import { uuidv7 } from '@sims/domain'
import { writeAudit } from './audit'
import type { DB } from './db'
import { getClient } from './repos-clients'
import { getClientModule, priceOn, type Kind } from './repos-modules'

/** Recurring billing plans — plain functions over the handle (D12 portable-repo pattern). */

export type Cadence = 'monthly' | 'yearly'
export const CADENCE_KIND: Record<Cadence, Kind> = { monthly: 'monthly', yearly: 'yearly' }

export interface RecurringPlan {
  id: string; clientId: string; clientModuleId: string | null; cadence: Cadence
  amountPaise: number | null; nextRun: string; policy: 'auto' | 'manual'; active: boolean
}

interface RecurringRow {
  id: string; client_id: string; client_module_id: string | null; cadence: string
  amount_paise: number | null; next_run: string; policy: string; active: number
}

function toPlan(r: RecurringRow): RecurringPlan {
  return {
    id: r.id, clientId: r.client_id, clientModuleId: r.client_module_id,
    cadence: r.cadence as Cadence, amountPaise: r.amount_paise, nextRun: r.next_run,
    policy: r.policy as 'auto' | 'manual', active: r.active === 1,
  }
}

export async function getRecurringPlan(db: DB, id: string): Promise<RecurringPlan | null> {
  const row = await db.get<RecurringRow>(`SELECT * FROM recurring_plan WHERE id=?`, id)
  return row === undefined ? null : toPlan(row)
}

export async function listRecurringPlans(db: DB, clientId?: string): Promise<RecurringPlan[]> {
  const rows = clientId === undefined
    ? await db.all<RecurringRow>(`SELECT * FROM recurring_plan ORDER BY id DESC`)
    : await db.all<RecurringRow>(`SELECT * FROM recurring_plan WHERE client_id=? ORDER BY id DESC`, clientId)
  return rows.map(toPlan)
}

export interface CreateRecurringInput {
  clientId: string; clientModuleId: string; cadence: Cadence
  amountPaise?: number; nextRun: string; policy?: 'auto' | 'manual'
}

export async function createRecurringPlan(db: DB, userId: string, input: CreateRecurringInput): Promise<RecurringPlan> {
  if ((await getClient(db, input.clientId)) === null) throw new Error('Client not found')
  const cm = await getClientModule(db, input.clientModuleId)
  if (cm === null) throw new Error('Client module not found')
  if (cm.clientId !== input.clientId) throw new Error('Client module belongs to another client')
  if (input.amountPaise !== undefined && (!Number.isInteger(input.amountPaise) || input.amountPaise < 0)) {
    throw new Error('amountPaise must be a non-negative integer (paise)')
  }
  // A plan must be priceable at generation time: explicit amount, or a resolvable module price.
  if (input.amountPaise === undefined) {
    const kind = CADENCE_KIND[input.cadence]
    if ((await priceOn(db, cm.moduleId, kind, cm.edition, input.nextRun)) === null) {
      throw new Error(`No ${kind} price for the module on ${input.nextRun}; set an amount or add a price`)
    }
  }
  const id = uuidv7()
  await db.run(
    `INSERT INTO recurring_plan (id, client_id, client_module_id, cadence, amount_paise, next_run, policy, active)
     VALUES (?, ?, ?, ?, ?, ?, ?, 1)`,
    id, input.clientId, input.clientModuleId, input.cadence,
    input.amountPaise ?? null, input.nextRun, input.policy ?? 'manual',
  )
  const plan = (await getRecurringPlan(db, id))!
  await writeAudit(db, userId, 'create', 'recurring_plan', id, undefined, plan)
  return plan
}

export interface RecurringPatch {
  cadence?: Cadence; amountPaise?: number | null; nextRun?: string
  policy?: 'auto' | 'manual'; active?: boolean
}

export async function updateRecurringPlan(db: DB, userId: string, id: string, patch: RecurringPatch): Promise<RecurringPlan> {
  const before = await getRecurringPlan(db, id)
  if (before === null) throw new Error('Recurring plan not found')
  const sets: string[] = []
  const args: unknown[] = []
  if (patch.cadence !== undefined) { sets.push('cadence=?'); args.push(patch.cadence) }
  if (patch.amountPaise !== undefined) { sets.push('amount_paise=?'); args.push(patch.amountPaise) }
  if (patch.nextRun !== undefined) { sets.push('next_run=?'); args.push(patch.nextRun) }
  if (patch.policy !== undefined) { sets.push('policy=?'); args.push(patch.policy) }
  if (patch.active !== undefined) { sets.push('active=?'); args.push(patch.active ? 1 : 0) }
  if (sets.length > 0) {
    args.push(id)
    await db.run(`UPDATE recurring_plan SET ${sets.join(', ')} WHERE id=?`, ...args)
  }
  const after = (await getRecurringPlan(db, id))!
  await writeAudit(db, userId, 'update', 'recurring_plan', id, before, after)
  return after
}

export async function deactivateRecurringPlan(db: DB, userId: string, id: string): Promise<RecurringPlan> {
  return updateRecurringPlan(db, userId, id, { active: false })
}