package checkin

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

	"github.com/bluesky-social/indigo/atproto/syntax"
)

// ImportFromPDS caches a set of quest.atmo.checkin records (as returned by
// ListFromPDS) into the local checkins table for did, so the user reads as
// checked in locally.
//
// Check-ins whose referenced event isn't cached locally are skipped: the
// checkins.event_uri foreign key requires the event row to exist, and we only
// know about events that have been imported. Idempotent — rows that already
// exist (by record_uri) are left untouched.
//
// Returns how many rows were newly imported and how many were skipped (event
// not present locally, already cached, or malformed).
func ImportFromPDS(ctx context.Context, db *sql.DB, did syntax.DID, entries []PDSEntry) (imported, skipped int, err error) {
	for _, e := range entries {
		if e.RecordURI == "" || e.EventURI == "" {
			skipped++
			continue
		}

		// The FK requires the event to be cached locally first.
		var exists int
		scanErr := db.QueryRowContext(ctx, `SELECT 1 FROM events WHERE uri = ?`, e.EventURI).Scan(&exists)
		if scanErr == sql.ErrNoRows {
			skipped++
			continue
		}
		if scanErr != nil {
			return imported, skipped, scanErr
		}

		at := e.CheckedInAt
		if at.IsZero() {
			at = time.Now().UTC()
		}

		res, execErr := db.ExecContext(ctx, `
			INSERT INTO checkins (record_uri, did, event_uri, checked_in_at, cached_at)
			VALUES (?, ?, ?, ?, CURRENT_TIMESTAMP)
			ON CONFLICT(record_uri) DO NOTHING
		`, e.RecordURI, did.String(), e.EventURI, at.UTC())
		if execErr != nil {
			return imported, skipped, execErr
		}
		if n, _ := res.RowsAffected(); n > 0 {
			imported++
		} else {
			skipped++ // already cached
		}
	}
	return imported, skipped, nil
}