/**
 * High-level run API over {@link HarnessClient}: route text to prompts or native
 * commands and collect prompt activity for text and image input.
 *
 * @module @deepseek-ai/dsh-sdk-client/api
 */

import { randomUUID } from 'node:crypto'
import { resolve } from 'node:path'
import type { SessionEvent, TurnEndReason } from '@deepseek-ai/dsh-session'
import { createProcessHarnessClient, HarnessClient, isRecord, queryInput, SdkProtocolError } from './client.ts'
import type { RuntimeProcessOptions } from './launch.ts'
import type { ContentBlock, DeepSeekHarnessOptions, HarnessNotification, RunResult, SdkPromptContentBlock } from './types.ts'

/**
 * Reusable SDK for running DeepSeek Harness agent turns in a runtime
 * subprocess. The subprocess starts lazily on first use and stays owned by
 * this instance until {@link close}; always close (or `await using`) so the
 * child is reaped.
 */
export class DeepSeekHarness implements AsyncDisposable {
  private clientInstance: HarnessClient
  private readonly createClient: () => HarnessClient
  private readonly cwd: string
  private readonly provider: string
  private readonly model: string
  private readonly reasoningEffort: DeepSeekHarnessOptions['reasoningEffort']
  private readonly maxTokens: number | undefined
  private readonly approvalRequests: boolean | undefined
  private initialized: Promise<void> | undefined
  private closed = false

  /** @param options - dsh launch configuration plus the session route, effort, and output cap. */
  constructor(options?: DeepSeekHarnessOptions)
  constructor(options: DeepSeekHarnessOptions = {}, clientFactory?: () => HarnessClient) {
    this.createClient = clientFactory ?? (() => new HarnessClient(options))
    this.clientInstance = this.createClient()
    // Absolute before the handshake: the child spawns relative to THIS
    // process's cwd, but the wire cwd is resolved again inside the child — a
    // relative value would double-resolve (e.g. `worker` → `worker/worker`).
    this.cwd = resolve(options.cwd ?? options.processCwd ?? process.cwd())
    this.provider = options.provider ?? 'deepseek-official'
    this.model = options.model ?? 'deepseek-v4-flash'
    this.reasoningEffort = options.reasoningEffort
    this.maxTokens = options.maxTokens
    this.approvalRequests = options.approvalRequests
  }

  /**
   * The underlying JSON-RPC client (exposed for low-level access). A failed
   * handshake swaps in a fresh instance only after cleanup proves the runtime
   * exited; cleanup failure retains this client, so do not cache it across a
   * failed {@link start}.
   * @returns the client currently owning the runtime subprocess.
   */
  get client(): HarnessClient {
    return this.clientInstance
  }

  /**
   * Start the subprocess and perform the `initialize` handshake once. On
   * failure, successful SDK-owned cleanup reaps the runtime and installs a
   * fresh client (`HarnessClient.close` is permanent), so a later call retries
   * with a new subprocess unless {@link close} already ended this harness. If
   * cleanup also fails, rejects with an `AggregateError` whose ordered errors
   * preserve both causes and retains the failed client rather than spawning
   * alongside a process whose exit was not proved.
   * @returns settlement of the (memoized) handshake.
   */
  start(): Promise<void> {
    this.initialized ??= (async () => {
      try {
        this.clientInstance.start()
        await this.clientInstance.initialize({
          cwd: this.cwd,
          provider: this.provider,
          model: this.model,
          ...this.reasoningEffort === undefined ? {} : { reasoningEffort: this.reasoningEffort },
          ...this.maxTokens === undefined ? {} : { maxTokens: this.maxTokens },
          ...this.approvalRequests === undefined ? {} : { approvalRequests: this.approvalRequests },
        })
      } catch (error) {
        this.initialized = undefined
        try {
          await this.clientInstance.close()
        } catch (cleanupError: unknown) {
          throw new AggregateError(
            [error, cleanupError],
            'DeepSeek Harness initialization and cleanup failed',
          )
        }
        if (!this.closed) this.clientInstance = this.createClient()
        throw error
      }
    })()
    return this.initialized
  }

  /**
   * Open a session handle (no wire traffic; the runtime creates the session
   * on its first prompt or working-directory operation).
   * @param sessionId - explicit id to reuse; omitted mints a fresh one.
   * @returns the session handle.
   */
  session(sessionId?: string): HarnessSession {
    return new HarnessSession(this, sessionId ?? `session-${randomUUID().replaceAll('-', '')}`)
  }

  /**
   * Start the runtime and restore a persisted session without sending input.
   * The configured Harness home must contain its history; missing or occupied sessions reject.
   * @param sessionId - exact persisted identity to continue.
   * @returns a handle ready to run new prompts on the restored history.
   */
  async resumeSession(sessionId: string): Promise<HarnessSession> {
    await this.start()
    await this.client.resumeSession(sessionId)
    return new HarnessSession(this, sessionId)
  }

  /**
   * Run text or content blocks on a fresh or named Session through native input routing.
   * @param input - prompt or command text, optionally accompanied by image content blocks.
   * @param options - optional Session identity and notification observer.
   * @returns the completed input's RunResult, including its Session id.
   */
  run(input: string | SdkPromptContentBlock[], options?: RunOptions): Promise<RunResult> {
    return this.session(options?.sessionId).run(input, options)
  }

  /**
   * Shut down and reap the runtime subprocess. Idempotent and terminal —
   * a closed harness no longer retries a failed handshake.
   * @returns settlement of the complete teardown.
   */
  close(): Promise<void> {
    this.closed = true
    return this.clientInstance.close()
  }

  /**
   * `await using` support: {@link close}.
   * @returns settlement of the teardown.
   */
  [Symbol.asyncDispose](): Promise<void> {
    return this.close()
  }
}

/** Construct the high-level API against a generic process for package-local fake-runtime tests. */
export function createProcessDeepSeekHarness(
  runtime: RuntimeProcessOptions,
  options: DeepSeekHarnessOptions = {},
): DeepSeekHarness {
  const Constructor = DeepSeekHarness as new (
    publicOptions: DeepSeekHarnessOptions,
    clientFactory: () => HarnessClient,
  ) => DeepSeekHarness
  return new Constructor({
    ...runtime.cwd === undefined ? {} : { processCwd: runtime.cwd },
    ...options,
  }, () => createProcessHarnessClient(runtime))
}

/** Per-run Session identity and notification observer. */
export interface RunOptions {
  /** Session id to run on; omitted mints a fresh session per call. */
  sessionId?: string
  /**
   * Observe the input's Session-tree activity in wire order until completion.
   * The interval can include overlapping work from other inputs.
   */
  onNotification?: (notification: HarnessNotification) => void
}

/** Collect one input's root events and Session-tree notifications from its admission. */
class RunActivity {
  commandDone = false
  private received = false
  private readonly events: SessionEvent[] = []
  private readonly notifications: HarnessNotification[] = []

  constructor(private readonly sessionId: string, private readonly receipt: { messageId: string } | { commandId: string }) {}

  /** Ignore pre-receipt traffic; validate root events before invoking the observer. */
  record(notification: HarnessNotification, onNotification?: RunOptions['onNotification']): boolean {
    if (notification.method === 'session.query.completed') return false
    if (!this.received) {
      if (notification.method !== 'session.event' || notification.params.sessionId !== this.sessionId
        || !this.matchesReceipt(notification.params.event)) return false
      this.received = true
    }
    const event = notification.method === 'session.event' && notification.params.sessionId === this.sessionId
      ? validatedSessionEvent(notification.params.event) : undefined
    if (event?.type === 'command/done' && 'commandId' in this.receipt
      && isRecord(event.data) && event.data.commandId === this.receipt.commandId) this.commandDone = true
    this.notifications.push(notification)
    onNotification?.(notification)
    if (event !== undefined) this.events.push(event)
    return true
  }

  private matchesReceipt(event: unknown): boolean {
    return 'messageId' in this.receipt ? isInboxReceipt(event, this.receipt.messageId)
      : isRecord(event) && event.type === 'command/run' && isRecord(event.data)
        && event.data.commandId === this.receipt.commandId
  }

  result(completed?: { finalResponse: string; finishReason: string }): RunResult {
    if (completed !== undefined && !this.commandDone) {
      throw new SdkProtocolError('Command completion is missing matching lifecycle events')
    }
    const terminal = this.events.findLast(event => event.type === 'turn/end')
    return {
      sessionId: this.sessionId, finalResponse: completed?.finalResponse ?? finalResponse(this.events),
      finishReason: completed?.finishReason ?? terminal?.data.reason.kind ?? null,
      events: this.events, notifications: this.notifications,
    }
  }
}

/**
 * One SDK session: a stable id plus owned activity intervals.
 */
export class HarnessSession {
  /**
   * @param harness - the owning harness (supplies the client and handshake).
   * @param id - the wire session id this handle runs on.
   */
  constructor(readonly harness: DeepSeekHarness, readonly id: string) {}

  /**
   * Read the effective directory and recover a missing directory to the Session origin.
   * @returns the absolute directory used by new independent operations.
   */
  async getWorkingDirectory(): Promise<string> {
    await this.harness.start()
    return this.harness.client.getWorkingDirectory(this.id)
  }

  /**
   * Change the effective directory without moving existing processes or changing permissions.
   * @param path - absolute or Session-current-directory-relative directory.
   * @returns the validated absolute directory.
   */
  async setWorkingDirectory(path: string): Promise<string> {
    await this.harness.start()
    return this.harness.client.setWorkingDirectory(this.id, path)
  }

  /**
   * Run text or content blocks through native prompt-or-command routing.
   * @param input - prompt or command text, optionally accompanied by image content blocks; image-only input is an ordinary prompt.
   * @param options - a per-notification observer.
   * @returns RunResult after prompt activity, a state-only command, or command-started model work ends.
   * Goal creation and resume include automatic rounds through goal termination and the closing reply.
   * Native handler refusals return finishReason="error".
   * @throws on routing, protocol, transport or observer failure; runtime work is not rolled back.
   */
  async run(input: string | SdkPromptContentBlock[], options?: Pick<RunOptions, 'onNotification'>): Promise<RunResult> {
    await this.harness.start()
    const client = this.harness.client
    const subscription = client.subscribeSessionTree(this.id)
    try {
      const response = await queryInput(client, this.id, input)
      if (response.kind === 'command') {
        const activity = new RunActivity(this.id, { commandId: response.execution.commandId })
        while (true) {
          const notification = await subscription.next()
          const params = notification.params
          if (notification.method === 'session.query.completed' && params.sessionId === this.id) {
            if (typeof params.commandId !== 'string' || params.commandId.length === 0) {
              throw new SdkProtocolError('Invalid session.query.completed command identity')
            }
            if (params.commandId !== response.execution.commandId) continue
            if (typeof params.finalResponse !== 'string' || typeof params.finishReason !== 'string'
              || params.finishReason.length === 0) throw new SdkProtocolError('Invalid session.query.completed result')
            // Failure completion can precede handler settlement; its lifecycle is queued before the RPC response.
            while (!activity.commandDone) {
              const queued = subscription.tryNext()
              if (queued === undefined) break
              activity.record(queued, options?.onNotification)
            }
            return activity.result({ finalResponse: params.finalResponse, finishReason: params.finishReason })
          }
          activity.record(notification, options?.onNotification)
        }
      }
      const activity = new RunActivity(this.id, { messageId: response.messageId })
      while (true) {
        const notification = await subscription.next()
        if (!activity.record(notification, options?.onNotification)) continue
        if (notification.method === 'session.status'
          && notification.params.sessionId === this.id
          && notification.params.status === 'idle') break
      }
      return activity.result()
    } finally {
      subscription.close()
    }
  }

}

/** Validate the provider-read fields of one wire turn-end reason. */
function validatedTurnEndReason(value: unknown): TurnEndReason {
  if (!isRecord(value) || typeof value.kind !== 'string') {
    throw new SdkProtocolError(`turn/end carried no reason envelope: ${JSON.stringify(value)}`)
  }
  if (value.kind === 'aborted') {
    if (!isRecord(value.reason) || typeof value.reason.kind !== 'string') {
      throw new SdkProtocolError(`turn/end carried a malformed aborted reason: ${JSON.stringify(value)}`)
    }
    switch (value.reason.kind) {
      case 'user':
      case 'parent':
      case 'disposed':
      case 'legacy':
        break
      case 'hook':
        if (typeof value.reason.reason !== 'string') {
          throw new SdkProtocolError(`turn/end carried a malformed hook abort reason: ${JSON.stringify(value)}`)
        }
        break
      default:
        throw new SdkProtocolError(`turn/end carried an unknown abort reason: ${JSON.stringify(value)}`)
    }
  }
  return value as TurnEndReason
}

/**
 * Validate the event envelope and assistant/turn fields consumed by SDK readers.
 * @param value - the raw `session.event` event payload.
 * @returns the event, or throws a protocol error for malformed consumed fields.
 */
export function validatedSessionEvent(value: unknown): SessionEvent {
  if (!isRecord(value) || typeof value.type !== 'string') {
    throw new SdkProtocolError(`session.event carried no event envelope: ${JSON.stringify(value)}`)
  }
  // The one variant this module reads into (finalResponse) must carry
  // kind-tagged content blocks; other variants pass through under their
  // envelope shape.
  if (value.type === 'assistant/message') {
    const message = isRecord(value.data) ? value.data.message : undefined
    const content = isRecord(message) ? message.content : undefined
    if (!Array.isArray(content) || !content.every(block => isRecord(block) && typeof block.type === 'string')) {
      throw new SdkProtocolError(`assistant/message event carried malformed content: ${JSON.stringify(value)}`)
    }
  }
  if (value.type === 'turn/end') {
    const data = isRecord(value.data) ? value.data : undefined
    if (data === undefined) {
      throw new SdkProtocolError(`turn/end event carried malformed data: ${JSON.stringify(value)}`)
    }
    validatedTurnEndReason(data.reason)
  }
  return value as SessionEvent
}

/** Whether a raw session event is the durable enqueue receipt for `messageId`. */
function isInboxReceipt(value: unknown, messageId: string): boolean {
  if (!isRecord(value) || value.type !== 'agent/inbox/spliced' || !isRecord(value.data)) return false
  const inserted = value.data.inserted
  return Array.isArray(inserted) && inserted.some(message => isRecord(message) && message.id === messageId)
}

/**
 * Extract the concatenated text of the last assistant message.
 * @param events - the activity interval's `session.event` payloads in wire order.
 * @returns the final response text, or `''` when no assistant message exists.
 */
export function finalResponse(events: SessionEvent[]): string {
  for (let index = events.length - 1; index >= 0; index--) {
    const event = events[index]
    if (event?.type !== 'assistant/message') continue
    return event.data.message.content
      .filter((block): block is ContentBlock & { type: 'text' } => block.type === 'text')
      .map(block => block.text)
      .join('')
  }
  return ''
}