package gateway

import (
	"encoding/json"
	"net/http"
	"strings"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/auth"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/session"
	apperr "git.yeij.top/AskaEth/Cyrene_v2/internal/errors"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
)

// tokenTTL is how long an issued JWT remains valid.
const tokenTTL = 24 * time.Hour

// PersonaSummary is the wire shape of a persona in REST/admin list responses.
type PersonaSummary struct {
	ID        string `json:"id"`
	Name      string `json:"name"`
	Character string `json:"character"`
	IsDefault bool   `json:"isDefault"`
	Mode      string `json:"mode"`
	MemoryNS  string `json:"memoryNamespace"`
}

// MemorySummary is the wire shape of a memory entry in the admin list response.
type MemorySummary struct {
	ID    string `json:"id"`
	Scope string `json:"scope"`
	Text  string `json:"text"`
}

// SessionSummary is the wire shape of a channel session in list responses.
type SessionSummary struct {
	Platform  string `json:"platform"`
	ChannelID string `json:"channelId"`
	SessionID string `json:"sessionId"`
	ActorRole string `json:"actorRole"`
	Owner     bool   `json:"owner"`
	IsGroup   bool   `json:"isGroup"`
	MemWrite  bool   `json:"memWritable"`
}

// loginRequest is the POST /api/v1/auth/login body.
type loginRequest struct {
	Username string `json:"username"`
	Password string `json:"password"`
}

// loginResponse is the login success payload.
type loginResponse struct {
	Token     string `json:"token"`
	ExpiresAt int64  `json:"expiresAt"`
	Role      string `json:"role"`
}

// chatRequest is the POST /api/v1/chat body. When Stream is true the gateway
// triggers streaming over the WebSocket channel and returns immediately.
type chatRequest struct {
	SessionID string `json:"sessionId"`
	Text      string `json:"text"`
	Stream    bool   `json:"stream"`
}

// chatResponse is the synchronous chat reply payload.
type chatResponse struct {
	Reply      string `json:"reply"`
	Steps      int    `json:"steps"`
	StopReason string `json:"stopReason"`
}

// handleHealth reports liveness. It is unauthenticated because it is a probe.
func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]any{"status": "ok"})
}

// handleLogin exchanges the admin username/password for a signed JWT.
func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
	var req loginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "invalid request body"))
		return
	}
	cfg := s.cfg.Auth
	if req.Username != cfg.AdminUser || req.Password != cfg.AdminPass {
		writeError(w, apperr.Wrap(apperr.ErrUnauthorized, "unauthorized", "invalid username or password"))
		return
	}
	token, err := s.auth.Sign(req.Username, auth.RoleOwner, tokenTTL)
	if err != nil {
		s.log.Error("login sign", "err", err)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "login_failed", "could not sign token"))
		return
	}
	writeJSON(w, http.StatusOK, loginResponse{
		Token:     token,
		ExpiresAt: time.Now().Add(tokenTTL).Unix(),
		Role:      string(auth.RoleOwner),
	})
}

// handleChat runs one synchronous agent turn (or triggers streaming).
func (s *Server) handleChat(w http.ResponseWriter, r *http.Request) {
	var req chatRequest
	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.Text) == "" {
		writeError(w, apperr.Wrap(apperr.ErrBadRequest, "bad_request", "text is required"))
		return
	}
	if req.Stream {
		s.publishChatStream(r.Context(), req.SessionID, req.Text)
		writeJSON(w, http.StatusOK, map[string]any{"stream": true})
		return
	}
	if s.runner == nil {
		writeError(w, apperr.Wrap(apperr.ErrInternal, "chat_unavailable", "chat service is not configured"))
		return
	}
	if req.SessionID == "" {
		req.SessionID = "web"
	}
	res, err := s.runner.Run(r.Context(), req.SessionID, []model.Message{model.TextMessage(model.RoleUser, req.Text)})
	if err != nil {
		s.log.Error("chat run", "err", err, "session", req.SessionID)
		writeError(w, apperr.Wrap(apperr.ErrInternal, "chat_failed", "chat failed"))
		return
	}
	writeJSON(w, http.StatusOK, chatResponse{Reply: res.Text, Steps: res.Steps, StopReason: res.StopReason})
}

// handleListSessions returns the known sessions (or [] when no store is wired).
func (s *Server) handleListSessions(w http.ResponseWriter, r *http.Request) {
	out := make([]SessionSummary, 0)
	if s.sessions != nil {
		list, err := s.sessions.List(r.Context())
		if err != nil {
			s.log.Error("list sessions", "err", err)
			writeError(w, apperr.Wrap(apperr.ErrInternal, "sessions_failed", "failed to list sessions"))
			return
		}
		for _, sess := range list {
			out = append(out, summaryOfSession(sess))
		}
	}
	writeJSON(w, http.StatusOK, out)
}

// handleListPersonas returns the personas (or [] when no store is wired).
func (s *Server) handleListPersonas(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, s.collectPersonas())
}

// collectPersonas returns a non-nil persona slice from the configured store.
func (s *Server) collectPersonas() []PersonaSummary {
	out := make([]PersonaSummary, 0)
	if s.personas != nil {
		out = append(out, s.personas.List()...)
	}
	return out
}

// summaryOfSession maps a session.Session to its wire shape.
func summaryOfSession(sess session.Session) SessionSummary {
	return SessionSummary{
		Platform:  sess.Platform,
		ChannelID: sess.ChannelID,
		SessionID: sess.SessionID,
		ActorRole: string(sess.ActorRole),
		Owner:     sess.Owner,
		IsGroup:   sess.IsGroup,
		MemWrite:  sess.MemWritable,
	}
}

// writeJSON encodes v as the {data: v} envelope with the given status.
func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(map[string]any{"data": v})
}

// writeError encodes err as the {error:{code,message}} envelope with the status
// resolved by apperr.HTTPStatus.
func writeError(w http.ResponseWriter, err error) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(apperr.HTTPStatus(err))
	_ = json.NewEncoder(w).Encode(apperr.ToJSON(err))
}