using Microsoft.EntityFrameworkCore.Migrations;

#nullable disable

namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
{
    /// <summary>
    /// Moves composition-derived templates to AVEVA-style contained names: a
    /// derived template stores only its slot name (e.g. <c>Pump</c>), not the
    /// dotted qualified path (<c>Motor Controller.Pump</c>). The qualified name
    /// is computed on read by walking the OwnerComposition chain. The unique
    /// index on Template.Name becomes filtered to base templates only —
    /// derived templates' uniqueness is the (TemplateId, InstanceName) index on
    /// TemplateComposition.
    /// </summary>
    public partial class ContainedDerivedTemplateNames : Migration
    {
        /// <inheritdoc />
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            // Drop the global unique index first: derived rows are about to be
            // renamed to contained names that may duplicate one another or a
            // base template.
            migrationBuilder.DropIndex(
                name: "IX_Templates_Name",
                table: "Templates");

            // Collapse every derived template's dotted name to its contained
            // name — the owning composition slot's InstanceName.
            migrationBuilder.Sql(@"
                UPDATE t
                SET t.Name = c.InstanceName
                FROM Templates t
                INNER JOIN TemplateCompositions c ON c.Id = t.OwnerCompositionId
                WHERE t.IsDerived = 1;");

            // Recreate the uniqueness guarantee for base templates only.
            migrationBuilder.CreateIndex(
                name: "IX_Templates_Name",
                table: "Templates",
                column: "Name",
                unique: true,
                filter: "[IsDerived] = 0");
        }

        /// <inheritdoc />
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropIndex(
                name: "IX_Templates_Name",
                table: "Templates");

            // Rebuild the dotted qualified names so the global unique index can
            // be restored — derived templates' contained names are not globally
            // unique. The recursive CTE walks the OwnerComposition chain down
            // from each base template.
            migrationBuilder.Sql(@"
                WITH q AS (
                    SELECT t.Id, CAST(t.Name AS NVARCHAR(MAX)) AS Qualified
                    FROM Templates t
                    WHERE t.IsDerived = 0
                    UNION ALL
                    SELECT t.Id, CAST(q.Qualified + N'.' + c.InstanceName AS NVARCHAR(MAX))
                    FROM Templates t
                    INNER JOIN TemplateCompositions c ON c.Id = t.OwnerCompositionId
                    INNER JOIN q ON q.Id = c.TemplateId
                )
                UPDATE t
                SET t.Name = q.Qualified
                FROM Templates t
                INNER JOIN q ON q.Id = t.Id
                WHERE t.IsDerived = 1;");

            migrationBuilder.CreateIndex(
                name: "IX_Templates_Name",
                table: "Templates",
                column: "Name",
                unique: true);
        }
    }
}