import { findIndexOfData } from "./findIndexOfData"

/** 从二级制数据中找到一块数据，根据标识头与标识尾 */
export function findBlockOfData(
    data: ArrayBuffer | Uint8Array,
    blockStart: ArrayBuffer | Uint8Array,
    blockEnd: ArrayBuffer | Uint8Array,
    startOffset: number = 0,
    /** 结果不包含起始与结束 */
    withoutStarEnd: boolean = false
): { block: Uint8Array; offsetStart: number; offsetEnd: number } | void {
    let offset = startOffset

    if (data instanceof ArrayBuffer) data = new Uint8Array(data)
    let dataOrg = <Uint8Array>data

    let findStartIndex = findIndexOfData(dataOrg, blockStart, offset)
    if (findStartIndex === -1) return

    offset = findStartIndex + blockStart.byteLength
    let findEndIndex = findIndexOfData(dataOrg, blockEnd, offset)
    // console.log("findEndIndex", { findEndIndex, offset, findStartIndex })
    if (findEndIndex === -1) return

    let block = dataOrg.slice(findStartIndex, findEndIndex + blockEnd.byteLength)

    if (withoutStarEnd) {
        block = block.slice(blockStart.byteLength, block.byteLength - blockEnd.byteLength)
    }

    return { block, offsetStart: findStartIndex, offsetEnd: findEndIndex + blockEnd.byteLength }
}