#!/usr/bin/env node
/**
 * cli:derive-change-impact — entry point.
 *
 * READ-ONLY engine of `/ba-change`: for ONE element added to (or modified in)
 * a finished BA scope, reports the owner document, the next free code, the
 * near-duplicates, the fail-closed blockers and the ORDERED downstream
 * checklist (authoring hand-offs, derive-* CLIs, audit rules, /ba-develop
 * re-entries). `mode: verify` re-parses the owner doc after the skill's Write.
 *
 * Invocation (prefer --spec-file on Windows — multi-line inline JSON breaks
 * under Git Bash / PowerShell quoting):
 *   npx --prefer-offline tsx skills/business-analyse/change/cli/derive-change-impact/index.ts \
 *     --spec-file <scratchpad>/change.json [--workdir <dir>]
 *   npx --prefer-offline tsx skills/business-analyse/change/cli/derive-change-impact/index.ts \
 *     --spec '{"baRoot":".smartstack/ba","app":"CRM","module":"PIPELINE","section":"opportunites","kind":"use-case","target":{"title":"Relancer un prospect","actor":"BA-001-AC-001"}}'
 *
 * Drift is DATA (exit 0, `blocked[]` may be non-empty); exit 1 = spec error.
 */
import { parseArgs } from 'node:util'
import { executeEnvelope, failExecute, printEnvelope } from '../../../../lib/output.js'
import { readSpecArg } from '../../../../lib/spec-arg.js'
import { loadScopeCorpus } from './corpus.js'
import { executeChangeImpact, executeVerify } from './execute.js'
import type { ChangeImpactReport } from './types.js'
import { validateSpec } from './validate.js'

const COMMAND = 'derive-change-impact'

function main(): void {
  const { values } = parseArgs({
    options: {
      spec: { type: 'string' },
      'spec-file': { type: 'string' },
      workdir: { type: 'string' },
    },
    strict: true,
  })

  const specArg = readSpecArg(values)
  if ('error' in specArg) {
    printEnvelope(failExecute<ChangeImpactReport>(COMMAND, [specArg.error]))
    process.exit(1)
  }
  let raw: unknown
  try {
    raw = JSON.parse(specArg.raw)
  } catch {
    printEnvelope(failExecute<ChangeImpactReport>(COMMAND, ['Invalid JSON in --spec / --spec-file']))
    process.exit(1)
  }
  const validation = validateSpec(raw, values.workdir)
  if (!validation.valid || !validation.spec || !validation.scope) {
    printEnvelope(failExecute<ChangeImpactReport>(COMMAND, validation.errors))
    process.exit(1)
  }
  const spec = validation.spec
  const corpus = loadScopeCorpus(validation.scope, spec.projectPath)
  const report = spec.mode === 'verify' ? executeVerify(spec, corpus) : executeChangeImpact(spec, corpus)

  const nextSteps: string[] = []
  if (report.blocked.length > 0) {
    for (const b of report.blocked) {
      nextSteps.push(
        `BLOCKED ${b.code}: ${b.reason}${b.routeTo ? ` → ${b.routeTo.skill}${b.routeTo.kind ? ` kind=${b.routeTo.kind}` : ''}` : ''}${b.candidates && b.candidates.length > 0 ? ` (candidates: ${b.candidates.join(', ')})` : ''}`,
      )
    }
  } else if (report.mode === 'verify' && report.verify) {
    nextSteps.push(
      report.verify.ok
        ? `VERIFIED ${spec.verify!.expectCode}: ${report.verify.count} item(s) in ${report.owner.file} (delta ${report.verify.delta >= 0 ? '+' : ''}${report.verify.delta}), nothing lost, machine blocks ${report.verify.machineBlocksIntact === null ? 'not compared' : 'intact'}, sources ${report.verify.sourcesCited}.`
        : `NOT VERIFIED — fix before continuing: found=${report.verify.found}, delta=${report.verify.delta}, lost=${report.verify.lost.length}, duplicates=${report.verify.duplicates.length}, machineBlocksIntact=${report.verify.machineBlocksIntact}, sources=${report.verify.sourcesCited}.`,
    )
  } else {
    if (report.existing.exact.length > 0) {
      nextSteps.push(`${report.existing.exact.length} existing item(s) match — ask: reuse / modify the existing one / continue as new.`)
    }
    if (report.allocation) {
      nextSteps.push(
        `Next code: ${report.allocation.next} (headings up to ${String(report.allocation.maxTaken).padStart(3, '0')}, ${report.allocation.reserved.length} reserved number(s); limits: ${report.allocation.limits.join('; ')}).`,
      )
    }
    nextSteps.push(`Load kinds/${spec.kind}.md and walk the ${report.impact.length} impact step(s) IN ORDER; a \`skipped\` step is announced with its reason, never silently dropped.`)
    nextSteps.push('After the Write of the owner doc, re-run this CLI with mode=verify {expectCode, baselineCount: existing.count, machineBlocksHash: owner.machineBlocksHash}.')
  }

  printEnvelope(
    executeEnvelope<ChangeImpactReport>(COMMAND, {
      success: true,
      data: {
        kind: report.kind,
        op: report.op,
        mode: report.mode,
        blocked: report.blocked.length,
        next: report.allocation?.next ?? null,
        steps: report.impact.length,
        existingExact: report.existing.exact.length,
        verified: report.verify?.ok ?? null,
      },
      report,
      warnings: report.warnings,
      nextSteps,
    }),
  )
  process.exit(0)
}

main()