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import type { Database } from "./database.ts";import ffi from "./ffi.ts";import { toCString, unwrap } from "./util.ts";
const {  sqlite3_blob_open,  sqlite3_blob_bytes,  sqlite3_blob_close,  sqlite3_blob_read,  sqlite3_blob_write,} = ffi;
/** Various options that can be configured when opening a Blob via `Database#openBlob`. */export interface BlobOpenOptions {  /** Whether to open Blob in readonly mode. True by default. */  readonly?: boolean;  /** Database to open Blob from, "main" by default. */  db?: string;  /** Table the Blob is in */  table: string;  /** Column name of the Blob Field */  column: string;  /** Row ID of which column to select */  row: number;}
/** * Enumerates SQLite3 Blob opened for streamed I/O. * * BLOB columns still return a `Uint8Array` of the data. * You can instead open this from `Database.openBlob()`. * * @see https://www.sqlite.org/c3ref/blob_open.html */export class SQLBlob {  #handle: Deno.PointerValue;
  constructor(db: Database, options: BlobOpenOptions) {    options = Object.assign({      readonly: true,      db: "main",    }, options);    const pHandle = new Uint32Array(2);    unwrap(sqlite3_blob_open(      db.unsafeHandle,      toCString(options.db ?? "main"),      toCString(options.table),      toCString(options.column),      options.row,      options.readonly === false ? 1 : 0,      pHandle,    ));    this.#handle = pHandle[0] + 2 ** 32 * pHandle[1];  }
  /** Byte size of the Blob */  get byteLength(): number {    return sqlite3_blob_bytes(this.#handle);  }
  /** Read from the Blob at given offset into a buffer (Uint8Array) */  readSync(offset: number, p: Uint8Array): void {    unwrap(sqlite3_blob_read(this.#handle, p, p.byteLength, offset));  }
  /** Write a buffer (Uint8Array) at given offset in the Blob */  writeSync(offset: number, p: Uint8Array): void {    unwrap(sqlite3_blob_write(this.#handle, p, p.byteLength, offset));  }
  /** Close the Blob. It **must** be called to prevent leaks. */  close(): void {    unwrap(sqlite3_blob_close(this.#handle));  }
  /** Obtains Web Stream for reading the Blob */  get readable(): ReadableStream<Uint8Array> {    const length = this.byteLength;    let offset = 0;    return new ReadableStream({      type: "bytes",      pull: (ctx) => {        try {          const byob = ctx.byobRequest;          if (byob) {            const toRead = Math.min(              length - offset,              byob.view!.byteLength,            );            this.readSync(              offset,              (byob.view as Uint8Array).subarray(0, toRead),            );            offset += toRead;            byob.respond(toRead);          } else {            const toRead = Math.min(              length - offset,              ctx.desiredSize || 1024 * 16,            );            if (toRead === 0) {              ctx.close();              return;            }            const buffer = new Uint8Array(toRead);            this.readSync(offset, buffer);            offset += toRead;            ctx.enqueue(buffer);          }        } catch (e) {          ctx.error(e);          ctx.byobRequest?.respond(0);        }      },    });  }
  /** Obtains Web Stream for writing to the Blob */  get writable(): WritableStream<Uint8Array> {    const length = this.byteLength;    let offset = 0;    return new WritableStream({      write: (chunk, ctx) => {        if (offset + chunk.byteLength > length) {          ctx.error(new Error("Write exceeds blob length"));          return;        }        this.writeSync(offset, chunk);        offset += chunk.byteLength;      },    });  }
  *[Symbol.iterator](): IterableIterator<Uint8Array> {    const length = this.byteLength;    let offset = 0;    while (offset < length) {      const toRead = Math.min(length - offset, 1024 * 16);      const buffer = new Uint8Array(toRead);      this.readSync(offset, buffer);      offset += toRead;      yield buffer;    }  }
  [Symbol.for("Deno.customInspect")](): string {    return `SQLite3.Blob(0x${this.byteLength.toString(16)})`;  }}