package gateway

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	capreg "git.yeij.top/AskaEth/Cyrene_v2/internal/capability/registry"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/session"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/config/runtimeconfig"
	apperr "git.yeij.top/AskaEth/Cyrene_v2/internal/errors"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/user"
	"git.yeij.top/AskaEth/Cyrene_v2/pkg/plugins/sdk"
	"git.yeij.top/AskaEth/Cyrene_v2/plugins/channels/weixin_ilink"
)

// LLM-provider and channel-lifecycle admin writes (owner-only, audited). The LLM
// test performs a real model call; provider "add" records a process-lifetime
// entry. Channel open/close drive the real adapter lifecycle; the identity test
// is the structural actor × whitelist rule, never prompt text.

const (
	// ownerProfilePath is the owner whitelist loaded for the structural identity
	// test. It mirrors the path wire.go uses for owner recognition.
	ownerProfilePath = "configs/users/owner.yaml"
	// llmTestTimeout bounds a single LLM probe request.
	llmTestTimeout = 30 * time.Second
	// llmProbePrompt is the minimal prompt used to verify a model responds.
	llmProbePrompt = "Reply with the single word: OK"
)

// llmProviderRequest is the POST /api/v1/admin/llm body for adding/updating a
// provider group. Every field is a pointer so the handler can tell "absent"
// (preserve the stored value) from "explicitly zero" (overwrite): a partial edit
// from the panel must never wipe a field it did not touch. Name is a client-side
// display label (not persisted — the models.json schema carries id/provider/
// baseUrl/apiKey/model/fallback/multimodal/maxTokens).
type llmProviderRequest struct {
	ID         *string `json:"id"`
	Name       *string `json:"name"`
	Provider   *string `json:"provider"`
	BaseURL    *string `json:"baseUrl"`
	APIKey     *string `json:"apiKey"`
	Model      *string `json:"model"`
	Multimodal *bool   `json:"multimodal"`
	Fallback   *string `json:"fallback"`
	// MaxTokens is the group's own token budget. Absent preserves the stored
	// budget (0 = unset for a new group). Negative is rejected.
	MaxTokens *int `json:"maxTokens"`
}

// adminAddLlmProvider saves a provider group to models.json (read-modify-write,
// promoting it to the active group) and hot-reloads the running LLM stack so the
// new provider/model takes effect without a restart (design/04 §3.1). A field the
// client omits keeps its stored value, so a partial edit never resets a budget or
// key. The API key is persisted to the gitignored file but never returned/logged.
func (s *Server) adminAddLlmProvider(w http.ResponseWriter, r *http.Request) {
	var req llmProviderRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
		return
	}
	if req.MaxTokens != nil && *req.MaxTokens < 0 {
		s.auditClaims(r, "llm.addProvider", "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "maxTokens must be >= 0"))
		return
	}
	if s.llm == nil {
		s.auditClaims(r, "llm.addProvider", "error")
		writeError(w, apperr.Wrap(apperr.ErrInternal, "llm_unavailable", "LLM 配置服务未注入"))
		return
	}
	group, err := mergeLlmProvider(s.llm.Groups(), req)
	if err != nil {
		s.auditClaims(r, "llm.addProvider", "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "%v", err))
		return
	}
	// Promote the saved group to the active (index 0) slot, then persist and
	// hot-reload so Current() reflects the new provider/model immediately.
	groups := runtimeconfig.Activate(s.llm.Groups(), group)
	if err := runtimeconfig.SaveModels(s.llm.Path(), groups); err != nil {
		s.auditClaims(r, "llm.addProvider", "error")
		s.log.Error("llm save models", "path", s.llm.Path(), "error", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "llm_persist_failed", "failed to save models.json"))
		return
	}
	if err := s.llm.Reload(); err != nil {
		s.auditClaims(r, "llm.addProvider", "error")
		s.log.Error("llm reload", "error", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "llm_reload_failed", "saved but failed to hot-reload"))
		return
	}
	saved := AdminLlmProvider{
		ID:         group.ID,
		Name:       providerDisplayName(group),
		Provider:   group.Provider,
		BaseURL:    group.BaseURL,
		Model:      group.Model,
		Multimodal: group.Multimodal,
		Enabled:    group.ID == s.llm.Group().ID,
		Fallback:   group.Fallback,
		MaxTokens:  group.MaxTokens,
	}
	s.auditClaims(r, "llm.addProvider", "ok")
	writeJSON(w, http.StatusCreated, map[string]any{
		"provider":  saved,
		"persisted": true,
		"path":      s.llm.Path(),
	})
}

// mergeLlmProvider applies a partial provider patch over the stored groups: a
// field present in the request wins, an absent field keeps the stored value (or
// its default for a new group). It returns a validated group.
func mergeLlmProvider(groups []runtimeconfig.Group, req llmProviderRequest) (runtimeconfig.Group, error) {
	id := ""
	if req.ID != nil {
		id = strings.TrimSpace(*req.ID)
	}
	g, found := runtimeconfig.Find(groups, id)
	if !found {
		g = runtimeconfig.Group{}
	}
	g.ID = id
	if g.ID == "" {
		g.ID = runtimeconfig.NewID()
	}
	if req.Provider != nil {
		g.Provider = strings.TrimSpace(*req.Provider)
	}
	if g.Provider == "" {
		g.Provider = model.ProviderOpenAI
	}
	if g.Provider != model.ProviderOpenAI && g.Provider != model.ProviderAnthropic {
		return runtimeconfig.Group{}, fmt.Errorf("provider must be openai or anthropic")
	}
	if req.BaseURL != nil {
		g.BaseURL = strings.TrimSpace(*req.BaseURL)
	}
	if req.APIKey != nil {
		g.APIKey = *req.APIKey
	}
	if req.Model != nil {
		g.Model = strings.TrimSpace(*req.Model)
	}
	if req.Fallback != nil {
		g.Fallback = strings.TrimSpace(*req.Fallback)
	}
	if req.Multimodal != nil {
		g.Multimodal = *req.Multimodal
	}
	if req.MaxTokens != nil {
		g.MaxTokens = *req.MaxTokens
	}
	if g.BaseURL == "" || g.Model == "" {
		return runtimeconfig.Group{}, fmt.Errorf("baseUrl and model are required")
	}
	return g, nil
}

// llmTestRequest is the POST /api/v1/admin/llm/test body.
type llmTestRequest struct {
	Provider string `json:"provider"`
	BaseURL  string `json:"baseUrl"`
	APIKey   string `json:"apiKey"`
	Model    string `json:"model"`
	Prompt   string `json:"prompt"`
}

// adminTestLlm performs a real completion against the supplied provider/model
// endpoint and reports the result — a genuine round-trip, not a placeholder.
func (s *Server) adminTestLlm(w http.ResponseWriter, r *http.Request) {
	var req llmTestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
		return
	}
	if strings.TrimSpace(req.Model) == "" || strings.TrimSpace(req.BaseURL) == "" {
		s.auditClaims(r, "llm.test", "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "model and baseUrl are required"))
		return
	}
	provider := req.Provider
	if provider == "" {
		provider = model.ProviderOpenAI
	}
	adapter, err := model.NewChatAdapter(config.LLMConfig{Provider: provider, BaseURL: req.BaseURL, APIKey: req.APIKey, Model: req.Model})
	if err != nil {
		s.auditClaims(r, "llm.test", "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid provider"))
		return
	}
	prompt := strings.TrimSpace(req.Prompt)
	if prompt == "" {
		prompt = llmProbePrompt
	}
	ctx, cancel := context.WithTimeout(r.Context(), llmTestTimeout)
	defer cancel()
	resp, err := adapter.Chat(ctx, model.Request{
		Messages: []model.Message{model.TextMessage(model.RoleUser, prompt)},
	}, model.Options{Timeout: llmTestTimeout})
	if err != nil {
		s.auditClaims(r, "llm.test", "error")
		s.log.Error("llm test", "provider", provider, "model", req.Model, "err", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "llm_test_failed", "model call failed: %s", err.Error()))
		return
	}
	s.auditClaims(r, "llm.test", "ok")
	writeJSON(w, http.StatusOK, map[string]any{"ok": true, "provider": provider, "model": resp.Model, "reply": resp.Content, "tokens": resp.TotalTokens})
}

// channelActionRequest is the POST /api/v1/admin/channels/open|close body.
type channelActionRequest struct {
	Name string `json:"name"`
}

// adminChannelOpen connects a registered channel adapter (real lifecycle call).
func (s *Server) adminChannelOpen(w http.ResponseWriter, r *http.Request) {
	name, ok := s.channelName(r, w, "channel.open")
	if !ok {
		return
	}
	ch, found := findChannel(s.caps, name)
	if !found {
		s.auditClaims(r, "channel.open", "error")
		writeError(w, apperr.Wrap(apperr.ErrNotFound, "not_found", "channel %q not found", name))
		return
	}
	if err := ch.Connect(r.Context()); err != nil {
		s.auditClaims(r, "channel.open", "error")
		// weixin-iLink with no token yet must not hang nor read as a credential
		// error: the panel routes the owner to the out-of-band 扫码登录 flow.
		if errors.Is(err, weixin_ilink.ErrNeedsLogin) {
			writeError(w, apperr.Wrap(apperr.ErrConflict, "needs_login", "该渠道尚未登录：请先用「扫码登录」绑定，再连接"))
			return
		}
		s.log.Error("channel open", "name", name, "err", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "channel_connect_failed", "connect failed (check credentials): %s", err.Error()))
		return
	}
	s.auditClaims(r, "channel.open", "ok")
	writeJSON(w, http.StatusOK, map[string]any{"name": name, "connected": true})
}

// adminChannelClose disconnects a registered channel adapter (real lifecycle call).
func (s *Server) adminChannelClose(w http.ResponseWriter, r *http.Request) {
	name, ok := s.channelName(r, w, "channel.close")
	if !ok {
		return
	}
	ch, found := findChannel(s.caps, name)
	if !found {
		s.auditClaims(r, "channel.close", "error")
		writeError(w, apperr.Wrap(apperr.ErrNotFound, "not_found", "channel %q not found", name))
		return
	}
	if err := ch.Disconnect(r.Context()); err != nil {
		s.auditClaims(r, "channel.close", "error")
		s.log.Error("channel close", "name", name, "err", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "channel_disconnect_failed", "disconnect failed: %s", err.Error()))
		return
	}
	s.auditClaims(r, "channel.close", "ok")
	writeJSON(w, http.StatusOK, map[string]any{"name": name, "connected": false})
}

// channelTestRequest is the POST /api/v1/admin/channels/test body: a channel
// account id plus the conversation shape, resolved by the structural actor rule.
type channelTestRequest struct {
	Platform  string `json:"platform"`
	AccountID string `json:"accountId"`
	IsGroup   bool   `json:"isGroup"`
}

// adminChannelTest runs the structural identity rule (actor metadata × owner
// whitelist), never prompt text. It loads the owner whitelist from disk so a
// mismatch degrades to the conservative default (member/stranger).
func (s *Server) adminChannelTest(w http.ResponseWriter, r *http.Request) {
	var req channelTestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
		return
	}
	if strings.TrimSpace(req.AccountID) == "" {
		s.auditClaims(r, "channel.identity-test", "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "accountId is required"))
		return
	}
	msg := adapter.UnifiedMessage{
		Platform:  req.Platform,
		ChannelID: req.AccountID,
		SenderID:  req.AccountID,
		Sender:    adapter.Actor{UserID: req.AccountID, IsGroup: req.IsGroup},
	}
	if req.IsGroup {
		msg.ChannelType = adapter.ChannelGroup
	} else {
		msg.ChannelType = adapter.ChannelDirect
	}
	owner := loadOwnerProfile()
	actor := session.ResolveActor(msg, owner)
	env := session.EnvFor(actor)
	s.auditClaims(r, "channel.identity-test", "ok")
	writeJSON(w, http.StatusOK, map[string]any{
		"role":    string(actor.Role),
		"owner":   actor.IsOwner(),
		"isGroup": actor.IsGroupChat(),
		"env":     string(env),
		"verdict": describeIdentity(actor, owner),
	})
}

// channelName decodes the {name} body for open/close routes, writing a 400 on
// failure. It reports uniqueness of the decode via ok.
func (s *Server) channelName(r *http.Request, w http.ResponseWriter, op string) (string, bool) {
	var req channelActionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
		return "", false
	}
	if strings.TrimSpace(req.Name) == "" {
		s.auditClaims(r, op, "error")
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "name is required"))
		return "", false
	}
	return req.Name, true
}

// findChannel returns the registered channel adapter named name, if any. An exact
// adapter name ("kook:conf0") wins; a bare platform name ("kook") that is not an
// exact name still resolves to that platform's first registered account, so the
// panel/CLI "connect kook" reaches the token-bearing account even when it is named
// "kook:conf0" (the empty-token bare placeholder is never registered).
func findChannel(caps CapabilityStore, name string) (sdk.Channel, bool) {
	if caps == nil {
		return nil, false
	}
	var first sdk.Channel
	for _, cap := range caps.List(capreg.KindChannel) {
		ch, ok := cap.Value.(sdk.Channel)
		if !ok {
			continue
		}
		if ch.Name() == name {
			return ch, true
		}
		if first == nil && channelBasePlatform(ch.Name()) == name {
			first = ch
		}
	}
	if first != nil {
		return first, true
	}
	return nil, false
}

// loadOwnerProfile loads the owner whitelist from disk, returning nil on any
// failure so the identity test degrades to the conservative deny.
func loadOwnerProfile() *user.OwnerProfile {
	p, err := user.LoadOwnerProfile(ownerProfilePath)
	if err != nil {
		return nil
	}
	return p
}

// describeIdentity renders the structural verdict for the identity test.
func describeIdentity(a adapter.Actor, _ *user.OwnerProfile) string {
	switch {
	case a.IsGroupChat():
		return "群聊上下文 → 隔离；记忆只读不写；仅可调用标记允许的工具"
	case a.IsOwner():
		return "匹配主人白名单 → owner（全量访问，记忆可读写）"
	default:
		return "未命中主人白名单 → 按陌生人处理（default deny，记忆只读不写）"
	}
}