package ucl

type evalCtx struct {
	root       *evalCtx
	parent     *evalCtx
	commands   map[string]invokable
	macros     map[string]macroable
	vars       map[string]Object
	pseudoVars map[string]pseudoVar
}

func (ec *evalCtx) forkAndIsolate() *evalCtx {
	newEc := &evalCtx{parent: ec}
	newEc.root = newEc
	return newEc
}

func (ec *evalCtx) fork() *evalCtx {
	return &evalCtx{parent: ec, root: ec.root}
}

func (ec *evalCtx) addCmd(name string, inv invokable) {
	if ec.root.commands == nil {
		ec.root.commands = make(map[string]invokable)
	}

	ec.root.commands[name] = inv
}

func (ec *evalCtx) addMacro(name string, inv macroable) {
	if ec.root.macros == nil {
		ec.root.macros = make(map[string]macroable)
	}

	ec.root.macros[name] = inv
}

func (ec *evalCtx) setVar(name string, val Object) bool {
	if ec == nil || ec.vars == nil {
		return false
	}

	if _, ok := ec.vars[name]; ok {
		ec.vars[name] = val
		return true
	}

	return ec.parent.setVar(name, val)
}

func (ec *evalCtx) setOrDefineVar(name string, val Object) {
	if ec.setVar(name, val) {
		return
	}

	if ec.vars == nil {
		ec.vars = make(map[string]Object)
	}
	ec.vars[name] = val
}

func (ec *evalCtx) getVar(name string) (Object, bool) {
	if ec.vars == nil {
		if ec.parent == nil {
			return nil, false
		}
		return ec.parent.getVar(name)
	}

	if v, ok := ec.vars[name]; ok {
		return v, true
	} else if ec.parent != nil {
		return ec.parent.getVar(name)
	}

	return nil, false
}

func (ec *evalCtx) getPseudoVar(name string) (pseudoVar, bool) {
	if ec.root.pseudoVars == nil {
		return nil, false
	}
	pvar, ok := ec.root.pseudoVars[name]
	return pvar, ok
}

func (ec *evalCtx) lookupInvokable(name string) invokable {
	if ec == nil {
		return nil
	}

	for e := ec; e != nil; e = e.parent {
		if cmd, ok := e.commands[name]; ok {
			return cmd
		}
	}

	return ec.parent.lookupInvokable(name)
}

func (ec *evalCtx) lookupMacro(name string) macroable {
	if ec == nil {
		return nil
	}

	for e := ec; e != nil; e = e.parent {
		if cmd, ok := e.macros[name]; ok {
			return cmd
		}
	}

	return ec.parent.lookupMacro(name)
}