import { ButtonInteraction, MessageFlags } from "discord.js";
import { config } from "@/lib/config";
import { getEnrollmentErrorEmbed, getEnrollmentSuccessMessage } from "./enrollment.view";
import { classService } from "@modules/class/class.service";
import { userService } from "@modules/user/user.service";
import { sendWebhookMessage } from "@/lib/webhookUtils";

export async function handleEnrollmentInteraction(interaction: ButtonInteraction) {
    if (!interaction.inCachedGuild()) {
        await interaction.reply({ content: "This action can only be performed in a server.", flags: MessageFlags.Ephemeral });
        return;
    }

    const { studentRole, visitorRole } = config;

    if (!studentRole || !visitorRole) {
        await interaction.reply({
            ...getEnrollmentErrorEmbed("No student or visitor role configured for enrollment.", "Configuration Error"),
            flags: MessageFlags.Ephemeral
        });
        return;
    }

    try {
        // 1. Ensure user exists in DB and check current enrollment status
        const user = await userService.getOrCreateUser(interaction.user.id, interaction.user.username);

        // Check DB enrollment
        if (user.class) {
            await interaction.reply({
                ...getEnrollmentErrorEmbed("You are already enrolled in a class.", "Enrollment Failed"),
                flags: MessageFlags.Ephemeral
            });
            return;
        }

        const member = interaction.member;

        // Check Discord role enrollment (Double safety)
        if (member.roles.cache.has(studentRole)) {
            await interaction.reply({
                ...getEnrollmentErrorEmbed("You already have the student role.", "Enrollment Failed"),
                flags: MessageFlags.Ephemeral
            });
            return;
        }

        // 2. Get available classes
        const allClasses = await classService.getAllClasses();
        const validClasses = allClasses.filter(c => c.roleId);

        if (validClasses.length === 0) {
            await interaction.reply({
                ...getEnrollmentErrorEmbed("No classes with specified roles found in database.", "Configuration Error"),
                flags: MessageFlags.Ephemeral
            });
            return;
        }

        // 3. Pick random class
        const selectedClass = validClasses[Math.floor(Math.random() * validClasses.length)]!;
        const classRoleId = selectedClass.roleId!;

        // Check if the role exists in the guild
        const classRole = interaction.guild.roles.cache.get(classRoleId);
        if (!classRole) {
            await interaction.reply({
                ...getEnrollmentErrorEmbed(`The configured role ID \`${classRoleId}\` for class **${selectedClass.name}** does not exist in this server.`, "Configuration Error"),
                flags: MessageFlags.Ephemeral
            });
            return;
        }

        // 4. Perform Enrollment Actions

        await member.roles.remove(visitorRole);
        await member.roles.add(studentRole);
        await member.roles.add(classRole);

        // Persist to DB
        await classService.assignClass(user.id.toString(), selectedClass.id);

        await interaction.reply({
            ...getEnrollmentSuccessMessage(classRole.name),
            flags: MessageFlags.Ephemeral
        });

        // 5. Send Welcome Message (if configured)
        if (config.welcomeChannelId) {
            const welcomeChannel = interaction.guild.channels.cache.get(config.welcomeChannelId);
            if (welcomeChannel && welcomeChannel.isTextBased()) {
                const rawMessage = config.welcomeMessage || "Welcome to Aurora, {user}! You have been enrolled as a **{class}**.";

                const processedMessage = rawMessage
                    .replace(/{user}/g, member.toString())
                    .replace(/{username}/g, member.user.username)
                    .replace(/{class}/g, selectedClass.name)
                    .replace(/{guild}/g, interaction.guild.name);

                let payload;
                try {
                    payload = JSON.parse(processedMessage);
                } catch {
                    payload = processedMessage;
                }

                // Fire and forget webhook
                sendWebhookMessage(welcomeChannel, payload, interaction.client.user, "New Student Enrollment")
                    .catch((err: any) => console.error("Failed to send welcome message:", err));
            }
        }

    } catch (error) {
        console.error("Enrollment error:", error);
        await interaction.reply({
            ...getEnrollmentErrorEmbed("An unexpected error occurred during enrollment. Please contact an administrator.", "System Error"),
            flags: MessageFlags.Ephemeral
        });
    }
}