// SPDX-License-Identifier: MIT

package cli

import (
	"context"
	"fmt"
	"io"

	"github.com/spf13/cobra"

	"prx/internal/config"
	"prx/internal/proto"
	"prx/internal/state"
)

func (a *app) newBypassCmd() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "bypass",
		Short: "Manage destinations that must bypass the proxy",
	}
	cmd.AddCommand(a.newBypassAddCmd(), a.newBypassRmCmd(), a.newBypassLsCmd())
	return cmd
}

func (a *app) newBypassAddCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "add <cidr|ip|domain>",
		Short: "Add a CIDR/IP (routed direct) or domain (engine hint) to the bypass list",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := a.loadConfig()
			if err != nil {
				return err
			}
			arg := args[0]
			var changed bool
			if config.IsCIDR(arg) {
				changed, err = cfg.AddExtraCIDR(arg)
			} else {
				changed, err = cfg.AddDomain(arg)
			}
			if err != nil {
				return err
			}
			if !changed {
				fmt.Fprintln(a.out, "already present")
				return nil
			}
			if err := config.Save(a.configPath, cfg); err != nil {
				return err
			}
			fmt.Fprintf(a.out, "added %s to bypass list\n", arg)
			return a.reapplyIfEnabled(cmd.Context(), cfg)
		},
	}
}

func (a *app) newBypassRmCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "rm <cidr|ip|domain>",
		Short: "Remove an entry from the bypass list",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := a.loadConfig()
			if err != nil {
				return err
			}
			arg := args[0]
			var changed bool
			if config.IsCIDR(arg) {
				changed, err = cfg.RemoveExtraCIDR(arg)
			} else {
				changed = cfg.RemoveDomain(arg)
			}
			if err != nil {
				return err
			}
			if !changed {
				fmt.Fprintln(a.out, "not present")
				return nil
			}
			if err := config.Save(a.configPath, cfg); err != nil {
				return err
			}
			fmt.Fprintf(a.out, "removed %s from bypass list\n", arg)
			return a.reapplyIfEnabled(cmd.Context(), cfg)
		},
	}
}

func (a *app) newBypassLsCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "ls",
		Short: "List bypass entries",
		Args:  cobra.NoArgs,
		RunE: func(_ *cobra.Command, _ []string) error {
			cfg, err := a.loadConfig()
			if err != nil {
				return err
			}
			writeList(a.out, "always (engine hints):", cfg.Bypass.AlwaysCIDRs, false)
			writeList(a.out, "extra CIDRs (routed direct):", cfg.Bypass.ExtraCIDRs, true)
			writeList(a.out, "domains (engine hints):", cfg.Bypass.Domains, true)
			return nil
		},
	}
}

// writeList prints a labelled list, showing "(none)" when empty and showEmpty.
func writeList(w io.Writer, label string, items []string, showEmpty bool) {
	fmt.Fprintln(w, label)
	if len(items) == 0 && showEmpty {
		fmt.Fprintln(w, "  (none)")
	}
	for _, item := range items {
		fmt.Fprintln(w, "  "+item)
	}
}

// reapplyIfEnabled refreshes the routing rules when prx is currently enabled so
// bypass changes take effect immediately.
func (a *app) reapplyIfEnabled(ctx context.Context, cfg *config.Config) error {
	st, err := state.Load(cfg.State.Path)
	if err != nil {
		return err
	}
	if !st.Enabled {
		fmt.Fprintln(a.out, "takes effect on the next 'prx on'")
		return nil
	}
	if err := a.dispatch(ctx, cfg, proto.ActionApply, nil); err != nil {
		return err
	}
	fmt.Fprintln(a.out, "routing rules refreshed")
	return nil
}