
      'evaluateSendRules',
    )
    expect(r.missing).toEqual(['gone'])
    expect(r.inSync).toBe(false)
    expect(formatDrift(r)).toContain('could not be found')
  })

  it('flags a single copy as NOT ASSESSED, not in sync', () => {
    // One copy cannot disagree with itself; calling that a pass would let a
    // deleted sibling read as clean.
    const r = compareImplementations([{ label: 'a', source: A }], 'evaluateSendRules')
    expect(r.vacuous).toBe(true)
    const text = formatDrift(r)
    expect(text).toContain('NOT ASSESSED')
    expect(text).toContain('One copy cannot disagree with itself')
    // The word it replaced needed a glossary.
    expect(text).not.toContain('VACUOUS')
  })

  it('an empty input set is vacuous', () => {
    expect(compareImplementations([], 'f').vacuous).toBe(true)
  })
})

describe('fingerprint', () => {
  it('is stable and differs on changed code', () => {
    expect(fingerprint('abc')).toBe(fingerprint('abc'))
    expect(fingerprint('abc')).not.toBe(fingerprint('abd'))
  })
})

describe('conformance with the evidence-record standard', () => {
  const A = 'function evaluateSendRules(c) {\n  if (c.unsub) return false\n  return true\n}'
  const B = 'function evaluateSendRules(c) {\n  return true\n}'

  it('cites the file of every copy that disagrees', () => {
    const r = compareImplementations([
      { label: 'crm', path: 'service-a/lib/send.js', source: A },
      { label: 'hosting', path: 'service-b/lib/send.js', source: B },
    ], 'evaluateSendRules')
    const text = formatDrift(r, { evidence: 'full' })
    expect(text).toContain('service-a/lib/send.js')
    expect(text).toContain('service-b/lib/send.js')
    expect(overall(toReport(r))).toBe('fail')
  })

  it('cites the copies behind an in-sync pass', () => {
    // A pass that cannot name what it compared is an asserted result.
    const r = compareImplementations([
      { label: 'crm', path: 'a/send.js', source: A },
      { label: 'hosting', path: 'b/send.js', source: A },
    ], 'evaluateSendRules')
    expect(overall(toReport(r))).toBe('pass')
    expect(formatDrift(r, { evidence: 'full' })).toContain('a/send.js')
  })

  it('every conclusion carries a citation', () => {
    const r = compareImplementations([
      { label: 'crm', path: 'a/send.js', source: A },
      { label: 'hosting', path: 'b/send.js', source: B },
    ], 'evaluateSendRules')
    expect(validateReport(toReport(r))).toEqual([])
  })
})

describe('a missing subject is a finding, not an absence of one', () => {
  it('stays assessed when one copy is present and one is missing', () => {
    // `vacuous` counts LOCATED copies, so this pair is vacuous by that
    // definition. Reporting it as NOT ASSESSED would hide a deleted or
    // renamed sibling behind "nothing was compared" — the exact failure this
    // library exists to catch.
    const r = compareImplementations(
      [
        { label: 'a', path: 'a/send.js', source: 'function evaluateSendRules(c) { return true }' },
        { label: 'gone', path: 'b/send.js', source: 'function other() {}' },
      ],
      'evaluateSendRules',
    )
    expect(r.vacuous).toBe(true)
    expect(overall(toReport(r))).toBe('fail')
    expect(formatDrift(r)).toContain('could not be found')
    expect(formatDrift(r)).not.toContain('NOT ASSESSED')
  })
})