/**
 * @local/dsh-abap-adt-ui — Host half.
 *
 * Visual configuration surface for @nefevcore/abap-adt-dsh-plugin:
 *   - reads/writes the workspace destinations file
 *     `<workspace>/.dsh-abap-adt/destinations.yaml` (the nearest config layer
 *     the abap-adt plugin re-reads on every adt_* tool call, so edits apply
 *     instantly without a restart);
 *   - tests an ADT endpoint (GET /sap/bc/adt/discovery with Basic auth);
 *   - exposes everything through three plain HTTP routes consumed by the
 *     Client half (settings page + composer status chip).
 *
 * No npm dependencies: only node builtins, so a workspace-linked bundle
 * resolves without its own node_modules. Password values are never accepted:
 * the page only stores a `passwordEnv` reference, which is resolved through
 * the DSH credential service (falling back to the process environment).
 */

import { existsSync, readdirSync } from 'node:fs'
import { mkdir, readFile, writeFile } from 'node:fs/promises'
import { request as httpRequest } from 'node:http'
import { request as httpsRequest } from 'node:https'
import { isAbsolute, join } from 'node:path'
import { pathToFileURL } from 'node:url'

const name = 'abap-adt-ui'
const CONFIG_DIR = '.dsh-abap-adt'
const FILE_NAMES = ['destinations.yaml', 'destinations.yml']

const DESTINATION_KEYS = [
  'name',
  'url',
  'description',
  'client',
  'language',
  'username',
  'passwordEnv',
  'strictSSL',
  'timeoutMs',
  'profile',
]

const POLICY_KEYS = [
  'enableTransports',
  'allowedTransports',
  'allowTransportableEdits',
  'allowedPackages',
  'allowExecution',
  'allowBatchWrites',
  'blockedTablesProfile',
  'blockedTables',
  'allowedTables',
  'allowDebugger',
  'allowDebugVariables',
]

/** Routes are prefix-matched so the Client can add query strings freely. */
const ROUTE_PREFIX = '/abap-adt'

/**
 * Run modes a workspace can switch between. Each mode is written as top-level
 * policy keys into that workspace's destinations.yaml, which the abap-adt
 * plugin applies to the destinations defined in the same file (nearest layer).
 * The preset keeps a read-only baseline, so an untouched workspace stays safe.
 */
const MODE_POLICIES = {
  'read-only': {
    // Transport READS stay available in read-only mode: `enableTransports`
    // gates the transport tool family (adt_transports / adt_object_versions —
    // both read-only tools); writes are blocked by the package sentinel below
    // plus allowTransportableEdits=false.
    enableTransports: true,
    allowedTransports: '*',
    allowTransportableEdits: false,
    allowedPackages: '__READ_ONLY_NO_PACKAGE__',
    allowExecution: false,
    allowBatchWrites: false,
    allowDebugger: false,
    allowDebugVariables: false,
  },
  debug: {
    // Same transport-read exception as read-only; the debugger/execution are
    // what this mode adds.
    enableTransports: true,
    allowedTransports: '*',
    allowTransportableEdits: false,
    allowedPackages: '__READ_ONLY_NO_PACKAGE__',
    allowExecution: true,
    allowBatchWrites: false,
    allowDebugger: true,
    allowDebugVariables: false,
  },
  change: {
    enableTransports: true,
    allowedTransports: '*',
    allowTransportableEdits: true,
    allowedPackages: 'Z*,$TMP',
    allowExecution: true,
    allowBatchWrites: false,
    // Change mode also carries the debugger: editing code needs the debugger.
    allowDebugger: true,
    allowDebugVariables: false,
  },
}

/** Defaults for the change-mode whitelists, editable from the settings page. */
const WHITELIST_DEFAULTS = { allowedPackages: 'Z*,$TMP', allowedTransports: '*' }
/** Per-workspace UI-only settings (never read by the abap-adt plugin). */
const UI_SETTINGS_FILE = 'ui-settings.json'

const MANAGED_MODE_START = '# >>> ABAP 运行模式（由设置页「ABAP ADT」维护，切换模式会重写本段）'
const MANAGED_MODE_END = '# <<< ABAP 运行模式'
const MANAGED_MODE_KEYS = Object.keys(MODE_POLICIES['read-only'])

/** Derive the workspace mode from the policy actually present in its file. */
function modeFromPolicy(policy) {
  if (policy?.allowTransportableEdits === true) return 'change'
  if (policy?.allowDebugger === true || policy?.allowExecution === true) return 'debug'
  return 'read-only'
}

export const inject = ['webServer']

export function apply(ctx, config) {
  const cfg = config ?? {}
  const log = ctx.logger?.(name) ?? console
  const profileDir = cfg.profileDir || process.env.DSH_PROFILE_DIR || ''

  /**
   * Candidate paths of the abap-adt core entry, first existing wins. The Host
   * process does not necessarily inherit DSH_PROFILE_DIR, so fall back to the
   * DSH home layout and scan the profile roots for an installed core.
   */
  function coreEntryCandidates() {
    const suffix = 'node_modules/@nefevcore/abap-adt-core/lib/index.js'
    const candidates = []
    if (cfg.coreEntry) candidates.push(cfg.coreEntry)
    const home = process.env.USERPROFILE || process.env.HOME || ''
    const dshHome = process.env.DSH_HOME || (home ? join(home, '.dsh') : '')
    const profilesRoot = dshHome ? join(dshHome, 'profiles') : ''
    if (profileDir) candidates.push(join(profileDir, suffix))
    if (profilesRoot) {
      if (process.env.DSH_PROFILE) candidates.push(join(profilesRoot, process.env.DSH_PROFILE, suffix))
      try {
        for (const entry of readdirSync(profilesRoot)) candidates.push(join(profilesRoot, entry, suffix))
      } catch {
        /* no profiles directory */
      }
    }
    return [...new Set(candidates)].filter((candidate) => candidate && existsSync(candidate))
  }

  // The abap-adt core is imported lazily and cached: it is a heavy module
  // (abaplint) and only needed when the page actually reads an existing file.
  let corePromise
  function loadCore() {
    if (!corePromise) {
      const [entry] = coreEntryCandidates()
      corePromise = entry
        ? import(pathToFileURL(entry).href).catch((err) => {
            log.warn?.(`abap-adt-ui: core import failed: ${err.message}`)
            return undefined
          })
        : Promise.resolve(undefined)
    }
    return corePromise
  }

  // ---------------------------------------------------------------- YAML ----
  const tokens = ['true', 'false', 'null', '~']

  function yamlScalar(value) {
    if (value === true || value === false) return String(value)
    if (typeof value === 'number' && Number.isFinite(value)) return String(value)
    if (value === null || value === undefined) return "''"
    const text = String(value)
    if (text === '') return "''"
    // Keep numeric-looking values (SAP client '100', system numbers) as
    // strings: the abap-adt schema declares them as strings, and an unquoted
    // 100 would parse as a number.
    if (/^-?\d+(\.\d+)?$/.test(text)) return `'${text}'`
    if (/^[A-Za-z0-9_@.$*?\-/]+$/.test(text) && !tokens.includes(text.toLowerCase())) {
      // A leading `*`/`?` would be a YAML alias/indicator; quote those.
      if (!/^[*?&!|>%@`{]/.test(text)) return text
    }
    return `'${text.replace(/'/g, "''")}'`
  }

  function parseScalar(raw) {
    let text = String(raw ?? '').trim()
    if (text === '') return ''
    if (text.startsWith("'") && text.endsWith("'") && text.length >= 2) {
      return text.slice(1, -1).replace(/''/g, "'")
    }
    if (text.startsWith('"') && text.endsWith('"') && text.length >= 2) {
      try {
        return JSON.parse(text)
      } catch {
        return text.slice(1, -1)
      }
    }
    const lower = text.toLowerCase()
    if (lower === 'true') return true
    if (lower === 'false') return false
    if (lower === 'null' || lower === '~') return null
    return text
  }

  /**
   * Parse the destinations file. The abap-adt core's own parser is used when
   * it is resolvable (full schema compatibility, including files the plugin
   * itself generated); otherwise this tolerant line parser handles the format
   * this page writes plus ordinary hand edits.
   */
  async function parseDestinations(raw) {
    const core = await loadCore()
    if (core?.parseExternalConfigText) {
      try {
        const parsed = core.parseExternalConfigText(raw)
        const layer = parsed?.config ?? parsed?.layer ?? parsed
        if (layer && typeof layer === 'object') {
          return {
            destinations: Array.isArray(layer.destinations) ? layer.destinations : [],
            defaultDestination: layer.defaultDestination,
            policy: pickPolicy(layer),
            parser: 'core',
          }
        }
      } catch (err) {
        log.warn?.(`abap-adt-ui: core parse failed, using fallback: ${err.message}`)
      }
    }
    return { ...fallbackParse(raw), parser: 'fallback' }
  }

  function pickPolicy(layer) {
    const policy = {}
    for (const key of POLICY_KEYS) {
      if (layer[key] !== undefined && layer[key] !== null) policy[key] = layer[key]
    }
    return policy
  }

  function fallbackParse(raw) {
    const result = { destinations: [], defaultDestination: undefined, policy: {} }
    let current
    let inDestinations = false
    for (const rawLine of raw.split(/\r?\n/)) {
      const line = rawLine.replace(/\s+$/, '')
      if (!line.trim() || line.trim().startsWith('#')) continue
      const indent = line.match(/^\s*/)[0].length
      const body = line.trim()
      if (indent === 0) {
        current = undefined
        inDestinations = false
        const m = body.match(/^([A-Za-z_][\w-]*)\s*:\s*(.*)$/)
        if (!m) continue
        const [, key, rest] = m
        if (key === 'destinations') {
          inDestinations = true
          if (rest.trim() === '[]') result.destinations = []
          continue
        }
        if (key === 'defaultDestination') {
          result.defaultDestination = parseScalar(rest)
          continue
        }
        if (POLICY_KEYS.includes(key)) {
          result.policy[key] = parseScalar(rest)
        }
        continue
      }
      if (!inDestinations) continue
      const item = body.match(/^-\s*(.*)$/)
      if (item) {
        current = {}
        result.destinations.push(current)
        const m = item[1].trim().match(/^([A-Za-z_][\w-]*)\s*:\s*(.*)$/)
        if (m) current[m[1]] = parseScalar(m[2])
        continue
      }
      const pair = body.match(/^([A-Za-z_][\w-]*)\s*:\s*(.*)$/)
      if (pair && current) current[pair[1]] = parseScalar(pair[2])
    }
    return result
  }

  function emitDestinations({ defaultDestination, destinations, policy }) {
    const lines = [
      '# ABAP ADT 目的地配置 — 由 DSH 设置页「ABAP ADT」维护，也可手动编辑。',
      '# abap-adt 插件在每次 adt_* 工具调用时重读本文件，改动无需重启。',
      '# 密码只写引用名（passwordEnv），真值走 DSH 凭据库或进程环境变量。',
      '',
    ]
    if (defaultDestination) lines.push(`defaultDestination: ${yamlScalar(defaultDestination)}`)
    if (!destinations.length) {
      lines.push('destinations: []')
    } else {
      lines.push('destinations:')
      for (const dest of destinations) {
        lines.push(`  - name: ${yamlScalar(dest.name)}`)
        for (const key of DESTINATION_KEYS) {
          if (key === 'name') continue
          const value = dest[key]
          if (value === undefined || value === null || value === '') continue
          lines.push(`    ${key}: ${yamlScalar(value)}`)
        }
      }
    }
    for (const key of POLICY_KEYS) {
      const value = policy?.[key]
      if (value === undefined || value === null || value === '') continue
      if (Array.isArray(value)) {
        if (!value.length) continue
        lines.push(`${key}:`)
        for (const item of value) lines.push(`  - ${yamlScalar(item)}`)
      } else {
        lines.push(`${key}: ${yamlScalar(value)}`)
      }
    }
    return `${lines.join('\n')}\n`
  }

  /**
   * Change only the top-level `defaultDestination` line of an existing file,
   * preserving the rest of the text (comments, ordering, hand edits). Used by
   * the composer status chip, which switches the default without rewriting the
   * destination list.
   */
  function setDefaultInText(raw, value) {
    const lines = raw.split(/\r?\n/)
    const index = lines.findIndex((line) => /^defaultDestination\s*:/.test(line))
    const rendered = value ? `defaultDestination: ${yamlScalar(value)}` : undefined
    if (index >= 0) {
      if (rendered) lines[index] = rendered
      else lines.splice(index, 1)
    } else if (rendered) {
      // Insert after the leading comment/blank header, before the first key.
      let insertAt = 0
      for (let i = 0; i < lines.length; i += 1) {
        const text = lines[i].trim()
        if (text === '' || text.startsWith('#')) insertAt = i + 1
        else break
      }
      lines.splice(insertAt, 0, rendered, '')
    }
    return lines.join('\n')
  }

  /**
   * Rewrite the managed run-mode policy block. Any previous managed block and
   * any top-level copies of the managed keys are removed first so the YAML can
   * never contain duplicate keys (the abap-adt parser rejects those).
   */
  /** The policy actually written for a mode, with the change-mode whitelists. */
  function policyForMode(mode, whitelist = {}) {
    const base = MODE_POLICIES[mode]
    if (!base) throw new Error(`unknown mode: ${mode}`)
    if (mode !== 'change') return { ...base }
    return {
      ...base,
      allowedPackages: whitelist.allowedPackages || WHITELIST_DEFAULTS.allowedPackages,
      allowedTransports: whitelist.allowedTransports || WHITELIST_DEFAULTS.allowedTransports,
    }
  }

  /** Read the workspace's UI-only settings (whitelists + display labels). */
  async function readUiSettings(workspace) {
    const fallback = { ...WHITELIST_DEFAULTS, labels: {} }
    try {
      const raw = await readFile(join(workspace, CONFIG_DIR, UI_SETTINGS_FILE), 'utf8')
      const parsed = JSON.parse(raw)
      const pick = (key) =>
        typeof parsed?.[key] === 'string' && parsed[key].trim() ? parsed[key].trim() : fallback[key]
      const labels = {}
      if (parsed?.labels && typeof parsed.labels === 'object') {
        for (const [name, label] of Object.entries(parsed.labels)) {
          if (typeof name === 'string' && name && typeof label === 'string' && label.trim()) {
            labels[name] = label.trim().slice(0, 80)
          }
        }
      }
      return { allowedPackages: pick('allowedPackages'), allowedTransports: pick('allowedTransports'), labels }
    } catch {
      return fallback
    }
  }

  async function writeUiSettings(workspace, values) {
    const payload = {
      allowedPackages: values.allowedPackages || WHITELIST_DEFAULTS.allowedPackages,
      allowedTransports: values.allowedTransports || WHITELIST_DEFAULTS.allowedTransports,
      labels: values.labels && typeof values.labels === 'object' ? values.labels : {},
    }
    await mkdir(join(workspace, CONFIG_DIR), { recursive: true })
    await writeFile(join(workspace, CONFIG_DIR, UI_SETTINGS_FILE), `${JSON.stringify(payload, null, 2)}\n`, 'utf8')
    return payload
  }

  /**
   * Rewrite the managed run-mode policy block. Any previous managed block and
   * any top-level copies of the managed keys are removed first so the YAML can
   * never contain duplicate keys (the abap-adt parser rejects those).
   */
  function setModeInText(raw, mode, whitelist = {}) {
    const policy = policyForMode(mode, whitelist)
    const lines = raw.split(/\r?\n/)
    const start = lines.findIndex((line) => line.trim() === MANAGED_MODE_START)
    const end = lines.findIndex((line) => line.trim() === MANAGED_MODE_END)
    if (start >= 0 && end > start) lines.splice(start, end - start + 1)
    const managed = new RegExp(`^(?:${MANAGED_MODE_KEYS.join('|')})\\s*:`)
    const body = lines.filter((line) => !managed.test(line)).join('\n').replace(/\n+$/, '')
    const block = [
      MANAGED_MODE_START,
      ...MANAGED_MODE_KEYS.map((key) => `${key}: ${yamlScalar(policy[key])}`),
      MANAGED_MODE_END,
    ].join('\n')
    return `${body}\n\n${block}\n`
  }

  function samePath(a, b) {
    const norm = (value) =>
      String(value ?? '')
        .trim()
        .replace(/[/\\]+$/, '')
        .replace(/\//g, '\\')
        .toLowerCase()
    return norm(a) === norm(b)
  }

  /**
   * Whether the composer status chip should appear for this workspace. By
   * default it only shows where ABAP is actually configured (a destinations
   * file exists); an explicit `workspaces` config allowlist narrows that
   * further so unrelated workspaces stay clean.
   */
  function chipGate(cwd, exists) {
    const allow = Array.isArray(cfg.workspaces)
      ? cfg.workspaces.filter((value) => typeof value === 'string' && value.trim())
      : []
    if (!allow.length) {
      return { enabled: exists, reason: exists ? 'workspace-configured' : 'workspace-not-configured' }
    }
    const allowed = allow.some((value) => samePath(value, cwd))
    return {
      enabled: exists && allowed,
      reason: allowed ? (exists ? 'workspace-configured' : 'workspace-not-configured') : 'workspace-not-allowed',
    }
  }

  // ------------------------------------------------------------ workspace ----
  function workspaceFile(workspace) {
    return join(workspace, CONFIG_DIR, FILE_NAMES[0])
  }

  function existingWorkspaceFile(workspace) {
    for (const fileName of FILE_NAMES) {
      const candidate = join(workspace, CONFIG_DIR, fileName)
      if (existsSync(candidate)) return candidate
    }
    return workspaceFile(workspace)
  }

  function resolveCwd(sessionId) {
    try {
      const agent = ctx.get?.('agents')?.get?.(sessionId)
      const cwd = agent?.session?.header?.cwd
      if (typeof cwd === 'string' && cwd) return cwd
    } catch {
      /* optional service */
    }
    return undefined
  }

  function listWorkspaces() {
    try {
      const registry = ctx.get?.('workspaceRegistry')
      const rows = registry?.list?.() ?? []
      return rows.map((row) => ({
        id: String(row.id ?? ''),
        path: String(row.path ?? ''),
        title: String(row.title ?? row.path ?? ''),
      }))
    } catch {
      return []
    }
  }

  /** Session preset id → ABAP mode, used by the composer chip badge. */
  function presetInfoOf(sessionId) {
    const modes = cfg.modes ?? {
      'abap-adt': 'read-only',
      'abap-adt-debug': 'debug',
      'abap-adt-change': 'change',
    }
    try {
      const agent = ctx.get?.('agents')?.get?.(sessionId)
      if (!agent) return { presetId: undefined, mode: undefined }
      const registry = ctx.get?.('agentPresets')
      let presetId = registry?.composedPreset?.(agent.ctx)
      if (typeof presetId !== 'string' || !presetId) {
        presetId = agent?.session?.header?.agentPreset ?? agent?.agentPreset
      }
      if (typeof presetId !== 'string' || !presetId) return { presetId: undefined, mode: undefined }
      return { presetId, mode: typeof modes === 'object' ? modes[presetId] : undefined }
    } catch {
      return { presetId: undefined, mode: undefined }
    }
  }

  async function stateOf({ sessionId, workspace }) {
    const cwd = workspace || resolveCwd(sessionId) || listWorkspaces()[0]?.path || process.cwd()
    const file = existingWorkspaceFile(cwd)
    let raw = ''
    let exists = false
    try {
      raw = await readFile(file, 'utf8')
      exists = true
    } catch {
      /* first run: no file yet */
    }
    const parsed = exists
      ? await parseDestinations(raw)
      : { destinations: [], defaultDestination: undefined, policy: {}, parser: 'none' }
    const presetInfo = presetInfoOf(sessionId)
    const mode = modeFromPolicy(parsed.policy)
    const whitelist = await readUiSettings(cwd)
    // Display labels are UI-only: attach the Chinese label beside the stable
    // destination name so the page/chip can show it without touching the plugin
    // schema (which accepts only the known destination keys).
    const labels = whitelist.labels || {}
    const destinations = normalizeDestinations(parsed.destinations).map((dest) => ({
      ...dest,
      label: labels[dest.name] || '',
    }))
    return {
      workspace: cwd,
      workspaces: listWorkspaces(),
      file: { path: file, exists, bytes: raw.length },
      chip: chipGate(cwd, exists),
      destinations,
      labels,
      defaultDestination: parsed.defaultDestination || '',
      policy: parsed.policy || {},
      parser: parsed.parser,
      presetId: presetInfo.presetId,
      mode,
      // Change-mode whitelists are UI-only settings; only the change mode
      // writes them into the plugin policy, so they are editable just there.
      whitelist: {
        allowedPackages: whitelist.allowedPackages,
        allowedTransports: whitelist.allowedTransports,
        defaults: { ...WHITELIST_DEFAULTS },
        editable: mode === 'change' && exists,
      },
      preset: {
        // The policy itself is pinned by the session's ABAP preset row; this
        // page only displays it. Keep the wording deployment-neutral.
        note: String(
          cfg.policyNote ??
            '运行模式由本工作区决定（上方切换），以 policy 段写入 destinations.yaml；预设本身只带安全基线（只读）。',
        ),
      },
    }
  }

  function normalizeDestinations(rows) {
    return (Array.isArray(rows) ? rows : []).map((row) => {
      const out = {}
      for (const key of DESTINATION_KEYS) {
        if (row?.[key] !== undefined) out[key] = row[key]
      }
      return out
    })
  }

  // ---------------------------------------------------------------- HTTP -----
  function sendJson(res, status, payload) {
    const body = JSON.stringify(payload)
    res.writeHead(status, {
      'Content-Type': 'application/json; charset=utf-8',
      'Cache-Control': 'no-store',
    })
    res.end(body)
  }

  async function readJson(req) {
    let text = ''
    for await (const chunk of req) {
      text += chunk
      if (text.length > 512 * 1024) throw new Error('request body too large')
    }
    return text ? JSON.parse(text) : {}
  }

  function validateDestinations(input) {
    const rows = Array.isArray(input) ? input : []
    if (rows.length > 50) throw new Error('too many destinations (max 50)')
    const names = new Set()
    const cleaned = []
    for (const [index, row] of rows.entries()) {
      if (!row || typeof row !== 'object') throw new Error(`destination #${index + 1}: invalid entry`)
      const dest = {}
      for (const key of DESTINATION_KEYS) {
        if (row[key] === undefined || row[key] === null || row[key] === '') continue
        dest[key] = typeof row[key] === 'boolean' ? row[key] : String(row[key])
      }
      if (!dest.name) throw new Error(`destination #${index + 1}: name is required`)
      if (!/^[A-Za-z0-9_.-]{1,40}$/.test(dest.name)) {
        throw new Error(`destination "${dest.name}": name may only contain letters, digits, _ . - (max 40)`)
      }
      if (names.has(dest.name.toLowerCase())) throw new Error(`duplicate destination name: ${dest.name}`)
      names.add(dest.name.toLowerCase())
      if (!dest.url) throw new Error(`destination "${dest.name}": url is required`)
      let parsedUrl
      try {
        parsedUrl = new URL(dest.url)
      } catch {
        throw new Error(`destination "${dest.name}": url is not a valid absolute URL`)
      }
      if (!['http:', 'https:'].includes(parsedUrl.protocol)) {
        throw new Error(`destination "${dest.name}": url must be http(s)`)
      }
      if (typeof dest.strictSSL === 'string') {
        dest.strictSSL = dest.strictSSL === 'true' ? true : dest.strictSSL === 'false' ? false : dest.strictSSL
        if (typeof dest.strictSSL !== 'boolean') throw new Error(`destination "${dest.name}": strictSSL must be boolean`)
      }
      // timeoutMs is a NUMBER in the abap-adt schema; a quoted value makes the
      // whole workspace file invalid for the plugin, so normalize it here.
      if (dest.timeoutMs !== undefined) {
        const timeoutMs = Number(dest.timeoutMs)
        if (!Number.isFinite(timeoutMs) || timeoutMs <= 0) {
          throw new Error(`destination "${dest.name}": timeoutMs must be a positive number`)
        }
        dest.timeoutMs = timeoutMs
      }
      if (dest.profile && !['dev', 'qa', 'prd'].includes(String(dest.profile))) {
        throw new Error(`destination "${dest.name}": profile must be dev, qa or prd`)
      }
      cleaned.push(dest)
    }
    return cleaned
  }

  async function resolvePassword(ref) {
    if (!ref) return undefined
    try {
      const credentials = ctx.get?.('credentials')
      if (credentials?.resolve) {
        const resolved = await credentials.resolve(ref)
        if (resolved?.value) return resolved.value
      }
    } catch {
      /* fall through to env */
    }
    return process.env[ref]
  }

  function pingAdt(options) {
    return new Promise((resolve) => {
      let target
      try {
        target = new URL(options.url)
      } catch {
        resolve({ ok: false, status: 0, ms: 0, error: 'invalid url' })
        return
      }
      const basePath = target.pathname.replace(/\/+$/, '')
      const discoveryPath = basePath.endsWith('/sap/bc/adt')
        ? `${basePath}/discovery`
        : `${basePath}/sap/bc/adt/discovery`
      const query = new URLSearchParams()
      if (options.client) query.set('sap-client', String(options.client))
      if (options.language) query.set('sap-language', String(options.language))
      const suffix = query.toString()
      const path = suffix ? `${discoveryPath}?${suffix}` : discoveryPath
      const isHttps = target.protocol === 'https:'
      const requestFn = isHttps ? httpsRequest : httpRequest
      const timeoutMs = Number(options.timeoutMs) > 0 ? Number(options.timeoutMs) : 15000
      const started = Date.now()
      const headers = { Accept: 'application/xml, text/plain, */*', 'User-Agent': 'dsh-abap-adt-ui' }
      if (options.username && options.password !== undefined) {
        headers.Authorization = `Basic ${Buffer.from(`${options.username}:${options.password}`).toString('base64')}`
      }
      const req = requestFn(
        {
          hostname: target.hostname,
          port: target.port || (isHttps ? 443 : 80),
          path,
          method: 'GET',
          headers,
          timeout: timeoutMs,
          rejectUnauthorized: options.strictSSL !== false,
        },
        (res) => {
          res.resume()
          res.on('end', () => {
            const status = res.statusCode ?? 0
            resolve({
              ok: status >= 200 && status < 500 && status !== 401,
              status,
              ms: Date.now() - started,
              // 401 already proves the endpoint is alive; surface it distinctly.
              error: status === 401 ? 'unauthorized (endpoint reachable, check user/password)' : undefined,
            })
          })
        },
      )
      req.on('timeout', () => req.destroy(new Error(`timeout after ${timeoutMs}ms`)))
      req.on('error', (err) => resolve({ ok: false, status: 0, ms: Date.now() - started, error: err.message }))
      req.end()
    })
  }

  async function handle(req, res) {
    const url = new URL(req.url ?? '/', 'http://localhost')
    const route = url.pathname.startsWith(ROUTE_PREFIX) ? url.pathname.slice(ROUTE_PREFIX.length) : ''

    try {
      if (req.method === 'GET' && route === '/state') {
        const payload = await stateOf({
          sessionId: url.searchParams.get('sessionId') || undefined,
          workspace: url.searchParams.get('workspace') || undefined,
        })
        sendJson(res, 200, { ok: true, ...payload })
        return
      }

      if (req.method === 'GET' && route === '/workspaces') {
        sendJson(res, 200, { ok: true, workspaces: listWorkspaces() })
        return
      }

      if (req.method === 'POST' && route === '/save') {
        const body = await readJson(req)
        const workspace = String(body.workspace ?? '')
        if (!workspace || !isAbsolute(workspace) || !existsSync(workspace)) {
          sendJson(res, 400, { ok: false, error: 'workspace must be an existing absolute directory' })
          return
        }
        const destinations = validateDestinations(body.destinations)
        const defaultDestination = String(body.defaultDestination ?? '')
        // `demo` is the plugin's built-in in-process mock destination and is
        // always valid even though it never appears in the destinations list.
        if (
          defaultDestination &&
          defaultDestination !== 'demo' &&
          !destinations.some((dest) => dest.name === defaultDestination)
        ) {
          sendJson(res, 400, {
            ok: false,
            error: `defaultDestination "${defaultDestination}" is not a destination name (available: demo, ${destinations.map((dest) => dest.name).join(', ') || '(none)'})`,
          })
          return
        }
        const file = existingWorkspaceFile(workspace)
        // Preserve the current run mode: mode lives in its own managed block.
        let existingMode = 'read-only'
        if (existsSync(file)) {
          try {
            existingMode = modeFromPolicy((await parseDestinations(await readFile(file, 'utf8'))).policy)
          } catch {
            /* keep the safe baseline */
          }
        }
        await mkdir(join(workspace, CONFIG_DIR), { recursive: true })
        const uiSettings = await readUiSettings(workspace)
        // Display labels: keep only labels of destinations that still exist.
        const names = new Set(destinations.map((dest) => dest.name))
        let labels = uiSettings.labels || {}
        if (body.labels && typeof body.labels === 'object') {
          labels = {}
          for (const [name, label] of Object.entries(body.labels)) {
            if (typeof name === 'string' && name && typeof label === 'string' && label.trim()) {
              labels[name] = label.trim().slice(0, 80)
            }
          }
        }
        labels = Object.fromEntries(Object.entries(labels).filter(([name]) => names.has(name)))
        await writeUiSettings(workspace, { ...uiSettings, labels })
        const text = setModeInText(emitDestinations({ defaultDestination, destinations }), existingMode, uiSettings)
        await writeFile(file, text, 'utf8')
        sendJson(res, 200, { ok: true, path: file, destinations: destinations.length, mode: existingMode, labels })
        return
      }

      if (req.method === 'POST' && route === '/mode') {
        const body = await readJson(req)
        const workspace = String(body.workspace ?? '')
        if (!workspace || !isAbsolute(workspace) || !existsSync(workspace)) {
          sendJson(res, 400, { ok: false, error: 'workspace must be an existing absolute directory' })
          return
        }
        const mode = String(body.mode ?? '')
        if (!MODE_POLICIES[mode]) {
          sendJson(res, 400, { ok: false, error: `mode must be one of ${Object.keys(MODE_POLICIES).join(', ')}` })
          return
        }
        const file = existingWorkspaceFile(workspace)
        let raw = ''
        try {
          raw = await readFile(file, 'utf8')
        } catch {
          throw new Error('该工作区还没有 destinations.yaml，请先保存目的地配置')
        }
        const current = await readUiSettings(workspace)
        const nextWhitelist = {
          allowedPackages:
            typeof body.allowedPackages === 'string' && body.allowedPackages.trim()
              ? body.allowedPackages.trim()
              : current.allowedPackages,
          allowedTransports:
            typeof body.allowedTransports === 'string' && body.allowedTransports.trim()
              ? body.allowedTransports.trim()
              : current.allowedTransports,
        }
        for (const [key, value] of Object.entries(nextWhitelist)) {
          if (value.length > 400 || /[\r\n]/.test(value)) {
            sendJson(res, 400, { ok: false, error: `${key} must be a single line under 400 characters` })
            return
          }
        }
        if (body.allowedPackages !== undefined || body.allowedTransports !== undefined) {
          // Preserve display labels when persisting whitelists.
          await writeUiSettings(workspace, { ...current, ...nextWhitelist })
        }
        await writeFile(file, setModeInText(raw, mode, nextWhitelist), 'utf8')
        sendJson(res, 200, {
          ok: true,
          path: file,
          mode,
          policy: policyForMode(mode, nextWhitelist),
          whitelist: nextWhitelist,
        })
        return
      }

      if (req.method === 'POST' && route === '/default') {
        const body = await readJson(req)
        const workspace = String(body.workspace ?? '')
        if (!workspace || !isAbsolute(workspace) || !existsSync(workspace)) {
          sendJson(res, 400, { ok: false, error: 'workspace must be an existing absolute directory' })
          return
        }
        const next = String(body.defaultDestination ?? '')
        const file = existingWorkspaceFile(workspace)
        let raw = ''
        try {
          raw = await readFile(file, 'utf8')
        } catch {
          throw new Error('该工作区还没有 destinations.yaml，请先在「设置 → ABAP ADT」里保存配置')
        }
        const parsed = await parseDestinations(raw)
        const names = normalizeDestinations(parsed.destinations).map((dest) => dest.name)
        if (next && next !== 'demo' && !names.includes(next)) {
          sendJson(res, 400, { ok: false, error: `defaultDestination "${next}" is not a destination name (have: demo, ${names.join(', ') || '(none)'})` })
          return
        }
        await writeFile(file, setDefaultInText(raw, next), 'utf8')
        sendJson(res, 200, { ok: true, path: file, defaultDestination: next })
        return
      }

      if (req.method === 'POST' && route === '/ping') {
        const body = await readJson(req)
        if (!body.url) {
          sendJson(res, 400, { ok: false, error: 'url is required' })
          return
        }
        const password = await resolvePassword(String(body.passwordEnv ?? body.passwordRef ?? ''))
        const result = await pingAdt({
          url: String(body.url),
          client: body.client,
          language: body.language,
          username: body.username,
          password,
          strictSSL: body.strictSSL,
          timeoutMs: body.timeoutMs,
        })
        sendJson(res, 200, { ok: true, result })
        return
      }

      sendJson(res, 404, { ok: false, error: `unknown route: ${req.method} ${url.pathname}` })
    } catch (err) {
      log.warn?.(`abap-adt-ui: ${req.method} ${url.pathname} failed: ${err.message}`)
      sendJson(res, 400, { ok: false, error: err.message })
    }
  }

  const dispose = ctx.webServer.register({ kind: 'prefix', path: ROUTE_PREFIX, handler: handle })
  ctx.effect?.(() => dispose)
  log.info?.(`abap-adt-ui: routes registered under ${ROUTE_PREFIX}`)
}