package dashboard

import (
	"context"
	"database/sql"
	"log/slog"
	"time"

	"github.com/redis/go-redis/v9"

	"dashboard-cdc-worker/internal/config"
)

type Projector struct {
	cfg         config.Config
	store       Store
	redisClient *redis.Client
	storageZone *time.Location
	statZones   map[string]*time.Location
}

func NewProjector(cfg config.Config, store Store, redisClient *redis.Client) *Projector {
	storageZone := mustLocation(cfg.Dashboard.StorageTimezone)
	statZones := make(map[string]*time.Location, len(cfg.Dashboard.StatTimezones))
	for _, zone := range cfg.Dashboard.StatTimezones {
		statZones[zone] = mustLocation(zone)
	}
	return &Projector{
		cfg:         cfg,
		store:       store,
		redisClient: redisClient,
		storageZone: storageZone,
		statZones:   statZones,
	}
}

func (p *Projector) Apply(ctx context.Context, eventKey string, source string, contributions []Contribution) error {
	return p.apply(ctx, eventKey, source, nil, contributions)
}

func (p *Projector) ApplyUser(ctx context.Context, eventKey string, source string, user UserCountry, contributions []Contribution) error {
	return p.apply(ctx, eventKey, source, &user, contributions)
}

func (p *Projector) apply(ctx context.Context, eventKey string, source string, user *UserCountry, contributions []Contribution) error {
	if user == nil && len(contributions) == 0 {
		return nil
	}
	if len(contributions) == 0 {
		contributions = nil
	}
	if p.cfg.CDC.DryRun {
		slog.Info("dashboard cdc dry run", "eventKey", eventKey, "source", source, "user", user != nil, "contributions", len(contributions))
		return nil
	}
	if err := p.store.WithTx(ctx, func(tx *sql.Tx) error {
		applied, err := p.store.MarkEventApplied(ctx, tx, eventKey, source)
		if err != nil {
			return err
		}
		if !applied {
			return nil
		}
		if user != nil {
			if err := p.store.UpsertUserCountry(ctx, tx, *user); err != nil {
				return err
			}
		}
		for _, contribution := range contributions {
			if contribution.Empty() {
				continue
			}
			if contribution.DeltaSign == 0 {
				contribution.DeltaSign = 1
			}
			if err := p.store.ApplyDailyContribution(ctx, tx, contribution, p.cfg.Dashboard.StorageTimezone); err != nil {
				return err
			}
			for statTimezone := range p.statZones {
				if err := p.store.ApplyPeriodContribution(ctx, tx, contribution, statTimezone); err != nil {
					return err
				}
				if err := p.store.ApplyGamePeriodContribution(ctx, tx, contribution, statTimezone); err != nil {
					return err
				}
			}
		}
		return nil
	}); err != nil {
		return err
	}
	return p.writeRealtimeRedis(ctx, contributions)
}

func mustLocation(name string) *time.Location {
	location, err := time.LoadLocation(name)
	if err != nil {
		slog.Warn("invalid timezone, fallback to UTC", "timezone", name, "error", err)
		return time.UTC
	}
	return location
}