package main

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/spf13/cobra"

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

// uninstallPlan lists everything netssh has written to this machine.
type uninstallPlan struct {
	Profiles []string // shell profiles with a netssh block or legacy lines
	Paths    []string // files and directories to delete
	Config   string   // config file to back up and delete; empty when kept
	Binaries []string
}

func buildUninstallPlan(cfg *config.Config, keepConfig bool) uninstallPlan {
	var plan uninstallPlan
	seen := make(map[string]bool)
	addPath := func(path string) {
		if path == "" || seen[path] {
			return
		}
		if _, err := os.Lstat(path); err == nil {
			seen[path] = true
			plan.Paths = append(plan.Paths, path)
		}
	}

	for _, profile := range hook.ProfileCandidates() {
		target, err := filepath.EvalSymlinks(profile)
		if err != nil || seen[target] {
			continue
		}
		seen[target] = true
		if hook.HasEntries(profile) {
			plan.Profiles = append(plan.Profiles, profile)
		}
	}

	aliases := []string{hook.CompletionAliasState()}
	if cfg != nil {
		aliases = append(aliases, cfg.Shell.Alias)
	}
	for _, path := range hook.CompletionFiles(aliases...) {
		if hook.IsGenerated(path) {
			addPath(path)
		}
	}

	// The cache directory holds hosts, aliases, refresh stamps, and instance caches.
	cacheDir := filepath.Dir(hook.AliasesPath())
	addPath(cacheDir)
	if cfg != nil {
		for _, path := range []string{cfg.Cache.Path, cfg.CachePath()} {
			if path == "" || strings.HasPrefix(path, cacheDir+string(filepath.Separator)) {
				continue
			}
			addPath(path)
			addPath(path + ".lock")
			addPath(filepath.Join(filepath.Dir(path), "last_refresh"))
			if strings.HasPrefix(filepath.Base(filepath.Dir(path)), "instances-") {
				addPath(filepath.Dir(path))
			}
		}
	}

	if !keepConfig {
		if _, err := os.Stat(config.Path()); err == nil {
			plan.Config = config.Path()
		}
		// Local server notes live next to the config file.
		addPath(filepath.Join(filepath.Dir(config.Path()), "netssh"))
	}

	plan.Binaries = installedBinaries()
	return plan
}

// installedBinaries finds the running binary and any other netssh in PATH.
func installedBinaries() []string {
	var out []string
	seen := make(map[string]bool)
	add := func(path string) {
		real, err := filepath.EvalSymlinks(path)
		if err != nil || seen[real] {
			return
		}
		if info, err := os.Stat(real); err != nil || info.IsDir() || filepath.Base(real) != "netssh" {
			return
		}
		seen[real] = true
		out = append(out, real)
	}
	if self, err := os.Executable(); err == nil {
		add(self)
	}
	for _, dir := range filepath.SplitList(os.Getenv("PATH")) {
		if dir != "" {
			add(filepath.Join(dir, "netssh"))
		}
	}
	return out
}

func (p uninstallPlan) empty() bool {
	return len(p.Profiles) == 0 && len(p.Paths) == 0 && p.Config == "" && len(p.Binaries) == 0
}

func (p uninstallPlan) print(w io.Writer) {
	for _, profile := range p.Profiles {
		fmt.Fprintf(w, "  edit    %s (remove netssh entries)\n", profile)
	}
	for _, path := range p.Paths {
		fmt.Fprintf(w, "  delete  %s\n", path)
	}
	if p.Config != "" {
		fmt.Fprintf(w, "  delete  %s (a backup is kept)\n", p.Config)
	}
	for _, binary := range p.Binaries {
		fmt.Fprintf(w, "  delete  %s\n", binary)
	}
}

// execute applies the plan. It continues after errors so that one protected
// file does not leave the rest behind, and returns commands that need sudo.
func (p uninstallPlan) execute(w io.Writer) (manual []string, err error) {
	var errs []error
	for _, profile := range p.Profiles {
		if _, err := hook.Uninstall(profile); err != nil {
			errs = append(errs, err)
			continue
		}
		fmt.Fprintf(w, "cleaned  %s\n", profile)
	}
	for _, path := range p.Paths {
		if err := os.RemoveAll(path); err != nil {
			errs = append(errs, err)
			continue
		}
		fmt.Fprintf(w, "removed  %s\n", path)
	}
	if p.Config != "" {
		backup, err := backupConfig(p.Config)
		if err != nil {
			errs = append(errs, fmt.Errorf("config not removed: %w", err))
		} else if err := os.Remove(p.Config); err != nil {
			errs = append(errs, err)
		} else {
			fmt.Fprintf(w, "removed  %s (backup: %s)\n", p.Config, backup)
		}
	}
	for _, binary := range p.Binaries {
		if err := os.Remove(binary); err != nil {
			if errors.Is(err, fs.ErrPermission) {
				manual = append(manual, "sudo rm -f "+shellQuote(binary))
				continue
			}
			errs = append(errs, err)
			continue
		}
		fmt.Fprintf(w, "removed  %s\n", binary)
	}
	return manual, errors.Join(errs...)
}

// backupConfig keeps a private copy, because the config holds API tokens.
func backupConfig(path string) (string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}
	backup := path + ".backup-" + time.Now().Format("20060102-150405")
	if err := storage.WriteFile(backup, data, 0o600); err != nil {
		return "", err
	}
	return backup, nil
}

func shellQuote(s string) string {
	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
}

func uninstallCmd() *cobra.Command {
	var keepConfig, yes, dryRun bool
	cmd := &cobra.Command{
		Use:   "uninstall",
		Short: "Remove netssh, its shell integration, cache, and config",
		Long: `Removes everything netssh and install.sh have set up:

  - netssh blocks and unmarked entries of older versions in bash, zsh, and fish profiles
  - shell completion files (bash, zsh, fish, oh-my-zsh cache, command alias)
  - the cache directory with hosts, aliases, and per-instance caches
  - the config file (a private backup is kept) and local server notes
  - the netssh binary

Use --keep-config to keep the config file and notes for a reinstall.`,
		Args: cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := config.Load()
			if err != nil {
				// A broken config must not block the uninstall.
				fmt.Fprintf(os.Stderr, "warning: %v\n", err)
				cfg = nil
			}
			plan := buildUninstallPlan(cfg, keepConfig)
			out := cmd.OutOrStdout()
			if plan.empty() {
				fmt.Fprintln(out, "Nothing to remove.")
				return nil
			}
			fmt.Fprintln(out, "netssh uninstall will:")
			plan.print(out)
			if dryRun {
				return nil
			}
			if !yes {
				fmt.Fprint(out, "Proceed? [y/N] ")
				answer, _ := bufio.NewReader(cmd.InOrStdin()).ReadString('\n')
				if a := strings.ToLower(strings.TrimSpace(answer)); a != "y" && a != "yes" {
					return fmt.Errorf("aborted")
				}
			}
			manual, err := plan.execute(out)
			for _, command := range manual {
				fmt.Fprintf(out, "Permission denied. Run: %s\n", command)
			}
			if len(plan.Profiles) > 0 {
				fmt.Fprintln(out, "Open a new terminal. For zsh, also run: rm -f ~/.zcompdump*")
			}
			return err
		},
	}
	cmd.Flags().BoolVar(&keepConfig, "keep-config", false, "Keep the config file and local notes")
	cmd.Flags().BoolVarP(&yes, "yes", "y", false, "Do not ask for confirmation")
	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "Only show what would be removed")
	return cmd
}