package proc

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

// deriveDisplayCommand returns a human-readable command name that avoids
// kernel comm-field truncation (typically 15-16 chars on Linux/macOS/FreeBSD)
// by falling back to the executable name extracted from the full command line
// when the short name looks clipped.
func deriveDisplayCommand(comm, cmdline string) string {
	trimmedComm := strings.TrimSpace(comm)
	exe := extractExecutableName(cmdline)
	if trimmedComm == "" {
		return exe
	}
	if exe == "" {
		return trimmedComm
	}
	if strings.HasPrefix(exe, trimmedComm) && len(trimmedComm) < len(exe) {
		return exe
	}
	return trimmedComm
}

// containsWholeWord checks if s contains word as a standalone token,
// not as a substring of a larger number or identifier.
func containsWholeWord(s, word string) bool {
	idx := 0
	for {
		i := strings.Index(s[idx:], word)
		if i < 0 {
			return false
		}
		start := idx + i
		end := start + len(word)

		leftOK := start == 0 || !isWordChar(s[start-1])
		rightOK := end == len(s) || !isWordChar(s[end])
		if leftOK && rightOK {
			return true
		}
		idx = start + 1
	}
}

func isWordChar(c byte) bool {
	return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_'
}

// binaryBasename returns the executable name from a string that is known to
// be a single full binary path (e.g. from `lsof ftxt`, `/proc/<pid>/exe`, or
// `ps -o comm=` on its own line). Unlike extractExecutableName it does NOT
// tokenize on whitespace, so paths containing spaces — like macOS .app
// bundles ("/Applications/Microsoft Teams.app/Contents/MacOS/Microsoft Teams")
// — are preserved intact.
func binaryBasename(rawPath string) string {
	s := strings.TrimSpace(rawPath)
	s = strings.Trim(s, `"'`)
	if s == "" {
		return ""
	}
	base := filepath.Base(s)
	if base == "." || isPathSeparator(base) {
		return ""
	}
	return base
}

// isPathSeparator reports whether s is a single bare path separator. filepath.Base
// returns the platform separator for a root path ("/" on Unix, "\\" on Windows),
// which is never a real binary name.
func isPathSeparator(s string) bool {
	return len(s) == 1 && os.IsPathSeparator(s[0])
}

func extractExecutableName(cmdline string) string {
	args := splitCmdline(cmdline)
	for _, arg := range args {
		if arg == "" {
			continue
		}
		if strings.Contains(arg, "=") && !strings.Contains(arg, "/") {
			// Skip leading environment assignments.
			continue
		}
		clean := strings.Trim(arg, "\"'")
		if clean == "" {
			continue
		}
		base := filepath.Base(clean)
		if base == "." || base == "" || isPathSeparator(base) {
			continue
		}
		return base
	}
	return ""
}