import { db } from "@/db";
import { submissions } from "@/db/schema";
import { asc, count, inArray } from "drizzle-orm";

export type FormSubmissionStats = {
  totalAnswers: number;
  queueNumber: number | null;
};

export async function getFormSubmissionStats(
  formIds: string[],
  discordId: string | null
): Promise<Map<string, FormSubmissionStats>> {
  if (formIds.length === 0) {
    return new Map();
  }

  const totals = await db
    .select({
      formId: submissions.formId,
      totalAnswers: count(),
    })
    .from(submissions)
    .where(inArray(submissions.formId, formIds))
    .groupBy(submissions.formId);

  const stats = new Map<string, FormSubmissionStats>(
    totals.map((row) => [
      row.formId,
      {
        totalAnswers: row.totalAnswers,
        queueNumber: null,
      },
    ])
  );

  if (!discordId) {
    return stats;
  }

  const orderedSubmissions = await db
    .select({
      formId: submissions.formId,
      userDiscordId: submissions.userDiscordId,
    })
    .from(submissions)
    .where(inArray(submissions.formId, formIds))
    .orderBy(
      asc(submissions.formId),
      asc(submissions.submittedAt),
      asc(submissions.id)
    );

  const queueByForm = new Map<string, number>();
  const lastUserQueueByForm = new Map<string, number>();

  for (const submission of orderedSubmissions) {
    const queueNumber = (queueByForm.get(submission.formId) ?? 0) + 1;
    queueByForm.set(submission.formId, queueNumber);
    if (submission.userDiscordId === discordId) {
      lastUserQueueByForm.set(submission.formId, queueNumber);
    }
  }

  for (const [formId, queueNumber] of lastUserQueueByForm) {
    const current = stats.get(formId) ?? {
      totalAnswers: queueByForm.get(formId) ?? 0,
      queueNumber: null,
    };
    stats.set(formId, { ...current, queueNumber });
  }

  return stats;
}