package lua

import (
	"fmt"
	"sort"
	"strings"

	golua "github.com/aarzilli/golua/lua"
)

// Package lua — 插件额外出站主机的声明与批准
//
// 内核的职责里有一条是"维护源"。源的 host 天然进出站白名单。但有些插件需要去
// **源以外**的 host（比如一个账号平台的门户、领取额度的接口），这些 host 默认
// 被白名单拒绝 —— 这是正确的默认：白名单的意义就是"插件只能去它该去的地方"。
//
// 所以给出一个**通用**机制（不含任何"登录"概念——登录是插件自己的事）：
//
//	插件在源码里声明 plugin.hosts = { "portal.example.com", ... }   ← 请求
//	运维在设置页逐个批准                                              ← 授权
//
// 声明是请求，批准才是授权。为什么不给个"允许任意 host"的开关：一个能访问任意
// host 的插件等于没有白名单。要求逐个列出，运维才有机会看出"这个插件为什么要
// 访问一个我没听说过的域名"。
//
// 内核在这里**只做白名单加减**，不认识这些 host 是用来登录、领额度还是别的 ——
// 那是插件的业务。

// PluginExtraHosts returns the extra outbound hosts a plugin declared.
func (ps *Plugins) PluginExtraHosts(plugin string) []string {
	ps.mu.RLock()
	defer ps.mu.RUnlock()
	for _, p := range ps.plugins {
		if p.Info.Name == plugin {
			return append([]string(nil), p.ExtraHosts...)
		}
	}
	return nil
}

// GrantExtraHosts approves a set of outbound hosts for a plugin.
//
// Only hosts the plugin DECLARED may be granted: accepting an arbitrary host from
// the settings page would make the declaration decorative, and the point of the
// declaration is that the operator reviews a list the plugin itself committed to
// in source that is on disk and reviewable.
func (ps *Plugins) GrantExtraHosts(plugin string, hosts []string) error {
	if ps.find(plugin) == nil {
		return fmt.Errorf("plugin %s not found", plugin)
	}
	declared := map[string]bool{}
	for _, h := range ps.PluginExtraHosts(plugin) {
		declared[normalizeHost(h)] = true
	}
	clean := make([]string, 0, len(hosts))
	for _, h := range hosts {
		hn := normalizeHost(h)
		if hn == "" {
			continue
		}
		if !declared[hn] {
			return fmt.Errorf("plugin %s did not declare outbound host %q", plugin, hn)
		}
		clean = append(clean, hn)
	}
	sort.Strings(clean)
	ps.mu.Lock()
	if ps.extraHosts == nil {
		ps.extraHosts = map[string][]string{}
	}
	if len(clean) == 0 {
		delete(ps.extraHosts, plugin)
	} else {
		ps.extraHosts[plugin] = clean
	}
	ps.rebuildOutboundAllowlistLocked()
	ps.saveKernelPermissionsLocked()
	ps.mu.Unlock()
	return nil
}

// ExtraHostsGranted returns the approved hosts for each plugin (for the UI).
func (ps *Plugins) ExtraHostsGranted() map[string][]string {
	ps.mu.RLock()
	defer ps.mu.RUnlock()
	out := make(map[string][]string, len(ps.extraHosts))
	for k, v := range ps.extraHosts {
		out[k] = append([]string(nil), v...)
	}
	return out
}

// normalizeHost lowercases a host and strips a port, so "Portal.Example.com:443"
// and "portal.example.com" cannot both be granted under different names.
func normalizeHost(h string) string {
	h = strings.ToLower(strings.TrimSpace(h))
	if i := strings.LastIndex(h, ":"); i > 0 && !strings.Contains(h[i:], "]") {
		// Leave IPv6 literals ("[::1]:443") alone apart from the port.
		h = h[:i]
	}
	h = strings.Trim(h, "[]")
	return h
}

// rebuildOutboundAllowlistLocked folds the SOURCE hosts and every GRANTED extra
// host into the allowlist the HTTP bridge consults. Caller holds ps.mu.
//
// Declared-but-not-granted hosts are deliberately excluded: that exclusion is the
// whole security property, so it is the one thing this function must not be
// tempted to "helpfully" relax.
func (ps *Plugins) rebuildOutboundAllowlistLocked() {
	hosts := append([]string(nil), ps.sourceHosts...)
	for _, granted := range ps.extraHosts {
		hosts = append(hosts, granted...)
	}
	ps.allowHTTP = newHTTPAllowlist(hosts)
}

// readPluginExtraHosts reads `plugin.hosts`, the outbound hosts a plugin needs
// beyond the operator-configured sources.
//
//	plugin.hosts = { "portal.example.com", "api.partner.example" }
//
// Bare hostnames, not URLs: the allowlist matches on host, and accepting a full
// URL would invite a plugin to smuggle a path or scheme the operator did not
// read. Entries are normalised so declared and granted forms compare equal.
func readPluginExtraHosts(L *golua.State) []string {
	raw, ok := pluginFieldValue(L, "hosts")
	if !ok {
		return nil
	}
	items, isList := raw.([]interface{})
	if !isList {
		return nil
	}
	out := make([]string, 0, len(items))
	seen := map[string]bool{}
	for _, it := range items {
		s, ok := it.(string)
		if !ok {
			continue
		}
		h := normalizeHost(s)
		if h == "" || seen[h] {
			continue
		}
		seen[h] = true
		out = append(out, h)
	}
	sort.Strings(out)
	return out
}