package main

import (
	"context"
	"encoding/json"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"github.com/spf13/cobra"

	"jarl/internal/config"
	"jarl/internal/engine"
	"jarl/internal/render"
	"jarl/internal/validate"
	"jarl/internal/version"
)

// dirOwner restores file ownership after commands run as root.
type dirOwner struct {
	uid, gid int
	active   bool
}

func newDirOwner(dir string) *dirOwner {
	o := &dirOwner{}
	if os.Geteuid() != 0 {
		return o
	}
	fi, err := os.Stat(dir)
	if err != nil {
		return o
	}
	if st, ok := fi.Sys().(*syscall.Stat_t); ok && st.Uid != 0 {
		o.uid, o.gid, o.active = int(st.Uid), int(st.Gid), true
	}
	return o
}

// fix gives root-owned files under dirs to the daemon's user (keeping
// their group, which matters for named).
func (o *dirOwner) fix(dirs ...string) {
	if !o.active {
		return
	}
	for _, d := range dirs {
		filepath.WalkDir(d, func(path string, de fs.DirEntry, err error) error {
			if err != nil {
				return nil
			}
			info, err := de.Info()
			if err != nil {
				return nil
			}
			if st, ok := info.Sys().(*syscall.Stat_t); ok && st.Uid == 0 {
				gid := int(st.Gid)
				if path == d || strings.HasSuffix(path, ".db") || strings.Contains(path, ".db-") {
					gid = o.gid
				}
				os.Lchown(path, o.uid, gid)
			}
			return nil
		})
	}
}

func printJSON(v any) {
	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	enc.Encode(v)
}

func printProblems(ps []validate.Problem) {
	for _, p := range ps {
		fmt.Println("  " + p.String())
	}
}

func printResult(res *engine.Result) {
	if res == nil {
		return
	}
	if len(res.Problems) > 0 {
		fmt.Println("Problems:")
		printProblems(res.Problems)
	}
	for _, m := range res.Check {
		if m.Error {
			obj := ""
			if m.Object != "" {
				obj = " [" + m.Object + "]"
			}
			fmt.Printf("  named-checkconf: %s%s\n", m.Text, obj)
		}
	}
	for _, w := range res.Warnings {
		fmt.Println("warning:", w)
	}
	for _, d := range res.Drift {
		fmt.Printf("drift: %s (%s)\n", d.Path, d.Reason)
	}
}

func importCmd() *cobra.Command {
	var from string
	var dryRun, asJSON bool
	cmd := &cobra.Command{
		Use:   "import",
		Short: "Import the existing BIND configuration into Jarl",
		Long: `Reads named.conf (following includes) and all primary zone files into
Jarl. Key files used by rndc (rndc.key) stay as include statements.

If the imported configuration is valid it is applied right away: Jarl
writes its own files (bind.config_dir, bind.zone_dir), but named keeps
running on the old configuration until you run 'jarld adopt'. If there
are problems, the import is kept as an open changeset that you can fix in
the web UI or with the CLI.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.close()
			ctx := context.Background()
			if from == "" {
				from = a.cfg.BIND.MainConfig
			}
			p, err := a.localPrincipal(ctx, "")
			if err != nil {
				return err
			}
			res, err := a.eng.Import(ctx, from, p, dryRun)
			if err != nil {
				return err
			}
			if asJSON {
				printJSON(res)
				return nil
			}
			rep := res.Report
			fmt.Printf("Read %s:\n", from)
			fmt.Printf("  %d views, %d zones, %d records, %d ACLs, %d TSIG keys, %d options\n",
				rep.Counts["views"], rep.Counts["zones"], rep.Counts["records"], rep.Counts["acls"], rep.Counts["tsig_keys"], rep.Counts["options"])
			for _, z := range rep.Zones {
				view := ""
				if z.View != "" {
					view = " [view " + z.View + "]"
				}
				extra := ""
				if z.Skipped > 0 {
					extra = fmt.Sprintf(", %d skipped", z.Skipped)
				}
				fmt.Printf("  zone %-35s %-10s %4d records%s\n", z.Name+view, z.Type, z.Records, extra)
			}
			for _, k := range rep.Kept {
				fmt.Printf("  kept as include: %s\n", k)
			}
			for _, w := range rep.Warnings {
				fmt.Println("warning:", w)
			}
			if len(rep.Skipped) > 0 {
				fmt.Println("Not imported:")
				for _, s := range rep.Skipped {
					fmt.Println("  " + s)
				}
			}
			if dryRun {
				fmt.Printf("\nDry run: %d operations would be applied; nothing was changed.\n", len(res.Changeset.Ops))
				return nil
			}
			if !res.Applied {
				fmt.Printf("\nThe import is saved as changeset #%d but was NOT applied:\n", res.Changeset.ID)
				if res.Result != nil && res.Result.Error != nil {
					fmt.Println("  " + res.Result.Error.Message)
				}
				printResult(res.Result)
				fmt.Println("\nFix the problems (web UI: Changes, or 'jarl changeset show " + fmt.Sprint(res.Changeset.ID) + "'), apply the changeset, then run 'jarld adopt'.")
				return nil
			}
			printResult(res.Result)
			fmt.Printf("\nImported and applied as changeset #%d. Jarl's files are in %s and %s.\n", res.Result.ChangesetID, a.cfg.BIND.ConfigDir, a.cfg.BIND.ZoneDir)
			fmt.Println("named still uses the old configuration. Review Jarl's files, then switch named over with:")
			fmt.Println("\n  sudo jarld adopt")
			return nil
		},
	}
	cmd.Flags().StringVar(&from, "from", "", "named.conf to import (default: bind.main_config)")
	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "only show what would be imported")
	cmd.Flags().BoolVar(&asJSON, "json", false, "print the result as JSON")
	return cmd
}

func adoptCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "adopt",
		Short: "Switch named over to Jarl's configuration (run as root)",
		Long: `Makes named load Jarl's configuration:

  1. bumps the serial of every primary zone,
  2. saves bind.main_config (e.g. /etc/bind/named.conf) as
     named.conf.pre-jarl-<date> and replaces it with a single include of
     Jarl's named.conf,
  3. runs named-checkconf, rndc reconfig and reloads every zone,
  4. checks that named serves every zone from Jarl's files.

If anything fails the previous named.conf is restored. Writing
named.conf needs root.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.close()
			ctx := context.Background()
			p, err := a.localPrincipal(ctx, "")
			if err != nil {
				return err
			}
			res, err := a.eng.Adopt(ctx, p)
			if err != nil {
				if ee, ok := engine.AsError(err); ok && len(ee.Problems) > 0 {
					fmt.Println("Problems:")
					printProblems(ee.Problems)
				}
				return err
			}
			if res.Already {
				fmt.Printf("named already loads Jarl's configuration (%s includes %s).\n", res.MainConfig, filepath.Join(a.cfg.BIND.ConfigDir, "named.conf"))
				return nil
			}
			fmt.Printf("named now loads Jarl's configuration.\n  %s includes %s\n  previous configuration saved as %s\n", res.MainConfig, filepath.Join(a.cfg.BIND.ConfigDir, "named.conf"), res.Backup)
			for _, s := range res.Serials {
				fmt.Printf("  zone %s serial %d -> %d\n", strings.TrimSuffix(s.Zone, "."), s.Old, s.New)
			}
			fmt.Println("\nFrom now on, change DNS only through Jarl. To go back: restore the saved file and run 'rndc reconfig'.")
			return nil
		},
	}
}

func checkCmd() *cobra.Command {
	var asJSON bool
	cmd := &cobra.Command{
		Use:   "check",
		Short: "Validate the current configuration and run named-checkconf on it",
		RunE: func(cmd *cobra.Command, args []string) error {
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.close()
			res, err := a.eng.CheckCurrent(context.Background())
			if err != nil {
				return err
			}
			if asJSON {
				printJSON(res)
			} else {
				printResult(res)
				if res.Diff != "" {
					fmt.Println("Files on disk differ from the configuration; 'jarld resync' rewrites them:")
					fmt.Print(res.Diff)
				}
			}
			if !res.Valid {
				return fmt.Errorf("the configuration has errors")
			}
			if !asJSON {
				fmt.Println("OK: the configuration is valid and named-checkconf accepts it.")
			}
			return nil
		},
	}
	cmd.Flags().BoolVar(&asJSON, "json", false, "print the result as JSON")
	return cmd
}

func renderCmd() *cobra.Command {
	var out string
	cmd := &cobra.Command{
		Use:   "render",
		Short: "Write the generated configuration to a directory (for inspection)",
		RunE: func(cmd *cobra.Command, args []string) error {
			if out == "" {
				return fmt.Errorf("--out is required")
			}
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.store.Close()
			st, err := a.store.LoadState(context.Background())
			if err != nil {
				return err
			}
			paths := render.Paths{ConfigDir: filepath.Join(out, "config"), ZoneDir: filepath.Join(out, "zones"), CacheDir: filepath.Join(out, "cache")}
			o := render.Render(st, paths)
			for _, f := range o.Files {
				if err := os.MkdirAll(filepath.Dir(f.Path), 0o750); err != nil {
					return err
				}
				if err := os.WriteFile(f.Path, f.Content, 0o640); err != nil {
					return err
				}
				fmt.Println(f.Path)
			}
			return nil
		},
	}
	cmd.Flags().StringVarP(&out, "out", "o", "", "output directory")
	return cmd
}

func resyncCmd() *cobra.Command {
	var force, dryRun bool
	cmd := &cobra.Command{
		Use:   "resync",
		Short: "Rewrite all generated files from the database and reload named",
		RunE: func(cmd *cobra.Command, args []string) error {
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.close()
			ctx := context.Background()
			p, err := a.localPrincipal(ctx, "")
			if err != nil {
				return err
			}
			res, err := a.eng.Resync(ctx, p, engine.ApplyOptions{Force: force, DryRun: dryRun})
			printResult(res)
			if err != nil {
				return err
			}
			if res.Diff != "" {
				fmt.Print(res.Diff)
			}
			if dryRun {
				fmt.Printf("Dry run: %d files would be written.\n", len(res.Files))
			} else {
				fmt.Printf("%d files written; named reloaded: %v\n", len(res.Files), res.Reloaded)
			}
			return nil
		},
	}
	cmd.Flags().BoolVar(&force, "force", false, "overwrite files changed outside Jarl")
	cmd.Flags().BoolVar(&dryRun, "dry-run", false, "only show what would change")
	return cmd
}

func backupCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "backup FILE",
		Short: "Write a consistent copy of the database to FILE (safe while jarld runs)",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			a, err := openApp(true)
			if err != nil {
				return err
			}
			defer a.close()
			if _, err := os.Stat(args[0]); err == nil {
				return fmt.Errorf("%s already exists", args[0])
			}
			if err := a.store.Backup(context.Background(), args[0]); err != nil {
				return err
			}
			os.Chmod(args[0], 0o600)
			fmt.Println("Database copied to", args[0])
			return nil
		},
	}
}

func configCmd() *cobra.Command {
	var example bool
	cmd := &cobra.Command{
		Use:   "config",
		Short: "Show the effective configuration (or an example file)",
		RunE: func(cmd *cobra.Command, args []string) error {
			if example {
				fmt.Print(config.Example)
				return nil
			}
			cfg, err := config.Load(configPath, true)
			if err != nil {
				return err
			}
			printJSON(cfg)
			return nil
		},
	}
	cmd.Flags().BoolVar(&example, "example", false, "print a commented example configuration file")
	return cmd
}

func versionCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "version",
		Short: "Print the version",
		Run: func(cmd *cobra.Command, args []string) {
			fmt.Println("jarld", version.Version)
		},
	}
}