package fingerprint

import (
	"path/filepath"
	"regexp"
	"strings"
)

const maxFrames = 8

var (
	hexAddrRe       = regexp.MustCompile(`0x[0-9a-fA-F]+`)
	templateParamRe = regexp.MustCompile(`<[^>]*>`)
	abiTagRe        = regexp.MustCompile(`\[abi:[^\]]*\]`)
)

// runtimePrefixes are function prefixes for runtime/library frames to filter out.
var runtimePrefixes = []string{
	"__libc_",
	"__GI_",
	"_start",
	"__clone",
	"start_thread",
	"__pthread_",
	"__sigaction",
	"_dl_",
	"__tls_",
	// glibc allocator internals
	"__libc_malloc",
	"__libc_free",
	"malloc",
	"free",
	"realloc",
	"calloc",
	// ASan runtime
	"__asan_",
	"__sanitizer_",
	"__interceptor_",
	"__interception::",
	// Zig std runtime
	"std.debug.",
	"std.start.",
	"std.os.linux.",
	"posixCallNative",
}

// Normalize applies stability-oriented transformations to parsed frames.
func Normalize(frames []Frame) []NormalizedFrame {
	var result []NormalizedFrame

	for _, f := range frames {
		// Skip inline frames.
		if f.Inline {
			continue
		}

		fn := f.Function

		// Skip runtime/library frames.
		if isRuntimeFrame(fn) {
			continue
		}

		// Strip hex addresses.
		fn = hexAddrRe.ReplaceAllString(fn, "")

		// Strip C++ template parameters.
		fn = templateParamRe.ReplaceAllString(fn, "<>")

		// Strip ABI tags.
		fn = abiTagRe.ReplaceAllString(fn, "")

		// Clean up whitespace.
		fn = strings.TrimSpace(fn)

		// Strip paths to just filename.
		file := f.File
		if file != "" {
			file = filepath.Base(file)
		}

		if fn == "" {
			continue
		}

		result = append(result, NormalizedFrame{
			Function: fn,
			File:     file,
		})

		if len(result) >= maxFrames {
			break
		}
	}

	return result
}

func isRuntimeFrame(fn string) bool {
	for _, prefix := range runtimePrefixes {
		if strings.HasPrefix(fn, prefix) {
			return true
		}
	}
	return false
}