/**
 * cli:derive-test-data — validate.ts
 *
 * Spec validation + prerequisites. The module folder and its `entité.md` are
 * existence-gated (a dataset is checked AGAINST a data model — without one
 * there is nothing to be coherent with, and the error names the skill that
 * produces it). `jeu-de-test.md` is deliberately NOT a prerequisite: the
 * dataset is optional, its absence is a RESULT the report says out loud.
 */
import { existsSync, statSync } from 'node:fs'
import { isAbsolute, join } from 'node:path'
import { DeriveTestDataInputSchema, type ValidationResult } from './types.js'

/** entité.md exists on disk under either Unicode normalization. */
export function entiteDocPath(moduleDir: string): string | null {
  for (const fileName of ['entité.md', 'entité.md'.normalize('NFD')]) {
    const p = join(moduleDir, fileName)
    try {
      if (existsSync(p) && statSync(p).isFile()) return p
    } catch {
      /* unreadable — treated as absent */
    }
  }
  return null
}

export function validateSpec(raw: unknown, workdir?: string): ValidationResult {
  const parsed = DeriveTestDataInputSchema.safeParse(raw)
  if (!parsed.success) {
    return {
      valid: false,
      errors: parsed.error.issues.map((i) => `[${i.path.join('.')}] ${i.message}`),
    }
  }
  const spec = parsed.data
  const resolvedBaRoot = isAbsolute(spec.baRoot) ? spec.baRoot : join(workdir ?? process.cwd(), spec.baRoot)

  const errors: string[] = []
  const moduleDir = join(resolvedBaRoot, spec.app, spec.module)
  if (!existsSync(moduleDir)) {
    errors.push(`Module folder not found: ${moduleDir}`)
    return { valid: false, errors, spec, resolvedBaRoot }
  }
  if (entiteDocPath(moduleDir) === null) {
    errors.push(`${spec.app}/${spec.module} has no entité.md — run /ba-create-data-model (phase 6) first.`)
  }
  return { valid: errors.length === 0, errors, spec, resolvedBaRoot }
}