package networkifs

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"os/exec"
	"strings"

	"git.netcell-it.de/projekte/edgeguard-native/internal/configgen"
)

// ConfPath is read by edgeguard-apply-interfaces.
const ConfPath = "/etc/edgeguard/interfaces.conf"

type Generator struct {
	Repo *Repo
}

func NewGenerator(repo *Repo) *Generator { return &Generator{Repo: repo} }

// Render writes /etc/edgeguard/interfaces.conf (format: type|name|parent|vlan_id|mtu|members)
// for VLAN/bridge/bond interfaces and triggers edgeguard-interfaces.service.
// Ethernet and WireGuard interfaces are managed by the OS / wg-quick and are excluded.
func (g *Generator) Render(ctx context.Context) error {
	rows, err := g.Repo.Pool.Query(ctx, `
		SELECT type, name,
		       COALESCE(parent, ''),
		       COALESCE(vlan_id::text, ''),
		       COALESCE(mtu::text, ''),
		       members
		FROM network_interfaces
		WHERE active = true
		  AND type IN ('vlan', 'bridge', 'bond')
		  AND (type = 'vlan' OR jsonb_array_length(members) > 0)
		ORDER BY type, name`,
	)
	if err != nil {
		return fmt.Errorf("query: %w", err)
	}
	defer rows.Close()

	type ifRow struct {
		typ     string
		name    string
		parent  string
		vlanID  string
		mtu     string
		members []string
	}

	var entries []ifRow
	for rows.Next() {
		var r ifRow
		var membersRaw []byte
		if err := rows.Scan(&r.typ, &r.name, &r.parent, &r.vlanID, &r.mtu, &membersRaw); err != nil {
			return fmt.Errorf("scan: %w", err)
		}
		if len(membersRaw) > 0 {
			_ = json.Unmarshal(membersRaw, &r.members)
		}
		entries = append(entries, r)
	}
	if err := rows.Err(); err != nil {
		return err
	}

	var buf bytes.Buffer
	buf.WriteString("# Generated by edgeguard-api — DO NOT EDIT.\n")
	buf.WriteString("# Read by edgeguard-apply-interfaces. Format: type|name|parent|vlan_id|mtu|members\n")
	for _, e := range entries {
		fmt.Fprintf(&buf, "%s|%s|%s|%s|%s|%s\n",
			sanitizeIf(e.typ), sanitizeIf(e.name), sanitizeIf(e.parent),
			sanitizeIf(e.vlanID), sanitizeIf(e.mtu),
			sanitizeIf(strings.Join(e.members, ",")))
	}

	if err := configgen.AtomicWrite(ConfPath, buf.Bytes(), 0o644); err != nil {
		return fmt.Errorf("write %s: %w", ConfPath, err)
	}
	if err := applyInterfaces(); err != nil {
		return fmt.Errorf("apply: %w", err)
	}
	return nil
}

func applyInterfaces() error {
	cmd := exec.Command("sudo", "-n", "/usr/bin/systemctl",
		"restart", "edgeguard-interfaces.service")
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("systemctl restart edgeguard-interfaces.service: %s: %w",
			strings.TrimSpace(string(out)), err)
	}
	return nil
}

func sanitizeIf(s string) string {
	s = strings.ReplaceAll(s, "|", "")
	s = strings.ReplaceAll(s, "\n", "")
	return strings.TrimSpace(s)
}