//
// MIT License
//
// Copyright (c) 2023 Ihar Katkavets

// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

import Foundation

public final class BufferInputStream: InputStream {
    private var offset = 0
    private var buffer: [UInt8]

    public var hasBytesAvailable: Bool {
        return offset < buffer.count
    }
    
    public init(withBuffer payload: [UInt8]) {
        self.buffer = payload
    }
    
    public func open() throws { }

    public func read(_ toBuffer: UnsafeMutablePointer<UInt8>, maxLength len: Int) throws -> Int {
        if offset == buffer.count {
            return 0
        }

        let bytesLeft = buffer.count-offset
        let readLen = min(bytesLeft, len)
        buffer.withUnsafeBufferPointer { ubp in
            if let ptr = ubp.baseAddress {
                toBuffer.initialize(from: ptr.advanced(by: offset), count: readLen)
            }
        }
        offset += readLen
        return readLen
    }
    
    public func close() { }
}