/**
 * Module Database ABI v1 (ADR 0050): the stable boundary between Core and a module's database code.
 *
 * Only PostgreSQL concepts cross it: SQL text, ordered bound parameter values, decoded result rows
 * with their column metadata, and transaction scopes that Core controls. **Nothing in this file
 * names an ORM, a query builder, or a driver.** A module may build its SQL with Drizzle, Kysely, raw
 * text, or anything else, and Core never learns which; Core may change its own ORM without any
 * module noticing.
 *
 * This is a correctness and compatibility boundary, **not a security sandbox**. Installed modules
 * remain trusted backend code that runs in the API process with its database role (ADR 0048), and
 * nothing here, including table prefixes, `SET ROLE`, or PostgreSQL roles, can stop a module from
 * reaching data that is not its own.
 */

/** The ABI version these types describe. A module declares it; every executor reports it. */
export const MODULE_DATABASE_ABI_VERSION = 1;
export type ModuleDatabaseAbiVersion = typeof MODULE_DATABASE_ABI_VERSION;

/**
 * A scalar parameter value. Deliberately small: each has exactly one PostgreSQL text encoding.
 *
 * - `number` is sent as its JavaScript decimal text; `NaN`, `Infinity`, and `-Infinity` as
 *   PostgreSQL's own spellings.
 * - `bigint` is sent as its decimal text.
 * - `Uint8Array` is sent as `bytea`.
 *
 * A JavaScript `Date` is **not** a parameter: whether it means a `timestamp` or a `timestamptz`, and
 * in which zone, depends on a column the ABI cannot see. Plain objects are not implicit JSON; encode
 * JSON explicitly as a string. Identifiers are never parameters.
 */
export type ModuleDatabaseScalar = null | boolean | number | bigint | string | Uint8Array;

/** A parameter value: a scalar, or a PostgreSQL array of scalars, nested for more dimensions. */
export type ModuleDatabaseParameter = ModuleDatabaseScalar | readonly ModuleDatabaseParameter[];

/**
 * A decoded result value. Values that a generic conversion could change arrive as PostgreSQL's
 * exact text: `int8`, `numeric`, every date and time type, `json`, and `jsonb`. `bytea` arrives as a
 * `Uint8Array`, and arrays of the built-in types decode element by element.
 */
export type ModuleDatabaseValue =
  | null
  | boolean
  | number
  | string
  | Uint8Array
  | readonly ModuleDatabaseValue[];

/** `"object"` rows are keyed by column name; `"array"` rows are positional, in `fields` order. */
export type ModuleDatabaseRowMode = "object" | "array";

export type ModuleDatabaseObjectRow = Readonly<Record<string, ModuleDatabaseValue>>;
export type ModuleDatabaseArrayRow = readonly ModuleDatabaseValue[];

/** One query: exactly one PostgreSQL statement with `$1 … $n` placeholders. */
export interface ModuleDatabaseQuery {
  readonly text: string;
  readonly values?: readonly ModuleDatabaseParameter[];
  /** Defaults to `"object"`. */
  readonly rowMode?: ModuleDatabaseRowMode;
}

/** The ordered column metadata of a result, present even when it has no rows. */
export interface ModuleDatabaseField {
  readonly name: string;
  /** The column's PostgreSQL type OID. */
  readonly typeOid: number;
}

export interface ModuleDatabaseQueryResult<Row> {
  /** PostgreSQL's command tag word, such as `SELECT`, `INSERT`, `UPDATE`, or `DELETE`. */
  readonly command: string;
  /** The number of rows PostgreSQL reports as processed, or `null` when it reports none. */
  readonly rowCount: number | null;
  readonly rows: readonly Row[];
  readonly fields: readonly ModuleDatabaseField[];
}

/** What every executor can do: run one statement. */
export interface ModuleDatabaseQueryable {
  readonly abiVersion: ModuleDatabaseAbiVersion;
  query(
    query: ModuleDatabaseQuery & { readonly rowMode: "array" },
  ): Promise<ModuleDatabaseQueryResult<ModuleDatabaseArrayRow>>;
  query(
    query: ModuleDatabaseQuery & { readonly rowMode?: "object" },
  ): Promise<ModuleDatabaseQueryResult<ModuleDatabaseObjectRow>>;
  query(
    query: ModuleDatabaseQuery,
  ): Promise<ModuleDatabaseQueryResult<ModuleDatabaseObjectRow | ModuleDatabaseArrayRow>>;
}

export type ModuleDatabaseIsolationLevel = "read committed" | "repeatable read" | "serializable";

/** Transaction options. Any other key or value is refused, never ignored. Omitted, a transaction is
 * `read committed` and read-write. */
export interface ModuleDatabaseTransactionOptions {
  readonly isolation?: ModuleDatabaseIsolationLevel;
  readonly readOnly?: boolean;
}

/**
 * The executor inside a transaction or a savepoint. It is valid only while its callback runs: once
 * that callback settles it is revoked, and every later call fails without reaching PostgreSQL.
 *
 * Only the innermost open scope may run statements: while a savepoint is open, its parent refuses
 * statements and new savepoints. A callback must await every operation it starts before it returns.
 * One that resolves with work outstanding forgot an `await`: it fails with
 * `MODULE_DATABASE_SCOPE_WORK_OUTSTANDING` and is rolled back. One that rejects keeps its own error.
 * Either way, outstanding work never leads to a commit or a release.
 *
 * Transaction-control SQL (`BEGIN`, `COMMIT`, `ROLLBACK`, `SAVEPOINT`, `RELEASE SAVEPOINT`, …) is
 * forbidden through `query`; the callbacks control the transaction.
 */
export interface ModuleDatabaseTransaction extends ModuleDatabaseQueryable {
  /** Core names the savepoint. A resolved callback with no work outstanding releases it; a rejected
   * one rolls back to it and keeps its own error. */
  savepoint<T>(callback: (savepoint: ModuleDatabaseTransaction) => Promise<T> | T): Promise<T>;
}

/**
 * A module's database service under ABI v1. Top-level `query` calls are separate autocommit
 * statements on whichever pooled connection is free: no session state carries from one to the
 * next, and none survives the operation that made it.
 */
export interface ModuleDatabaseExecutor extends ModuleDatabaseQueryable {
  /** Core begins the transaction, commits when `callback` resolves with no work outstanding, and
   * rolls back otherwise; a rejected callback's own error is the transaction's error. Core never
   * retries it. These guarantees apply to conforming use: no transaction-control SQL through
   * `query`. */
  transaction<T>(
    callback: (transaction: ModuleDatabaseTransaction) => Promise<T> | T,
    options?: ModuleDatabaseTransactionOptions,
  ): Promise<T>;
}

/**
 * Every failure category an ABI v1 executor reports. A code is a stable category for programmatic
 * handling and keeps its meaning once published; the specific reason is in the static message.
 * PostgreSQL's own condition, when there is one, is `sqlState`, a separate field.
 */
export const MODULE_DATABASE_ERROR_CODES = [
  /** The call is not valid ABI use: a malformed query request or callback, a statement text that
   * holds no statement, an object-mode result with duplicate column names, or a transaction-control
   * statement sent through `query`. A programming error.
   *
   * The last two are only detectable once PostgreSQL has run the statement, so its effects may
   * already have happened: a mutation with duplicate result columns has been applied (inside a
   * transaction, it rolls back with it), and transaction control has taken effect, which Core cannot
   * undo. */
  "MODULE_DATABASE_REQUEST_INVALID",
  /** A parameter value is outside the ABI's parameter set. Refused before anything reaches
   * PostgreSQL. */
  "MODULE_DATABASE_PARAMETER_INVALID",
  /** The statement did not complete. `sqlState` is present when PostgreSQL reported the condition;
   * absent when the database could not be reached or the connection failed. */
  "MODULE_DATABASE_QUERY_FAILED",
  /** A transaction option or value is not one the ABI defines. Refused before the transaction
   * starts. */
  "MODULE_DATABASE_TRANSACTION_OPTION_INVALID",
  /** The transaction could not be begun or completed, or a savepoint could not be completed.
   * `sqlState` is present when PostgreSQL reported the condition. A transaction left aborted by a
   * failed statement ends here too: PostgreSQL rolls it back, and nothing is committed. */
  "MODULE_DATABASE_TRANSACTION_FAILED",
  /** The executor's scope has finished, so it is revoked. */
  "MODULE_DATABASE_SCOPE_CLOSED",
  /** The executor's scope is open but not active, because a savepoint inside it is open. */
  "MODULE_DATABASE_SCOPE_INACTIVE",
  /** A transaction or savepoint callback resolved while work it started was still outstanding: a
   * forgotten `await`. The scope was rolled back, never committed or released. (A callback that
   * rejects keeps its own error instead.) */
  "MODULE_DATABASE_SCOPE_WORK_OUTSTANDING",
] as const;

export type ModuleDatabaseErrorCode = (typeof MODULE_DATABASE_ERROR_CODES)[number];

const databaseErrorMessages: Readonly<Record<ModuleDatabaseErrorCode, string>> = Object.freeze({
  MODULE_DATABASE_PARAMETER_INVALID: "A database parameter value is not supported.",
  MODULE_DATABASE_QUERY_FAILED: "The database statement did not complete.",
  MODULE_DATABASE_REQUEST_INVALID: "The database request is not valid.",
  MODULE_DATABASE_SCOPE_CLOSED: "The database scope has finished and can no longer be used.",
  MODULE_DATABASE_SCOPE_INACTIVE: "The database scope cannot be used while a savepoint is open.",
  MODULE_DATABASE_SCOPE_WORK_OUTSTANDING:
    "The database scope finished with work still outstanding, so it was rolled back.",
  MODULE_DATABASE_TRANSACTION_FAILED: "The database transaction could not be completed.",
  MODULE_DATABASE_TRANSACTION_OPTION_INVALID: "A database transaction option is not supported.",
});

const sqlStatePattern = /^[0-9A-Z]{5}$/u;

/**
 * The one error an ABI v1 executor reports, sanitized by construction: a stable `code`, PostgreSQL's
 * `sqlState` when the database supplied one, and a static message. It never carries SQL text,
 * parameter values, the driver's message, detail, hint, or object names, a cause, a stack beyond
 * its own name and message, or any driver or ORM object.
 *
 * Recognize it with `isModuleDatabaseError`, never `instanceof`: a module bundles its own copy of
 * this package (ADR 0049), so class identity across the boundary is not a contract.
 */
export class ModuleDatabaseError extends Error {
  readonly code: ModuleDatabaseErrorCode;
  /** Declared, not initialized, so the property exists only when PostgreSQL supplied a SQLSTATE. */
  declare readonly sqlState?: string;

  constructor(code: ModuleDatabaseErrorCode, options: { readonly sqlState?: string } = {}) {
    super(databaseErrorMessages[code]);
    this.name = "ModuleDatabaseError";
    this.code = code;
    if (options.sqlState !== undefined && sqlStatePattern.test(options.sqlState)) {
      this.sqlState = options.sqlState;
    }
    this.stack = `${this.name}: ${this.message}`;
    Object.freeze(this);
  }
}

/** Whether `value` is a Module Database ABI error, judged by its shape rather than its class. */
export function isModuleDatabaseError(
  value: unknown,
): value is Pick<ModuleDatabaseError, "code" | "message" | "name" | "sqlState"> {
  if (!(value instanceof Error) || value.name !== "ModuleDatabaseError") {
    return false;
  }
  const { code, sqlState } = value as { code?: unknown; sqlState?: unknown };
  return (
    typeof code === "string" &&
    (MODULE_DATABASE_ERROR_CODES as readonly string[]).includes(code) &&
    (sqlState === undefined || (typeof sqlState === "string" && sqlStatePattern.test(sqlState)))
  );
}