-- DropForeignKey
-- Category.userId is becoming optional -- a category now belongs to
-- exactly one of a User (Home) or a Project, never both.
ALTER TABLE "Category" DROP CONSTRAINT "Category_userId_fkey";

-- AlterTable
ALTER TABLE "Category" ALTER COLUMN "userId" DROP NOT NULL;
ALTER TABLE "Category" ADD COLUMN "projectId" TEXT;

-- CreateTable
CREATE TABLE "Project" (
    "id" TEXT NOT NULL,
    "title" TEXT NOT NULL,
    "ownerId" TEXT NOT NULL,
    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    "updatedAt" TIMESTAMP(3) NOT NULL,

    CONSTRAINT "Project_pkey" PRIMARY KEY ("id")
);

-- CreateIndex
CREATE INDEX "Project_ownerId_createdAt_idx" ON "Project"("ownerId", "createdAt");

-- CreateIndex
CREATE INDEX "Category_projectId_order_idx" ON "Category"("projectId", "order");

-- AddForeignKey
ALTER TABLE "Category" ADD CONSTRAINT "Category_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User"("id") ON DELETE CASCADE ON UPDATE CASCADE;

-- AddForeignKey
ALTER TABLE "Category" ADD CONSTRAINT "Category_projectId_fkey" FOREIGN KEY ("projectId") REFERENCES "Project"("id") ON DELETE CASCADE ON UPDATE CASCADE;

-- AddForeignKey
ALTER TABLE "Project" ADD CONSTRAINT "Project_ownerId_fkey" FOREIGN KEY ("ownerId") REFERENCES "User"("id") ON DELETE CASCADE ON UPDATE CASCADE;

-- Every existing Category row already has userId set and projectId null,
-- so this holds immediately with no backfill -- enforce the "exactly one
-- of userId/projectId" invariant at the database level too, not just in
-- application code (lib/access.ts).
ALTER TABLE "Category" ADD CONSTRAINT "Category_owner_xor_project" CHECK (
  ("userId" IS NOT NULL AND "projectId" IS NULL) OR
  ("userId" IS NULL AND "projectId" IS NOT NULL)
);