// simple-var-store.go
package expr

import "fmt"

type SimpleFuncStore struct {
	varStore  map[string]any
	funcStore map[string]FuncTemplate
}

type funcInfo struct {
	name string
	// minArgs int
	// maxArgs int
}

func (info *funcInfo) Name() string {
	return info.name
}

func (info *funcInfo) MinArgs() int {
	return 0
}

func (info *funcInfo) MaxArgs() int {
	return -1
}

func NewSimpleFuncStore() *SimpleFuncStore {
	return &SimpleFuncStore{
		varStore:  make(map[string]any),
		funcStore: make(map[string]FuncTemplate),
	}
}

func (ctx *SimpleFuncStore) GetValue(varName string) (v any, exists bool) {
	v, exists = ctx.varStore[varName]
	return
}

func (ctx *SimpleFuncStore) SetValue(varName string, value any) {
	ctx.varStore[varName] = value
}

func (ctx *SimpleFuncStore) GetFuncInfo(name string) (f exprFunc) {
	var exists bool
	if _, exists = ctx.funcStore[name]; exists {
		f = &funcInfo{name: name}
	}
	return
}

func (ctx *SimpleFuncStore) RegisterFunc(name string, f FuncTemplate, minArgs, maxArgs int) {
	ctx.funcStore[name] = f
}

func (ctx *SimpleFuncStore) Call(name string, args []any) (result any, err error) {
	if f, exists := ctx.funcStore[name]; exists {
		result, err = f(ctx, name, args)
	} else {
		err = fmt.Errorf("unknown function %s()", name)
	}
	return
}