package adapter

import (
	"encoding/base64"
	"net/url"
	"strconv"
	"strings"

	"github.com/perfect-panel/server/pkg/simnet"
)

// buildOmnxtSimnetConfigs is a subscription template function (registered in
// Client.Build) that produces the per-user OmnXT SimNet JSON config array.
//
// It mirrors the Pro reference (NPanel-backend
// internal/biz/public/subscription/template.go buildOmnxtSimnetConfigs):
//   - per-user simnet_psk / simnet_key_id are DERIVED from the user's
//     subscription (uuid + user_subscribe.id), never stored.
//   - the server PSK (key_id=0) is passed through as simnet_server_psk so the
//     client SDK can derive AF path/magic with the same key material.
//
// Template usage: {{ buildOmnxtSimnetConfigs .Proxies .UserInfo .Params | toPrettyJson }}
func buildOmnxtSimnetConfigs(proxies []map[string]interface{}, userInfo User, params map[string]string) []map[string]interface{} {
	result := make([]map[string]interface{}, 0)

	proxyMode := strings.TrimSpace(params["proxy_mode"])
	if proxyMode == "" {
		proxyMode = "global"
	}

	dnsServers := []string{"1.1.1.1"}
	if raw := strings.TrimSpace(params["dns_servers"]); raw != "" {
		parts := strings.FieldsFunc(raw, func(r rune) bool {
			return r == ',' || r == '\n' || r == '\r'
		})
		parsed := make([]string, 0, len(parts))
		for _, item := range parts {
			if item = strings.TrimSpace(item); item != "" {
				parsed = append(parsed, item)
			}
		}
		if len(parsed) > 0 {
			dnsServers = parsed
		}
	}

	// Per-user credentials derived from the subscription record (see pkg/simnet).
	userKeyID := simnet.DeriveKeyID(userInfo.SubscribeID)
	userPSK := simnet.DeriveUserPSK(userInfo.Password)

	for _, proxy := range proxies {
		if smString(proxy["Type"]) != "simnet" {
			continue
		}

		afEnabled := smBool(proxy["SimnetAfEnabled"])
		item := map[string]interface{}{
			"tag":            smString(proxy["Name"]),
			"server_addr":    smString(proxy["Server"]),
			"server_port":    smInt(proxy["Port"]),
			"protocol":       "simnet",
			"sni":            smString(proxy["SNI"]),
			"allow_insecure": smBool(proxy["AllowInsecure"]),
			"simnet_psk":     userPSK,
			"simnet_key_id":  userKeyID,
			// Server PSK is required for AF path/magic/content-type derivation.
			"simnet_server_psk":                       smStringOrNil(proxy["SimnetPsk"]),
			"simnet_server_key_id":                    smInt(proxy["SimnetKeyID"]),
			"simnet_ticket_id":                        smStringOrNil(proxy["SimnetTicketID"]),
			"simnet_path":                             smDefaultString(smString(proxy["SimnetPath"]), "/simnet/session"),
			"simnet_carrier":                          smDefaultString(smString(proxy["SimnetCarrier"]), "h2"),
			"simnet_af_enabled":                       afEnabled,
			"simnet_client_max_concurrent_streams":    smDefaultInt(smInt(proxy["SimnetClientMaxConcurrentStreams"]), 32),
			"simnet_client_max_streams_per_session":   smDefaultInt(smInt(proxy["SimnetClientMaxStreamsPerSession"]), 512),
			"simnet_client_session_idle_timeout_secs": smDefaultInt(smInt(proxy["SimnetClientSessionIdleTimeoutSecs"]), 90),
			"simnet_client_max_udp_sessions":          smDefaultInt(smInt(proxy["SimnetClientMaxUDPSessions"]), 64),
			"proxy_mode":                              proxyMode,
			"dns_servers":                             dnsServers,
		}
		if afEnabled {
			item["simnet_af_path_mode"] = smDefaultString(smString(proxy["SimnetAfPathMode"]), "api")
			item["simnet_af_path_prefix"] = smStringOrNil(proxy["SimnetAfPathPrefix"])
			item["simnet_af_path_suffix"] = smStringOrNil(proxy["SimnetAfPathSuffix"])
			item["simnet_af_magic_mode"] = smDefaultString(smString(proxy["SimnetAfMagicMode"]), "derived")
			item["simnet_af_response_jitter_ms"] = smDefaultInt(smInt(proxy["SimnetAfResponseJitterMs"]), 50)
			item["simnet_af_handshake_polymorphism"] = smBool(proxy["SimnetAfHandshakePolymorphism"])
			item["simnet_af_settings_jitter"] = smBool(proxy["SimnetAfSettingsJitter"])
			item["simnet_af_fake_header_injection"] = smBool(proxy["SimnetAfFakeHeaderInjection"])
		}
		result = append(result, item)
	}

	return result
}

func smString(v interface{}) string {
	if s, ok := v.(string); ok {
		return s
	}
	return ""
}

func smStringOrNil(v interface{}) interface{} {
	if s, ok := v.(string); ok && s != "" {
		return s
	}
	return nil
}

func smBool(v interface{}) bool {
	b, ok := v.(bool)
	return ok && b
}

func smInt(v interface{}) int {
	switch n := v.(type) {
	case int:
		return n
	case int8:
		return int(n)
	case int16:
		return int(n)
	case int32:
		return int(n)
	case int64:
		return int(n)
	case uint:
		return int(n)
	case uint8:
		return int(n)
	case uint16:
		return int(n)
	case uint32:
		return int(n)
	case uint64:
		return int(n)
	case float32:
		return int(n)
	case float64:
		return int(n)
	default:
		return 0
	}
}

func smDefaultString(s, def string) string {
	if strings.TrimSpace(s) == "" {
		return def
	}
	return s
}

func smDefaultInt(i, def int) int {
	if i == 0 {
		return def
	}
	return i
}

// buildOmnxtProtocolLinks wraps each simnet config into a base64 "simnet://"
// link, matching the Pro reference's final delivery format (migration 02140,
// template.go buildOmnxtProtocolLinks). Template usage:
//
//	{{- range $link := buildOmnxtProtocolLinks .Proxies .UserInfo .Params }}{{ $link }}
//	{{- end }}
func buildOmnxtProtocolLinks(proxies []map[string]interface{}, userInfo User, params map[string]string) []string {
	configs := buildOmnxtSimnetConfigs(proxies, userInfo, params)
	result := make([]string, 0, len(configs))

	for _, item := range configs {
		serverAddr := smString(item["server_addr"])
		serverPort := smInt(item["server_port"])
		tag := smString(item["tag"])
		if serverAddr == "" || serverPort == 0 {
			continue
		}

		afEnabled := smBool(item["simnet_af_enabled"])
		payload := map[string]interface{}{
			"protocol":                              "simnet",
			"server_addr":                           serverAddr,
			"server_port":                           serverPort,
			"sni":                                   smString(item["sni"]),
			"simnet_psk":                            smString(item["simnet_psk"]),
			"simnet_key_id":                         smInt(item["simnet_key_id"]),
			"simnet_server_psk":                     item["simnet_server_psk"],
			"simnet_server_key_id":                  smInt(item["simnet_server_key_id"]),
			"simnet_ticket_id":                      item["simnet_ticket_id"],
			"simnet_path":                           item["simnet_path"],
			"simnet_carrier":                        smString(item["simnet_carrier"]),
			"simnet_af_enabled":                     afEnabled,
			"simnet_client_max_concurrent_streams":  smInt(item["simnet_client_max_concurrent_streams"]),
			"simnet_client_max_streams_per_session": smInt(item["simnet_client_max_streams_per_session"]),
			"simnet_client_session_idle_timeout_secs": smInt(item["simnet_client_session_idle_timeout_secs"]),
			"simnet_client_max_udp_sessions":          smInt(item["simnet_client_max_udp_sessions"]),
			"proxy_mode":                              item["proxy_mode"],
			"dns_servers":                             item["dns_servers"],
		}
		if afEnabled {
			payload["simnet_af_path_mode"] = smString(item["simnet_af_path_mode"])
			payload["simnet_af_path_prefix"] = item["simnet_af_path_prefix"]
			payload["simnet_af_path_suffix"] = item["simnet_af_path_suffix"]
			payload["simnet_af_magic_mode"] = smString(item["simnet_af_magic_mode"])
			payload["simnet_af_response_jitter_ms"] = smInt(item["simnet_af_response_jitter_ms"])
			payload["simnet_af_handshake_polymorphism"] = smBool(item["simnet_af_handshake_polymorphism"])
			payload["simnet_af_settings_jitter"] = smBool(item["simnet_af_settings_jitter"])
			payload["simnet_af_fake_header_injection"] = smBool(item["simnet_af_fake_header_injection"])
		}

		encoded := encodeProtocolPayload(payload)
		if encoded == "" {
			continue
		}
		result = append(result, "simnet://"+encoded+"#"+url.QueryEscape(tag))
	}

	return result
}

// encodeProtocolPayload url-encodes a payload map and base64-encodes it,
// matching the reference encodeProtocolPayload.
func encodeProtocolPayload(payload map[string]interface{}) string {
	values := url.Values{}
	for key, value := range payload {
		switch v := value.(type) {
		case nil:
			continue
		case string:
			if strings.TrimSpace(v) != "" {
				values.Set(key, v)
			}
		case bool:
			if v {
				values.Set(key, "1")
			}
		case int:
			if v != 0 {
				values.Set(key, strconv.Itoa(v))
			}
		case int32:
			if v != 0 {
				values.Set(key, strconv.FormatInt(int64(v), 10))
			}
		case int64:
			if v != 0 {
				values.Set(key, strconv.FormatInt(v, 10))
			}
		case []string:
			if len(v) > 0 {
				values.Set(key, strings.Join(v, ","))
			}
		case []interface{}:
			items := make([]string, 0, len(v))
			for _, item := range v {
				if s := smString(item); s != "" {
					items = append(items, s)
				}
			}
			if len(items) > 0 {
				values.Set(key, strings.Join(items, ","))
			}
		default:
			if s := smString(v); s != "" {
				values.Set(key, s)
			}
		}
	}

	if len(values) == 0 {
		return ""
	}
	return base64.StdEncoding.EncodeToString([]byte(values.Encode()))
}