-- CreateEnum
CREATE TYPE "EnrollmentStatus" AS ENUM ('pending', 'active', 'expired', 'cancelled');

-- CreateTable
CREATE TABLE "Enrollment" (
    "id" SERIAL NOT NULL,
    "studentId" INTEGER NOT NULL,
    "subjectId" INTEGER NOT NULL,
    "status" "EnrollmentStatus" NOT NULL DEFAULT 'active',
    "startAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
    "expiresAt" TIMESTAMP(3),
    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,

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

-- CreateIndex
CREATE UNIQUE INDEX "Enrollment_studentId_subjectId_key" ON "Enrollment"("studentId", "subjectId");

-- AddForeignKey
ALTER TABLE "Enrollment" ADD CONSTRAINT "Enrollment_studentId_fkey" FOREIGN KEY ("studentId") REFERENCES "User"("id") ON DELETE RESTRICT ON UPDATE CASCADE;

-- AddForeignKey
ALTER TABLE "Enrollment" ADD CONSTRAINT "Enrollment_subjectId_fkey" FOREIGN KEY ("subjectId") REFERENCES "Subject"("id") ON DELETE RESTRICT ON UPDATE CASCADE;