package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"gopkg.in/yaml.v3"
)

// Config structures
type Config struct {
	Server     ServerConfig             `yaml:"server"`
	DataDir    string                   `yaml:"data_dir"`
	Accounts   map[string]AccountConfig `yaml:"accounts"`
	Connectors ConnectorsConfig         `yaml:"connectors"`
	Webhook    WebhookConfig            `yaml:"webhook"`
}

type ServerConfig struct {
	Host string `yaml:"host"`
	Port int    `yaml:"port"`
}

type AccountConfig struct {
	Host     string   `yaml:"host"`
	Port     int      `yaml:"port"`
	Username string   `yaml:"username"`
	Password string   `yaml:"password"`
	TLS      string   `yaml:"tls"`
	Watch    []string `yaml:"watch"`
	SMTP     struct {
		Host     string `yaml:"host"`
		Port     int    `yaml:"port"`
		Username string `yaml:"username"`
		Password string `yaml:"password"`
		From     string `yaml:"from"`
	} `yaml:"smtp"`
}

type ConnectorsConfig struct {
	WhatsApp struct {
		Enabled bool   `yaml:"enabled"`
		Name    string `yaml:"name"`
		BaseURL string `yaml:"base_url"`
	} `yaml:"whatsapp"`
}

type WebhookConfig struct {
	Enabled bool   `yaml:"enabled"`
	URL     string `yaml:"url"`
	Token   string `yaml:"token"`
}

// Global state
var (
	config Config
	store  *MessageStore
	orch   *OrchestrationDB
)

func main() {
	configPath := flag.String("config", "config.yaml", "Path to config file")
	flag.Parse()

	// Load config
	data, err := os.ReadFile(*configPath)
	if err != nil {
		log.Fatalf("Failed to read config: %v", err)
	}

	// Expand env vars in config
	expanded := os.ExpandEnv(string(data))
	if err := yaml.Unmarshal([]byte(expanded), &config); err != nil {
		log.Fatalf("Failed to parse config: %v", err)
	}

	// Default data directory
	if config.DataDir == "" {
		home, _ := os.UserHomeDir()
		config.DataDir = filepath.Join(home, ".message-center")
	} else if strings.HasPrefix(config.DataDir, "~/") {
		home, _ := os.UserHomeDir()
		config.DataDir = filepath.Join(home, config.DataDir[2:])
	}
	os.MkdirAll(config.DataDir, 0755)

	log.Printf("Message Center starting...")
	log.Printf("Data directory: %s", config.DataDir)

	// Initialize store
	store = NewMessageStore(config.DataDir)

	// Initialize orchestration DB
	orchPath := filepath.Join(config.DataDir, "orchestration.db")
	orch, err = NewOrchestrationDB(orchPath)
	if err != nil {
		log.Fatalf("Failed to open orchestration DB: %v", err)
	}
	defer orch.Close()

	// Register email connectors
	for name, acc := range config.Accounts {
		smtpConfig := SMTPConfig{
			Host:     acc.SMTP.Host,
			Port:     acc.SMTP.Port,
			Username: acc.SMTP.Username,
			Password: acc.SMTP.Password,
			From:     acc.SMTP.From,
		}
		// Default SMTP to same credentials if not specified
		if smtpConfig.Host == "" {
			smtpConfig.Host = acc.Host
			smtpConfig.Port = 1025 // Default Proton Bridge SMTP
			smtpConfig.Username = acc.Username
			smtpConfig.Password = acc.Password
			smtpConfig.From = acc.Username
		}

		connector := NewEmailConnector(name, acc, smtpConfig)
		store.RegisterConnector(connector)
		log.Printf("Registered email connector: %s", name)
	}

	// Register WhatsApp connector
	if config.Connectors.WhatsApp.Enabled {
		name := config.Connectors.WhatsApp.Name
		if name == "" {
			name = "whatsapp"
		}
		baseURL := config.Connectors.WhatsApp.BaseURL
		if baseURL == "" {
			baseURL = "http://localhost:8030"
		}

		connector := NewWhatsAppConnector(name, baseURL)
		store.RegisterConnector(connector)
		log.Printf("Registered WhatsApp connector: %s -> %s", name, baseURL)
	}

	// Start all connectors with webhook callback
	webhookCallback := func() {
		if config.Webhook.Enabled {
			sendWebhook()
		}
	}
	if err := store.StartAll(webhookCallback); err != nil {
		log.Fatalf("Failed to start connectors: %v", err)
	}

	// HTTP server
	mux := http.NewServeMux()

	// Health check
	mux.HandleFunc("/health", handleHealth)

	// Unified message endpoints
	mux.HandleFunc("/messages", handleMessages)
	mux.HandleFunc("/messages/", handleMessageRoutes)

	// Legacy account-based endpoints (for backwards compatibility)
	mux.HandleFunc("/accounts", handleListAccounts)
	mux.HandleFunc("/accounts/", handleAccountRoutes)

	addr := fmt.Sprintf("%s:%d", config.Server.Host, config.Server.Port)
	server := &http.Server{Addr: addr, Handler: logMiddleware(mux)}

	// Graceful shutdown
	go func() {
		sigCh := make(chan os.Signal, 1)
		signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
		<-sigCh
		log.Println("Shutting down...")
		store.StopAll()
		server.Shutdown(nil)
	}()

	log.Printf("Server listening on %s", addr)
	if err := server.ListenAndServe(); err != http.ErrServerClosed {
		log.Fatalf("Server error: %v", err)
	}
}

func logMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		next.ServeHTTP(w, r)
		log.Printf("%s %s %v", r.Method, r.URL.Path, time.Since(start).Round(time.Millisecond))
	})
}

func sendWebhook() {
	if !config.Webhook.Enabled || config.Webhook.URL == "" {
		return
	}

	// Simple webhook: just notify that there are new messages
	payload := map[string]string{"event": "new"}
	data, _ := json.Marshal(payload)

	req, err := http.NewRequest("POST", config.Webhook.URL, bytes.NewReader(data))
	if err != nil {
		log.Printf("Webhook request error: %v", err)
		return
	}

	req.Header.Set("Content-Type", "application/json")
	if config.Webhook.Token != "" {
		req.Header.Set("Authorization", "Bearer "+config.Webhook.Token)
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Printf("Webhook send error: %v", err)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(resp.Body)
		log.Printf("Webhook error %d: %s", resp.StatusCode, string(body))
	} else {
		log.Printf("Webhook sent: new")
	}
}

// HTTP handlers

func handleHealth(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("ok"))
}

// GET /messages?since=24h - list messages
// GET /messages/new - unseen messages
// POST /messages/ack - acknowledge messages (advance cursor)
func handleMessages(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	// Handle /messages/new and /messages/ack via the path
	if strings.HasSuffix(r.URL.Path, "/new") {
		handleMessagesNew(w, r)
		return
	}
	if strings.HasSuffix(r.URL.Path, "/ack") {
		handleMessagesAck(w, r)
		return
	}

	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Parse since parameter
	sinceStr := r.URL.Query().Get("since")
	if sinceStr == "" {
		sinceStr = "24h" // Default to last 24 hours
	}

	duration, err := ParseDuration(sinceStr)
	if err != nil {
		http.Error(w, fmt.Sprintf("Invalid since parameter: %v", err), http.StatusBadRequest)
		return
	}

	messages, err := store.FetchSince(duration)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	json.NewEncoder(w).Encode(messages)
}

func handleMessagesNew(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	messages, err := store.FetchNew()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Filter by orchestration state and record new messages
	var filtered []UnifiedMessage
	for _, msg := range messages {
		// Record that we've seen this message
		source, sourceID, _ := parseMessageID(msg.ID)
		orch.RecordSeen(msg.ID, source, sourceID, "INBOX")

		// Only include if no action has been taken
		if !orch.HasAction(msg.ID) {
			filtered = append(filtered, msg)
		}
	}

	json.NewEncoder(w).Encode(filtered)
}

func handleMessagesAck(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Consumer  string    `json:"consumer"`
		Timestamp time.Time `json:"timestamp"`
		IDs       []string  `json:"ids"` // Optional: specific message IDs to ack
	}

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if req.Consumer == "" {
		http.Error(w, "consumer is required", http.StatusBadRequest)
		return
	}

	if req.Timestamp.IsZero() {
		req.Timestamp = time.Now()
	}

	// Ack cursor-based
	if err := store.Ack(req.Consumer, req.Timestamp); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Also record per-message acks in orchestration DB
	for _, id := range req.IDs {
		orch.RecordAck(id, req.Consumer)
	}

	json.NewEncoder(w).Encode(map[string]interface{}{
		"status":    "ok",
		"consumer":  req.Consumer,
		"timestamp": req.Timestamp,
		"acked":     len(req.IDs),
	})
}

// Handle /messages/{id} and /messages/{id}/action
func handleMessageRoutes(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	// Parse path: /messages/{id}[/action]
	path := strings.TrimPrefix(r.URL.Path, "/messages/")
	if path == "" || path == "new" || path == "ack" {
		handleMessages(w, r)
		return
	}

	parts := strings.SplitN(path, "/", 2)
	messageID := parts[0]

	// Reconstruct full message ID if it doesn't contain ':'
	// This handles URL-encoded colons
	messageID = strings.ReplaceAll(messageID, "%3A", ":")

	if len(parts) == 1 {
		// GET /messages/{id}
		handleGetMessage(w, r, messageID)
		return
	}

	action := parts[1]
	switch action {
	case "archive":
		handleArchive(w, r, messageID)
	case "delete":
		handleDelete(w, r, messageID)
	case "reply":
		handleReply(w, r, messageID)
	case "to-docs":
		handleToDocs(w, r, messageID)
	case "attachments":
		handleAttachments(w, r, messageID)
	default:
		http.Error(w, "Unknown action", http.StatusNotFound)
	}
}

func handleGetMessage(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	msg, err := store.FetchOne(id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	}

	json.NewEncoder(w).Encode(msg)
}

func handleArchive(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	if err := store.Archive(id); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Record action in orchestration DB
	orch.RecordAction(id, "archive")

	json.NewEncoder(w).Encode(map[string]string{"status": "archived"})
}

func handleDelete(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	if err := store.Delete(id); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Record action in orchestration DB
	orch.RecordAction(id, "delete")

	json.NewEncoder(w).Encode(map[string]string{"status": "deleted"})
}

func handleReply(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Body        string   `json:"body"`
		Attachments []string `json:"attachments"`
	}

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if req.Body == "" {
		http.Error(w, "body is required", http.StatusBadRequest)
		return
	}

	if err := store.Reply(id, req.Body, req.Attachments); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Record action in orchestration DB
	orch.RecordAction(id, "reply")

	json.NewEncoder(w).Encode(map[string]string{"status": "sent"})
}

func handleToDocs(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req struct {
		Attachments []string `json:"attachments"` // Optional: specific attachments, empty = all
	}

	json.NewDecoder(r.Body).Decode(&req) // Ignore error, req is optional

	// Get the message
	msg, err := store.FetchOne(id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	}

	if len(msg.Attachments) == 0 {
		http.Error(w, "Message has no attachments", http.StatusBadRequest)
		return
	}

	// Create inbox directory
	home, _ := os.UserHomeDir()
	inboxDir := filepath.Join(home, "documents", "inbox")
	os.MkdirAll(inboxDir, 0755)

	// Download and save each attachment
	var saved []string
	var errors []string

	wantedSet := make(map[string]bool)
	for _, name := range req.Attachments {
		wantedSet[name] = true
	}

	for _, att := range msg.Attachments {
		// Skip if not in requested list (when list is specified)
		if len(req.Attachments) > 0 && !wantedSet[att.Name] {
			continue
		}

		content, err := store.GetAttachment(id, att.Name)
		if err != nil {
			errors = append(errors, fmt.Sprintf("%s: %v", att.Name, err))
			continue
		}

		destPath := filepath.Join(inboxDir, att.Name)
		if err := os.WriteFile(destPath, content, 0644); err != nil {
			errors = append(errors, fmt.Sprintf("%s: %v", att.Name, err))
			continue
		}

		saved = append(saved, destPath)
	}

	result := map[string]interface{}{
		"saved":  saved,
		"errors": errors,
	}

	if len(errors) > 0 && len(saved) == 0 {
		w.WriteHeader(http.StatusInternalServerError)
	} else if len(saved) > 0 {
		// Record action in orchestration DB (only if we saved something)
		orch.RecordAction(id, "to-docs")
	}

	json.NewEncoder(w).Encode(result)
}

func handleAttachments(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Check for specific attachment name in query
	filename := r.URL.Query().Get("name")
	if filename != "" {
		content, err := store.GetAttachment(id, filename)
		if err != nil {
			http.Error(w, err.Error(), http.StatusNotFound)
			return
		}

		// Return raw content
		w.Header().Set("Content-Type", "application/octet-stream")
		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", filename))
		w.Write(content)
		return
	}

	// Return attachment list
	msg, err := store.FetchOne(id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	}

	json.NewEncoder(w).Encode(msg.Attachments)
}

// Legacy endpoints for backwards compatibility

func handleListAccounts(w http.ResponseWriter, r *http.Request) {
	accounts := make([]string, 0, len(config.Accounts))
	for name := range config.Accounts {
		accounts = append(accounts, name)
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(accounts)
}

func handleAccountRoutes(w http.ResponseWriter, r *http.Request) {
	// Parse path: /accounts/{account}/...
	parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
	if len(parts) < 2 {
		http.Error(w, "Invalid path", http.StatusBadRequest)
		return
	}

	accountName := parts[1]
	acc, ok := config.Accounts[accountName]
	if !ok {
		http.Error(w, "Account not found", http.StatusNotFound)
		return
	}

	if len(parts) == 2 {
		// /accounts/{account} - account info
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]interface{}{
			"name":  accountName,
			"host":  acc.Host,
			"watch": acc.Watch,
		})
		return
	}

	switch parts[2] {
	case "mailboxes":
		handleLegacyMailboxes(w, r, accountName)
	case "messages":
		handleLegacyMessages(w, r, accountName, parts[3:])
	default:
		http.Error(w, "Not found", http.StatusNotFound)
	}
}

func handleLegacyMailboxes(w http.ResponseWriter, r *http.Request, accountName string) {
	// Get connector
	c, ok := store.GetConnector(accountName)
	if !ok {
		http.Error(w, "Account not found", http.StatusNotFound)
		return
	}

	// Only email connectors support mailboxes
	emailConn, ok := c.(*EmailConnector)
	if !ok {
		http.Error(w, "Not an email account", http.StatusBadRequest)
		return
	}

	client, err := emailConn.connect()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer client.Close()

	mailboxes, err := client.List("", "*", nil).Collect()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	result := make([]map[string]interface{}, 0, len(mailboxes))
	for _, mbox := range mailboxes {
		result = append(result, map[string]interface{}{
			"name":      mbox.Mailbox,
			"delimiter": string(mbox.Delim),
		})
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(result)
}

func handleLegacyMessages(w http.ResponseWriter, r *http.Request, accountName string, pathParts []string) {
	// Redirect to unified API
	if len(pathParts) == 0 {
		// List messages from this account only
		c, ok := store.GetConnector(accountName)
		if !ok {
			http.Error(w, "Account not found", http.StatusNotFound)
			return
		}

		since := time.Now().Add(-24 * time.Hour)
		if s := r.URL.Query().Get("since"); s != "" {
			if d, err := ParseDuration(s); err == nil {
				since = time.Now().Add(-d)
			}
		}

		msgs, err := c.FetchSince(since)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(msgs)
		return
	}

	// Single message - redirect to unified endpoint
	uid := pathParts[0]
	fullID := fmt.Sprintf("%s:%s", accountName, uid)
	handleMessageRoutes(w, r)
	_ = fullID // Silence unused variable warning
}