import type { Database } from 'bun:sqlite';
import { db, ensureUserExists } from '../db';
import { normalizeWhatsAppId } from '../utils/whatsapp';
import { TaskService } from '../tasks/service';
import { GroupSyncService } from './group-sync';

type CommandContext = {
  sender: string;     // normalized user id (digits only), but accept raw too
  groupId: string;    // full JID (e.g., xxx@g.us)
  message: string;    // raw message text
  mentions: string[]; // array of raw JIDs mentioned
};

export type CommandResponse = {
  recipient: string;
  message: string;
  mentions?: string[]; // full JIDs to mention in the outgoing message
};

export class CommandService {
  static dbInstance: Database = db;

  private static parseNueva(message: string, mentionsNormalized: string[]): {
    action: string;
    description: string;
    dueDate: string | null;
  } {
    const parts = (message || '').trim().split(/\s+/);
    const action = (parts[1] || '').toLowerCase();

    // Buscar última fecha futura con formato YYYY-MM-DD
    const dateIndices: { index: number; text: string }[] = [];
    for (let i = 2; i < parts.length; i++) {
      const p = parts[i];
      if (/^\d{4}-\d{2}-\d{2}$/.test(p)) {
        const d = new Date(p);
        const today = new Date();
        today.setHours(0, 0, 0, 0);
        if (!isNaN(d.getTime()) && d >= today) {
          dateIndices.push({ index: i, text: p });
        }
      }
    }

    let dueDate: string | null = null;
    let descriptionTokens: string[] = [];

    const isMentionToken = (token: string) => token.startsWith('@');

    if (dateIndices.length > 0) {
      const last = dateIndices[dateIndices.length - 1];
      dueDate = last.text;
      for (let i = 2; i < parts.length; i++) {
        if (i === last.index) continue;
        const token = parts[i];
        if (isMentionToken(token)) continue; // quitar @menciones del texto
        descriptionTokens.push(token);
      }
    } else {
      for (let i = 2; i < parts.length; i++) {
        const token = parts[i];
        if (isMentionToken(token)) continue;
        descriptionTokens.push(token);
      }
    }

    const description = descriptionTokens.join(' ').trim();

    return {
      action,
      description,
      dueDate,
    };
  }

  private static async processTareaCommand(
    context: CommandContext
  ): Promise<CommandResponse[]> {
    const trimmed = (context.message || '').trim();
    const tokens = trimmed.split(/\s+/);
    const action = (tokens[1] || '').toLowerCase();

    if (action !== 'nueva') {
      return [{
        recipient: context.sender,
        message: `Acción ${action || '(vacía)'} no implementada aún`
      }];
    }

    // Parseo específico de "nueva"
    // Normalizar menciones del contexto para parseo y asignaciones
    const mentionsNormalizedFromContext = Array.from(new Set(
      (context.mentions || [])
        .map(j => normalizeWhatsAppId(j))
        .filter((id): id is string => !!id)
    ));
    // Detectar también tokens de texto que empiezan por '@' como posibles asignados
    const atTokenCandidates = tokens.slice(2)
      .filter(t => t.startsWith('@'))
      .map(t => t.replace(/^@+/, ''));
    const normalizedFromAtTokens = Array.from(new Set(
      atTokenCandidates
        .map(v => normalizeWhatsAppId(v))
        .filter((id): id is string => !!id)
    ));
    const combinedAssigneeCandidates = Array.from(new Set([
      ...mentionsNormalizedFromContext,
      ...normalizedFromAtTokens
    ]));

    const { description, dueDate } = this.parseNueva(trimmed, mentionsNormalizedFromContext);

    // Asegurar creador
    const createdBy = ensureUserExists(context.sender, this.dbInstance);
    if (!createdBy) {
      throw new Error('No se pudo asegurar el usuario creador');
    }

    // Normalizar menciones y excluir duplicados y el número del bot
    const botNumber = process.env.CHATBOT_PHONE_NUMBER || '';
    const assigneesNormalized = Array.from(new Set(
      combinedAssigneeCandidates
        .filter(id => !botNumber || id !== botNumber)
    ));

    // Asegurar usuarios asignados
    const ensuredAssignees = assigneesNormalized
      .map(id => ensureUserExists(id, this.dbInstance))
      .filter((id): id is string => !!id);

    // Si no hay asignados, asignar al creador
    const assignmentUserIds = ensuredAssignees.length > 0 ? ensuredAssignees : [createdBy];

    // Definir group_id solo si el grupo está activo
    const groupIdToUse = (context.groupId && GroupSyncService.isGroupActive(context.groupId))
      ? context.groupId
      : null;

    // Crear tarea y asignaciones
    const taskId = TaskService.createTask(
      {
        description: description || '',
        due_date: dueDate ?? null,
        group_id: groupIdToUse,
        created_by: createdBy,
      },
      assignmentUserIds.map(uid => ({
        user_id: uid,
        assigned_by: createdBy,
      }))
    );

    const mentionsForSending = assignmentUserIds.map(uid => `${uid}@s.whatsapp.net`);

    const assignedList = assignmentUserIds.map(uid => `@${uid}`).join(' ');
    const resp =
      `✅ Tarea ${taskId} creada: "${description || '(sin descripción)'}"` +
      (dueDate ? ` (vence ${dueDate})` : '') +
      (assignedList ? ` — asignados: ${assignedList}` : '');

    // Enviar al grupo si está activo; si no, al creador (DM)
    const recipient = groupIdToUse || createdBy;

    return [{
      recipient,
      message: resp,
      mentions: mentionsForSending.length > 0 ? mentionsForSending : undefined
    }];
  }

  static async handle(context: CommandContext): Promise<CommandResponse[]> {
    if (!context.message.startsWith('/tarea')) {
      return [];
    }

    try {
      return await this.processTareaCommand(context);
    } catch (error) {
      return [{
        recipient: context.sender,
        message: 'Error processing command'
      }];
    }
  }
}