const ArrayBufferTools = {
    delete: arrayBufferDelete,
    insert: arrayBufferInsert,
    replaceByPosition: arrayBufferReplaceByPosition,
    replaceByData: arrayBufferReplaceByData,
    find: arrayBufferFind,
    toArrayBuffer,
    toString: arrayBufferToString,
}
export { ArrayBufferTools }

/** 删除指定范围的数据 */
export function arrayBufferDelete(buffer: ArrayBuffer, start: number, end: number): ArrayBuffer {
    const view = new Uint8Array(buffer)
    const newArray = new Uint8Array(view.length - (end - start))
    newArray.set(view.subarray(0, start))
    newArray.set(view.subarray(end), start)
    return newArray.buffer
}

/** 插入数据到指定位置 */
export function arrayBufferInsert(buffer: ArrayBuffer, start: number, data: ArrayBuffer | string): ArrayBuffer {
    const view = new Uint8Array(buffer)
    const insertView = typeof data === "string" ? new TextEncoder().encode(data) : new Uint8Array(data)
    if (insertView.length === 0) return buffer.slice(0)

    const insertPos = Math.max(0, Math.min(view.length, start))
    const newArray = new Uint8Array(view.length + insertView.length)
    newArray.set(view.subarray(0, insertPos))
    newArray.set(insertView, insertPos)
    newArray.set(view.subarray(insertPos), insertPos + insertView.length)
    return newArray.buffer
}

/** 替换指定范围的数据 */
export function arrayBufferReplaceByPosition(
    buffer: ArrayBuffer,
    start: number,
    end: number,
    data: ArrayBuffer | string
): ArrayBuffer {
    const view = new Uint8Array(buffer)
    const replaceView = typeof data === "string" ? new TextEncoder().encode(data) : new Uint8Array(data)
    if (replaceView.length === 0) return buffer.slice(0)

    const replaceStart = Math.max(0, Math.min(view.length, start))
    const replaceEnd = Math.max(replaceStart, Math.min(view.length, end))
    const newArray = new Uint8Array(view.length - (replaceEnd - replaceStart) + replaceView.length)
    newArray.set(view.subarray(0, replaceStart))
    newArray.set(replaceView, replaceStart)
    newArray.set(view.subarray(replaceEnd), replaceStart + replaceView.length)
    return newArray.buffer
}

/** 替换数据中指定部分为新内容 */
export function arrayBufferReplaceByData(
    buffer: ArrayBuffer,
    find: ArrayBuffer | string,
    replace: ArrayBuffer | string | ((findIndex: number) => ArrayBuffer | string),
    options?: {
        start?: number
        end?: number
        all?: boolean
    }
): ArrayBuffer {
    const view = new Uint8Array(buffer)
    const pattern = typeof find === "string" ? new TextEncoder().encode(find) : new Uint8Array(find)
    if (pattern.length === 0) return buffer.slice(0)

    const start = Math.max(0, Math.min(view.length, options?.start ?? 0))
    const end = Math.max(start, Math.min(view.length, options?.end ?? view.length))
    if (pattern.length > end - start) return buffer.slice(0)

    // 先收集所有匹配位置（基于原始 buffer 的索引）
    const matches: number[] = []
    let i = start
    while (i <= end - pattern.length) {
        let matched = true
        for (let j = 0; j < pattern.length; j++) {
            if (view[i + j] !== pattern[j]) {
                matched = false
                break
            }
        }
        if (matched) {
            matches.push(i)
            if (!options?.all) break
            i += pattern.length
        } else {
            i++
        }
    }
    if (matches.length === 0) return buffer.slice(0)

    // 分两种情况处理：replace 为函数 vs 固定数据
    if (typeof replace === "function") {
        let result = buffer
        let offset = 0

        for (const match of matches) {
            // 针对该次匹配生成替换内容
            const out = replace(match)
            const replaceBytes =
                typeof out === "string" ? new TextEncoder().encode(out) : new Uint8Array(out)

            // 与原实现保持一致：若替换内容长度为 0，则不作修改
            if (replaceBytes.length === 0) {
                continue
            }

            const replaceStart = match + offset
            const replaceEnd = replaceStart + pattern.length

            // 确保传入的 ArrayBuffer 与 replaceBytes 的可见区间一致
            const replaceAB =
                replaceBytes.byteOffset === 0 && replaceBytes.byteLength === replaceBytes.buffer.byteLength
                    ? replaceBytes.buffer
                    : replaceBytes.buffer.slice(
                          replaceBytes.byteOffset,
                          replaceBytes.byteOffset + replaceBytes.byteLength
                      )

            result = arrayBufferReplaceByPosition(result, replaceStart, replaceEnd, replaceAB)
            offset += replaceBytes.length - pattern.length
        }

        return result
    } else {
        // 固定数据路径（保持原有逻辑与行为）
        const replaceView =
            typeof replace === "string" ? new TextEncoder().encode(replace) : new Uint8Array(replace)
        if (replaceView.length === 0) return buffer.slice(0)

        let result = buffer
        let offset = 0
        const delta = replaceView.length - pattern.length

        for (const match of matches) {
            const replaceStart = match + offset
            const replaceEnd = replaceStart + pattern.length
            result = arrayBufferReplaceByPosition(result, replaceStart, replaceEnd, replace)
            offset += delta
        }

        return result
    }
}

/** 在数据中查找指定内容，未找到时返回 -1 */
export function arrayBufferFind(
    buffer: ArrayBuffer,
    find: ArrayBuffer | string,
    options?: {
        start?: number
        end?: number
    }
): number {
    const view = new Uint8Array(buffer)
    const pattern = typeof find === "string" ? new TextEncoder().encode(find) : new Uint8Array(find)

    const start = Math.max(0, Math.min(view.length, options?.start ?? 0))
    const end = Math.max(start, Math.min(view.length, options?.end ?? view.length))

    if (pattern.length === 0) return start
    if (pattern.length > end - start) return -1

    for (let i = start; i <= end - pattern.length; i++) {
        let matched = true
        for (let j = 0; j < pattern.length; j++) {
            if (view[i + j] !== pattern[j]) {
                matched = false
                break
            }
        }
        if (matched) return i
    }

    return -1
}

/** 将 Buffer、ArrayBuffer 或 Uint8Array 转换为 ArrayBuffer */
export function toArrayBuffer(buffer: Buffer | ArrayBuffer | Uint8Array): ArrayBuffer {
    if (buffer instanceof ArrayBuffer) return buffer
    if (buffer instanceof Uint8Array) return buffer.buffer as ArrayBuffer
    return buffer
}

/** 将 ArrayBuffer 转换为字符串 */
export function arrayBufferToString(buffer: ArrayBuffer, encoding?: string): string {
    const uint8Array = new Uint8Array(buffer)
    const decoder = new TextDecoder(encoding || "utf-8")
    return decoder.decode(uint8Array)
}