-- =====================================================
-- TABLE: education.enrollments
-- =====================================================
-- Proyecto: OrbiQuant IA (Trading Platform)
-- Módulo: OQI-002 - Education
-- Especificación: ET-EDU-001-database.md
-- =====================================================

CREATE TABLE education.enrollments (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),

  -- Relaciones
  user_id UUID NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
  course_id UUID NOT NULL REFERENCES education.courses(id) ON DELETE RESTRICT,

  -- Estado
  status education.enrollment_status DEFAULT 'active',

  -- Progreso
  progress_percentage DECIMAL(5,2) DEFAULT 0.00,
  completed_lessons INTEGER DEFAULT 0,
  total_lessons INTEGER DEFAULT 0, -- Snapshot del total al enrollarse

  -- Fechas importantes
  enrolled_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  started_at TIMESTAMPTZ, -- Primera lección vista
  completed_at TIMESTAMPTZ,
  expires_at TIMESTAMPTZ, -- Para cursos con límite de tiempo

  -- Gamificación
  total_xp_earned INTEGER DEFAULT 0,

  -- Metadata
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),

  CONSTRAINT unique_user_course UNIQUE(user_id, course_id),
  CONSTRAINT valid_progress CHECK (progress_percentage >= 0 AND progress_percentage <= 100),
  CONSTRAINT valid_completion CHECK (
    (status != 'completed') OR
    (completed_at IS NOT NULL AND progress_percentage = 100)
  )
);

-- Índices
CREATE INDEX idx_enrollments_user ON education.enrollments(user_id);
CREATE INDEX idx_enrollments_course ON education.enrollments(course_id);
CREATE INDEX idx_enrollments_status ON education.enrollments(status);
CREATE INDEX idx_enrollments_user_active ON education.enrollments(user_id, status)
  WHERE status = 'active';

-- Comentarios
COMMENT ON TABLE education.enrollments IS 'Inscripciones de usuarios a cursos';
COMMENT ON COLUMN education.enrollments.total_lessons IS 'Snapshot del total de lecciones al momento de enrollarse';
COMMENT ON COLUMN education.enrollments.started_at IS 'Timestamp de la primera lección vista';
COMMENT ON COLUMN education.enrollments.expires_at IS 'Fecha de expiración para cursos con límite de tiempo';