package darwindb

import (
	"context"
	"fmt"
	"log"

	pgx "github.com/jackc/pgx/v4"
	"hg.lukegb.com/lukegb/depot/go/trains/darwin"
)

// handleDataResponse handles a Darwin DataResponse message (i.e. a SnapshotResponse or a UpdateResponse).
func handleDataResponse(ctx context.Context, tx pgx.Tx, dr *darwin.DataResponse, a *Affected) error {
	for _, s := range dr.Schedule {
		if err := handleSchedule(ctx, tx, &s, a, scheduleModeOverwrite); err != nil {
			return fmt.Errorf("handling schedule for RID %v: %w", s.RID, err)
		}
	}
	for _, ts := range dr.TrainStatus {
		if err := handleTrainStatus(ctx, tx, &ts, a); err != nil {
			return fmt.Errorf("handling trainstatus for RID %v: %w", ts.RID, err)
		}
	}
	for _, ds := range dr.Deactivated {
		var tid int
		row := tx.QueryRow(ctx, "UPDATE train_services SET active=FALSE WHERE rid=$1 RETURNING id", ds.RID)
		if err := row.Scan(&tid); err == pgx.ErrNoRows {
			log.Printf("deactivated schedule for unknown RID %v", ds.RID)
		} else if err != nil {
			return fmt.Errorf("handling deactivateschedule for RID %v: %w", ds.RID, err)
		}
		a.RID(ds.RID)
		a.TSID(tid)
	}
	return nil
}

// ProcessTimetable updates the database by processing a PportTimetable message in the given transaction.
func ProcessTimetable(ctx context.Context, tx pgx.Tx, ppt *darwin.PushPortTimetable, a *Affected) error {
	for _, s := range ppt.Journey {
		if err := handleSchedule(ctx, tx, &s, a, scheduleModeIgnoreExisting); err != nil {
			return fmt.Errorf("handling timetable journey for RID %v: %w", s.RID, err)
		}
	}

	return nil
}

// Process updates the database by processing a single PushPort message in the given transaction.
func Process(ctx context.Context, tx pgx.Tx, pp *darwin.PushPort, a *Affected) error {
	drs := make([]*darwin.DataResponse, 0, len(pp.SnapshotResp)+len(pp.UpdateResp))
	for _, r := range pp.SnapshotResp {
		drs = append(drs, &r.DataResponse)
	}
	for _, r := range pp.UpdateResp {
		drs = append(drs, &r.DataResponse)
	}

	if len(drs) == 0 {
		// Short-circuit if we don't have anything we're interested in - which is very unlikely.
		return nil
	}

	for _, dr := range drs {
		if err := handleDataResponse(ctx, tx, dr, a); err != nil {
			return fmt.Errorf("handling data response: %w", err)
		}
	}

	return nil
}