import { Injectable, NotFoundException } from '@nestjs/common';
import { DataSource } from 'typeorm';
import {
  AssetVersionChangeType,
  AuditSource,
} from '../database/entities';
import type {
  ListTemporalAssetsQueryDto,
  TemporalAtQueryDto,
} from './dto/list-temporal-assets-query.dto';

export interface TemporalAssetSummary {
  id: string;
  assetId: string;
  assetCode: string;
  assetName: string;
  typeId: string;
  typeName: string;
  informationStatus: string;
  operationalStatus: string;
  versionNumber: number;
  changeType: AssetVersionChangeType;
  changedFields: string[];
  occurredAt: Date;
  effectiveUntil: Date | null;
  actorUserId: string | null;
  actorUsername: string | null;
  source: AuditSource;
  requestId: string | null;
  isCurrent: boolean;
}

export interface TemporalAssetDetail extends TemporalAssetSummary {
  snapshot: Record<string, unknown>;
  asOf: Date;
}

function temporalAssetNotFound(): NotFoundException {
  return new NotFoundException({
    code: 'ASSET_NOT_EXISTING_AT_DATE',
    message: 'El activo no tenía una versión registrada en la fecha solicitada',
  });
}

@Injectable()
export class AssetTemporalService {
  constructor(private readonly dataSource: DataSource) {}

  async list(query: ListTemporalAssetsQueryDto) {
    const parameters: unknown[] = [new Date(query.at)];
    const conditions: string[] = [];
    const add = (value: unknown): string => {
      parameters.push(value);
      return `$${parameters.length}`;
    };

    if (query.search?.trim()) {
      const search = add(`%${query.search.trim()}%`);
      conditions.push(`(
        version.snapshot->>'code' ILIKE ${search}
        OR version.snapshot->>'name' ILIKE ${search}
      )`);
    }
    if (query.typeId) {
      conditions.push(`version.snapshot #>> '{type,id}' = ${add(query.typeId)}`);
    }
    if (query.status) {
      conditions.push(`version.snapshot->>'informationStatus' = ${add(query.status)}`);
    }
    const where = conditions.length ? `WHERE ${conditions.join(' AND ')}` : '';
    const selected = this.selectedAt('$1');
    const [countRow] = (await this.dataSource.query(
      `WITH selected_version AS (${selected})
       SELECT COUNT(*)::integer AS total
       FROM selected_version version
       ${where}`,
      parameters,
    )) as Array<{ total: number }>;
    const total = Number(countRow?.total ?? 0);
    const paginated = [
      ...parameters,
      query.pageSize,
      (query.page - 1) * query.pageSize,
    ];
    const limit = `$${parameters.length + 1}`;
    const offset = `$${parameters.length + 2}`;
    const data = (await this.dataSource.query(
      `WITH selected_version AS (${selected})
       ${this.selectSummary()}
       FROM selected_version version
       INNER JOIN assets current_asset ON current_asset.id = version.asset_id
       LEFT JOIN LATERAL (
         SELECT candidate.occurred_at
         FROM asset_versions candidate
         WHERE candidate.asset_id = version.asset_id
           AND candidate.version_number > version.version_number
         ORDER BY candidate.version_number ASC
         LIMIT 1
       ) next_version ON true
       ${where}
       ORDER BY "assetName" ASC, "assetCode" ASC
       LIMIT ${limit} OFFSET ${offset}`,
      paginated,
    )) as TemporalAssetSummary[];

    return {
      data,
      asOf: new Date(query.at),
      meta: {
        page: query.page,
        pageSize: query.pageSize,
        total,
        totalPages: total === 0 ? 0 : Math.ceil(total / query.pageSize),
      },
    };
  }

  async get(assetId: string, query: TemporalAtQueryDto): Promise<TemporalAssetDetail> {
    const [row] = (await this.dataSource.query(
      `${this.selectSummary()}, version.snapshot
       FROM asset_versions version
       INNER JOIN assets current_asset ON current_asset.id = version.asset_id
       LEFT JOIN LATERAL (
         SELECT candidate.occurred_at
         FROM asset_versions candidate
         WHERE candidate.asset_id = version.asset_id
           AND candidate.version_number > version.version_number
         ORDER BY candidate.version_number ASC
         LIMIT 1
       ) next_version ON true
       WHERE version.asset_id = $1
         AND version.occurred_at <= $2
       ORDER BY version.occurred_at DESC, version.version_number DESC
       LIMIT 1`,
      [assetId, new Date(query.at)],
    )) as TemporalAssetDetail[];
    if (!row) throw temporalAssetNotFound();
    const asOf = new Date(query.at);
    row.asOf = asOf;
    const [context] = (await this.dataSource.query(`
      SELECT
        CASE WHEN parent.id IS NULL THEN NULL ELSE JSONB_BUILD_OBJECT('id',parent.id,'code',parent.code,'name',parent.name) END AS parent,
        CASE WHEN area.id IS NULL THEN NULL ELSE JSONB_BUILD_OBJECT('id',area.id,'code',area.code,'name',area.name) END AS "operationalArea",
        CASE WHEN company.id IS NULL THEN NULL ELSE JSONB_BUILD_OBJECT('id',company.id,'code',company.code,'name',company.name) END AS "operatorCompany"
      FROM asset_context_history history
      LEFT JOIN assets parent ON parent.id=history.parent_id
      LEFT JOIN assets area ON area.id=history.operational_area_id
      LEFT JOIN assets company ON company.id=history.operator_company_id
      WHERE history.asset_id=$1
        AND history.valid_from <= $2
        AND (history.valid_until IS NULL OR history.valid_until > $2)
      ORDER BY history.valid_from DESC
      LIMIT 1
    `, [assetId, asOf])) as Array<{ parent: Record<string, unknown> | null; operationalArea: Record<string, unknown> | null; operatorCompany: Record<string, unknown> | null }>;
    if (context && row.snapshot) {
      row.snapshot = {
        ...row.snapshot,
        parent: context.parent,
        operationalArea: context.operationalArea,
        operatorCompany: context.operatorCompany,
      };
    }
    return row;
  }

  private selectedAt(atParameter: string): string {
    return `SELECT DISTINCT ON (candidate.asset_id) candidate.*
      FROM asset_versions candidate
      WHERE candidate.occurred_at <= ${atParameter}
      ORDER BY candidate.asset_id, candidate.occurred_at DESC, candidate.version_number DESC`;
  }

  private selectSummary(): string {
    return `SELECT
      version.id,
      version.asset_id AS "assetId",
      version.snapshot->>'code' AS "assetCode",
      version.snapshot->>'name' AS "assetName",
      version.snapshot #>> '{type,id}' AS "typeId",
      version.snapshot #>> '{type,name}' AS "typeName",
      version.snapshot->>'informationStatus' AS "informationStatus",
      version.snapshot->>'operationalStatus' AS "operationalStatus",
      version.version_number AS "versionNumber",
      version.change_type AS "changeType",
      version.changed_fields AS "changedFields",
      version.occurred_at AS "occurredAt",
      next_version.occurred_at AS "effectiveUntil",
      version.actor_user_id AS "actorUserId",
      version.actor_username AS "actorUsername",
      version.source,
      version.request_id AS "requestId",
      (version.version_number = current_asset.current_version) AS "isCurrent"`;
  }
}