/**
 * cli:scaffold-external-api — validate.ts
 *
 * Fail-closed. Everything rejected here is something that would otherwise fail
 * at boot (a colliding catalogue code breaks the unique index and takes the
 * whole seeding pass down with it) or answer a silent runtime 403/404 to the
 * third party — the two failure modes this stratum is prone to.
 */
import {
  catalogRowsFor,
  validatePublicApiCode,
} from '../../../lib/external-api-catalog.js'
import { ScaffoldExternalApiInputSchema, type ValidationResult } from './types.js'

export function validate(raw: unknown): ValidationResult {
  const parsed = ScaffoldExternalApiInputSchema.safeParse(raw)
  if (!parsed.success) {
    return {
      valid: false,
      errors: parsed.error.issues.map(i => `[${i.path.join('.')}] ${i.message}`),
      warnings: [],
    }
  }

  const spec = parsed.data
  const errors: string[] = []
  const warnings: string[] = []
  const seen = new Map<string, string>()

  for (const resource of spec.resources) {
    const label = `${resource.entity} (${resource.module}/${resource.section})`

    const rows = catalogRowsFor({
      applicationCode: spec.applicationCode,
      moduleCode: resource.module,
      sectionCode: resource.section,
      entityName: resource.entity,
      operations: resource.operations,
      granularity: resource.granularity,
      maxPageSize: resource.maxPageSize,
      rateLimitPerMinute: resource.rateLimitPerMinute,
    })

    for (const row of rows) {
      const codeError = validatePublicApiCode(row.code, resource.section)
      if (codeError) errors.push(`${label}: ${codeError}`)

      const owner = seen.get(row.code)
      if (owner && owner !== label) {
        errors.push(
          `catalogue code "${row.code}" is claimed by both ${owner} and ${label} — DataApiEndpoint.Code is UNIQUE database-wide, so the boot seed would fail`,
        )
      }
      seen.set(row.code, label)
    }

    // A write surface with no readable counterpart leaves the third party
    // unable to confirm what it wrote — and no id to address on update/delete.
    const writes = resource.operations.filter(o => o !== 'read')
    if (writes.length > 0 && !resource.operations.includes('read')) {
      errors.push(
        `${label}: publishes ${writes.join('/')} without read — a third party would have no way to read back what it wrote, nor any id to address`,
      )
    }

    // Create/Update map the DTO members positionally onto the command record:
    // an empty field list emits `new CreateXCommand()`, which is CS7036.
    if ((resource.operations.includes('create') || resource.operations.includes('update')) && resource.fields.length === 0) {
      errors.push(
        `${label}: create/update published but fields[] is empty — the generated command call would have no arguments and fail to compile`,
      )
    }

    if (resource.operations.includes('create') && resource.naturalKey.length === 0) {
      warnings.push(
        `${label}: create published without naturalKey[] — a retried POST creates a duplicate. Declare the natural key AND a unique index on the entity (DEV-XAPI-009).`,
      )
    }

    for (const key of resource.naturalKey) {
      if (!resource.fields.some(f => f.name.toLowerCase() === key.toLowerCase())) {
        errors.push(`${label}: naturalKey member "${key}" is not among fields[]`)
      }
    }

    if (resource.granularity === 'resource' && writes.length > 0) {
      warnings.push(
        `${label}: granularity 'resource' with writes forces the wildcard permission "${rows[0]?.requiredPermission}" — one grant covers every verb, a read-only partner becomes impossible, and any action later added to the section is granted retroactively (DEV-XAPI-013).`,
      )
    }

    if (!resource.modifiedSinceFilter) {
      warnings.push(
        `${label}: no modifiedSince filter — the third party can only page full snapshots. Declare the filter on the pagespec so it reaches Get${resource.pluralName ?? resource.entity + 's'}Query, then set modifiedSinceFilter: true.`,
      )
    }
  }

  return { valid: errors.length === 0, errors, warnings }
}