CREATE TABLE users (
    id text PRIMARY KEY,
    wechat_identity text NOT NULL UNIQUE,
    created_at timestamptz NOT NULL DEFAULT now()
);

CREATE TABLE sessions (
    token_hash text PRIMARY KEY,
    user_id text NOT NULL REFERENCES users(id),
    expires_at timestamptz NOT NULL
);
CREATE INDEX sessions_expiry ON sessions(expires_at);

CREATE TABLE projects (
    id text PRIMARY KEY,
    user_id text NOT NULL REFERENCES users(id),
    name text NOT NULL CHECK (char_length(btrim(name)) BETWEEN 1 AND 40),
    archived boolean NOT NULL DEFAULT false,
    created_at timestamptz NOT NULL DEFAULT now(),
    position bigint GENERATED ALWAYS AS IDENTITY,
    UNIQUE (user_id, id)
);
CREATE INDEX projects_owner ON projects(user_id, position);

CREATE TABLE records (
    id text PRIMARY KEY,
    user_id text NOT NULL REFERENCES users(id),
    project_id text NOT NULL,
    practice_date date NOT NULL CHECK (practice_date >= DATE '0001-01-01'),
    minutes integer NOT NULL CHECK (minutes > 0),
    note text NOT NULL DEFAULT '' CHECK (char_length(note) <= 2000),
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now(),
    FOREIGN KEY (user_id, project_id) REFERENCES projects(user_id, id) ON DELETE RESTRICT
);
CREATE INDEX records_owner_date ON records(user_id, practice_date DESC, id DESC);
CREATE INDEX records_owner_updated ON records(user_id, updated_at DESC, id DESC);
CREATE INDEX records_project ON records(user_id, project_id);

-- Keep submission receipts after a record is deleted so a delayed retry cannot resurrect it.
CREATE TABLE submissions (
    user_id text NOT NULL REFERENCES users(id),
    request_id text NOT NULL,
    payload_hash text NOT NULL,
    record_id text NOT NULL,
    PRIMARY KEY (user_id, request_id)
);