package pool

// Pool tracks worker FDs and busy state for a single worker type.
// Holds only the common management state; request/response types are
// caller-specific and handled by the caller.
type Pool struct {
	FDs     []int32
	Busy    []bool
	Readers []FrameReader
}

// NewPool creates a Pool with capacity n.
func NewPool(n int) Pool {
	return Pool{
		FDs:     []int32{:0:n},
		Busy:    []bool{:n},
		Readers: []FrameReader{:n},
	}
}

// FindByFD returns the index of the worker whose FD matches fd, or -1.
func (p *Pool) FindByFD(fd int32) int {
	for i, wfd := range p.FDs {
		if wfd == fd {
			return i
		}
	}
	return -1
}

// AddFD appends a new worker FD to the pool.
func (p *Pool) AddFD(fd int32) {
	p.FDs = append(p.FDs, fd)
}

// Len returns the number of workers.
func (p *Pool) Len() int { return len(p.FDs) }

// IdleIndex returns the index of the first idle worker, or -1 if all busy.
func (p *Pool) IdleIndex() int {
	for i, busy := range p.Busy {
		if !busy {
			return i
		}
	}
	return -1
}