import { ButtonInteraction, MessageFlags } from "discord.js";
import { config } from "@/lib/config";
import { createErrorEmbed } from "@/lib/embeds";
import { classService } from "@modules/class/class.service";
import { userService } from "@modules/user/user.service";

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({
            embeds: [createErrorEmbed("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({
                embeds: [createErrorEmbed("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({
                embeds: [createErrorEmbed("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({
                embeds: [createErrorEmbed("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({
                embeds: [createErrorEmbed(`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({
            content: `🎉 You have been successfully enrolled! You received the **${classRole.name}** role.`,
            flags: MessageFlags.Ephemeral
        });

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