CREATE TYPE aftersale_kind AS ENUM ('refund_only', 'return_refund');

CREATE TYPE aftersale_status AS ENUM (
    'pending',
    'approved',
    'rejected',
    'buyer_shipping',
    'merchant_confirmed',
    'refunded',
    'cancelled'
);

-- Authoritative per-order refund total; every increment is a guarded UPDATE.
ALTER TABLE orders
    ADD COLUMN refund_total_minor BIGINT NOT NULL DEFAULT 0
        CHECK (refund_total_minor >= 0);

CREATE TABLE aftersales (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    order_id UUID NOT NULL REFERENCES orders (id),
    order_item_id UUID NOT NULL REFERENCES order_items (id),
    shop_id UUID NOT NULL REFERENCES shops (id),
    user_id UUID NOT NULL REFERENCES users (id),
    kind aftersale_kind NOT NULL,
    status aftersale_status NOT NULL DEFAULT 'pending',
    reason JSONB NOT NULL,
    amount_minor BIGINT NOT NULL CHECK (amount_minor > 0),
    evidence JSONB NOT NULL DEFAULT '[]',
    reopened BOOLEAN NOT NULL DEFAULT false,
    return_carrier TEXT,
    return_tracking_no TEXT,
    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- At most one active (non-terminal) aftersale per order item.
CREATE UNIQUE INDEX aftersales_one_active_per_item
    ON aftersales (order_item_id)
    WHERE status NOT IN ('refunded', 'rejected', 'cancelled');
CREATE INDEX idx_aftersales_user ON aftersales (user_id);
CREATE INDEX idx_aftersales_shop ON aftersales (shop_id);
CREATE INDEX idx_aftersales_order ON aftersales (order_id);

-- Append-only bilateral message log; no UPDATE/DELETE paths exist.
CREATE TABLE aftersale_messages (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    aftersale_id UUID NOT NULL REFERENCES aftersales (id) ON DELETE CASCADE,
    author_role TEXT NOT NULL CHECK (author_role IN ('buyer', 'merchant', 'platform')),
    author_id UUID NOT NULL REFERENCES users (id),
    content JSONB NOT NULL,
    evidence JSONB NOT NULL DEFAULT '[]',
    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX idx_aftersale_messages_aftersale ON aftersale_messages (aftersale_id);