import * as Data from "effect/Data";
import type * as Effect from "effect/Effect";

export type MigrationDialect = "postgres" | "mysql" | "sqlite";

/**
 * A single migration read from disk, normalized across directory layouts.
 */
export interface MigrationRecord {
  /**
   * The bookkeeping key used for applied-detection. Layout-dependent: the
   * directory name for drizzle-kit/Prisma-layout dirs
   * (`20260721033159_init`), the relative file path for flat dirs
   * (`0001_users.sql`).
   */
  name: string;
  /** sha256 hex of the raw file content. */
  hash: string;
  /**
   * Millis derived from a 14-digit `YYYYMMDDHHMMSS` prefix when present.
   */
  createdAtMillis: number | undefined;
  /** Raw file content. */
  sql: string;
  /** Individual statements (split on `--> statement-breakpoint`). */
  statements: string[];
}

/**
 * The minimal query surface the migration flow needs from its target
 * database. Each database resource adapts its native access path (the D1
 * HTTP API, a `pg.Client` over a Planetscale temp role, a `mysql2`
 * connection, the local workerd D1 tunnel) into this shape once.
 */
export interface SqlExecutor {
  readonly dialect: MigrationDialect;
  /**
   * Run a single query and return its rows as objects. `params` bind as
   * `?`/`$n` placeholders; adapters without native parameter support inline
   * them as SQL literals (see `inlineSqlParams`).
   */
  readonly query: (
    sql: string,
    params?: ReadonlyArray<unknown>,
  ) => Effect.Effect<Array<Record<string, unknown>>, MigrationError>;
  /**
   * Execute one or more statements as a unit — a transaction where the
   * target supports one (pg/mysql), a single batched query on D1 (which has
   * no transactions over HTTP).
   */
  readonly batch: (
    statements: ReadonlyArray<string>,
  ) => Effect.Effect<void, MigrationError>;
}

/** A migration failed to read, convert, or apply. */
export class MigrationError extends Data.TaggedError("MigrationError")<{
  message: string;
  cause?: unknown;
}> {}

/**
 * The migrations directory uses drizzle-kit's pre-v1 layout
 * (`meta/_journal.json`). The fix is upstream: `drizzle-kit up`.
 */
export class DrizzleV0LayoutError extends Data.TaggedError(
  "DrizzleV0LayoutError",
)<{
  dir: string;
  message: string;
}> {}

/**
 * A row recorded in an applied-migrations table (ours, or a foreign one
 * being converted) matches no local migration file. Guessing would corrupt
 * history, so this is a hard error — migrations were applied to the
 * database that the local environment does not have.
 */
export class MigrationHistoryConflictError extends Data.TaggedError(
  "MigrationHistoryConflictError",
)<{
  table: string;
  unmatched: ReadonlyArray<string>;
  message: string;
}> {}

export type MigrationApplyError =
  | MigrationError
  | MigrationHistoryConflictError;