-- Kvitt server schema v4: card purchases (SPEC §9.12, FR-22, D-167). Do not edit; add a new migration and bump the
-- schema version (SPEC §14.8). Applied on top of 0003_device_version_name.sql.
--
-- Card data is private to the card holder (D-161): none of these rows is in the household sync stream (GET /sync), the
-- audit log or a push. Card rows carry card_version from their own sequence and are read through GET /cards/sync.

CREATE TABLE card_sequence (
    id    INTEGER PRIMARY KEY CHECK (id = 1),
    value INTEGER NOT NULL
) STRICT;
INSERT INTO card_sequence (id, value) VALUES (1, 0);

-- One connection per user and card provider. session_id is an Enable Banking session: a credential usable only with the
-- application's private key, which is never in the database or a backup (D-161). Erased when disconnected.
CREATE TABLE card_connections (
    id                 TEXT PRIMARY KEY NOT NULL,
    user_id            TEXT NOT NULL REFERENCES users (id),
    provider_id        TEXT NOT NULL CHECK (length(provider_id) BETWEEN 1 AND 64),
    status             TEXT NOT NULL CHECK (status IN ('active', 'expired', 'disconnected')),
    session_id         TEXT,
    account_uid        TEXT,
    valid_until        TEXT,
    history_days       INTEGER NOT NULL CHECK (history_days BETWEEN 1 AND 365),
    last_fetch_at      TEXT,
    last_fetch_error   TEXT,
    last_user_fetch_at TEXT,
    background_fetches TEXT NOT NULL DEFAULT '[]',
    created_at         TEXT NOT NULL,
    updated_at         TEXT NOT NULL,
    card_version       INTEGER NOT NULL UNIQUE,
    CHECK ((status = 'disconnected') = (session_id IS NULL))
) STRICT;
CREATE UNIQUE INDEX card_connections_user_provider ON card_connections (user_id, provider_id);

-- Single-use authorisation attempts (D-162); state is stored only as its SHA-256 hash. Pruned 7 days after creation.
CREATE TABLE card_auth_attempts (
    id            TEXT PRIMARY KEY NOT NULL,
    user_id       TEXT NOT NULL REFERENCES users (id),
    device_id     TEXT NOT NULL REFERENCES devices (id),
    provider_id   TEXT NOT NULL CHECK (length(provider_id) BETWEEN 1 AND 64),
    client        TEXT NOT NULL CHECK (client IN ('android', 'web')),
    state_hash    TEXT NOT NULL UNIQUE,
    history_days  INTEGER NOT NULL CHECK (history_days BETWEEN 1 AND 365),
    status        TEXT NOT NULL CHECK (status IN ('pending', 'connected', 'failed', 'expired')),
    failure       TEXT,
    connection_id TEXT REFERENCES card_connections (id),
    created_at    TEXT NOT NULL,
    expires_at    TEXT NOT NULL,
    finished_at   TEXT
) STRICT;
CREATE INDEX card_auth_attempts_created ON card_auth_attempts (created_at);

-- Purchases as the bank reports them, mapped per SPEC §9.12 CP-7. amount_ore is null only for a non-SEK purchase
-- (original_amount and original_currency then set) and for a tombstone. A tombstone has its content erased (D-167).
CREATE TABLE card_purchases (
    id                TEXT PRIMARY KEY NOT NULL,
    user_id           TEXT NOT NULL REFERENCES users (id),
    connection_id     TEXT NOT NULL REFERENCES card_connections (id),
    provider_ref      TEXT NOT NULL,
    status            TEXT NOT NULL CHECK (status IN ('pending', 'booked')),
    direction         TEXT NOT NULL CHECK (direction IN ('debit', 'credit')),
    purchase_date     TEXT NOT NULL,
    booking_date      TEXT,
    amount_ore        INTEGER CHECK (amount_ore IS NULL OR amount_ore >= 1),
    original_amount   TEXT,
    original_currency TEXT CHECK (original_currency IS NULL OR length(original_currency) = 3),
    merchant          TEXT NOT NULL CHECK (length(merchant) <= 140),
    expense_id        TEXT REFERENCES expenses (id),
    ignored           INTEGER NOT NULL DEFAULT 0 CHECK (ignored IN (0, 1)),
    created_at        TEXT NOT NULL,
    updated_at        TEXT NOT NULL,
    deleted_at        TEXT,
    card_version      INTEGER NOT NULL UNIQUE,
    CHECK (NOT (ignored = 1 AND expense_id IS NOT NULL)),
    CHECK (deleted_at IS NOT NULL OR (amount_ore IS NULL) = (original_currency IS NOT NULL))
) STRICT;
CREATE UNIQUE INDEX card_purchases_ref ON card_purchases (connection_id, provider_ref) WHERE deleted_at IS NULL;
CREATE UNIQUE INDEX card_purchases_expense_once ON card_purchases (user_id, expense_id)
    WHERE expense_id IS NOT NULL AND deleted_at IS NULL;
CREATE INDEX card_purchases_user_version ON card_purchases (user_id, card_version);
CREATE INDEX card_purchases_expense ON card_purchases (expense_id);

UPDATE meta SET value = '4' WHERE key = 'schema_version';