package assert

import (
	"fmt"
	"runtime"
	"strings"
	"unicode"
	"unicode/utf8"
)

func errorTrace() []string {
	pc := uintptr(0)
	file := ""
	line := 0
	ok := false
	name := ""

	var callers []string
	for i := 0; ; i++ {
		pc, file, line, ok = runtime.Caller(i)
		if !ok {
			break
		}

		if file == "<autogenerated>" {
			break
		}

		f := runtime.FuncForPC(pc)
		if f == nil {
			break
		}
		name = f.Name()

		if name == "testing.tRunner" {
			break
		}

		parts := strings.Split(file, "/")
		file = parts[len(parts)-1]
		if len(parts) > 1 {
			dir := parts[len(parts)-2]
			if (dir != "assert" && dir != "mock" && dir != "require") || file == "mock_test.go" {
				callers = append(callers, fmt.Sprintf("%s:%d", file, line))
			}
		}

		// Drop the package
		segments := strings.Split(name, ".")
		name = segments[len(segments)-1]
		if isTest(name, "Test") ||
			isTest(name, "Benchmark") ||
			isTest(name, "Example") {
			break
		}
	}

	return callers
}

func isTest(name, prefix string) bool {
	if !strings.HasPrefix(name, prefix) {
		return false
	}
	if len(name) == len(prefix) { // "Test" is ok
		return true
	}

	rune_, _ := utf8.DecodeRuneInString(name[len(prefix):])

	return !unicode.IsLower(rune_)
}