// Copyright 2021 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
//go:build script
// +build script

package js

import (
	"rogchap.com/v8go"
	"sync/atomic"
)

const maxContextsPerIsolate = 8 // TODO 根据系统内存动态调整

type Isolate struct {
	rawIsolate *v8go.Isolate

	contextPool *ContextPool
	countUses   uint32

	isDisposed bool
}

func NewIsolate() (*Isolate, error) {
	return NewIsolateWithContexts(maxContextsPerIsolate)
}

func NewIsolateWithContexts(contextSize int) (*Isolate, error) {
	var isolate = &Isolate{
		rawIsolate:  v8go.NewIsolate(),
		contextPool: NewContextPool(contextSize),
	}
	err := isolate.init()
	if err != nil {
		isolate.Dispose()
		return nil, err
	}
	return isolate, nil
}

func (this *Isolate) init() error {
	// 初始化context
	for i := 0; i < this.contextPool.MaxSize(); i++ {
		ctx, err := this.createContext()
		if err != nil {
			return err
		}
		this.contextPool.Put(ctx)
	}

	return nil
}

func (this *Isolate) OverUses() bool {
	return atomic.LoadUint32(&this.countUses) > 4096
}

func (this *Isolate) GetContext() (*Context, error) {
	atomic.AddUint32(&this.countUses, 1)

	ctx := this.contextPool.Get()
	if ctx != nil {
		return ctx, nil
	}

	ctx, err := this.createContext()
	if err != nil {
		return nil, err
	}
	return ctx, nil
}

func (this *Isolate) PutContext(ctx *Context) {
	ctx.Done()
	this.contextPool.Put(ctx)
}

func (this *Isolate) Compile(source string, origin string) (*Script, error) {
	script, err := this.rawIsolate.CompileUnboundScript(source, origin, v8go.CompileOptions{
		Mode: v8go.CompileModeDefault,
	})
	if err != nil {
		return nil, err
	}
	return NewScript(script), nil
}

func (this *Isolate) ContextPool() *ContextPool {
	return this.contextPool
}

func (this *Isolate) RawIsolate() *v8go.Isolate {
	return this.rawIsolate
}

func (this *Isolate) ThrowException(value *v8go.Value) *v8go.Value {
	return this.rawIsolate.ThrowException(value)
}

func (this *Isolate) IsUsing() bool {
	return this.contextPool.IsUsing()
}

func (this *Isolate) Dispose() {
	if this.isDisposed {
		return
	}
	this.isDisposed = true

	this.contextPool.Close()
	this.rawIsolate.Dispose()
}

func (this *Isolate) createContext() (*Context, error) {
	return NewContext(v8go.NewContext(this.rawIsolate), this)
}