import { asc, count, desc, eq, sql } from "drizzle-orm";
import { db } from "@/lib/db";
import { users } from "@/modules/_core/schema";
import { bangEvents } from "../schema";

export type BangStatsDto = {
  total: number;
  recent: RecentBangDto[];
};

export type RecentBangDto = {
  id: string;
  occurredOn: string;
  recordedByName: string | null;
};

export type BangAggregatesDto = {
  thisMonth: number;
  thisYear: number;
  averageDaysBetween: number | null;
  monthlyCounts: { month: string; count: number }[];
};

export async function getBangStatsForScope(
  householdId: string,
  limit: number,
): Promise<BangStatsDto> {
  const [totalRow] = await db
    .select({ total: count() })
    .from(bangEvents)
    .where(eq(bangEvents.householdId, householdId));

  const recent = await db
    .select({
      id: bangEvents.id,
      occurredOn: bangEvents.occurredOn,
      recordedByName: users.name,
    })
    .from(bangEvents)
    .leftJoin(users, eq(bangEvents.recordedBy, users.id))
    .where(eq(bangEvents.householdId, householdId))
    .orderBy(desc(bangEvents.occurredOn), desc(bangEvents.createdAt))
    .limit(limit);

  return {
    total: totalRow?.total ?? 0,
    recent: recent.map((r) => ({
      id: r.id,
      occurredOn: r.occurredOn,
      recordedByName: r.recordedByName,
    })),
  };
}

export async function getBangStats(householdId: string, limit: number): Promise<BangStatsDto> {
  return getBangStatsForScope(householdId, limit);
}

export async function getBangAggregates(householdId: string): Promise<BangAggregatesDto> {
  const now = new Date();
  const monthPrefix = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, "0")}`;
  const yearPrefix = `${now.getFullYear()}-`;

  const [thisMonthRow] = await db
    .select({ count: sql<number>`count(*)::int` })
    .from(bangEvents)
    .where(
      sql`${bangEvents.householdId} = ${householdId} and ${bangEvents.occurredOn} like ${`${monthPrefix}%`}`,
    );

  const [thisYearRow] = await db
    .select({ count: sql<number>`count(*)::int` })
    .from(bangEvents)
    .where(
      sql`${bangEvents.householdId} = ${householdId} and ${bangEvents.occurredOn} like ${`${yearPrefix}%`}`,
    );

  const monthlyRows = await db
    .select({
      month: sql<string>`substring(${bangEvents.occurredOn}, 1, 7)`,
      count: sql<number>`count(*)::int`,
    })
    .from(bangEvents)
    .where(eq(bangEvents.householdId, householdId))
    .groupBy(sql`substring(${bangEvents.occurredOn}, 1, 7)`)
    .orderBy(asc(sql`substring(${bangEvents.occurredOn}, 1, 7)`));

  const dateRows = await db
    .select({ occurredOn: bangEvents.occurredOn })
    .from(bangEvents)
    .where(eq(bangEvents.householdId, householdId))
    .orderBy(asc(bangEvents.occurredOn));

  let averageDaysBetween: number | null = null;
  if (dateRows.length >= 2) {
    const dates = dateRows.map((row) => parseBangDate(row.occurredOn).getTime());
    let totalGapDays = 0;
    for (let i = 1; i < dates.length; i++) {
      totalGapDays += (dates[i]! - dates[i - 1]!) / (1000 * 60 * 60 * 24);
    }
    averageDaysBetween = Math.round((totalGapDays / (dates.length - 1)) * 10) / 10;
  }

  return {
    thisMonth: thisMonthRow?.count ?? 0,
    thisYear: thisYearRow?.count ?? 0,
    averageDaysBetween,
    monthlyCounts: monthlyRows.map((row) => ({ month: row.month, count: row.count })),
  };
}

function parseBangDate(isoDate: string): Date {
  const [year, month, day] = isoDate.split("-").map(Number);
  return new Date(year!, month! - 1, day!);
}