package render

import (
	"strings"

	"github.com/peterqiu0516/sub-store/internal/model"
	"github.com/peterqiu0516/sub-store/internal/util"
	"gopkg.in/yaml.v3"
)

// RenderEgernYaml renders proxies as an Egern YAML document.
func RenderEgernYaml(proxies []model.ProxyNode) (string, error) {
	var list []map[string]any
	for _, p := range proxies {
		if e := ToEgernProxy(p); e != nil {
			list = append(list, e)
		}
	}
	if len(list) == 0 {
		return "", errNoNodes("egern")
	}
	data, err := yaml.Marshal(map[string]any{"proxies": list})
	if err != nil {
		return "", err
	}
	return string(data), nil
}

// ToEgernProxy converts a proxy node to an Egern proxy map.
// Returns nil for unsupported proxy types.
func ToEgernProxy(proxy model.ProxyNode) map[string]any {
	common := util.StripUndefined(map[string]any{
		"name":      proxy["name"],
		"server":    proxy["server"],
		"port":      proxy["port"],
		"tfo":       proxy["tfo"],
		"udp_relay": proxy["udp"],
	})

	ptype := getString(proxy, "type")

	switch ptype {
	case "ss":
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":     "shadowsocks",
			"method":   proxy["cipher"],
			"password": proxy["password"],
		}))

	case "vmess", "vless":
		security := ""
		if ptype == "vmess" {
			security = strOr(proxy, "cipher", "auto")
		}
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":     ptype,
			"uuid":     proxy["uuid"],
			"alter_id": proxy["alterId"],
			"security": security,
			"flow":     proxy["flow"],
			"tls":      proxy["tls"],
			"sni":      proxy["servername"],
			"network":  proxy["network"],
			"ws_opts":  egernWsOptions(proxy),
			"reality":  egernRealityOptions(proxy),
		}))

	case "trojan", "anytls", "hysteria2":
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":            ptype,
			"password":        proxy["password"],
			"sni":             sniOr(proxy, "sni", "servername"),
			"skip_tls_verify": proxy["skip-cert-verify"],
			"obfs":            proxy["obfs"],
			"obfs_password":   proxy["obfs-password"],
			"reality":         egernRealityOptions(proxy),
		}))

	case "http", "socks5":
		egernType := ptype
		if ptype == "http" && getBool(proxy, "tls") {
			egernType = "https"
		} else if ptype == "socks5" && getBool(proxy, "tls") {
			egernType = "socks5_tls"
		}
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":            egernType,
			"username":        proxy["username"],
			"password":        proxy["password"],
			"skip_tls_verify": proxy["skip-cert-verify"],
		}))

	case "tuic":
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":            "tuic",
			"uuid":            proxy["uuid"],
			"password":        proxy["password"],
			"sni":             proxy["sni"],
			"skip_tls_verify": proxy["skip-cert-verify"],
		}))

	case "wireguard":
		return util.StripUndefined(mergeMap(common, map[string]any{
			"type":           "wireguard",
			"private_key":    proxy["private-key"],
			"public_key":     proxy["public-key"],
			"pre_shared_key": proxy["pre-shared-key"],
			"address":        proxy["ip"],
			"ipv6_address":   proxy["ipv6"],
		}))
	}

	return nil
}

func egernWsOptions(proxy model.ProxyNode) any {
	if getString(proxy, "network") != "ws" {
		return nil
	}
	wsOpts, _ := proxy["ws-opts"].(map[string]any)
	path := "/"
	if wsOpts != nil {
		if p, ok := wsOpts["path"].(string); ok && p != "" {
			path = p
		}
	}
	result := map[string]any{"path": path}
	if wsOpts != nil {
		if h, ok := wsOpts["headers"]; ok && h != nil {
			result["headers"] = h
		}
	}
	return result
}

func egernRealityOptions(proxy model.ProxyNode) any {
	realityOpts, _ := proxy["reality-opts"].(map[string]any)
	if realityOpts == nil {
		return nil
	}
	pubKey := realityOpts["public-key"]
	if pubKey == nil {
		return nil
	}
	return util.StripUndefined(map[string]any{
		"public_key": pubKey,
		"short_id":   realityOpts["short-id"],
	})
}

func mergeMap(base, next map[string]any) map[string]any {
	result := make(map[string]any, len(base)+len(next))
	for k, v := range base {
		result[k] = v
	}
	for k, v := range next {
		result[k] = v
	}
	return result
}

func errNoNodes(target string) error {
	return &noNodesError{target: target}
}

type noNodesError struct {
	target string
}

func (e *noNodesError) Error() string {
	var sb strings.Builder
	sb.WriteString("No supported nodes for ")
	sb.WriteString(e.target)
	sb.WriteString(" output")
	return sb.String()
}