package frameserver

import (
	"git.gammaspectra.live/S.O.N.G/Ignite/frame"
	"os"
	"path"
	"runtime"
	"sync"
)

// Pool automatically grows and shrinks as-needed based on how many frame requests come in.
type Pool struct {
	cachedFrameSeekTable []int64
	seekTableLock        sync.RWMutex
	sourcePath           string
	pool                 sync.Pool
}

func NewPool(sourcePath string, cachedFrameSeekTable []int64) *Pool {
	p := &Pool{
		sourcePath:           sourcePath,
		cachedFrameSeekTable: cachedFrameSeekTable,
	}
	p.pool.New = func() any {
		if f, err := os.Open(p.sourcePath); err != nil {
			return nil
		} else {
			p.seekTableLock.RLock()
			defer p.seekTableLock.RUnlock()

			if path.Ext(p.sourcePath) == ".xz" {
				if s := NewXZCompressed(f, p.cachedFrameSeekTable); s != nil {
					runtime.SetFinalizer(s, func(s *FrameServer) {
						f.Close()
					})
					return s
				} else {
					return nil
				}
			} else {
				if s := New(f, p.cachedFrameSeekTable); s != nil {
					runtime.SetFinalizer(s, func(s *FrameServer) {
						f.Close()
					})
					return s
				} else {
					return nil
				}
			}
		}
	}

	return p
}

func (p *Pool) getServer() *FrameServer {
	if a := p.pool.Get(); a == nil {
		return nil
	} else {
		return a.(*FrameServer)
	}
}

func (p *Pool) GetFrameSeekTable() []int64 {
	p.seekTableLock.RLock()
	defer p.seekTableLock.RUnlock()
	return p.cachedFrameSeekTable
}

func (p *Pool) putServer(s *FrameServer) {
	if func() bool {
		p.seekTableLock.RLock()
		defer p.seekTableLock.RUnlock()

		return len(p.cachedFrameSeekTable) < len(s.GetFrameSeekTable())
	}() {
		//cache longer table
		p.seekTableLock.Lock()
		defer p.seekTableLock.Unlock()
		//avoid races overwriting things
		if len(p.cachedFrameSeekTable) < len(s.GetFrameSeekTable()) {
			p.cachedFrameSeekTable = s.GetFrameSeekTable()
		}
	}
	p.pool.Put(s)
}

func (p *Pool) GetAllFrames() *frame.Stream {
	if s := p.getServer(); s == nil {
		return nil
	} else {
		defer p.putServer(s)
		return s.GetAllFramesLock()
	}
}

func (p *Pool) GetFrames(startFrameNumber, endFrameNumber int) *frame.Stream {
	if s := p.getServer(); s == nil {
		return nil
	} else {
		defer p.putServer(s)
		return s.GetFramesLock(startFrameNumber, endFrameNumber)
	}
}