import type { Interest, ValidLead } from '@kvarta/shared/lead';
import type { Db } from './db/index.js';
import type { ClarifiedField, LeadEvent } from './notifier.js';

/** Окно уточнений: от created_at заявки, уточнения его не продлевают. */
export const CLARIFY_WINDOW_MS = 10 * 60 * 1000;

export type SaveMeta = { now: Date; userAgent: string | null };

export type SaveResult =
  | { kind: 'created'; event: LeadEvent }
  | { kind: 'clarified'; event: LeadEvent }
  | { kind: 'unchanged'; leadId: number };

/** Версия заявки: сама заявка или уточнение к ней. */
export type Version = { name: string; interest: Interest; comment: string | null };

const CLARIFIED_FIELDS: readonly ClarifiedField[] = ['name', 'interest', 'comment'];

export function changedFields(previous: Version, next: Version): ClarifiedField[] {
  return CLARIFIED_FIELDS.filter((field) => previous[field] !== next[field]);
}

/**
 * Новая заявка, уточнение к заявке из окна или повтор без изменений.
 * Поиск и запись в одной IMMEDIATE-транзакции: два одновременных запроса с одного телефона
 * не создадут две заявки, даже если процессов станет больше одного.
 */
export function saveLead(db: Db, lead: ValidLead, meta: SaveMeta): SaveResult {
  const nowIso = meta.now.toISOString();
  // Время хранится в одном формате toISOString, поэтому строки сравниваются как даты.
  const windowStart = new Date(meta.now.getTime() - CLARIFY_WINDOW_MS).toISOString();

  return db
    .transaction((): SaveResult => {
      const open = db
        .prepare(
          `SELECT id, name, interest, comment FROM leads
           WHERE phone = ? AND created_at > ?
           ORDER BY created_at DESC, id DESC LIMIT 1`,
        )
        .get(lead.phone, windowStart) as ({ id: number } & Version) | undefined;

      if (!open) {
        const { lastInsertRowid } = db
          .prepare(
            `INSERT INTO leads (created_at, phone, name, interest, comment, first_touch, last_touch, user_agent)
             VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
          )
          .run(
            nowIso,
            lead.phone,
            lead.name,
            lead.interest,
            lead.comment,
            lead.firstTouch ? JSON.stringify(lead.firstTouch) : null,
            JSON.stringify(lead.lastTouch),
            meta.userAgent,
          );
        return { kind: 'created', event: { kind: 'lead', leadId: Number(lastInsertRowid) } };
      }

      const previous =
        (db
          .prepare(
            `SELECT name, interest, comment FROM lead_clarifications
             WHERE lead_id = ? ORDER BY id DESC LIMIT 1`,
          )
          .get(open.id) as Version | undefined) ?? open;

      const changed = changedFields(previous, lead);
      if (changed.length === 0) return { kind: 'unchanged', leadId: open.id };

      const { lastInsertRowid } = db
        .prepare(
          `INSERT INTO lead_clarifications (lead_id, created_at, name, interest, comment, last_touch)
           VALUES (?, ?, ?, ?, ?, ?)`,
        )
        .run(open.id, nowIso, lead.name, lead.interest, lead.comment, JSON.stringify(lead.lastTouch));
      return {
        kind: 'clarified',
        event: { kind: 'clarification', leadId: open.id, clarificationId: Number(lastInsertRowid), changed },
      };
    })
    .immediate();
}