import { RunnerManagerApi, failureKindFromError, terminalStatusForFailure, errorMessage } from "./manager-api.js";
import { runBackendTurn, type BackendAdapterOptions } from "../backend/adapter.js";
import { materializeResourceBundle } from "./resource-bundle.js";
import type { BackendEvent, BackendProfile, CommandRecord, FailureKind, JsonRecord, RunRecord, RunnerRecord, TerminalStatus } from "../common/types.js";
import { AgentRunError } from "../common/errors.js";

export interface RunnerOnceOptions extends BackendAdapterOptions {
  managerUrl: string;
  runId: string;
  commandId?: string;
  runnerId?: string;
  attemptId?: string;
  leaseMs?: number;
  backendProfile?: BackendProfile;
  placement?: "host-process" | "kubernetes-job";
  sourceCommit?: string;
  jobName?: string;
  podName?: string;
  logPath?: string;
  idleTimeoutMs?: number;
  pollIntervalMs?: number;
  oneShot?: boolean;
}

interface CommandExecutionResult extends JsonRecord {
  commandId: string;
  terminalStatus: TerminalStatus;
  failureKind: FailureKind | null;
}

export async function runOnce(options: RunnerOnceOptions): Promise<JsonRecord> {
  const api = new RunnerManagerApi(options.managerUrl);
  const targetRun = await api.getRun(options.runId);
  if (isTerminalRun(targetRun)) return { terminalStatus: targetRun.terminalStatus, failureKind: targetRun.failureKind, run: targetRun, skipped: "run-terminal" } as JsonRecord;
  if (options.backendProfile && options.backendProfile !== targetRun.backendProfile) {
    throw new AgentRunError("schema-invalid", `runner backendProfile ${options.backendProfile} does not match run backendProfile ${targetRun.backendProfile}`, { httpStatus: 400 });
  }
  const leaseMs = options.leaseMs ?? 60_000;
  const attemptId = options.attemptId ?? `attempt_${Date.now().toString(36)}`;
  const runner = await api.register({
    runId: options.runId,
    attemptId,
    backendProfile: targetRun.backendProfile,
    placement: options.placement ?? "host-process",
    sourceCommit: options.sourceCommit ?? process.env.AGENTRUN_SOURCE_COMMIT ?? "unknown",
    ...(options.runnerId ? { runnerId: options.runnerId } : {}),
    ...(options.jobName ? { jobName: options.jobName } : {}),
    ...(options.podName ? { podName: options.podName } : {}),
    ...(options.logPath ? { logPath: options.logPath } : {}),
  }) as RunnerRecord;
  let claimed: RunRecord;
  try {
    claimed = await api.claim(options.runId, runner.id, leaseMs);
    await api.heartbeat(options.runId, runner.id, leaseMs);
  } catch (error) {
    const failureKind = failureKindFromError(error);
    if (failureKind !== "runner-lease-conflict") {
      await api.reportFailure(options.runId, { terminalStatus: terminalStatusForFailure(failureKind), failureKind, failureMessage: errorMessage(error) });
    }
    throw error;
  }

  const stopHeartbeat = startHeartbeat(api, options.runId, runner.id, leaseMs);
  const idleTimeoutMs = options.idleTimeoutMs ?? 120_000;
  const pollIntervalMs = options.pollIntervalMs ?? 2_000;
  const commandResults: CommandExecutionResult[] = [];
  let workspacePath: string | undefined;
  let materializationAttempted = false;
  let materializationFailure: { failureKind: FailureKind; terminalStatus: TerminalStatus; message: string } | null = null;

  try {
    let idleSince = Date.now();
    let firstPoll = true;
    while (true) {
      const currentRun = await api.getRun(options.runId);
      if (isTerminalRun(currentRun)) return { runner, claimed, terminalStatus: currentRun.terminalStatus, failureKind: currentRun.failureKind, run: currentRun, commandsProcessed: commandResults.length, commandResults, stopped: "run-terminal" } as JsonRecord;

      const commandsResponse = await api.pollCommands(options.runId, { afterSeq: 0, limit: 20, ...(firstPoll && options.commandId ? { commandId: options.commandId } : {}) });
      firstPoll = false;
      const command = commandsResponse.selected;
      if (!command) {
        if (options.oneShot === true) return noPendingResult(runner, claimed, commandResults, commandsResponse.items.length, "one-shot-no-pending");
        if (Date.now() - idleSince >= idleTimeoutMs) return noPendingResult(runner, claimed, commandResults, commandsResponse.items.length, "idle-timeout");
        await sleep(pollIntervalMs);
        continue;
      }

      idleSince = Date.now();
      if (!materializationAttempted) {
        materializationAttempted = true;
        try {
          const materialized = await materializeResourceBundle(claimed.resourceBundleRef ?? null, options.env ?? process.env);
          if (materialized) {
            workspacePath = materialized.workspacePath;
            await api.appendEvent(options.runId, { type: "backend_status", payload: { ...materialized.event, commandId: command.id, attemptId, runnerId: runner.id } });
          }
        } catch (error) {
          const failureKind = failureKindFromError(error);
          materializationFailure = { failureKind, terminalStatus: terminalStatusForFailure(failureKind), message: errorMessage(error) };
        }
      }

      const result = materializationFailure
        ? await reportCommandFailure(api, options.runId, command.id, runner, attemptId, materializationFailure, "runner:resource-bundle")
        : await executeCommand(api, options, command, runner, attemptId, workspacePath);
      commandResults.push(result);
      if (options.oneShot === true) {
        const run = await api.reportStatus(options.runId, { terminalStatus: result.terminalStatus, failureKind: result.failureKind, failureMessage: null });
        return { runner, commandId: command.id, terminalStatus: result.terminalStatus, failureKind: result.failureKind, run, commandsProcessed: commandResults.length, commandResults, stopped: "one-shot" } as JsonRecord;
      }
    }
  } catch (error) {
    const failureKind = failureKindFromError(error);
    const terminalStatus = terminalStatusForFailure(failureKind);
    const message = errorMessage(error);
    await api.appendEvent(options.runId, { type: "error", payload: { failureKind, message, phase: "runner:loop", attemptId, runnerId: runner.id } });
    const finalRun = await api.reportStatus(options.runId, { terminalStatus, failureKind, failureMessage: message }) as RunRecord;
    return { runner, terminalStatus, failureKind, run: finalRun, commandsProcessed: commandResults.length, commandResults } as JsonRecord;
  } finally {
    stopHeartbeat();
  }
}

async function executeCommand(api: RunnerManagerApi, options: RunnerOnceOptions, command: CommandRecord, runner: RunnerRecord, attemptId: string, workspacePath: string | undefined): Promise<CommandExecutionResult> {
  await api.ackCommand(command.id);
  const acked = await api.getCommand(options.runId, command.id);
  if (acked.state === "cancelled") return await reportCancelled(api, options.runId, command.id, runner, attemptId, "command cancelled before backend start");
  await assertNotCancelled(api, options.runId, command.id);
  const abortController = new AbortController();
  const stopCancelWatch = watchCancellation(api, options.runId, command.id, abortController);
  try {
    const latestRun = await api.getRun(options.runId);
    const result = await runBackendTurn(latestRun, command, { ...options, ...(workspacePath ? { workspacePath } : {}), abortSignal: abortController.signal });
    for (const event of result.events) {
      await api.appendEvent(options.runId, annotateCommandEvent(event, command.id, attemptId, runner.id));
    }
    await api.reportCommandStatus(command.id, { terminalStatus: result.terminalStatus, failureKind: result.failureKind, failureMessage: result.failureMessage, ...(result.threadId ? { threadId: result.threadId } : {}), ...(result.turnId ? { turnId: result.turnId } : {}) });
    return { commandId: command.id, terminalStatus: result.terminalStatus, failureKind: result.failureKind } as CommandExecutionResult;
  } catch (error) {
    const failureKind = failureKindFromError(error);
    const failure = { failureKind, terminalStatus: terminalStatusForFailure(failureKind), message: errorMessage(error) };
    return await reportCommandFailure(api, options.runId, command.id, runner, attemptId, failure, "runner:execute");
  } finally {
    stopCancelWatch();
  }
}

function isTerminalRun(run: RunRecord): boolean {
  return run.status === "completed" || run.status === "failed" || run.status === "blocked" || run.status === "cancelled";
}

async function assertNotCancelled(api: RunnerManagerApi, runId: string, commandId: string): Promise<void> {
  const [run, command] = await Promise.all([api.getRun(runId), api.getCommand(runId, commandId)]);
  if (run.status === "cancelled" || command.state === "cancelled") throw new AgentRunError("cancelled", "run or command was cancelled", { httpStatus: 409 });
}

function watchCancellation(api: RunnerManagerApi, runId: string, commandId: string, controller: AbortController): () => void {
  let stopped = false;
  const check = async (): Promise<void> => {
    if (stopped || controller.signal.aborted) return;
    try {
      const [run, command] = await Promise.all([api.getRun(runId), api.getCommand(runId, commandId)]);
      if (run.status === "cancelled" || command.state === "cancelled") controller.abort();
    } catch {
      // Cancellation polling must not hide the backend's own terminal result.
    }
  };
  const timer = setInterval(() => { void check(); }, 2_000);
  void check();
  return () => {
    stopped = true;
    clearInterval(timer);
  };
}

function startHeartbeat(api: RunnerManagerApi, runId: string, runnerId: string, leaseMs: number): () => void {
  let stopped = false;
  const beat = async (): Promise<void> => {
    if (stopped) return;
    try {
      await api.heartbeat(runId, runnerId, leaseMs);
    } catch {
      // The next manager call will surface lease or run-terminal details.
    }
  };
  const timer = setInterval(() => { void beat(); }, Math.max(1_000, Math.floor(leaseMs / 3)));
  return () => {
    stopped = true;
    clearInterval(timer);
  };
}

function annotateCommandEvent(event: BackendEvent, commandId: string, attemptId: string, runnerId: string): BackendEvent {
  return { ...event, payload: { ...event.payload, commandId, attemptId, runnerId } };
}

async function reportCommandFailure(api: RunnerManagerApi, runId: string, commandId: string, runner: RunnerRecord, attemptId: string, failure: { terminalStatus: TerminalStatus; failureKind: FailureKind; message: string }, phase: string): Promise<CommandExecutionResult> {
  await api.appendEvent(runId, { type: "error", payload: { failureKind: failure.failureKind, message: failure.message, phase, commandId, attemptId, runnerId: runner.id } });
  await api.appendEvent(runId, { type: "terminal_status", payload: { terminalStatus: failure.terminalStatus, failureKind: failure.failureKind, message: failure.message, commandId, attemptId, runnerId: runner.id } });
  await api.reportCommandStatus(commandId, { terminalStatus: failure.terminalStatus, failureKind: failure.failureKind, failureMessage: failure.message });
  await api.reportStatus(runId, { terminalStatus: failure.terminalStatus, failureKind: failure.failureKind, failureMessage: failure.message });
  return { commandId, terminalStatus: failure.terminalStatus, failureKind: failure.failureKind } as CommandExecutionResult;
}

async function reportCancelled(api: RunnerManagerApi, runId: string, commandId: string, runner: RunnerRecord, attemptId: string, message: string): Promise<CommandExecutionResult> {
  await api.reportCommandStatus(commandId, { terminalStatus: "cancelled", failureKind: "cancelled", failureMessage: message });
  await api.reportStatus(runId, { terminalStatus: "cancelled", failureKind: "cancelled", failureMessage: message });
  await api.appendEvent(runId, { type: "backend_status", payload: { phase: "turn-cancelled", commandId, attemptId, runnerId: runner.id, failureKind: "cancelled", message } });
  await api.appendEvent(runId, { type: "terminal_status", payload: { terminalStatus: "cancelled", failureKind: "cancelled", message, commandId, attemptId, runnerId: runner.id } });
  return { commandId, terminalStatus: "cancelled", failureKind: "cancelled" };
}

function noPendingResult(runner: RunnerRecord, claimed: RunRecord, commandResults: CommandExecutionResult[], polledCommands: number, stopped: string): JsonRecord {
  if (commandResults.length > 0) {
    const last = commandResults.at(-1)!;
    return { runner, claimed, terminalStatus: last.terminalStatus, failureKind: last.failureKind, commandsProcessed: commandResults.length, commandResults, polledCommands, stopped };
  }
  return { runner, claimed, terminalStatus: "blocked", failureKind: "schema-invalid", commandsProcessed: 0, commandResults, polledCommands, stopped };
}

function sleep(ms: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, ms));
}