import { uuidv7, validateGstin } from '@sims/domain'
import { writeAudit } from './audit'
import type { DB } from './db'

/** Client registry — plain functions over the handle (D12 portable-repo pattern). */

export interface ClientContact { name: string; phone?: string; email?: string; role?: string }

export interface Client {
  id: string; code: string; name: string; gstin?: string; stateCode: string
  address: string; contacts: ClientContact[]
  status: 'lead' | 'active' | 'dormant' | 'lost'; notes: string
}

interface ClientRow {
  id: string; code: string; name: string; gstin: string | null; state_code: string
  address: string; contacts: string; status: string; notes: string
  source: string; created_at: string
}

function toClient(r: ClientRow): Client {
  return {
    id: r.id, code: r.code, name: r.name,
    ...(r.gstin !== null ? { gstin: r.gstin } : {}),
    stateCode: r.state_code, address: r.address,
    contacts: JSON.parse(r.contacts) as ClientContact[],
    status: r.status as Client['status'], notes: r.notes,
  }
}

function assertGstin(gstin: string): void {
  const v = validateGstin(gstin)
  if (!v.ok) throw new Error(`Invalid GSTIN (${v.reason ?? 'invalid'}): ${gstin}`)
}

export function listClients(db: DB, q?: string): Client[] {
  let rows: ClientRow[]
  if (q !== undefined && q !== '') {
    const like = `%${q}%`
    rows = db.prepare(
      `SELECT * FROM client WHERE name LIKE ? OR code LIKE ? OR gstin LIKE ? ORDER BY name`,
    ).all(like, like, like) as ClientRow[]
  } else {
    rows = db.prepare(`SELECT * FROM client ORDER BY name`).all() as ClientRow[]
  }
  return rows.map(toClient)
}

export function getClient(db: DB, id: string): Client | null {
  const row = db.prepare(`SELECT * FROM client WHERE id=?`).get(id) as ClientRow | undefined
  return row === undefined ? null : toClient(row)
}

export interface ClientInput {
  code?: string; name: string; gstin?: string; stateCode: string; address?: string
  contacts?: ClientContact[]; status?: Client['status']; notes?: string
}

export function createClient(db: DB, userId: string, input: ClientInput): Client {
  if (input.gstin !== undefined) assertGstin(input.gstin)
  const id = uuidv7()
  const n = (db.prepare(`SELECT COUNT(*) AS n FROM client`).get() as { n: number }).n
  const code = input.code ?? `CL${String(n + 1).padStart(4, '0')}`
  db.prepare(
    `INSERT INTO client (id, code, name, gstin, state_code, address, contacts, status, notes, created_at)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
  ).run(
    id, code, input.name, input.gstin ?? null, input.stateCode,
    input.address ?? '', JSON.stringify(input.contacts ?? []),
    input.status ?? 'active', input.notes ?? '', new Date().toISOString(),
  )
  const client = getClient(db, id)!
  writeAudit(db, userId, 'create', 'client', id, undefined, client)
  return client
}

export interface ClientPatch {
  name?: string; gstin?: string | null; stateCode?: string; address?: string
  contacts?: ClientContact[]; status?: Client['status']; notes?: string
}

export function updateClient(db: DB, userId: string, id: string, patch: ClientPatch): Client {
  const before = getClient(db, id)
  if (before === null) throw new Error('Client not found')
  if (patch.gstin !== undefined && patch.gstin !== null) assertGstin(patch.gstin)
  const sets: string[] = []
  const args: unknown[] = []
  if (patch.name !== undefined) { sets.push('name=?'); args.push(patch.name) }
  if (patch.gstin !== undefined) { sets.push('gstin=?'); args.push(patch.gstin) }
  if (patch.stateCode !== undefined) { sets.push('state_code=?'); args.push(patch.stateCode) }
  if (patch.address !== undefined) { sets.push('address=?'); args.push(patch.address) }
  if (patch.contacts !== undefined) { sets.push('contacts=?'); args.push(JSON.stringify(patch.contacts)) }
  if (patch.status !== undefined) { sets.push('status=?'); args.push(patch.status) }
  if (patch.notes !== undefined) { sets.push('notes=?'); args.push(patch.notes) }
  if (sets.length > 0) {
    args.push(id)
    db.prepare(`UPDATE client SET ${sets.join(', ')} WHERE id=?`).run(...args)
  }
  const after = getClient(db, id)!
  writeAudit(db, userId, 'update', 'client', id, before, after)
  return after
}