// Command jarl is the command line client for Jarl. It talks to jarld's
// REST API with an API token.
package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/url"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"text/tabwriter"

	"github.com/spf13/cobra"
	"go.yaml.in/yaml/v3"

	"jarl/internal/api"
	"jarl/internal/client"
	"jarl/internal/version"
)

func main() {
	root := rootCmd()
	err := root.Execute()
	if errors.Is(err, errFanOut) {
		os.Exit(fanOut(fanOutTargets))
	}
	finishPreflight()
	if err != nil {
		printError(err)
		os.Exit(exitCode(err))
	}
}

// Global flags.
var (
	flagServer    string
	flagToken     string
	flagConfig    string
	flagChangeset int64
	flagDryRun    bool
	flagForce     bool
	flagOutput    string
	flagInsecure  bool
	flagCACert    string
	flagQuiet     bool
)

// cliConfig is ~/.config/jarl/config.yaml. Server and Token are the
// simple, single-server form; Servers and Groups name several servers
// (see targets.go).
type cliConfig struct {
	Server   string                  `yaml:"server,omitempty"`
	Token    string                  `yaml:"token,omitempty"`
	Insecure bool                    `yaml:"insecure,omitempty"`
	CACert   string                  `yaml:"ca_cert,omitempty"`
	Default  string                  `yaml:"default,omitempty"`
	Servers  map[string]*serverEntry `yaml:"servers,omitempty"`
	Groups   map[string][]string     `yaml:"groups,omitempty"`
}

func defaultConfigPath() string {
	if p := os.Getenv("JARL_CLI_CONFIG"); p != "" {
		return p
	}
	dir, err := os.UserConfigDir()
	if err != nil {
		dir = filepath.Join(os.Getenv("HOME"), ".config")
	}
	return filepath.Join(dir, "jarl", "config.yaml")
}

func loadCLIConfig() (*cliConfig, error) {
	c := &cliConfig{}
	b, err := os.ReadFile(flagConfig)
	if errors.Is(err, os.ErrNotExist) {
		return c, nil
	}
	if err != nil {
		return nil, err
	}
	return c, yaml.Unmarshal(b, c)
}

func saveCLIConfig(c *cliConfig) error {
	if err := os.MkdirAll(filepath.Dir(flagConfig), 0o700); err != nil {
		return err
	}
	b, err := yaml.Marshal(c)
	if err != nil {
		return err
	}
	return os.WriteFile(flagConfig, b, 0o600)
}

func newClient() (*client.Client, error) {
	cfg, err := loadCLIConfig()
	if err != nil {
		return nil, fmt.Errorf("reading %s: %w", flagConfig, err)
	}
	ts, err := resolveTargets(cfg, targetSpec(cfg))
	if err != nil {
		return nil, err
	}
	if len(ts) > 1 {
		return nil, fmt.Errorf("--server names %d servers; this command works on one", len(ts))
	}
	t := ts[0]
	// A named server's own token wins: a token from the environment
	// belongs to some other server more often than not.
	token := firstNonEmpty(flagToken, os.Getenv("JARL_TOKEN"), t.Token)
	if t.Name != "" && t.Token != "" {
		token = t.Token
	}
	if token == "" {
		if t.Name != "" {
			return nil, fmt.Errorf("no API token for server %s: use 'jarl --server %s config set token'", t.Name, t.Name)
		}
		return nil, fmt.Errorf("no API token: use --token, JARL_TOKEN or 'jarl config set token'")
	}
	if strings.HasPrefix(token, "@") {
		b, err := os.ReadFile(token[1:])
		if err != nil {
			return nil, fmt.Errorf("reading token file: %w", err)
		}
		token = strings.TrimSpace(string(b))
	}
	c, err := client.New(client.Options{Server: t.URL, Token: token, Insecure: flagInsecure || t.Insecure, CACert: firstNonEmpty(flagCACert, t.CACert)})
	if err != nil {
		return nil, err
	}
	if os.Getenv(envPreflight) == "1" {
		c.Preflight = true
		preflightClients = append(preflightClients, c)
	}
	c.Changeset = flagChangeset
	if c.Changeset == 0 {
		if v := os.Getenv("JARL_CHANGESET"); v != "" {
			n, err := strconv.ParseInt(v, 10, 64)
			if err != nil {
				return nil, fmt.Errorf("invalid JARL_CHANGESET %q", v)
			}
			c.Changeset = n
		}
	}
	c.DryRun, c.Force = flagDryRun || c.Preflight, flagForce
	return c, nil
}

func firstNonEmpty(vals ...string) string {
	for _, v := range vals {
		if v != "" {
			return v
		}
	}
	return ""
}

func rootCmd() *cobra.Command {
	root := &cobra.Command{
		Use:   "jarl",
		Short: "Command line client for Jarl, the BIND manager",
		Long: `jarl manages a BIND server through Jarl's API.

Every command that changes the configuration is applied at once, as a
single changeset that is validated, checked with named-checkconf and loaded
into named. To batch several changes, create a changeset and pass
--changeset ID (or set JARL_CHANGESET), then apply it; or describe the
changes in a file and run 'jarl apply -f FILE'.

Configure the server and token once:

  jarl config set server https://dns.example.com:8053
  jarl config set token     (paste the token at the prompt)

Exit codes: 0 ok, 1 error, 3 not authenticated or not allowed, 4 not found,
5 conflict, 6 invalid or rejected by validation, 7 server or BIND error.`,
		SilenceUsage:  true,
		SilenceErrors: true,
		Version:       version.Version,
		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
			return checkFanOut(cmd)
		},
	}
	pf := root.PersistentFlags()
	pf.StringVarP(&flagServer, "server", "s", "", "server: a name or group from the config file, \"all\", a comma separated list, or a URL (env JARL_SERVER)")
	pf.StringVar(&flagToken, "token", "", "API token, or @FILE to read it from a file (env JARL_TOKEN)")
	pf.StringVar(&flagConfig, "config", defaultConfigPath(), "CLI configuration file")
	pf.Int64VarP(&flagChangeset, "changeset", "C", 0, "stage changes into this changeset instead of applying them (env JARL_CHANGESET)")
	pf.BoolVarP(&flagDryRun, "dry-run", "n", false, "validate and show the changes without applying them")
	pf.BoolVar(&flagForce, "force", false, "overwrite BIND files that were changed outside Jarl")
	pf.StringVarP(&flagOutput, "output", "o", "table", "output format: table, json or yaml")
	pf.BoolVar(&flagInsecure, "insecure", false, "don't verify the server's TLS certificate")
	pf.StringVar(&flagCACert, "ca-cert", "", "PEM file with a CA to trust for the server's certificate")
	pf.BoolVarP(&flagQuiet, "quiet", "q", false, "only print errors (and IDs where useful)")
	root.AddGroup(&cobra.Group{ID: "dns", Title: "DNS commands:"}, &cobra.Group{ID: "changes", Title: "Changes:"}, &cobra.Group{ID: "admin", Title: "Administration:"})
	add := func(group string, cmds ...*cobra.Command) {
		for _, c := range cmds {
			c.GroupID = group
			root.AddCommand(c)
		}
	}
	add("dns", zoneCmd(), recordCmd(), viewCmd(), aclCmd(), tsigCmd(), optionCmd(), settingsCmd(), acmeCmd(), searchCmd(), statsCmd())
	add("changes", applyCmd(), changesetCmd(), historyCmd())
	add("admin", statusCmd(), whoamiCmd(), userCmd(), tokenCmd(), auditCmd(), checkCmd(), resyncCmd(), configCmd())
	setupCompletion(root)
	return root
}

// ctx returns the context for API calls. The HTTP client's timeout bounds
// each request.
func ctx() context.Context { return context.Background() }

// ---- output

func output(v any, table func(w io.Writer)) error {
	switch flagOutput {
	case "json":
		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "  ")
		return enc.Encode(v)
	case "yaml":
		// Round-trip through JSON so field names match the API.
		b, err := json.Marshal(v)
		if err != nil {
			return err
		}
		var x any
		if err := json.Unmarshal(b, &x); err != nil {
			return err
		}
		return yaml.NewEncoder(os.Stdout).Encode(x)
	case "table", "":
		if table == nil {
			return output(v, nil)
		}
		tw := tabwriter.NewWriter(os.Stdout, 2, 4, 2, ' ', 0)
		table(tw)
		return tw.Flush()
	}
	return fmt.Errorf("unknown output format %q (use table, json or yaml)", flagOutput)
}

func dot(name string) string {
	if name == "." || name == "" {
		return "."
	}
	return strings.TrimSuffix(name, ".")
}

// where describes the zone and view a problem is about.
func where(p client.Problem) string {
	if p.Zone == "" {
		return ""
	}
	s := " [zone " + dot(p.Zone)
	if p.View != "" {
		s += ", view " + p.View
	}
	return s + "]"
}

func printProblems(w io.Writer, ps []client.Problem) {
	for _, p := range ps {
		fmt.Fprintf(w, "  %s: %s%s\n", p.Severity, p.Message, where(p))
	}
}

// printCheck prints named-checkconf's errors and warnings, but not its
// routine "loaded serial" lines.
func printCheck(w io.Writer, ms []client.CheckMessage) {
	for _, m := range ms {
		if !m.Error && (strings.HasPrefix(m.Text, "loaded serial") || m.Text == "OK") {
			continue
		}
		obj := ""
		if m.Object != "" {
			obj = " [" + m.Object + "]"
		}
		label := "named-checkconf"
		if !m.Error {
			label += " warning"
		}
		fmt.Fprintf(w, "  %s: %s%s\n", label, m.Text, obj)
	}
}

func printError(err error) {
	var ce *client.Error
	if errors.As(err, &ce) {
		// The message often repeats the first problem; print it once.
		head, ps := ce.Info.Message, ce.Problems()
		for i, p := range ps {
			if p.Message == head {
				head += where(p)
				ps = append(ps[:i:i], ps[i+1:]...)
				break
			}
			if strings.HasPrefix(head, p.Message+" (and ") {
				head = fmt.Sprintf("the change was rejected (%d problems):", len(ps))
				break
			}
		}
		fmt.Fprintln(os.Stderr, "error:", head)
		printProblems(os.Stderr, ps)
		printCheck(os.Stderr, ce.Check())
		if r := client.ParseResult(ce.Info.Result); r != nil && r.Diff != "" && flagDryRun {
			fmt.Fprint(os.Stderr, r.Diff)
		}
		return
	}
	fmt.Fprintln(os.Stderr, "error:", err)
}

// exitCode maps errors to exit codes for scripts: 1 other errors, 3 not
// authenticated or not allowed, 4 not found, 5 conflict, 6 invalid
// request or rejected by validation, 7 server error.
func exitCode(err error) int {
	var ce *client.Error
	if errors.As(err, &ce) {
		switch {
		case ce.Status == 401 || ce.Status == 403:
			return 3
		case ce.Status == 404:
			return 4
		case ce.Status == 409:
			return 5
		case ce.Status == 400 || ce.Status == 422:
			return 6
		case ce.Status >= 500:
			return 7
		}
	}
	return 1
}

// report prints the outcome of a change.
func report(resp *api.MutationResponse) error {
	if flagOutput == "json" || flagOutput == "yaml" {
		return output(resp, nil)
	}
	w := os.Stdout
	r := client.ParseResult(resp.Result)
	switch {
	case resp.Staged:
		if !flagQuiet {
			for _, op := range resp.Added {
				fmt.Fprintf(w, "staged #%d: %s\n", op.Seq, op.Summary)
			}
			fmt.Fprintf(w, "(changeset %d: review with 'jarl changeset diff %d', apply with 'jarl changeset apply %d')\n", resp.ChangesetID, resp.ChangesetID, resp.ChangesetID)
		}
	case resp.DryRun && r != nil:
		for _, op := range r.Ops {
			fmt.Fprintf(w, "would %s\n", op.Summary)
		}
		if len(r.Problems) > 0 {
			fmt.Fprintln(w, "problems:")
			printProblems(w, r.Problems)
		}
		if r.Diff != "" {
			fmt.Fprint(w, r.Diff)
		} else {
			fmt.Fprintln(w, "(no file changes)")
		}
		fmt.Fprintln(w, "dry run: nothing was changed")
	case resp.Applied && r != nil:
		if flagQuiet {
			break
		}
		for _, op := range r.Ops {
			fmt.Fprintf(w, "%s\n", op.Summary)
		}
		for _, s := range r.Serials {
			v := ""
			if s.View != "" {
				v = " [" + s.View + "]"
			}
			fmt.Fprintf(w, "zone %s%s serial %d -> %d\n", dot(s.Zone), v, s.Old, s.New)
		}
		fmt.Fprintf(w, "applied (changeset %d)\n", r.ChangesetID)
	}
	// Warnings the change introduced (errors would have blocked it).
	var introduced []client.Problem
	switch {
	case resp.Applied && r != nil:
		introduced = r.Problems
	case resp.Staged && len(resp.Problems) > 0:
		json.Unmarshal(resp.Problems, &introduced)
	}
	printProblems(os.Stderr, introduced)
	for _, warn := range resp.Warnings {
		fmt.Fprintln(os.Stderr, "warning:", warn)
	}
	if r != nil && !resp.Applied && !resp.Staged && !resp.DryRun {
		return fmt.Errorf("not applied")
	}
	return nil
}

func q(kv ...string) url.Values {
	v := url.Values{}
	for i := 0; i+1 < len(kv); i += 2 {
		if kv[i+1] != "" {
			v.Set(kv[i], kv[i+1])
		}
	}
	return v
}

// zonePath returns the API path for a zone given by name or ID.
func zonePath(zone, view string) (string, url.Values) {
	z := strings.TrimSuffix(zone, ".")
	if zone == "." {
		z = "root"
	}
	return "/zones/" + url.PathEscape(z), q("view", view)
}

func confirm(prompt string, yes bool) bool {
	if yes || flagDryRun || flagChangeset > 0 {
		return true
	}
	fmt.Fprintf(os.Stderr, "%s [y/N] ", prompt)
	var answer string
	fmt.Scanln(&answer)
	return strings.EqualFold(answer, "y") || strings.EqualFold(answer, "yes")
}