'use server'

import { z } from 'zod'
import { db } from '@/lib/db'
import { rounds, roundPlayers, roundInvites, tees, courses, user } from '@/lib/db/schema'
import { eq, and } from 'drizzle-orm'
import { auth } from '@/lib/auth'
import { headers } from 'next/headers'
import { sendEmail } from '@/lib/email'
import { revalidatePath } from 'next/cache'

const CreateRoundSchema = z.object({
  course_id:   z.string().uuid(),
  tee_id:      z.string().uuid(),
  name:        z.string().max(100).optional(),
  date:        z.string().regex(/^\d{4}-\d{2}-\d{2}$/),
  holes_count: z.union([z.literal(9), z.literal(18)]),
  emails:      z.array(z.string().email()).default([]),
})

export type CreateRoundInput = z.infer<typeof CreateRoundSchema>

function computeCourseHandicap(
  handicapIndex: number,
  slopeRating: number,
  courseRating: number,
  par: number,
): number {
  return Math.round(handicapIndex * (slopeRating / 113) + (courseRating - par))
}

export async function createRoundWithInvites(data: CreateRoundInput) {
  const parsed = CreateRoundSchema.safeParse(data)
  if (!parsed.success) return { error: parsed.error.issues[0]?.message ?? 'Invalid data' }

  const session = await auth.api.getSession({ headers: await headers() })
  if (!session) return { error: 'Not authenticated' }

  // Snapshot handicap
  const [creator] = await db
    .select({ handicapIndex: user.handicapIndex })
    .from(user)
    .where(eq(user.id, session.user.id))
    .limit(1)

  const [tee] = await db
    .select({ courseRating: tees.courseRating, slopeRating: tees.slopeRating })
    .from(tees)
    .where(eq(tees.id, parsed.data.tee_id))
    .limit(1)

  const [course] = await db
    .select({ par: courses.par })
    .from(courses)
    .where(eq(courses.id, parsed.data.course_id))
    .limit(1)

  const handicapIndex = creator?.handicapIndex ? parseFloat(creator.handicapIndex) : null
  const courseHandicap =
    handicapIndex !== null && tee && course
      ? computeCourseHandicap(
          handicapIndex,
          tee.slopeRating,
          parseFloat(tee.courseRating),
          course.par,
        )
      : null

  const [round] = await db
    .insert(rounds)
    .values({
      courseId:   parsed.data.course_id,
      teeId:      parsed.data.tee_id,
      name:       parsed.data.name ?? null,
      date:       parsed.data.date,
      holesCount: parsed.data.holes_count,
      createdBy:  session.user.id,
      status:     'lobby',
    })
    .returning({ id: rounds.id })

  await db.insert(roundPlayers).values({
    roundId:        round.id,
    userId:         session.user.id,
    role:           'admin',
    handicapIndex:  handicapIndex !== null ? String(handicapIndex) : null,
    courseHandicap: courseHandicap,
  })

  const failedInvites: string[] = []
  for (const email of parsed.data.emails) {
    const result = await inviteToRound(round.id, email, session.user.id)
    if (result.error) failedInvites.push(email)
  }

  return { roundId: round.id, failedInvites }
}

export async function startRound(roundId: string) {
  const session = await auth.api.getSession({ headers: await headers() })
  if (!session) return { error: 'Not authenticated' }

  const [round] = await db
    .select({ createdBy: rounds.createdBy, status: rounds.status })
    .from(rounds)
    .where(eq(rounds.id, roundId))
    .limit(1)

  if (!round) return { error: 'Round not found' }
  if (round.createdBy !== session.user.id) return { error: 'Only the round creator can start it' }
  if (round.status !== 'lobby') return { error: 'Round is not in lobby' }

  await db.update(rounds).set({ status: 'active' }).where(eq(rounds.id, roundId))
  revalidatePath(`/rounds/${roundId}`)
  return { success: true }
}

export async function completeRound(roundId: string) {
  const session = await auth.api.getSession({ headers: await headers() })
  if (!session) return { error: 'Not authenticated' }

  const [round] = await db
    .select({ createdBy: rounds.createdBy, status: rounds.status })
    .from(rounds)
    .where(eq(rounds.id, roundId))
    .limit(1)

  if (!round) return { error: 'Round not found' }
  if (round.createdBy !== session.user.id) return { error: 'Only the round creator can complete it' }
  if (round.status !== 'active') return { error: 'Round is not active' }

  await db.update(rounds).set({ status: 'completed' }).where(eq(rounds.id, roundId))
  revalidatePath(`/rounds/${roundId}`)
  return { success: true }
}

export async function joinRound(roundId: string) {
  const session = await auth.api.getSession({ headers: await headers() })
  if (!session) return { error: 'Not authenticated' }

  const [roundData] = await db
    .select({ teeId: rounds.teeId, courseId: rounds.courseId, status: rounds.status })
    .from(rounds)
    .where(eq(rounds.id, roundId))
    .limit(1)

  if (!roundData) return { error: 'Round not found' }
  if (roundData.status !== 'lobby') return { error: 'Round is not accepting new players' }

  const [me] = await db
    .select({ handicapIndex: user.handicapIndex })
    .from(user)
    .where(eq(user.id, session.user.id))
    .limit(1)

  const [tee] = await db
    .select({ courseRating: tees.courseRating, slopeRating: tees.slopeRating })
    .from(tees)
    .where(eq(tees.id, roundData.teeId))
    .limit(1)

  const [course] = await db
    .select({ par: courses.par })
    .from(courses)
    .where(eq(courses.id, roundData.courseId))
    .limit(1)

  const handicapIndex = me?.handicapIndex ? parseFloat(me.handicapIndex) : null
  const courseHandicap =
    handicapIndex !== null && tee && course
      ? computeCourseHandicap(
          handicapIndex,
          tee.slopeRating,
          parseFloat(tee.courseRating),
          course.par,
        )
      : null

  try {
    await db.insert(roundPlayers).values({
      roundId,
      userId:         session.user.id,
      role:           'player',
      handicapIndex:  handicapIndex !== null ? String(handicapIndex) : null,
      courseHandicap: courseHandicap,
    })
  } catch {
    return { error: 'Already a member of this round' }
  }

  // Mark invite as accepted
  await db
    .update(roundInvites)
    .set({ acceptedAt: new Date() })
    .where(and(eq(roundInvites.roundId, roundId), eq(roundInvites.email, session.user.email!)))

  revalidatePath(`/rounds/${roundId}`)
  return { success: true }
}

// Shared helper used by both createRoundWithInvites and inviteFromLobby
export async function inviteToRound(roundId: string, email: string, invitedByUserId: string) {
  // Create user if they don't exist yet
  const [existing] = await db
    .select({ id: user.id })
    .from(user)
    .where(eq(user.email, email.toLowerCase()))
    .limit(1)

  if (!existing) {
    await db.insert(user).values({
      id:            crypto.randomUUID(),
      email:         email.toLowerCase(),
      name:          email.split('@')[0],
      emailVerified: false,
      createdAt:     new Date(),
      updatedAt:     new Date(),
    })
  }

  // Send magic link via better-auth
  const callbackURL = `${process.env.SITE_URL}/rounds/${roundId}/join`
  try {
    await auth.api.signInMagicLink({
      body:    { email: email.toLowerCase(), callbackURL },
      headers: await headers(),
    })
  } catch (err: any) {
    return { error: err?.message ?? 'Failed to send invite email' }
  }

  // Record invite
  await db
    .insert(roundInvites)
    .values({ roundId, email: email.toLowerCase(), invitedBy: invitedByUserId })
    .onConflictDoNothing()

  return { success: true }
}