import "server-only";

import { and, asc, desc, eq, lt, notInArray, sql } from "drizzle-orm";
import { db } from "@/lib/db";
import { canvasImageTask } from "@/lib/db/schema";
import {
  getCanvasImageBatchDispatchIntervalMs,
  getCanvasImageRunningCountForModel,
  getCanvasImageSingleModelConcurrency,
  normalizeCanvasImageModelKey,
} from "./image-concurrency";
import {
  generateCanvasImage,
  type CanvasGenerateImageRequest,
  type CanvasGenerateImageResult,
} from "./generate-image";
import { applyScaleAdjustModelRelight } from "./scale-adjust-model-relight";
import {
  executeStyleProTask,
  getStyleProTaskPrimaryModelKey,
  type StyleProTaskRequest,
  type StyleProTaskResult,
} from "@/lib/style-pro/task";

type CanvasImageTaskStatus = "pending" | "running" | "succeeded" | "failed";
type CanvasImageTaskRequest = CanvasGenerateImageRequest | StyleProTaskRequest;
type CanvasImageTaskResult = CanvasGenerateImageResult | StyleProTaskResult;

export type CanvasImageTaskQueueStatus = {
  status: CanvasImageTaskStatus;
  queuePosition: number;
  sameModelPendingCount: number;
  sameModelRunningCount: number;
  concurrencyLimit: number;
  estimatedWaitMs: number;
  source: "model_queue" | "batch_queue";
};

interface PendingTaskEntry {
  taskId: string;
  modelKey: string;
  userId: string;
}

interface RunningTaskEntry {
  modelKey: string;
  userId: string;
}

interface QueueState {
  pending: PendingTaskEntry[];
  pendingSet: Set<string>;
  running: Map<string, RunningTaskEntry>;
  runningByModel: Map<string, Set<string>>;
  runningByModelUser: Map<string, Set<string>>;
  nextBatchEligibleAt: Map<string, number>;
  nextBatchTimers: Map<string, ReturnType<typeof setTimeout>>;
  awaitingNextBatch: Set<string>;
  lastStaleRunningCleanupAt: number;
  draining: boolean;
}

const DEFAULT_RUNNING_TIMEOUT_MS = 10 * 60 * 1000;
const SCALE_ADJUST_RUNNING_TIMEOUT_MS = 12 * 60 * 1000;
const LOCAL_ACTIVE_RUNNING_HARD_TIMEOUT_MS = 30 * 60 * 1000;
const STALE_RUNNING_CLEANUP_INTERVAL_MS = 60 * 1000;
const PENDING_LOOKAHEAD_LIMIT = 100;
const QUEUE_STATUS_PENDING_LOOKAHEAD_LIMIT = 500;
const QUEUE_STATUS_RECENT_SAMPLE_LIMIT = 120;
const DEFAULT_ESTIMATED_WAIT_MS = 45 * 1000;
const queueStateKey = "__canvas_image_task_queue_state__";

function getQueueState(): QueueState {
  const globalObj = globalThis as typeof globalThis & {
    [queueStateKey]?: QueueState;
  };
  if (!globalObj[queueStateKey]) {
    globalObj[queueStateKey] = {
      pending: [],
      pendingSet: new Set<string>(),
      running: new Map<string, RunningTaskEntry>(),
      runningByModel: new Map<string, Set<string>>(),
      runningByModelUser: new Map<string, Set<string>>(),
      nextBatchEligibleAt: new Map<string, number>(),
      nextBatchTimers: new Map<string, ReturnType<typeof setTimeout>>(),
      awaitingNextBatch: new Set<string>(),
      lastStaleRunningCleanupAt: 0,
      draining: false,
    };
  }
  return globalObj[queueStateKey] as QueueState;
}

function normalizeTaskModelKey(request: unknown) {
  if (isStyleProTaskRequest(request)) {
    return normalizeCanvasImageModelKey(getStyleProTaskPrimaryModelKey(request));
  }

  if (!request || typeof request !== "object" || Array.isArray(request)) {
    return "__default__";
  }

  const rawModel = (request as Record<string, unknown>).model;
  return normalizeCanvasImageModelKey(rawModel);
}

function getRecord(value: unknown): Record<string, unknown> | null {
  return value && typeof value === "object" && !Array.isArray(value)
    ? (value as Record<string, unknown>)
    : null;
}

function getCanvasImageRunningTimeoutMs(request: unknown) {
  const record = getRecord(request);
  const debugMeta = getRecord(record?.debugMeta);
  const debugLabel = String(record?.debugLabel || "");
  const operation = String(debugMeta?.operation || "");
  const isScaleAdjust =
    debugLabel === "canvas-scale-adjust" ||
    operation === "scale-adjust" ||
    Boolean(debugMeta?.scaleAdjustPatchWorkflowApplied) ||
    Boolean(debugMeta?.scaleAdjustPatchForcedForShrink) ||
    Boolean(record?.scaleAdjustPatchComposite);

  return isScaleAdjust
    ? SCALE_ADJUST_RUNNING_TIMEOUT_MS
    : DEFAULT_RUNNING_TIMEOUT_MS;
}

async function withCanvasImageTaskExecutionTimeout<T>(
  operation: Promise<T>,
  timeoutMs: number,
  taskId: string
): Promise<T> {
  if (!Number.isFinite(timeoutMs) || timeoutMs <= 0) {
    return operation;
  }

  let timeoutId: ReturnType<typeof setTimeout> | null = null;
  try {
    return await Promise.race([
      operation,
      new Promise<T>((_, reject) => {
        timeoutId = setTimeout(() => {
          reject(
            new Error(
              `图片生成任务执行超时（${Math.round(timeoutMs / 1000)}秒，${taskId}）`
            )
          );
        }, timeoutMs);
      }),
    ]);
  } finally {
    if (timeoutId) {
      clearTimeout(timeoutId);
    }
  }
}

function isStyleProTaskRequest(request: unknown): request is StyleProTaskRequest {
  return Boolean(
    request &&
      typeof request === "object" &&
      !Array.isArray(request) &&
      (request as { taskKind?: unknown }).taskKind === "style-pro"
  );
}

function getModelUserKey(modelKey: string, userId: string) {
  return `${modelKey}::${userId || "__anonymous__"}`;
}

function getMaxConcurrentPerUser(maxConcurrentPerModel: number) {
  return Math.max(1, Math.ceil(Math.max(1, maxConcurrentPerModel) / 2));
}

async function getTaskQueueMeta(taskId: string) {
  const rows = await db
    .select({
      request: canvasImageTask.request,
      userId: canvasImageTask.userId,
    })
    .from(canvasImageTask)
    .where(eq(canvasImageTask.id, taskId))
    .limit(1);

  const row = rows[0];
  return {
    modelKey: normalizeTaskModelKey(row?.request),
    userId: String(row?.userId || "__anonymous__"),
  };
}

function getRunningCountForModel(modelKey: string) {
  const state = getQueueState();
  return state.runningByModel.get(modelKey)?.size || 0;
}

function getRunningCountForModelUser(modelKey: string, userId: string) {
  const state = getQueueState();
  return state.runningByModelUser.get(getModelUserKey(modelKey, userId))?.size || 0;
}

function markRunningTask(taskId: string, modelKey: string, userId: string) {
  const state = getQueueState();
  state.running.set(taskId, { modelKey, userId });
  const tasks = state.runningByModel.get(modelKey) || new Set<string>();
  tasks.add(taskId);
  state.runningByModel.set(modelKey, tasks);

  const modelUserKey = getModelUserKey(modelKey, userId);
  const userTasks = state.runningByModelUser.get(modelUserKey) || new Set<string>();
  userTasks.add(taskId);
  state.runningByModelUser.set(modelUserKey, userTasks);
}

function releaseRunningTask(taskId: string) {
  const state = getQueueState();
  const entry = state.running.get(taskId);
  if (!entry) {
    return null;
  }

  state.running.delete(taskId);
  const { modelKey, userId } = entry;
  const tasks = state.runningByModel.get(modelKey);
  if (tasks) {
    tasks.delete(taskId);
    if (tasks.size === 0) {
      state.runningByModel.delete(modelKey);
    }
  }

  const modelUserKey = getModelUserKey(modelKey, userId);
  const userTasks = state.runningByModelUser.get(modelUserKey);
  if (userTasks) {
    userTasks.delete(taskId);
    if (userTasks.size === 0) {
      state.runningByModelUser.delete(modelUserKey);
    }
  }

  return modelKey;
}

function isModelBatchDispatchDelayed(modelKey: string) {
  const state = getQueueState();
  const delayedUntil = state.nextBatchEligibleAt.get(modelKey);
  if (!delayedUntil) {
    return false;
  }

  if (delayedUntil <= Date.now()) {
    state.nextBatchEligibleAt.delete(modelKey);
    const timer = state.nextBatchTimers.get(modelKey);
    if (timer) {
      clearTimeout(timer);
      state.nextBatchTimers.delete(modelKey);
    }
    return false;
  }

  return true;
}

function markModelAwaitingNextBatch(modelKey: string) {
  getQueueState().awaitingNextBatch.add(modelKey);
}

function scheduleModelNextBatch(modelKey: string, delayMs: number) {
  const state = getQueueState();
  if (delayMs <= 0) {
    state.awaitingNextBatch.delete(modelKey);
    return false;
  }

  if (state.nextBatchTimers.has(modelKey)) {
    return true;
  }

  state.awaitingNextBatch.delete(modelKey);
  state.nextBatchEligibleAt.set(modelKey, Date.now() + delayMs);
  const timer = setTimeout(() => {
    const latestState = getQueueState();
    latestState.nextBatchTimers.delete(modelKey);
    latestState.nextBatchEligibleAt.delete(modelKey);
    void drainCanvasImageTaskQueue();
  }, delayMs);
  state.nextBatchTimers.set(modelKey, timer);
  return true;
}

async function enqueueLocalTask(
  taskId: string,
  meta?: { modelKey?: string; userId?: string } | string
) {
  const state = getQueueState();
  if (!taskId || state.running.has(taskId) || state.pendingSet.has(taskId)) {
    return;
  }

  const resolvedMeta =
    typeof meta === "string"
      ? { modelKey: meta, userId: undefined }
      : meta || {};
  const dbMeta =
    resolvedMeta.modelKey && resolvedMeta.userId
      ? null
      : await getTaskQueueMeta(taskId);
  const resolvedModelKey = resolvedMeta.modelKey || dbMeta?.modelKey || "__default__";
  const resolvedUserId = resolvedMeta.userId || dbMeta?.userId || "__anonymous__";
  state.pending.push({
    taskId,
    modelKey: resolvedModelKey,
    userId: resolvedUserId,
  });
  state.pendingSet.add(taskId);

  const maxConcurrentPerModel = await getCanvasImageSingleModelConcurrency();
  if (
    getRunningCountForModel(resolvedModelKey) >= maxConcurrentPerModel ||
    getRunningCountForModelUser(resolvedModelKey, resolvedUserId) >=
      getMaxConcurrentPerUser(maxConcurrentPerModel)
  ) {
    markModelAwaitingNextBatch(resolvedModelKey);
  }
}

function hasModelCapacity(
  modelKey: string,
  userId: string,
  maxConcurrentPerModel: number
) {
  return (
    getRunningCountForModel(modelKey) < maxConcurrentPerModel &&
    getRunningCountForModelUser(modelKey, userId) <
      getMaxConcurrentPerUser(maxConcurrentPerModel)
  );
}

async function claimNextPendingTask(
  maxConcurrentPerModel: number
): Promise<PendingTaskEntry | null> {
  const state = getQueueState();
  for (let index = 0; index < state.pending.length; index += 1) {
    const entry = state.pending[index];
    if (!entry) continue;
    if (state.running.has(entry.taskId)) continue;
    if (isModelBatchDispatchDelayed(entry.modelKey)) continue;
    if (!hasModelCapacity(entry.modelKey, entry.userId, maxConcurrentPerModel)) {
      markModelAwaitingNextBatch(entry.modelKey);
      continue;
    }

    state.pending.splice(index, 1);
    state.pendingSet.delete(entry.taskId);
    return entry;
  }

  const runningIds = Array.from(state.running.keys());
  const rows = await db
    .select({
      id: canvasImageTask.id,
      request: canvasImageTask.request,
      userId: canvasImageTask.userId,
    })
    .from(canvasImageTask)
    .where(
      runningIds.length > 0
        ? and(eq(canvasImageTask.status, "pending"), notInArray(canvasImageTask.id, runningIds))
        : eq(canvasImageTask.status, "pending")
    )
    .orderBy(asc(canvasImageTask.createdAt))
    .limit(PENDING_LOOKAHEAD_LIMIT);

  for (const row of rows) {
    if (!row?.id) continue;
    if (state.pendingSet.has(row.id) || state.running.has(row.id)) continue;

    const modelKey = normalizeTaskModelKey(row.request);
    if (isModelBatchDispatchDelayed(modelKey)) {
      continue;
    }
    const userId = String(row.userId || "__anonymous__");
    if (!hasModelCapacity(modelKey, userId, maxConcurrentPerModel)) {
      markModelAwaitingNextBatch(modelKey);
      continue;
    }

    return {
      taskId: row.id,
      modelKey,
      userId,
    };
  }

  return null;
}

async function markStaleDatabaseRunningTasksFailed() {
  const state = getQueueState();
  const now = Date.now();
  if (now - state.lastStaleRunningCleanupAt < STALE_RUNNING_CLEANUP_INTERVAL_MS) {
    return;
  }
  state.lastStaleRunningCleanupAt = now;

  const localRunningIds = Array.from(state.running.keys());
  const staleBefore = new Date(now - LOCAL_ACTIVE_RUNNING_HARD_TIMEOUT_MS);
  const staleWhere =
    localRunningIds.length > 0
      ? and(
          eq(canvasImageTask.status, "running"),
          lt(canvasImageTask.startedAt, staleBefore),
          notInArray(canvasImageTask.id, localRunningIds)
        )
      : and(
          eq(canvasImageTask.status, "running"),
          lt(canvasImageTask.startedAt, staleBefore)
        );

  const completedAt = new Date(now);
  const staleTasks = await db
    .update(canvasImageTask)
    .set({
      status: "failed",
      error: "图片生成任务已超时，请重新发起生成",
      completedAt,
      updatedAt: completedAt,
    })
    .where(staleWhere)
    .returning({ id: canvasImageTask.id });

  if (staleTasks.length > 0) {
    console.warn("[Canvas Image Task Queue] Marked stale running tasks failed:", {
      count: staleTasks.length,
      taskIds: staleTasks.slice(0, 10).map((task) => task.id),
    });
  }
}

async function runSingleTask(entry: PendingTaskEntry) {
  try {
    const [task] = await db
      .update(canvasImageTask)
      .set({
        status: "running",
        startedAt: new Date(),
        updatedAt: new Date(),
        completedAt: null,
        error: null,
        attempts: sql`${canvasImageTask.attempts} + 1`,
      })
      .where(and(eq(canvasImageTask.id, entry.taskId), eq(canvasImageTask.status, "pending")))
      .returning({
        id: canvasImageTask.id,
        request: canvasImageTask.request,
        userId: canvasImageTask.userId,
      });

    if (!task) {
      return;
    }

    const request = task.request as CanvasImageTaskRequest;
    const runningTimeoutMs = getCanvasImageRunningTimeoutMs(request);
    const execution: Promise<CanvasImageTaskResult> = isStyleProTaskRequest(request)
      ? executeStyleProTask({
          request,
          userId: String(task.userId || entry.userId),
        })
      : (async () => {
          const imageRequest = request as CanvasGenerateImageRequest;
          const ownerKey = String(task.userId || entry.userId);
          const initialResult = await generateCanvasImage({
            ...imageRequest,
            ownerKey,
          });
          return await applyScaleAdjustModelRelight({
            generateImage: generateCanvasImage,
            initialResult,
            ownerKey,
            request: imageRequest,
          });
        })();
    const result = await withCanvasImageTaskExecutionTimeout(
      execution,
      runningTimeoutMs,
      entry.taskId
    );
    await db
      .update(canvasImageTask)
      .set({
        status: "succeeded",
        result: result as CanvasImageTaskResult,
        error: null,
        completedAt: new Date(),
        updatedAt: new Date(),
      })
      .where(
        and(eq(canvasImageTask.id, entry.taskId), eq(canvasImageTask.status, "running"))
      );
  } catch (error) {
    await db
      .update(canvasImageTask)
      .set({
        status: "failed",
        error: error instanceof Error ? error.message : String(error),
        completedAt: new Date(),
        updatedAt: new Date(),
      })
      .where(
        and(eq(canvasImageTask.id, entry.taskId), eq(canvasImageTask.status, "running"))
      );
  } finally {
    const modelKey = releaseRunningTask(entry.taskId);
    if (modelKey) {
      const batchDispatchIntervalMs = await getCanvasImageBatchDispatchIntervalMs();
      if (getQueueState().awaitingNextBatch.has(modelKey)) {
        scheduleModelNextBatch(modelKey, batchDispatchIntervalMs);
      }
    }
    void drainCanvasImageTaskQueue();
  }
}

export async function drainCanvasImageTaskQueue() {
  const state = getQueueState();
  if (state.draining) return;

  state.draining = true;
  try {
    await markStaleDatabaseRunningTasksFailed();
    const maxConcurrentPerModel = await getCanvasImageSingleModelConcurrency();
    while (true) {
      const nextTask = await claimNextPendingTask(maxConcurrentPerModel);
      if (!nextTask) break;
      if (state.running.has(nextTask.taskId)) continue;
      markRunningTask(nextTask.taskId, nextTask.modelKey, nextTask.userId);
      void runSingleTask(nextTask);
    }
  } finally {
    state.draining = false;
  }
}

export async function enqueueCanvasImageTask(taskId: string) {
  await enqueueLocalTask(taskId);
  await drainCanvasImageTaskQueue();
}

export async function createCanvasImageTask(params: {
  userId: string;
  request: Record<string, unknown>;
}) {
  const [task] = await db
    .insert(canvasImageTask)
      .values({
        userId: params.userId,
        status: "pending",
        request: params.request as unknown as Record<string, unknown>,
        attempts: 0,
        createdAt: new Date(),
        updatedAt: new Date(),
      })
    .returning({
      id: canvasImageTask.id,
      status: canvasImageTask.status,
      createdAt: canvasImageTask.createdAt,
    });

  return task;
}

async function estimateModelQueueWaitMs(params: {
  modelKey: string;
  sameModelRunningCount: number;
  queuePosition: number;
  concurrencyLimit: number;
}) {
  const rows = await db
    .select({
      request: canvasImageTask.request,
      startedAt: canvasImageTask.startedAt,
      completedAt: canvasImageTask.completedAt,
    })
    .from(canvasImageTask)
    .where(eq(canvasImageTask.status, "succeeded"))
    .orderBy(desc(canvasImageTask.completedAt))
    .limit(QUEUE_STATUS_RECENT_SAMPLE_LIMIT);

  const durations = rows
    .filter((row) => normalizeTaskModelKey(row.request) === params.modelKey)
    .map((row) => {
      if (!row.startedAt || !row.completedAt) return 0;
      return row.completedAt.getTime() - row.startedAt.getTime();
    })
    .filter((value) => Number.isFinite(value) && value > 1000)
    .slice(0, 12);

  const averageDurationMs =
    durations.length > 0
      ? Math.round(durations.reduce((sum, value) => sum + value, 0) / durations.length)
      : DEFAULT_ESTIMATED_WAIT_MS;
  const immediatelyStartable = Math.max(
    params.concurrencyLimit - params.sameModelRunningCount,
    0
  );

  if (params.queuePosition < immediatelyStartable) {
    return 0;
  }

  const tasksAheadAfterImmediateSlots = Math.max(
    0,
    params.queuePosition - immediatelyStartable
  );
  const waveCount =
    Math.floor(
      tasksAheadAfterImmediateSlots / Math.max(1, params.concurrencyLimit)
    ) +
    (params.sameModelRunningCount > 0 || immediatelyStartable === 0 ? 1 : 0);

  return Math.max(0, waveCount * averageDurationMs);
}

async function buildCanvasImageTaskQueueStatus(task: {
  id: string;
  status: CanvasImageTaskStatus;
  request: unknown;
  createdAt: Date;
}) {
  const modelKey = normalizeTaskModelKey(task.request);
  const concurrencyLimit = await getCanvasImageSingleModelConcurrency();
  const runningRows = await db
    .select({
      request: canvasImageTask.request,
    })
    .from(canvasImageTask)
    .where(eq(canvasImageTask.status, "running"));
  const sameModelRunningCount = Math.max(
    runningRows.filter((row) => normalizeTaskModelKey(row.request) === modelKey).length,
    getCanvasImageRunningCountForModel(modelKey)
  );

  if (task.status !== "pending") {
    return {
      status: task.status,
      queuePosition: 0,
      sameModelPendingCount: 0,
      sameModelRunningCount,
      concurrencyLimit,
      estimatedWaitMs: 0,
      source: "model_queue" as const,
    };
  }

  const pendingRows = await db
    .select({
      id: canvasImageTask.id,
      request: canvasImageTask.request,
      createdAt: canvasImageTask.createdAt,
    })
    .from(canvasImageTask)
    .where(eq(canvasImageTask.status, "pending"))
    .orderBy(asc(canvasImageTask.createdAt))
    .limit(QUEUE_STATUS_PENDING_LOOKAHEAD_LIMIT);

  const sameModelPendingRows = pendingRows.filter(
    (row) => normalizeTaskModelKey(row.request) === modelKey
  );
  const queuePosition = Math.max(
    sameModelPendingRows.findIndex((row) => row.id === task.id),
    0
  );
  const sameModelPendingCount = sameModelPendingRows.length;
  const estimatedWaitMs = await estimateModelQueueWaitMs({
    modelKey,
    sameModelRunningCount,
    queuePosition,
    concurrencyLimit,
  });

  return {
    status: task.status,
    queuePosition,
    sameModelPendingCount,
    sameModelRunningCount,
    concurrencyLimit,
    estimatedWaitMs,
    source: "model_queue" as const,
  };
}

export async function getCanvasImageTaskForUser(params: {
  taskId: string;
  userId: string;
}) {
  const rows = await db
    .select({
      id: canvasImageTask.id,
      status: canvasImageTask.status,
      request: canvasImageTask.request,
      result: canvasImageTask.result,
      error: canvasImageTask.error,
      attempts: canvasImageTask.attempts,
      startedAt: canvasImageTask.startedAt,
      completedAt: canvasImageTask.completedAt,
      createdAt: canvasImageTask.createdAt,
      updatedAt: canvasImageTask.updatedAt,
    })
    .from(canvasImageTask)
    .where(and(eq(canvasImageTask.id, params.taskId), eq(canvasImageTask.userId, params.userId)))
    .limit(1);

  const task = rows[0];
  if (!task) return null;

  if (task.status === "running" && task.startedAt) {
    const now = Date.now();
    const runningAgeMs = now - task.startedAt.getTime();
    const runningTimeoutMs = getCanvasImageRunningTimeoutMs(task.request);
    const locallyRunning = getQueueState().running.has(task.id);
    const shouldMarkStale =
      runningAgeMs >= runningTimeoutMs &&
      (!locallyRunning || runningAgeMs >= LOCAL_ACTIVE_RUNNING_HARD_TIMEOUT_MS);

    if (shouldMarkStale) {
      const staleBefore = new Date(now - runningTimeoutMs);
      const timeoutMessage = "图片生成任务已超时，请重新发起生成";
      const completedAt = new Date();
      const [timedOutTask] = await db
        .update(canvasImageTask)
        .set({
          status: "failed",
          error: timeoutMessage,
          completedAt,
          updatedAt: completedAt,
        })
        .where(
          and(
            eq(canvasImageTask.id, task.id),
            eq(canvasImageTask.status, "running"),
            lt(canvasImageTask.startedAt, staleBefore)
          )
        )
        .returning({
          status: canvasImageTask.status,
          error: canvasImageTask.error,
          completedAt: canvasImageTask.completedAt,
        });

      if (timedOutTask) {
        releaseRunningTask(task.id);
        task.status = timedOutTask.status as CanvasImageTaskStatus;
        task.error = timedOutTask.error;
        task.completedAt = timedOutTask.completedAt;
      }
    }
  }

  if (task.status === "pending") {
    await enqueueLocalTask(task.id, {
      modelKey: normalizeTaskModelKey(task.request),
      userId: params.userId,
    });
    await drainCanvasImageTaskQueue();
  }

  return {
    ...task,
    queueStatus: await buildCanvasImageTaskQueueStatus({
      id: task.id,
      status: task.status as CanvasImageTaskStatus,
      request: task.request,
      createdAt: task.createdAt,
    }),
  };
}