-- ============================================================
-- Migration 009: Notification Channels + User Preferences
-- Phase 2: Channel-based opt-out system
-- ============================================================

-- 1. Notification channels (platform-managed)
--    Platform defines channels like "billing", "security", "marketing"
--    Users can opt out of non-mandatory channels
CREATE TABLE IF NOT EXISTS public.notification_channels (
  channel_key  VARCHAR(50)  PRIMARY KEY,
  name         VARCHAR(100) NOT NULL,
  description  TEXT,
  is_mandatory BOOLEAN      NOT NULL DEFAULT false,
  -- mandatory=true: users cannot opt out (e.g. security alerts)
  -- mandatory=false: users can disable (e.g. marketing)
  is_enabled   BOOLEAN      NOT NULL DEFAULT true,
  created_at   TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
  updated_at   TIMESTAMPTZ  NOT NULL DEFAULT NOW()
);

-- Seed default channels
INSERT INTO public.notification_channels (channel_key, name, description, is_mandatory) VALUES
  ('system',       '系统通知',     '平台级系统公告与维护通知', true),
  ('security',     '安全告警',     '账号安全、异常登录等安全相关通知', true),
  ('billing',      '账单通知',     '订阅续费、发票、扣款通知', false),
  ('feature',      '新功能',       '产品新功能与版本更新通知', false),
  ('marketing',    '营销推广',     '促销活动、优惠券、活动邀请', false),
  ('ops',          '运维报警',     '服务器异常、告警触发通知', false)
ON CONFLICT (channel_key) DO NOTHING;

-- 2. User notification preferences (per-user opt-out per channel)
--    Only non-mandatory channels can be opted out
CREATE TABLE IF NOT EXISTS public.user_notification_preferences (
  user_id     VARCHAR(100) NOT NULL,
  channel_key VARCHAR(50)  NOT NULL REFERENCES public.notification_channels(channel_key) ON DELETE CASCADE,
  enabled     BOOLEAN      NOT NULL DEFAULT true,
  updated_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
  PRIMARY KEY (user_id, channel_key)
);

CREATE INDEX IF NOT EXISTS idx_unp_user ON public.user_notification_preferences (user_id);

-- 3. Notification segment members (for BY_SEGMENT targeting, Phase 4)
--    Platform populates this table via ETL/cron jobs
CREATE TABLE IF NOT EXISTS public.notification_segment_members (
  segment_key VARCHAR(100) NOT NULL,
  tenant_id   VARCHAR(100) NOT NULL,
  synced_at   TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
  PRIMARY KEY (segment_key, tenant_id)
);

CREATE INDEX IF NOT EXISTS idx_nsm_segment ON public.notification_segment_members (segment_key);
CREATE INDEX IF NOT EXISTS idx_nsm_tenant  ON public.notification_segment_members (tenant_id);