/**
 * cli:aggregate-outbox — generate.ts
 *
 * Glob → parse → verify → emit (mirrors aggregate-component-registry's shape):
 *
 * 1. Walk `src/features` for `<...>/outbox/*Outbox.ts` modules (the files
 *    scaffold-api-client emits for offline: 'write' entities).
 * 2. Parse each for `export function register<X>Outbox` and
 *    `export const <X>_RESOURCE = '<key>'`.
 * 3. HARD ERROR on a resource key declared by two files (last-registration-wins
 *    at runtime would silently shadow one entity's specs).
 * 4. Emit src/extensions/outbox.generated.ts — one import + one call per module,
 *    alphabetical by path. When NO module exists the file is STILL emitted
 *    (header + placeholder comment) so main.tsx's unconditional import always
 *    resolves.
 *
 * Sync + self-contained fs reads so tests can drive it on mkdtemp fixtures.
 */
import fs from 'node:fs'
import path from 'node:path'
import type { GeneratedFile } from './types.js'

export const OUT_FILE = 'src/extensions/outbox.generated.ts'

const REGISTER_FN_RE = /export\s+function\s+(register\w*Outbox)\s*\(/g
const RESOURCE_RE = /export\s+const\s+([A-Z0-9_]+)_RESOURCE\s*=\s*'([^']+)'/g

export interface OutboxModule {
  /** Web-root-relative path, posix separators (e.g. src/features/.../outbox/employeeOutbox.ts). */
  file: string
  registerFns: string[]
  /** Resource keys declared via `export const X_RESOURCE = '...'`. */
  resources: string[]
}

export interface GenerateResult {
  files: GeneratedFile[]
  modules: OutboxModule[]
  errors: string[]
  warnings: string[]
}

/** Recursively collect `<...>/outbox/*Outbox.ts` files (skips node_modules). */
function walkOutboxFiles(dir: string): string[] {
  const out: string[] = []
  let entries: fs.Dirent[]
  try {
    entries = fs.readdirSync(dir, { withFileTypes: true })
  } catch {
    return out
  }
  for (const entry of entries) {
    const abs = path.join(dir, entry.name)
    if (entry.isDirectory()) {
      if (entry.name === 'node_modules') continue
      out.push(...walkOutboxFiles(abs))
    } else if (
      entry.isFile() &&
      /Outbox\.ts$/.test(entry.name) &&
      path.basename(dir) === 'outbox'
    ) {
      out.push(abs)
    }
  }
  return out
}

const HEADER = `// ============================================================================
// outbox.generated.ts — Auto-aggregated offline-write outbox registrations
// ============================================================================
// Generated by skills/development/frontend/pwa/cli/aggregate-outbox.
// Do NOT edit by hand — re-run the CLI to regenerate.
// Imported by src/main.tsx BEFORE initOutbox() so every spec is registered
// before the boot drain replays queued mutations.
`

export function generate(input: { webRootAbs: string }): GenerateResult {
  const errors: string[] = []
  const warnings: string[] = []

  const featuresDir = path.join(input.webRootAbs, 'src', 'features')
  const absFiles = fs.existsSync(featuresDir) ? walkOutboxFiles(featuresDir) : []

  const modules: OutboxModule[] = absFiles
    .map((abs) => {
      const rel = path.relative(input.webRootAbs, abs).replace(/\\/g, '/')
      let content = ''
      try {
        content = fs.readFileSync(abs, 'utf-8')
      } catch {
        warnings.push(`Could not read ${rel} — skipped.`)
        return null
      }
      const registerFns: string[] = []
      const resources: string[] = []
      REGISTER_FN_RE.lastIndex = 0
      let m: RegExpExecArray | null
      while ((m = REGISTER_FN_RE.exec(content)) !== null) registerFns.push(m[1])
      RESOURCE_RE.lastIndex = 0
      while ((m = RESOURCE_RE.exec(content)) !== null) resources.push(m[2])
      if (registerFns.length === 0) {
        warnings.push(`${rel} exports no register*Outbox function — skipped (not aggregated).`)
        return null
      }
      if (resources.length === 0) {
        warnings.push(`${rel} declares no *_RESOURCE const — duplicate-resource detection cannot cover it.`)
      }
      return { file: rel, registerFns, resources }
    })
    .filter((x): x is OutboxModule => x !== null)
    .sort((a, b) => a.file.localeCompare(b.file))

  // Duplicate resource keys across files → hard error (silent runtime shadowing).
  const owners = new Map<string, string[]>()
  for (const mod of modules) {
    for (const key of mod.resources) {
      const list = owners.get(key) ?? []
      list.push(mod.file)
      owners.set(key, list)
    }
  }
  for (const [key, files] of owners) {
    if (files.length > 1) {
      errors.push(
        `Duplicate outbox resource key '${key}' declared by ${files.join(' AND ')} — resource keys must be unique across the app (the outbox folds records by this key).`,
      )
    }
  }

  const files: GeneratedFile[] = []
  if (errors.length === 0) {
    let body: string
    if (modules.length === 0) {
      body = '\n// No offline-write outbox modules yet.\n'
    } else {
      const imports = modules
        .map((mod) => {
          const spec = '@/' + mod.file.replace(/^src\//, '').replace(/\.ts$/, '')
          return `import { ${mod.registerFns.join(', ')} } from '${spec}';`
        })
        .join('\n')
      const calls = modules
        .flatMap((mod) => mod.registerFns)
        .map((fn) => `${fn}();`)
        .join('\n')
      body = `\n${imports}\n\n${calls}\n`
    }
    files.push({ path: OUT_FILE, content: HEADER + body })
  }

  return { files, modules, errors, warnings }
}