package main

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

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/plugin"
)

// ServeHTTP handles HTTP requests to the plugin.
func (p *Plugin) ServeHTTP(c *plugin.Context, w http.ResponseWriter, r *http.Request) {
	path := r.URL.Path

	// Auth middleware: two auth paths.
	// 1. Shared secret (Bearer token) — used by the daemon for write operations.
	// 2. Mattermost session (Mattermost-User-Id header) — used by browser requests.
	//    The Mattermost server automatically injects this header for authenticated
	//    requests routed through the plugin HTTP handler.
	//
	// Read-only endpoints (GET /sessions, GET /health) accept either auth method.
	// Write endpoints (POST, PUT, DELETE) require the shared secret.
	isReadOnly := r.Method == http.MethodGet && (path == "/api/v1/sessions" || path == "/api/v1/health")

	config := p.getConfiguration()
	hasSharedSecret := false
	if config.SharedSecret != "" {
		auth := r.Header.Get("Authorization")
		expected := "Bearer " + config.SharedSecret
		hasSharedSecret = (auth == expected)
	}

	// Check Mattermost session auth (browser requests).
	// The MM server injects Mattermost-User-Id for authenticated users.
	mmUserID := r.Header.Get("Mattermost-User-Id")
	hasMattermostSession := mmUserID != ""

	if isReadOnly {
		// Read-only: accept either shared secret OR Mattermost session
		if !hasSharedSecret && !hasMattermostSession {
			http.Error(w, `{"error": "unauthorized: valid Mattermost session or shared secret required"}`, http.StatusUnauthorized)
			return
		}
	} else {
		// Write operations: require shared secret (daemon auth)
		if !hasSharedSecret {
			http.Error(w, `{"error": "unauthorized"}`, http.StatusUnauthorized)
			return
		}
	}

	switch {
	case path == "/api/v1/health" && r.Method == http.MethodGet:
		p.handleHealth(w, r)
	case path == "/api/v1/sessions" && r.Method == http.MethodGet:
		p.handleListSessions(w, r)
	case path == "/api/v1/sessions" && r.Method == http.MethodPost:
		p.handleCreateSession(w, r)
	case strings.HasPrefix(path, "/api/v1/sessions/") && r.Method == http.MethodPut:
		sessionKey := strings.TrimPrefix(path, "/api/v1/sessions/")
		p.handleUpdateSession(w, r, sessionKey)
	case strings.HasPrefix(path, "/api/v1/sessions/") && r.Method == http.MethodDelete:
		sessionKey := strings.TrimPrefix(path, "/api/v1/sessions/")
		p.handleDeleteSession(w, r, sessionKey)
	default:
		http.NotFound(w, r)
	}
}

// handleHealth returns plugin health status.
func (p *Plugin) handleHealth(w http.ResponseWriter, r *http.Request) {
	sessions, err := p.store.ListAllSessions()
	count := 0
	if err == nil {
		for _, s := range sessions {
			if s.Status == "active" {
				count++
			}
		}
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"status":          "healthy",
		"active_sessions": count,
		"plugin_id":       "com.openclaw.livestatus",
	})
}

// handleListSessions returns all sessions (active and non-active).
func (p *Plugin) handleListSessions(w http.ResponseWriter, r *http.Request) {
	sessions, err := p.store.ListAllSessions()
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	writeJSON(w, http.StatusOK, sessions)
}

// CreateSessionRequest is the request body for creating a new session.
type CreateSessionRequest struct {
	SessionKey string `json:"session_key"`
	ChannelID  string `json:"channel_id"`
	RootID     string `json:"root_id,omitempty"`
	AgentID    string `json:"agent_id"`
	BotUserID  string `json:"bot_user_id,omitempty"`
}

// handleCreateSession creates a new custom_livestatus post and starts tracking.
func (p *Plugin) handleCreateSession(w http.ResponseWriter, r *http.Request) {
	var req CreateSessionRequest
	if err := readJSON(r, &req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}

	if req.SessionKey == "" || req.ChannelID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "session_key and channel_id required"})
		return
	}

	// Validate KV key length — Mattermost enforces a 50-char limit.
	// Encoded key = kvPrefix (11 chars) + url.PathEscape(sessionKey).
	// Exceeding the limit causes KVSet to silently succeed but never store data.
	if len(encodeKey(req.SessionKey)) > 50 {
		writeJSON(w, http.StatusBadRequest, map[string]string{
			"error": fmt.Sprintf("session_key too long: encoded key length %d exceeds 50-char KV limit", len(encodeKey(req.SessionKey))),
		})
		return
	}

	// Check max active sessions
	config := p.getConfiguration()
	allSessions, _ := p.store.ListAllSessions()
	activeCount := 0
	for _, s := range allSessions {
		if s.Status == "active" {
			activeCount++
		}
	}
	if activeCount >= config.MaxActiveSessions {
		writeJSON(w, http.StatusTooManyRequests, map[string]string{"error": "max active sessions reached"})
		return
	}

	// Create the custom post — UserId is required
	// Use the bot user ID passed in the request, or fall back to plugin bot
	userID := req.BotUserID
	if userID == "" {
		// Try to get plugin's own bot
		userID = p.getBotUserID()
	}
	if userID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "bot_user_id required (no plugin bot available)"})
		return
	}

	post := &model.Post{
		UserId:    userID,
		ChannelId: req.ChannelID,
		RootId:    req.RootID,
		Type:      "custom_livestatus",
		Message:   "Agent session active",
	}
	post.AddProp("session_key", req.SessionKey)
	post.AddProp("agent_id", req.AgentID)
	post.AddProp("status", "active")

	createdPost, appErr := p.API.CreatePost(post)
	if appErr != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": appErr.Error()})
		return
	}
	if createdPost == nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "CreatePost returned nil without error"})
		return
	}

	// Store session data
	now := time.Now().UnixMilli()
	sessionData := SessionData{
		SessionKey:   req.SessionKey,
		PostID:       createdPost.Id,
		ChannelID:    req.ChannelID,
		RootID:       req.RootID,
		AgentID:      req.AgentID,
		Status:       "active",
		Lines:        []string{},
		StartTimeMs:  now,
		LastUpdateMs: now,
	}
	if err := p.store.SaveSession(req.SessionKey, sessionData); err != nil {
		p.API.LogWarn("Failed to save session", "error", err.Error())
	}

	// Broadcast initial state
	p.broadcastUpdate(req.ChannelID, sessionData)

	writeJSON(w, http.StatusCreated, map[string]string{
		"post_id":     createdPost.Id,
		"session_key": req.SessionKey,
	})
}

// UpdateSessionRequest is the request body for updating a session.
type UpdateSessionRequest struct {
	Status      string        `json:"status"`
	Lines       []string      `json:"lines"`
	ElapsedMs   int64         `json:"elapsed_ms"`
	TokenCount  int           `json:"token_count"`
	Children    []SessionData `json:"children,omitempty"`
	StartTimeMs int64         `json:"start_time_ms"`
}

// handleUpdateSession updates session data and broadcasts via WebSocket.
// Critically: does NOT call any Mattermost post API — no "(edited)" label.
func (p *Plugin) handleUpdateSession(w http.ResponseWriter, r *http.Request, sessionKey string) {
	var req UpdateSessionRequest
	if err := readJSON(r, &req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}

	// Get existing session
	existing, err := p.store.GetSession(sessionKey)
	if err != nil || existing == nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "session not found"})
		return
	}

	// Update fields
	existing.Status = req.Status
	existing.Lines = req.Lines
	existing.ElapsedMs = req.ElapsedMs
	existing.TokenCount = req.TokenCount
	existing.Children = req.Children
	existing.LastUpdateMs = time.Now().UnixMilli()
	if req.StartTimeMs > 0 {
		existing.StartTimeMs = req.StartTimeMs
	}

	// Save to KV store
	if err := p.store.SaveSession(sessionKey, *existing); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}

	// Broadcast update via WebSocket (for webapp — instant, no API call)
	p.broadcastUpdate(existing.ChannelID, *existing)

	// Mobile fallback: update the post message field with formatted markdown.
	// Mobile app doesn't render custom post types, so it shows the message field.
	// The webapp plugin overrides rendering entirely, so "(edited)" is invisible on web.
	go p.updatePostMessageForMobile(*existing)

	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// handleDeleteSession marks a session as complete.
func (p *Plugin) handleDeleteSession(w http.ResponseWriter, r *http.Request, sessionKey string) {
	existing, err := p.store.GetSession(sessionKey)
	if err != nil || existing == nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "session not found"})
		return
	}

	// Mark as done
	existing.Status = "done"

	// Update the post props to reflect completion (one final API call)
	post, appErr := p.API.GetPost(existing.PostID)
	if appErr == nil && post != nil {
		post.AddProp("status", "done")
		post.AddProp("final_lines", existing.Lines)
		post.AddProp("elapsed_ms", existing.ElapsedMs)
		post.AddProp("token_count", existing.TokenCount)
		_, _ = p.API.UpdatePost(post)
	}

	// Broadcast final state
	p.broadcastUpdate(existing.ChannelID, *existing)

	// Clean up KV store
	_ = p.store.DeleteSession(sessionKey)

	writeJSON(w, http.StatusOK, map[string]string{"status": "done"})
}

// updatePostMessageForMobile updates the post's Message field with formatted markdown.
// This provides a mobile fallback — mobile apps don't render custom post type components
// but DO display the Message field. On webapp, the plugin's React component overrides
// rendering entirely, so the "(edited)" indicator is invisible.
func (p *Plugin) updatePostMessageForMobile(data SessionData) {
	post, appErr := p.API.GetPost(data.PostID)
	if appErr != nil || post == nil {
		return
	}

	newMessage := formatStatusMarkdown(data)
	if post.Message == newMessage {
		return // Skip API call if content hasn't changed
	}

	post.Message = newMessage
	_, updateErr := p.API.UpdatePost(post)
	if updateErr != nil {
		p.API.LogDebug("Failed to update post message for mobile", "postId", data.PostID, "error", updateErr.Error())
	}
}

// formatStatusMarkdown generates a markdown blockquote status view for mobile clients.
func formatStatusMarkdown(data SessionData) string {
	// Status icon
	var statusIcon string
	switch data.Status {
	case "active":
		statusIcon = "[ACTIVE]"
	case "done":
		statusIcon = "[DONE]"
	case "error":
		statusIcon = "[ERROR]"
	case "interrupted":
		statusIcon = "[INTERRUPTED]"
	default:
		statusIcon = "[UNKNOWN]"
	}

	// Elapsed time
	elapsed := formatElapsedMs(data.ElapsedMs)

	// Build lines
	result := fmt.Sprintf("> **%s** `%s` | %s\n", statusIcon, data.AgentID, elapsed)

	// Show last N status lines (keep it compact for mobile)
	maxLines := 15
	lines := data.Lines
	if len(lines) > maxLines {
		lines = lines[len(lines)-maxLines:]
	}
	for _, line := range lines {
		if len(line) > 120 {
			line = line[:117] + "..."
		}
		result += "> " + line + "\n"
	}

	// Token count for completed sessions
	if data.Status != "active" && data.TokenCount > 0 {
		result += fmt.Sprintf("> **[%s]** %s | %s tokens\n", strings.ToUpper(data.Status), elapsed, formatTokenCount(data.TokenCount))
	}

	return result
}

// formatElapsedMs formats milliseconds as human-readable duration.
func formatElapsedMs(ms int64) string {
	if ms < 0 {
		ms = 0
	}
	s := ms / 1000
	m := s / 60
	h := m / 60
	if h > 0 {
		return fmt.Sprintf("%dh%dm", h, m%60)
	}
	if m > 0 {
		return fmt.Sprintf("%dm%ds", m, s%60)
	}
	return fmt.Sprintf("%ds", s)
}

// formatTokenCount formats a token count compactly.
func formatTokenCount(count int) string {
	if count >= 1000000 {
		return fmt.Sprintf("%.1fM", float64(count)/1000000)
	}
	if count >= 1000 {
		return fmt.Sprintf("%.1fk", float64(count)/1000)
	}
	return fmt.Sprintf("%d", count)
}

// Helper functions

func readJSON(r *http.Request, v interface{}) error {
	body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20)) // 1MB limit
	if err != nil {
		return fmt.Errorf("read body: %w", err)
	}
	defer r.Body.Close()
	return json.Unmarshal(body, v)
}

func writeJSON(w http.ResponseWriter, status int, v interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}