import { dbGlobal } from "drizzle-pkg/lib/db";
import { userExportTasks } from "drizzle-pkg/lib/schema/export";
import { and, desc, eq, or } from "drizzle-orm";
import { createError } from "h3";
import { nextIntegerId } from "../../utils/sqlite-id";

type ExportMaskPolicy = "masked" | "raw";

async function getExportTaskById(taskId: number) {
  const [row] = await dbGlobal
    .select()
    .from(userExportTasks)
    .where(eq(userExportTasks.id, taskId))
    .limit(1);
  return row ?? null;
}

async function getRequiredExportTaskById(taskId: number) {
  const row = await getExportTaskById(taskId);
  if (!row) {
    throw new Error(`export task not found: ${taskId}`);
  }
  return row;
}

export async function createExportTask(params: { userId: number; maskPolicy: ExportMaskPolicy }) {
  const [activeTask] = await dbGlobal
    .select({ id: userExportTasks.id })
    .from(userExportTasks)
    .where(
      and(
        eq(userExportTasks.userId, params.userId),
        or(eq(userExportTasks.status, "queued"), eq(userExportTasks.status, "running")),
      ),
    )
    .limit(1);
  if (activeTask) {
    throw createError({ statusCode: 409, statusMessage: "已有导出任务在处理中，请稍后再试" });
  }
  const id = await nextIntegerId(userExportTasks, userExportTasks.id);
  await dbGlobal.insert(userExportTasks).values({
    id,
    userId: params.userId,
    maskPolicy: params.maskPolicy,
    status: "queued",
  });
  return getRequiredExportTaskById(id);
}

export async function listExportTasksByUser(userId: number) {
  return dbGlobal
    .select()
    .from(userExportTasks)
    .where(eq(userExportTasks.userId, userId))
    .orderBy(desc(userExportTasks.id));
}

export async function markExportTaskRunning(taskId: number) {
  const cutoffAt = new Date();
  await dbGlobal
    .update(userExportTasks)
    .set({
      status: "running",
      exportCutoffAt: cutoffAt,
    })
    .where(and(eq(userExportTasks.id, taskId), eq(userExportTasks.status, "queued")));
  const row = await getRequiredExportTaskById(taskId);
  if (row.status !== "running" || row.exportCutoffAt?.getTime() !== cutoffAt.getTime()) {
    throw new Error(`invalid export task transition for ${taskId}: expected queued -> running`);
  }
  return row;
}

export async function claimNextQueuedTask() {
  for (let i = 0; i < 5; i += 1) {
    const [queued] = await dbGlobal
      .select({ id: userExportTasks.id })
      .from(userExportTasks)
      .where(eq(userExportTasks.status, "queued"))
      .orderBy(userExportTasks.id)
      .limit(1);
    if (!queued) {
      return null;
    }

    try {
      return await markExportTaskRunning(queued.id);
    } catch (error) {
      const message = error instanceof Error ? error.message : "";
      if (!message.includes("invalid export task transition")) {
        throw error;
      }
    }
  }
  return null;
}

export async function markExportTaskSucceeded(
  taskId: number,
  payload: {
    outputDir: string;
    outputName: string;
    totalBytes: number;
    expiresAt: Date;
  },
) {
  await dbGlobal
    .update(userExportTasks)
    .set({
      status: "succeeded",
      outputDir: payload.outputDir,
      outputName: payload.outputName,
      totalBytes: payload.totalBytes,
      expiresAt: payload.expiresAt,
      errorCode: null,
      errorMessage: null,
    })
    .where(and(eq(userExportTasks.id, taskId), eq(userExportTasks.status, "running")));
  const row = await getRequiredExportTaskById(taskId);
  if (row.status !== "succeeded") {
    throw new Error(`invalid export task transition for ${taskId}: expected running -> succeeded`);
  }
  return row;
}

export async function markExportTaskFailed(
  taskId: number,
  payload: {
    errorCode: string;
    errorMessage: string;
  },
) {
  await dbGlobal
    .update(userExportTasks)
    .set({
      status: "failed",
      errorCode: payload.errorCode,
      errorMessage: payload.errorMessage,
    })
    .where(and(eq(userExportTasks.id, taskId), eq(userExportTasks.status, "running")));
  const row = await getRequiredExportTaskById(taskId);
  if (row.status !== "failed") {
    throw new Error(`invalid export task transition for ${taskId}: expected running -> failed`);
  }
  return row;
}

export async function getExportTaskForUser(taskId: number, userId: number) {
  const [row] = await dbGlobal
    .select()
    .from(userExportTasks)
    .where(and(eq(userExportTasks.id, taskId), eq(userExportTasks.userId, userId)))
    .limit(1);
  return row ?? null;
}