// Copyright (C) 2022 Marius Schellenberger

package fs

import (
	"os"
	"sync"
)

type Metadata struct {
	mu      sync.RWMutex `json:"-"`
	f       *os.File     `json:"-"`
	Size    int64        `json:"s"`
	Chunks  Chunks       `json:"c"`
	preload bool         `json:"-"`
}

func (md *Metadata) HasChunk(off int64, n int) bool {
	md.mu.RLock()
	defer md.mu.RUnlock()
	return md.Chunks.Exists(off, n, md.Size)
}

func (md *Metadata) AddChunk(off int64, n int) {
	md.mu.Lock()
	defer md.mu.Unlock()
	md.Chunks.Add(off, n)
}

func (md *Metadata) ReadAt(p []byte, pos int64) (int, error) {
	return md.f.ReadAt(p, pos)
}

func (md *Metadata) WriteAt(data []byte, pos int64) (int, error) {
	return md.f.WriteAt(data, pos)
}

func (md *Metadata) Preload() bool {
	md.mu.Lock()
	defer md.mu.Unlock()
	if md.preload {
		return true
	}
	md.preload = true
	return false
}

func (md *Metadata) UnlockPreload() {
	md.mu.Lock()
	defer md.mu.Unlock()
	md.preload = false
}