import { desc } from 'drizzle-orm'
import * as schema from '@/lib/db/schema'
import type { GameDb } from '@/lib/db/client'

export interface EventDto {
  id: number
  turn: number
  type: string
  message: string
  createdAt: string
}

export const DEFAULT_LIMIT = 50
export const MAX_LIMIT = 200

export class EventError extends Error {
  constructor(
    public readonly status: number,
    message: string,
  ) {
    super(message)
  }
}

// Parses the optional ?limit= query param. Absent → default; anything that is not an integer in
// [1, MAX_LIMIT] is a 400 (the route maps EventError to its status).
export function parseEventLimit(raw: string | null): number {
  if (raw === null) return DEFAULT_LIMIT
  const limit = Number(raw)
  if (!Number.isInteger(limit) || limit < 1 || limit > MAX_LIMIT) {
    throw new EventError(400, `limit must be an integer between 1 and ${MAX_LIMIT}`)
  }
  return limit
}

// The latest N events of the save, newest first. Assumes a save exists (the route calls ensureSave).
export async function getEvents(db: GameDb, limit: number): Promise<EventDto[]> {
  const rows = await db.db.select().from(schema.events).orderBy(desc(schema.events.id)).limit(limit)
  return rows.map((e) => ({ id: e.id, turn: e.turn, type: e.type, message: e.message, createdAt: e.createdAt }))
}