package com.rit.whatsapp.controller;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.rit.whatsapp.handler.GrievanceHandler;
import com.rit.whatsapp.handler.LoginHandler;
import com.rit.whatsapp.handler.StudentMenuHandler;
import com.rit.whatsapp.model.UserState;
import com.rit.whatsapp.service.SessionService;
import com.rit.whatsapp.service.WhatsAppMessageService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/webhook")
public class WebhookController {

    @Value("${whatsapp.verify-token:my_secure_verify_token}")
    private String verifyToken;

    private final WhatsAppMessageService messageService;
    private final SessionService sessionService;
    private final StudentMenuHandler studentMenuHandler;
    private final GrievanceHandler grievanceHandler;
    private final LoginHandler loginHandler;
    private final ObjectMapper objectMapper;

    @Autowired
    public WebhookController(WhatsAppMessageService messageService, 
                             SessionService sessionService,
                             StudentMenuHandler studentMenuHandler,
                             GrievanceHandler grievanceHandler,
                             LoginHandler loginHandler) {
        this.messageService = messageService;
        this.sessionService = sessionService;
        this.studentMenuHandler = studentMenuHandler;
        this.grievanceHandler = grievanceHandler;
        this.loginHandler = loginHandler;
        this.objectMapper = new ObjectMapper();
    }

    @GetMapping
    public ResponseEntity<String> verifyWebhook(
            @RequestParam(name = "hub.mode", required = false) String mode,
            @RequestParam(name = "hub.verify_token", required = false) String token,
            @RequestParam(name = "hub.challenge", required = false) String challenge) {

        if ("subscribe".equals(mode) && verifyToken.equals(token)) {
            return ResponseEntity.ok(challenge);
        } else {
            return ResponseEntity.status(HttpStatus.FORBIDDEN).build();
        }
    }

    @PostMapping
    public ResponseEntity<String> receiveMessage(@RequestBody String payload) {
        System.out.println("Received Webhook Payload: " + payload);
        try {
            JsonNode rootNode = objectMapper.readTree(payload);
            
            if (rootNode.has("entry") && rootNode.get("entry").isArray()) {
                JsonNode entryNode = rootNode.get("entry").get(0);
                
                if (entryNode.has("changes") && entryNode.get("changes").isArray()) {
                    JsonNode changesNode = entryNode.get("changes").get(0);
                    JsonNode valueNode = changesNode.get("value");
                    
                    if (valueNode != null && valueNode.has("messages") && valueNode.get("messages").isArray()) {
                        JsonNode messageNode = valueNode.get("messages").get(0);
                        
                        String fromPhoneNumber = messageNode.get("from").asText();
                        String messageType = messageNode.get("type").asText();
                        
                        UserState currentState = sessionService.getUserState(fromPhoneNumber);
                        boolean isAuthenticated = sessionService.isAuthenticated(fromPhoneNumber);

                        // Global reset command
                        if ("text".equals(messageType) && messageNode.get("text").get("body").asText().trim().equalsIgnoreCase("reset")) {
                            sessionService.resetState(fromPhoneNumber);
                            if (isAuthenticated) {
                                studentMenuHandler.sendMainMenu(fromPhoneNumber);
                            } else {
                                loginHandler.startLoginFlow(fromPhoneNumber);
                            }
                            return ResponseEntity.ok("EVENT_RECEIVED");
                        }

                        // Route unauthenticated users strictly to Login Flow
                        if (!isAuthenticated) {
                            if ("text".equals(messageType)) {
                                String body = messageNode.get("text").get("body").asText();
                                handleUnauthenticatedUser(fromPhoneNumber, body, currentState);
                            } else {
                                // If they send a sticker/image/etc before logging in, force login
                                handleUnauthenticatedUser(fromPhoneNumber, "", currentState);
                            }
                            return ResponseEntity.ok("EVENT_RECEIVED");
                        }

                        // Authenticated users flow
                        if ("text".equals(messageType)) {
                            String messageBody = messageNode.get("text").get("body").asText();
                            handleAuthenticatedTextMessage(fromPhoneNumber, messageBody, currentState);
                        } else if ("interactive".equals(messageType)) {
                            JsonNode interactiveNode = messageNode.get("interactive");
                            String interactiveType = interactiveNode.get("type").asText();
                            
                            if ("list_reply".equals(interactiveType)) {
                                String selectedListId = interactiveNode.get("list_reply").get("id").asText();
                                handleInteractiveListSelection(fromPhoneNumber, selectedListId, currentState);
                            } else if ("button_reply".equals(interactiveType)) {
                                String selectedButtonId = interactiveNode.get("button_reply").get("id").asText();
                                handleInteractiveButtonSelection(fromPhoneNumber, selectedButtonId, currentState);
                            }
                        }
                    }
                }
            }
        } catch (Exception e) {
            System.err.println("Error processing webhook payload: " + e.getMessage());
        }
        
        return ResponseEntity.ok("EVENT_RECEIVED");
    }

    private void handleUnauthenticatedUser(String phoneNumber, String messageBody, UserState currentState) {
        switch (currentState) {
            case AWAITING_LOGIN_ID:
                loginHandler.handleLoginIdInput(phoneNumber, messageBody);
                break;
            case AWAITING_LOGIN_PASSCODE:
                loginHandler.handlePasscodeInput(phoneNumber, messageBody);
                break;
            default:
                // Trigger the start of the login flow
                loginHandler.startLoginFlow(phoneNumber);
                break;
        }
    }

    private void handleAuthenticatedTextMessage(String phoneNumber, String messageBody, UserState currentState) {
        switch (currentState) {
            case AWAITING_GRIEVANCE_DESC:
                grievanceHandler.handleGrievanceDescription(phoneNumber, messageBody);
                break;
            case MAIN_MENU:
            default:
                // Fallback to main menu
                studentMenuHandler.sendMainMenu(phoneNumber);
                break;
        }
    }

    private void handleInteractiveListSelection(String phoneNumber, String selectedListId, UserState currentState) {
        if (selectedListId.startsWith("student_")) {
            // They clicked an option from the main menu
            studentMenuHandler.handleMenuSelection(phoneNumber, selectedListId);
        } else if (selectedListId.startsWith("sem_")) {
            // They clicked an option from the semester selection list
            if (currentState == UserState.AWAITING_SEMESTER_SELECTION) {
                studentMenuHandler.handleSemesterSelection(phoneNumber, selectedListId);
            } else {
                messageService.sendMessage(phoneNumber, "This menu selection is no longer active.");
                studentMenuHandler.sendMainMenu(phoneNumber);
            }
        } else if (selectedListId.startsWith("receipt_")) {
            // They clicked a receipt download option
            if (currentState == UserState.AWAITING_RECEIPT_SELECTION) {
                studentMenuHandler.handleReceiptSelection(phoneNumber, selectedListId);
            } else {
                messageService.sendMessage(phoneNumber, "This menu selection is no longer active.");
                studentMenuHandler.sendMainMenu(phoneNumber);
            }
        } else {
            studentMenuHandler.sendMainMenu(phoneNumber);
        }
    }

    private void handleInteractiveButtonSelection(String phoneNumber, String selectedButtonId, UserState currentState) {
        if ("student_logout".equals(selectedButtonId)) {
            sessionService.logoutUser(phoneNumber);
            messageService.sendMessage(phoneNumber, "You have been logged out successfully. Type 'Hi' to log in again.");
            return;
        }

        if ("student_weekly_timetable".equals(selectedButtonId)) {
            studentMenuHandler.handleWeeklyTimetable(phoneNumber);
            return;
        }

        if (currentState == UserState.AWAITING_GRIEVANCE_CATEGORY) {
            grievanceHandler.handleCategorySelection(phoneNumber, selectedButtonId);
        } else {
            studentMenuHandler.sendMainMenu(phoneNumber);
        }
    }
}