import type { DynamicModule, OnModuleInit } from '@nestjs/common';
import { Module } from '@nestjs/common';
import { APP_INTERCEPTOR } from '@nestjs/core';
import type { ContextAPI, TraceAPI } from '@opentelemetry/api';
import { text } from '@rsdk/common';
import { ILogger, LoggerFactory } from '@rsdk/logging';

import { InjectLogger } from '../logging';
import type { PlatformOptions } from '../types';

import {
  DEFAULT_TRACING_HEADERS,
  DEFAULT_TRACING_OPTIONS,
  HEADER_MAPPINGS,
} from './constants';
import { TracingHeaders } from './tracing.actx';
import { TracingInterceptor } from './tracing.interceptor';
import type { TracingHeaderMappings } from './types';

export interface TracingOptions {
  includeDefault: boolean;
  additionalMappings?: TracingHeaderMappings[];
}

@Module({})
export class TracingModule implements OnModuleInit {
  private trace: TraceAPI | null = null;
  private context: ContextAPI | null = null;

  constructor(@InjectLogger(TracingModule) private readonly logger: ILogger) {}

  static forRoot({
    tracing = DEFAULT_TRACING_OPTIONS,
    plugins = [],
  }: PlatformOptions): DynamicModule {
    const mappings: TracingHeaderMappings[] = [];

    if (tracing?.includeDefault) {
      mappings.push(...DEFAULT_TRACING_HEADERS);
    }

    for (const plugin of plugins) {
      mappings.push(...(plugin.additionalTracingHeaders?.() ?? []));
    }

    mappings.push(...(tracing.additionalMappings ?? []));

    return {
      global: true,
      module: TracingModule,
      providers: [
        { provide: APP_INTERCEPTOR, useClass: TracingInterceptor },
        { provide: HEADER_MAPPINGS, useValue: mappings },
      ],
    };
  }

  // Можно добавить включение и выключение при изменении конфига.
  async onModuleInit(): Promise<void> {
    if (!this.context || !this.trace) {
      try {
        const { context, trace } = await import('@opentelemetry/api');

        this.context = context;
        this.trace = trace;
      } catch {
        this.logger.debug(text`
          @opentelemetry/api is not installed. Opentelemetry metadata will
          not appear in log messages.
        `);
      }
    }

    LoggerFactory.applyInstrumentations((record) => {
      Object.assign(record, TracingHeaders.get() || {});

      if (this.trace && this.context) {
        const { traceId, spanId } =
          this.trace.getSpan(this.context.active())?.spanContext() ?? {};

        record['trace_id'] = traceId;
        record['span_id'] = spanId;
      }
    });

    this.logger.info('Tracing is enabled');

    this.logger.debug('Attaching log messages to spans...');
    LoggerFactory.onMessage((level, msg) => {
      if (this.trace && this.context) {
        const span = this.trace.getSpan(this.context.active());

        span?.addEvent('log', { ...msg, level });
      }
    });
  }
}