package xdebug

import (
	"runtime"
	"strings"
)

const (
	maxDepth     = 1000
	xDebugCaller = "/xdebug/caller.go"
)

// GetSysPathSplitSymbol 根据系统获取路径分隔符
func GetSysPathSplitSymbol() (splitSymbol string) {
	if runtime.GOOS == "windows" {
		splitSymbol = "\\"
	} else {
		splitSymbol = "/"
	}
	return
}

// ParseCallFile 解析调用文件
func ParseCallFile(filename string) string {
	lastIndex := strings.LastIndex(filename, GetSysPathSplitSymbol())
	if lastIndex == -1 {
		return ""
	}
	return filename[lastIndex+1:]
}

// callerFromIndex 返回调用者的位置和信息
// 说明: 返回的索引值应该是 <index - 1> 作为调用者的起始点
func callerFromIndex(filters []string) (pc uintptr, file string, line int, index int) {
	var filtered, ok bool
	for index = 0; index < maxDepth; index++ {
		pc, file, line, ok = runtime.Caller(index)
		if !ok {
			break
		}

		filtered = false
		for _, filter := range filters {
			if filter != "" && strings.Contains(file, filter) {
				filtered = true
				break
			}
		}

		if filtered {
			continue
		}

		if strings.HasSuffix(file, xDebugCaller) {
			continue
		}
		return
	}
	return 0, "", -1, -1
}

// CallerPathWithFilter 返回函数名和绝对文件路径调用者的行号
// filter 用于过滤调用者的路径。
func CallerWithFilter(filter string, skip ...int) (function string, path string, line int) {
	num := 0
	if len(skip) > 0 {
		num = skip[0]
	}
	var ok bool
	pc, file, line, start := callerFromIndex([]string{filter})
	if start != -1 {
		for i := start + num; i < maxDepth; i++ {
			if i != start {
				pc, file, line, ok = runtime.Caller(i)
			}
			if ok {
				if filter != "" && strings.Contains(file, filter) {
					continue
				}
				function := ""
				if fn := runtime.FuncForPC(pc); fn == nil {
					function = "unknown"
				} else {
					function = fn.Name()
				}
				return function, file, line
			} else {
				break
			}
		}
		return function, file, line
	}
	return "", "", -1
}