package fingerprint

import (
	"regexp"
	"strconv"
	"strings"
)

// GDB backtrace frame patterns:
//   #0  function_name (args) at /path/to/file.c:42
//   #0  0x00007fff in function_name () from /lib/libfoo.so
//   #0  0x00007fff in ?? ()
var gdbFrameRe = regexp.MustCompile(
	`^\s*#(\d+)\s+(?:(0x[0-9a-fA-F]+)\s+in\s+)?(\S+)\s*\(([^)]*)\)\s*(?:at\s+(\S+?)(?::(\d+))?)?(?:\s+from\s+(\S+))?`,
)

// ParseGDB parses GDB/LLDB backtrace format.
func ParseGDB(raw string) []Frame {
	if !strings.Contains(raw, "#0") {
		return nil
	}

	var frames []Frame
	for _, line := range strings.Split(raw, "\n") {
		m := gdbFrameRe.FindStringSubmatch(line)
		if m == nil {
			continue
		}

		idx, _ := strconv.Atoi(m[1])
		addr := m[2]
		fn := m[3]
		// args := m[4] // ignored
		file := m[5]
		lineNo, _ := strconv.Atoi(m[6])
		module := m[7]

		// Skip unknown frames.
		if fn == "??" {
			continue
		}

		frames = append(frames, Frame{
			Index:    idx,
			Address:  addr,
			Function: fn,
			File:     file,
			Line:     lineNo,
			Module:   module,
		})
	}

	if len(frames) < 2 {
		return nil // Probably not a real GDB backtrace
	}

	return frames
}