package repo

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/dbiz/cdp/ingestion/ingest/internal/apperr"
)

// SchemaRepo records the data type observed for each (workspace, event_type, field)
// triple. The bulker / analytics layer uses this to detect type conflicts.
//
// In the ingest hot path we only *check* for conflict via UpsertField; the
// rebuild of the cached map is left to a background loader. We do not block
// the request waiting for upsert -- it is fire-and-forget.
type SchemaRepo interface {
	// GetType returns the recorded type, or "" if the field has never been seen.
	GetType(ctx context.Context, workspaceID, eventType, field string) (string, error)
	// UpsertField records a new (or re-confirmed) field type.
	UpsertField(ctx context.Context, workspaceID, eventType, field, dataType string) error
}

type schemaRepo struct {
	db *pgxpool.Pool
}

func NewSchemaRepo(db *pgxpool.Pool) SchemaRepo {
	return &schemaRepo{db: db}
}

func (r *schemaRepo) GetType(ctx context.Context, workspaceID, eventType, field string) (string, error) {
	const q = `
        SELECT data_type FROM schema_fields
        WHERE workspace_id = $1::uuid AND event_type = $2 AND field = $3`
	var t string
	err := r.db.QueryRow(ctx, q, workspaceID, eventType, field).Scan(&t)
	if err != nil {
		// pgx.ErrNoRows → return "" with nil error so caller treats as new field
		if err.Error() == "no rows in result set" {
			return "", nil
		}
		return "", apperr.Internal(fmt.Errorf("schema get: %w", err))
	}
	return t, nil
}

func (r *schemaRepo) UpsertField(ctx context.Context, workspaceID, eventType, field, dataType string) error {
	const q = `
        INSERT INTO schema_fields (workspace_id, event_type, field, data_type)
        VALUES ($1::uuid, $2, $3, $4)
        ON CONFLICT (workspace_id, event_type, field) DO UPDATE
        SET last_seen_at = now(),
            sample_count = schema_fields.sample_count + 1`
	_, err := r.db.Exec(ctx, q, workspaceID, eventType, field, dataType)
	if err != nil {
		return apperr.Internal(fmt.Errorf("schema upsert: %w", err))
	}
	return nil
}