package hook

import (
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"

	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/storage"
)

const (
	// Marker is the unique string used to detect an existing hook line.
	Marker     = "netssh shell-init"
	BlockStart = "# >>> netssh >>>"
	BlockEnd   = "# <<< netssh <<<"
	// Line is the full line written into the shell profile.
	Line = "netssh shell-init  # netssh cache auto-refresh"

	// AliasesMarker is the unique string used to detect the aliases source line.
	AliasesMarker = "netssh/aliases.sh"
	// AliasesSourceLine is the bash/zsh line that sources the generated aliases file.
	AliasesSourceLine = "source ~/.cache/netssh/aliases.sh 2>/dev/null  # netssh aliases"
)

// ProfilePath returns the canonical shell profile path for the given shell name.
func ProfilePath(shell string) (string, error) {
	switch shell {
	case "bash":
		return filepath.Join(os.Getenv("HOME"), ".bashrc"), nil
	case "zsh":
		dir := os.Getenv("ZDOTDIR")
		if dir == "" {
			dir = os.Getenv("HOME")
		}
		return filepath.Join(dir, ".zshrc"), nil
	case "fish":
		return filepath.Join(FishConfigDir(), "config.fish"), nil
	default:
		return "", fmt.Errorf("unsupported shell %q — supported: bash, zsh, fish", shell)
	}
}

// ReloadNote returns the shell-specific hint for reloading the profile.
func ReloadNote(profilePath string) string {
	return "Reload with: source " + profilePath
}

// IsInstalled reports whether the hook marker is present in the profile file.
// Returns false if the file does not exist or cannot be read.
func IsInstalled(profilePath string) bool {
	data, err := os.ReadFile(profilePath)
	if err != nil {
		return false
	}
	for _, line := range strings.Split(string(data), "\n") {
		if strings.TrimSpace(line) == BlockStart || hookLinePattern.MatchString(strings.TrimSpace(line)) {
			return true
		}
	}
	return false
}

// Install appends the hook line to the profile if it is not already present.
// Returns (true, nil) when newly installed, (false, nil) when already present.
// Creates the profile file (and any parent directories) if they do not exist.
func Install(profilePath string) (installed bool, err error) {
	if IsInstalled(profilePath) {
		return false, nil
	}
	if err := os.MkdirAll(filepath.Dir(profilePath), 0o755); err != nil {
		return false, fmt.Errorf("creating directory: %w", err)
	}
	f, err := os.OpenFile(profilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
	if err != nil {
		return false, fmt.Errorf("opening profile: %w", err)
	}
	defer f.Close()
	if _, err := fmt.Fprintf(f, "\n%s\n", Line); err != nil {
		return false, err
	}
	return true, nil
}

// InstallAliasesSource appends the aliases source line to a bash/zsh profile.
// This is a no-op for fish (which uses conf.d auto-sourcing instead).
// Returns (true, nil) when newly added, (false, nil) when already present.
func InstallAliasesSource(profilePath string) (installed bool, err error) {
	data, err := os.ReadFile(profilePath)
	if err != nil && !os.IsNotExist(err) {
		return false, fmt.Errorf("reading profile: %w", err)
	}
	for _, line := range strings.Split(string(data), "\n") {
		if strings.TrimSpace(line) == BlockStart || aliasesLinePattern.MatchString(strings.TrimSpace(line)) {
			return false, nil
		}
	}
	f, err := os.OpenFile(profilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
	if err != nil {
		return false, fmt.Errorf("opening profile: %w", err)
	}
	defer f.Close()
	if _, err := fmt.Fprintf(f, "%s\n", "source "+shellQuote(AliasesPath(), "bash")+" 2>/dev/null  # netssh aliases"); err != nil {
		return false, err
	}
	return true, nil
}

var hookLinePattern = regexp.MustCompile(`^(?:[^\s]*/)?netssh\s+shell-init\s*(?:#.*)?$`)
var aliasesLinePattern = regexp.MustCompile(`^(?:source|\.)\s+["']?[^;|&]*netssh/aliases\.sh["']?(?:\s+2>/dev/null)?\s*(?:#.*)?$`)

// Uninstall removes legacy hook lines and complete installer-managed blocks.
// Missing profiles are a no-op; malformed blocks leave the file unchanged.
func Uninstall(profilePath string) (removed bool, err error) {
	data, err := os.ReadFile(profilePath)
	if os.IsNotExist(err) {
		return false, nil
	}
	if err != nil {
		return false, fmt.Errorf("reading profile: %w", err)
	}
	var kept []string
	inside := false
	for _, line := range strings.Split(string(data), "\n") {
		value := strings.TrimSpace(line)
		switch value {
		case BlockStart:
			if inside {
				return false, fmt.Errorf("nested netssh block in %s", profilePath)
			}
			inside = true
			removed = true
			continue
		case BlockEnd:
			if !inside {
				return false, fmt.Errorf("unmatched netssh block in %s", profilePath)
			}
			inside = false
			continue
		}
		if inside {
			continue
		}
		if hookLinePattern.MatchString(value) || aliasesLinePattern.MatchString(value) {
			removed = true
			continue
		}
		kept = append(kept, line)
	}
	if inside {
		return false, fmt.Errorf("unclosed netssh block in %s", profilePath)
	}
	if !removed {
		return false, nil
	}
	cleaned := strings.ReplaceAll(strings.Join(kept, "\n"), "\n\n\n", "\n\n")
	target, err := filepath.EvalSymlinks(profilePath)
	if err != nil {
		return false, err
	}
	info, err := os.Stat(target)
	if err != nil {
		return false, err
	}
	if err := storage.WriteFile(target, []byte(cleaned), info.Mode().Perm()); err != nil {
		return false, fmt.Errorf("writing profile: %w", err)
	}
	return true, nil
}