import type { CallClickPayload, LeadPayload } from '../../shared/lead.ts'
import { AmoClient, type AmoContact, type AmoFieldEntry } from './amocrm.ts'
import {
  buildCallClickName,
  buildLeadName,
  mapCallClick,
  mapLead,
  resolveLeadFieldMap,
  type LeadFieldMap,
} from './lead-mapper.ts'

const digitsOnly = (value: string) => value.replace(/\D/g, '')

/**
 * Last ten digits — the part that is stable across "+7 (999) 123-45-67",
 * "8 999 1234567" and "9991234567". Used to decide whether amoCRM already
 * knows a phone number.
 */
const phoneKey = (value: string) => digitsOnly(value).slice(-10)

/**
 * amoCRM's full-text search matches digit substrings, but a contact stored as
 * "+7 999…" is not found by a query starting with "8 999…". Try every spelling
 * a Russian visitor might type.
 */
function phoneQueries(phone: string): string[] {
  const digits = digitsOnly(phone)
  const queries = new Set<string>([phone.trim(), digits])
  if (digits.length >= 10) {
    const national = digits.slice(-10)
    queries.add(national)
    queries.add(`7${national}`)
    queries.add(`8${national}`)
  }
  return [...queries].filter(Boolean)
}

/** Reads the values already stored in a contact's standard multitext field. */
function existingValues(contact: AmoContact, code: 'PHONE' | 'EMAIL'): string[] {
  const entry = contact.custom_fields_values?.find((f) => f.field_code === code)
  return (entry?.values ?? []).map((v) => String(v.value ?? '')).filter(Boolean)
}

function contactFieldEntries(payload: LeadPayload): AmoFieldEntry[] {
  const entries: AmoFieldEntry[] = [
    { field_code: 'PHONE', values: [{ value: payload.phone, enum_code: 'WORK' }] },
  ]
  if (payload.email) {
    entries.push({ field_code: 'EMAIL', values: [{ value: payload.email, enum_code: 'WORK' }] })
  }
  return entries
}

export interface CreatedLead {
  leadId: number
  contactId: number
  contactCreated: boolean
}

export class LeadService {
  private fieldMap?: Promise<LeadFieldMap>

  constructor(private readonly amo: AmoClient) {}

  private getFieldMap(): Promise<LeadFieldMap> {
    this.fieldMap ??= this.amo.getLeadFields().then(resolveLeadFieldMap)
    return this.fieldMap
  }

  async submit(payload: LeadPayload): Promise<CreatedLead> {
    const fieldMap = await this.getFieldMap()

    // 1. Reuse the existing contact when the phone or email is already known.
    const existing = await this.amo.findContact([...phoneQueries(payload.phone), payload.email ?? ''])

    let contactId: number
    let contactCreated = false

    if (existing) {
      contactId = existing.id
      // Add whichever channel amoCRM does not have on file yet.
      const missing: AmoFieldEntry[] = []
      const knownPhones = existingValues(existing, 'PHONE').map(phoneKey)
      if (!knownPhones.includes(phoneKey(payload.phone))) {
        missing.push({
          field_code: 'PHONE',
          values: [
            ...existingValues(existing, 'PHONE').map((value) => ({ value })),
            { value: payload.phone, enum_code: 'WORK' },
          ],
        })
      }
      if (payload.email) {
        const knownEmails = existingValues(existing, 'EMAIL').map((e) => e.toLowerCase())
        if (!knownEmails.includes(payload.email.toLowerCase())) {
          missing.push({
            field_code: 'EMAIL',
            values: [
              ...existingValues(existing, 'EMAIL').map((value) => ({ value })),
              { value: payload.email, enum_code: 'WORK' },
            ],
          })
        }
      }
      await this.amo.appendContactFields(contactId, missing)
    } else {
      const created = await this.amo.createContact({ name: payload.name, fields: contactFieldEntries(payload) })
      contactId = created.id
      contactCreated = true
    }

    // 2. Lead in the configured pipeline, first stage.
    const { fields, note } = mapLead(payload, fieldMap)
    const lead = await this.amo.createLead({
      name: buildLeadName(payload),
      contactId,
      fields,
      tags: [payload.form === 'callback' ? 'обратный звонок' : 'заявка с сайта'],
    })

    // 3. Everything the account has no field for lands in a readable note.
    // A failed note must not fail the lead — the lead is the valuable part.
    if (note) {
      await this.amo.addLeadNote(lead.id, note).catch((error: unknown) => {
        console.warn('[amo] lead %d created but the note failed:', lead.id, error)
      })
    }

    return { leadId: lead.id, contactId, contactCreated }
  }

  /**
   * A visitor tapped the phone button. There is no contact to reuse or create —
   * only the click itself — so the lead stands alone, and its tag and note are
   * what tell a manager to expect an incoming call from this landing.
   */
  async submitCallClick(payload: CallClickPayload): Promise<{ leadId: number }> {
    const fieldMap = await this.getFieldMap()
    const { fields, note } = mapCallClick(payload, fieldMap)

    const lead = await this.amo.createLead({
      name: buildCallClickName(),
      fields,
      tags: ['клик по телефону'],
    })

    // As above: a failed note must not fail the lead.
    if (note) {
      await this.amo.addLeadNote(lead.id, note).catch((error: unknown) => {
        console.warn('[amo] lead %d created but the note failed:', lead.id, error)
      })
    }

    return { leadId: lead.id }
  }
}