package main

import (
	"context"
	"fmt"
	"log/slog"
	"maps"
	"strings"
	"sync"
	"time"
	"tixel_watch/models"
)

type ExportManager struct {
	storage   StorageInterface
	exporters map[string]ExporterInterface
	config    ExportManagerConfig
	mu        sync.RWMutex
}

type ExportManagerConfig struct {
	BatchSize           int
	ExportInterval      time.Duration
	RetryAttempts       int
	RetryBackoff        time.Duration
	HealthCheckInterval time.Duration
}

func NewExportManager(storage StorageInterface, config ExportManagerConfig) *ExportManager {
	return &ExportManager{
		storage:   storage,
		exporters: make(map[string]ExporterInterface),
		config:    config,
	}
}

func (em *ExportManager) RegisterExporter(name string, exporter ExporterInterface) {
	em.mu.Lock()
	defer em.mu.Unlock()
	em.exporters[name] = exporter
	slog.Info("Exporter registered", "name", name)
}

func (em *ExportManager) UnregisterExporter(name string) {
	em.mu.Lock()
	defer em.mu.Unlock()
	delete(em.exporters, name)
	slog.Info("Exporter unregistered", "name", name)
}

func (em *ExportManager) Start(ctx context.Context) {
	exportTicker := time.NewTicker(em.config.ExportInterval)
	defer exportTicker.Stop()

	healthTicker := time.NewTicker(em.config.HealthCheckInterval)
	defer healthTicker.Stop()

	slog.Info("Export manager started",
		"batch_size", em.config.BatchSize,
		"export_interval", em.config.ExportInterval,
	)

	for {
		select {
		case <-ctx.Done():
			slog.Info("Export manager stopped")
			return
		case <-exportTicker.C:
			em.exportBatch(ctx)
		case <-healthTicker.C:
			em.performHealthChecks(ctx)
		}
	}
}

func (em *ExportManager) exportBatch(ctx context.Context) {
	entries, err := em.storage.(*SQLiteStorage).GetUnexportedEntries(ctx, em.config.BatchSize)
	if err != nil {
		slog.Error("Failed to get unexported entries", "error", err)
		return
	}

	if len(entries) == 0 {
		return
	}

	em.mu.RLock()
	exporters := make(map[string]ExporterInterface)
	maps.Copy(exporters, em.exporters)
	em.mu.RUnlock()

	successfulExports := make(map[string]bool)

	for name, exporter := range exporters {
		err := em.exportWithRetry(ctx, name, exporter, entries)
		if err != nil {
			slog.Error("Failed to export to target", "target", name, "error", err)
			successfulExports[name] = false
		} else {
			slog.Debug("Successfully exported batch", "target", name, "count", len(entries))
			successfulExports[name] = true
		}
	}

	hasSuccess := false
	for _, success := range successfulExports {
		if success {
			hasSuccess = true
			break
		}
	}

	if hasSuccess {
		ids := make([]int64, len(entries))
		for i, entry := range entries {
			if id, ok := entry.Fields["_internal_id"].(int64); ok {
				ids[i] = id
			}
		}

		backoff := time.Duration(0)
		var lastErr error

		for attempt := 0; attempt <= em.config.RetryAttempts; attempt++ {
			if attempt > 0 {
				backoff = time.Duration(attempt) * em.config.RetryBackoff
				time.Sleep(backoff)
			}
			err := em.storage.(*SQLiteStorage).MarkAsExported(ctx, ids)
			if err == nil {
				break
			}
			lastErr = err
			if strings.Contains(err.Error(), "database is locked") {
				continue
			} else {
				slog.Error("Failed to mark entries as exported", "error", err)
				break
			}
		}

		if lastErr != nil && backoff > 0 {
			slog.Error("Failed to mark entries as exported after retries", "error", lastErr)
		}
	}
}

func (em *ExportManager) exportWithRetry(ctx context.Context, name string, exporter ExporterInterface, entries []models.LogMessage) error {
	var lastErr error

	for attempt := 0; attempt <= em.config.RetryAttempts; attempt++ {
		if attempt > 0 {
			backoff := time.Duration(attempt) * em.config.RetryBackoff
			slog.Debug("Retrying export", "target", name, "attempt", attempt, "backoff", backoff)

			select {
			case <-ctx.Done():
				return ctx.Err()
			case <-time.After(backoff):
			}
		}

		err := exporter.Export(ctx, entries)
		if err == nil {
			if attempt > 0 {
				slog.Info("Export succeeded after retry", "target", name, "attempt", attempt)
			}
			return nil
		}

		lastErr = err
		slog.Warn("Export attempt failed", "target", name, "attempt", attempt, "error", err)
	}

	return fmt.Errorf("export failed after %d attempts: %w", em.config.RetryAttempts, lastErr)
}

func (em *ExportManager) performHealthChecks(ctx context.Context) {
	em.mu.RLock()
	exporters := make(map[string]ExporterInterface)
	maps.Copy(exporters, em.exporters)
	em.mu.RUnlock()

	for name, exporter := range exporters {
		err := exporter.HealthCheck(ctx)
		if err != nil {
			slog.Warn("Health check failed", "target", name, "error", err)
		} else {
			slog.Debug("Health check passed", "target", name)
		}
	}
}