/*
   GoToSocial
   Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package log

import (
	"runtime"
	"strings"
)

// Caller fetches the calling function name, skipping 'depth'. Results are cached per PC.
func Caller(depth int) string {
	var pcs [1]uintptr

	// Fetch calling function using calldepth
	_ = runtime.Callers(depth, pcs[:])
	fn := runtime.FuncForPC(pcs[0])

	if fn == nil {
		return ""
	}

	// return formatted name
	return callername(fn)
}

// callername generates a human-readable calling function name.
func callername(fn *runtime.Func) string {
	name := fn.Name()

	// Drop all but the package name and function name, no mod path
	if idx := strings.LastIndex(name, "/"); idx >= 0 {
		name = name[idx+1:]
	}

	const params = `[...]`

	// Drop any generic type parameter markers
	if idx := strings.Index(name, params); idx >= 0 {
		name = name[:idx] + name[idx+len(params):]
	}

	return name
}