import { and, isNotNull, eq, ne, sql } from 'drizzle-orm'
import { db } from '~/drizzle/db'
import { users, gradeClasses } from '~/drizzle/schema'
import { resolveGradeClassOptions, type GradeClassOption } from './grade-class-core'

export async function fetchGradeClassOptions(): Promise<GradeClassOption[]> {
  const [configRows, userRows] = await Promise.all([
    db.select({
      grade: gradeClasses.grade,
      class: gradeClasses.class
    }).from(gradeClasses),
    db
      .selectDistinct({
        grade: users.grade,
        class: users.class
      })
      .from(users)
      .where(and(eq(users.status, 'active'), isNotNull(users.grade), isNotNull(users.class)))
  ])

  return resolveGradeClassOptions(configRows, userRows)
}

export async function isGradeClassValid(grade: string, studentClass: string): Promise<boolean> {
  const configHit = await db.query.gradeClasses.findFirst({
    where: (t, { eq: eq_, and: and_ }) => and_(eq_(t.grade, grade), eq_(t.class, studentClass)),
    columns: { id: true }
  })

  if (configHit) return true

  const configCount = await db
    .select({ count: () => sql<number>`count(*)::int` })
    .from(gradeClasses)
    .where(and(ne(gradeClasses.grade, ''), ne(gradeClasses.class, '')))
  if ((configCount[0]?.count || 0) > 0) return false

  const userHit = await db.query.users.findFirst({
    where: (t, { eq: eq_, and: and_ }) =>
      and_(eq_(t.status, 'active'), eq_(t.grade, grade), eq_(t.class, studentClass)),
    columns: { id: true }
  })

  return Boolean(userHit)
}