// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

package flinkmetricsreceiver // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/flinkmetricsreceiver"

import (
	"context"
	"errors"
	"fmt"
	"time"

	"go.opentelemetry.io/collector/component"
	"go.opentelemetry.io/collector/pdata/pcommon"
	"go.opentelemetry.io/collector/pdata/pmetric"
	"go.opentelemetry.io/collector/receiver"
	"go.opentelemetry.io/collector/receiver/scrapererror"
	"go.uber.org/zap"

	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/flinkmetricsreceiver/internal/metadata"
)

var (
	errClientNotInit       = errors.New("client not initialized")
	jobmanagerFailedFetch  = "Failed to fetch jobmanager metrics"
	taskmanagerFailedFetch = "Failed to fetch taskmanager metrics"
	jobsFailedFetch        = "Failed to fetch jobs metrics"
	subtasksFailedFetch    = "Failed to fetch subtasks metrics"
)

type flinkmetricsScraper struct {
	client   client
	cfg      *Config
	settings component.TelemetrySettings
	mb       *metadata.MetricsBuilder
}

func newflinkScraper(config *Config, settings receiver.CreateSettings) *flinkmetricsScraper {
	return &flinkmetricsScraper{
		settings: settings.TelemetrySettings,
		cfg:      config,
		mb:       metadata.NewMetricsBuilder(config.MetricsBuilderConfig, settings),
	}
}

func (s *flinkmetricsScraper) start(_ context.Context, host component.Host) error {
	httpClient, err := newClient(s.cfg, host, s.settings, s.settings.Logger)
	if err != nil {
		return fmt.Errorf("create client: %w", err)
	}
	s.client = httpClient
	return nil
}

func (s *flinkmetricsScraper) scrape(ctx context.Context) (pmetric.Metrics, error) {
	// Validate we don't attempt to scrape without initializing the client
	if s.client == nil {
		return pmetric.NewMetrics(), errClientNotInit
	}

	now := pcommon.NewTimestampFromTime(time.Now())
	var scraperErrors scrapererror.ScrapeErrors

	jobmanagerMetrics, err := s.client.GetJobmanagerMetrics(ctx)
	if err != nil {
		s.settings.Logger.Error(jobmanagerFailedFetch, zap.Error(err))
		scraperErrors.AddPartial(1, fmt.Errorf("%s %w", jobmanagerFailedFetch, err))
	}

	taskmanagersMetrics, err := s.client.GetTaskmanagersMetrics(ctx)
	if err != nil {
		s.settings.Logger.Error(taskmanagerFailedFetch, zap.Error(err))
		scraperErrors.AddPartial(1, fmt.Errorf("%s %w", taskmanagerFailedFetch, err))
	}

	jobsMetrics, err := s.client.GetJobsMetrics(ctx)
	if err != nil {
		s.settings.Logger.Error(jobsFailedFetch, zap.Error(err))
		scraperErrors.AddPartial(1, fmt.Errorf("%s %w", jobsFailedFetch, err))
	}
	subtasksMetrics, err := s.client.GetSubtasksMetrics(ctx)
	if err != nil {
		s.settings.Logger.Error(subtasksFailedFetch, zap.Error(err))
		scraperErrors.AddPartial(1, fmt.Errorf("%s %w", subtasksFailedFetch, err))
	}

	s.processJobmanagerMetrics(now, jobmanagerMetrics)
	s.processTaskmanagerMetrics(now, taskmanagersMetrics)
	s.processJobsMetrics(now, jobsMetrics)
	s.processSubtaskMetrics(now, subtasksMetrics)

	return s.mb.Emit(), scraperErrors.Combine()
}