package logsdk

import (
	"runtime"
)

const (
	maximumFrames       = 32
	getCallerSkipOffset = 2
	entrySkipOffset     = 2
)

// Frame 调用相关信息
type Frame struct {
	Function string `json:"func"`
	File     string `json:"file"`
	Line     int    `json:"line"`
}

// IsValid 表示是否有效
func (frame Frame) IsValid() bool {
	return frame.Line > 0
}

func getCaller(skip int) Frame {
	pc := make([]uintptr, 1)
	n := runtime.Callers(skip+getCallerSkipOffset, pc)
	frame, _ := runtime.CallersFrames(pc[:n]).Next()
	if frame.PC == 0 {
		return Frame{}
	}
	return Frame{
		Function: frame.Function,
		File:     frame.File,
		Line:     frame.Line,
	}
}

func getStack(skip, maximumFrames int) []Frame {
	pc := make([]uintptr, maximumFrames)
	n := runtime.Callers(skip+getCallerSkipOffset, pc)
	stack := make([]Frame, 0, n)
	frames := runtime.CallersFrames(pc[:n])
	for {
		frame, more := frames.Next()
		if frame.PC != 0 {
			stack = append(stack, Frame{
				Function: frame.Function,
				File:     frame.File,
				Line:     frame.Line,
			})
		}
		if !more {
			break
		}
	}
	return stack
}