package api

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"time"

	"github.com/enmanuel/agents/shell/process"
)

// --- Response types ---

// AgentResponse is the JSON representation of an agent.
type AgentResponse struct {
	ID         string `json:"id"`
	Name       string `json:"name"`
	Version    string `json:"version"`
	Desc       string `json:"desc"`
	Enabled    bool   `json:"enabled"`
	Running    bool   `json:"running"`
	PID        int    `json:"pid,omitempty"`
	Instances  int    `json:"instances"`
	ConfigPath string `json:"config_path"`
}

// AgentDetailResponse extends AgentResponse with logs.
type AgentDetailResponse struct {
	AgentResponse
	Logs []string `json:"logs"`
}

func agentResponse(s process.AgentStatus) AgentResponse {
	return AgentResponse{
		ID:         s.ID,
		Name:       s.Name,
		Version:    s.Version,
		Desc:       s.Desc,
		Enabled:    s.Enabled,
		Running:    s.Running,
		PID:        s.PID,
		Instances:  s.Instances,
		ConfigPath: s.ConfigPath,
	}
}

// --- Health ---

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok", "time": time.Now().UTC().Format(time.RFC3339)})
}

// statusAllAuto chooses unified vs multi-process status based on runtime mode.
// In unified mode all agents run as goroutines under one launcher process — per-agent
// PID files do not exist, so StatusAll reports Running=false. StatusAllUnified
// reflects the real state.
func (s *Server) statusAllAuto() ([]process.AgentStatus, error) {
	if s.mgr.IsUnifiedRunning() {
		return s.mgr.StatusAllUnified()
	}
	return s.mgr.StatusAll()
}

// --- List agents ---

func (s *Server) handleListAgents(w http.ResponseWriter, r *http.Request) {
	statuses, err := s.statusAllAuto()
	if err != nil {
		writeError(w, http.StatusInternalServerError, fmt.Sprintf("scan: %v", err))
		return
	}
	resp := make([]AgentResponse, 0, len(statuses))
	for _, st := range statuses {
		resp = append(resp, agentResponse(st))
	}
	writeJSON(w, http.StatusOK, resp)
}

// --- Get single agent ---

func (s *Server) handleGetAgent(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	statuses, err := s.statusAllAuto()
	if err != nil {
		writeError(w, http.StatusInternalServerError, fmt.Sprintf("scan: %v", err))
		return
	}

	var found *process.AgentStatus
	for i, st := range statuses {
		if st.ID == id {
			found = &statuses[i]
			break
		}
	}
	if found == nil {
		writeError(w, http.StatusNotFound, "agent not found")
		return
	}

	n := 200
	if qn := r.URL.Query().Get("n"); qn != "" {
		if parsed, err := strconv.Atoi(qn); err == nil && parsed > 0 {
			n = parsed
		}
	}

	logs, _ := s.mgr.LogTail(id, n)
	writeJSON(w, http.StatusOK, AgentDetailResponse{
		AgentResponse: agentResponse(*found),
		Logs:          logs,
	})
}

// --- Start agent ---

func (s *Server) handleStartAgent(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	agents, err := s.mgr.Scan()
	if err != nil {
		writeError(w, http.StatusInternalServerError, fmt.Sprintf("scan: %v", err))
		return
	}

	var info *process.AgentInfo
	for i, a := range agents {
		if a.ID == id {
			info = &agents[i]
			break
		}
	}
	if info == nil {
		writeError(w, http.StatusNotFound, "agent not found")
		return
	}

	if err := s.mgr.Start(*info); err != nil {
		writeError(w, http.StatusConflict, fmt.Sprintf("start: %v", err))
		return
	}
	s.logger.Info("agent started via api", "id", id)
	writeJSON(w, http.StatusOK, map[string]string{"status": "started", "id": id})
}

// --- Stop agent ---

func (s *Server) handleStopAgent(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if err := s.mgr.Stop(id); err != nil {
		writeError(w, http.StatusConflict, fmt.Sprintf("stop: %v", err))
		return
	}
	s.logger.Info("agent stopped via api", "id", id)
	writeJSON(w, http.StatusOK, map[string]string{"status": "stopped", "id": id})
}

// --- Restart agent ---

func (s *Server) handleRestartAgent(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")

	// Stop first (ignore not-running error)
	_ = s.mgr.Stop(id)

	// Wait up to 3s for process to die
	deadline := time.Now().Add(3 * time.Second)
	for time.Now().Before(deadline) {
		if !s.mgr.IsRunning(id) {
			break
		}
		time.Sleep(200 * time.Millisecond)
	}

	// Find agent info for Start
	agents, err := s.mgr.Scan()
	if err != nil {
		writeError(w, http.StatusInternalServerError, fmt.Sprintf("scan: %v", err))
		return
	}

	var info *process.AgentInfo
	for i, a := range agents {
		if a.ID == id {
			info = &agents[i]
			break
		}
	}
	if info == nil {
		writeError(w, http.StatusNotFound, "agent not found")
		return
	}

	if err := s.mgr.Start(*info); err != nil {
		writeError(w, http.StatusConflict, fmt.Sprintf("restart/start: %v", err))
		return
	}
	s.logger.Info("agent restarted via api", "id", id)
	writeJSON(w, http.StatusOK, map[string]string{"status": "restarted", "id": id})
}

// --- Agent logs snapshot ---

func (s *Server) handleAgentLogs(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	n := 200
	if qn := r.URL.Query().Get("n"); qn != "" {
		if parsed, err := strconv.Atoi(qn); err == nil && parsed > 0 {
			n = parsed
		}
	}

	logs, err := s.mgr.LogTail(id, n)
	if err != nil {
		writeError(w, http.StatusNotFound, fmt.Sprintf("logs: %v", err))
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"id": id, "lines": logs, "count": len(logs)})
}

// --- SSE: status broadcast ---

func (s *Server) handleSSEStatus(w http.ResponseWriter, r *http.Request) {
	flusher, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "streaming unsupported", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")
	w.WriteHeader(http.StatusOK)
	flusher.Flush()

	sub := s.bus.Subscribe("status")
	defer s.bus.Unsubscribe("status", sub)

	ctx := r.Context()
	for {
		select {
		case <-ctx.Done():
			return
		case ev, ok := <-sub:
			if !ok {
				return
			}
			data, _ := json.Marshal(ev)
			fmt.Fprintf(w, "event: status\ndata: %s\n\n", data)
			flusher.Flush()
		}
	}
}

// --- SSE: agent log tail ---

func (s *Server) handleSSEAgentLogs(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")

	logPath := s.mgr.LogPath(id)
	if logPath == "" {
		http.Error(w, "agent not found", http.StatusNotFound)
		return
	}

	flusher, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "streaming unsupported", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")
	w.WriteHeader(http.StatusOK)
	flusher.Flush()

	ctx := r.Context()
	tailLogFile(ctx, logPath, w, flusher)
}