otiai10/openaigo

package functioncall

import (
    "encoding/json"
    "fmt"
    "reflect"
)

type Invocation interface {
    Name() string
    Args() map[string]any
}

func (funcs Funcs) Call(invocation Invocation) string {
    b, err := json.Marshal(funcs.invoke(invocation))
    if err != nil {
        return err.Error()
    }
    return string(b)
}

func (funcs Funcs) invoke(invocation Invocation) any {
    f, ok := funcs[invocation.Name()]
    if !ok {
        return fmt.Sprintf("function not found: `%s`", invocation.Name())
    }
    v := reflect.ValueOf(f.Value)
    if !v.IsValid() || v.IsZero() {
        return fmt.Sprintf("function is invalid: %s", invocation.Name())
    }
    if v.Kind() != reflect.Func {
        return fmt.Sprintf("function is not a function: %s", invocation.Name())
    }
    if v.Type().NumIn() != len(invocation.Args()) {
        return fmt.Sprintf("function argument length mismatch: %s", invocation.Name())
    }
    // Call the function with given arguments by using `reflect` package
    args := invocation.Args()
    params := []reflect.Value{}
    for i, p := range f.Parameters {
        if arg, ok := args[p.Name]; ok {
            params = append(params, reflect.ValueOf(arg))
        } else {
            params = append(params, reflect.Zero(v.Type().In(i)))
        }
    }
    rets := []any{}
    for _, r := range v.Call(params) {
        rets = append(rets, r.Interface())
    }
    return rets
}