import { webExtApi as api } from '../browser-api';
// Large-operation throttling, performance profile, and job-progress helpers.
import type { Job, JobProgressUpdate } from '../types';

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

export const LARGE_OPERATION_BATCH_SIZE = 25;
export const LARGE_OPERATION_PAUSE_MS = 25;
export const GENTLE_OPERATION_BATCH_SIZE = 8;
export const GENTLE_OPERATION_PAUSE_MS = 100;
const DEBUG_LARGE_OPERATIONS = false;

function debugLargeOperation(message: string) {
  if (DEBUG_LARGE_OPERATIONS) console.log(message);
}

export async function hasAudibleTabs() {
  const audibleTabs = await api.tabs.query({ audible: true });
  return audibleTabs.some(tab => !(tab.mutedInfo && tab.mutedInfo.muted));
}

let largeOperationQueue: Promise<void> = Promise.resolve();

export async function runLargeOperation<T>(name: string, fn: () => Promise<T>): Promise<T> {
  const run = largeOperationQueue.then(async () => {
    debugLargeOperation(`[browser-cli] large operation start: ${name}`);
    try {
      return await fn();
    } finally {
      debugLargeOperation(`[browser-cli] large operation done: ${name}`);
    }
  });
  largeOperationQueue = run.then(() => {}, () => {});
  return run;
}

export async function getPerformanceProfile() {
  const { performanceProfile } = await api.storage.local.get<{ performanceProfile?: string }>("performanceProfile");
  return performanceProfile || "auto";
}

export async function setPerformanceProfile(profile: string) {
  const allowed = new Set(["auto", "normal", "gentle", "ultra"]);
  const performanceProfile = allowed.has(profile) ? profile : "auto";
  await api.storage.local.set({ performanceProfile });
  return { performanceProfile };
}

export async function getLargeOperationThrottle(itemCount = 0, mode: string = "auto") {
  const audible = await hasAudibleTabs();
  const storedProfile = await getPerformanceProfile();
  const configuredMode = mode && mode !== "auto" ? mode : storedProfile;
  const gentle = configuredMode === "gentle" || configuredMode === "ultra" || (configuredMode === "auto" && audible);
  let batchSize = gentle ? GENTLE_OPERATION_BATCH_SIZE : LARGE_OPERATION_BATCH_SIZE;
  let pauseMs = gentle ? GENTLE_OPERATION_PAUSE_MS : LARGE_OPERATION_PAUSE_MS;

  if (configuredMode === "ultra" || itemCount >= 300) {
    batchSize = Math.max(3, Math.floor(batchSize / 2));
    pauseMs *= 2;
  } else if (itemCount >= 100) {
    batchSize = Math.max(5, Math.floor(batchSize * 0.75));
    pauseMs = Math.max(pauseMs, 75);
  }

  return { batchSize, pauseMs, gentle, audible, itemCount, mode: configuredMode };
}

export function updateJobProgress(job: Job | undefined | null, { phase, current, total }: JobProgressUpdate = {}) {
  if (!job) return;
  if (phase) job.phase = phase;
  if (total != null) job.total = total;
  if (current != null) job.current = current;
  if (job.total) job.percent = Math.min(100, Math.round((job.current || 0) * 100 / job.total));
  job.updatedAt = Date.now();
}

export function throwIfJobCancelled(job: Job | undefined | null) {
  if (job?.cancelRequested) {
    throw new Error(`Job '${job.id}' cancelled`);
  }
}

export async function yieldForLargeOperation(processed: number, batchSize = LARGE_OPERATION_BATCH_SIZE, pauseMs = LARGE_OPERATION_PAUSE_MS) {
  if (processed > 0 && processed % batchSize === 0) {
    await sleep(pauseMs);
  }
}

/**
 * Run `handler` over `items` in throttle-sized slices, threading job progress
 * and cancellation. Each slice is one `handler` call (so chrome batch APIs like
 * tabs.remove get an array); between slices it reports progress and yields.
 *
 * `total`/`baseCurrent` let callers report against a fixed total accumulated
 * across several calls (e.g. merging tabs from many windows). Returns the
 * running processed count so the next call can continue from it.
 */
export async function processInBatches<T>(
  items: T[],
  throttle: { batchSize: number; pauseMs: number },
  handler: (batch: T[]) => Promise<unknown>,
  progress: { job?: Job | null; phase: string; total?: number; baseCurrent?: number },
): Promise<number> {
  const total = progress.total ?? items.length;
  let done = progress.baseCurrent ?? 0;
  updateJobProgress(progress.job, { phase: progress.phase, current: done, total });
  for (let i = 0; i < items.length; i += throttle.batchSize) {
    throwIfJobCancelled(progress.job);
    const batch = items.slice(i, i + throttle.batchSize);
    await handler(batch);
    done += batch.length;
    updateJobProgress(progress.job, { phase: progress.phase, current: done, total });
    await yieldForLargeOperation(done, throttle.batchSize, throttle.pauseMs);
  }
  return done;
}