const {
    EmbedBuilder
} = require("discord.js");

const { mClient } = require("../index");


const DATABASE =
    "neo-db";

const DUTY_COLLECTION =
    "items_duties";

const EVENT_COLLECTION =
    "items_events";


/*
 * RAID SIGNUP EMOJIS
 */

const RAID_EMOJIS = {
    Tank: {
        id:
            "1537931883369726042",

        display:
            "<:TankRole:1537931883369726042>"
    },

    Healer: {
        id:
            "1537931880756805704",

        display:
            "<:HealerRole:1537931880756805704>"
    },

    DPS: {
        id:
            "1537931878668050442",

        display:
            "<:DPSRole:1537931878668050442>"
    },

    Flex: {
        id:
            "1537948665606574210",

        display:
            "<:AllRounderRole:1537948665606574210>"
    }
};


/*
 * MAIN REACTION HANDLER
 *
 * added = true
 *     MessageReactionAdd
 *
 * added = false
 *     MessageReactionRemove
 */

async function handleRaidReaction(
    reaction,
    user,
    added
) {

    /*
     * Ignore bots.
     *
     * This prevents ShaiBot's own initial
     * signup reactions from being counted.
     */

    if (user.bot)
        return;


    /*
     * Resolve partial reactions/messages.
     */

    if (reaction.partial) {
        try {
            await reaction.fetch();

        } catch (error) {
            console.error(
                "Failed to fetch partial reaction:",
                error
            );

            return;
        }
    }


    if (reaction.message.partial) {
        try {
            await reaction.message.fetch();

        } catch (error) {
            console.error(
                "Failed to fetch partial raid planner message:",
                error
            );

            return;
        }
    }


    const message =
        reaction.message;


    /*
     * Raid planner messages always contain
     * an embed.
     */

    if (
        !message.embeds ||
        message.embeds.length === 0
    ) {
        return;
    }


    const embed =
        message.embeds[0];


    /*
     * Footer format:
     *
     * raidPlanner:<raidId>
     */

    const footer =
        embed.footer?.text;


    if (
        !footer ||
        !footer.startsWith(
            "raidPlanner:"
        )
    ) {
        return;
    }


    const [
        prefix,
        raidId
    ] =
        footer.split(":");


    if (
        prefix !== "raidPlanner" ||
        !raidId
    ) {
        return;
    }


    /*
     * Determine which signup role
     * this reaction represents.
     */

    const role =
        getRoleFromEmoji(
            reaction.emoji
        );


    /*
     * Ignore unrelated reactions.
     */

    if (!role)
        return;


    const db =
        mClient.db(
            DATABASE
        );


    const events =
        db.collection(
            EVENT_COLLECTION
        );


    /*
     * Make sure event exists.
     */

    const raid =
        await events.findOne({
            raidId
        });


    if (!raid)
        return;


    /*
     * REACTION ADDED
     *
     * Each role is independent.
     * Users may select multiple roles.
     */

    if (added) {
        await events.updateOne(
            {
                raidId
            },
            {
                $addToSet: {
                    [`signups.${role}`]:
                        user.id
                }
            }
        );
    }


    /*
     * REACTION REMOVED
     *
     * Remove only this role.
     */

    else {
        await events.updateOne(
            {
                raidId
            },
            {
                $pull: {
                    [`signups.${role}`]:
                        user.id
                }
            }
        );
    }


    /*
     * Rebuild planner from current Mongo state.
     */

    await updateRaidPlanner(
        message,
        raidId
    );
}


/*
 * UPDATE RAID PLANNER EMBED
 */

async function updateRaidPlanner(
    message,
    raidId
) {
    const db =
        mClient.db(
            DATABASE
        );


    /*
     * Fetch raid state.
     */

    const raid =
        await db
            .collection(
                EVENT_COLLECTION
            )
            .findOne({
                raidId
            });


    if (!raid)
        return;


    /*
     * Fetch duty.
     */

    const duty =
        await db
            .collection(
                DUTY_COLLECTION
            )
            .findOne({
                _id:
                    raid.dutyId
            });


    if (!duty)
        return;


    /*
     * Role counts.
     */

    const counts = {
        Tank:
            raid.signups?.Tank
                ?.length
            ?? 0,

        Healer:
            raid.signups?.Healer
                ?.length
            ?? 0,

        DPS:
            raid.signups?.DPS
                ?.length
            ?? 0,

        Flex:
            raid.signups?.Flex
                ?.length
            ?? 0
    };


    /*
     * Count UNIQUE participants.
     *
     * A user who reacts Tank + DPS + Flex
     * still counts as one participant.
     */

    const uniqueParticipants =
        new Set([
            ...(
                raid.signups?.Tank
                ?? []
            ),

            ...(
                raid.signups?.Healer
                ?? []
            ),

            ...(
                raid.signups?.DPS
                ?? []
            ),

            ...(
                raid.signups?.Flex
                ?? []
            )
        ]).size;


    /*
     * Clone existing embed.
     */

    const oldEmbed =
        message.embeds[0];


    const updatedEmbed =
        EmbedBuilder.from(
            oldEmbed
        );


    /*
     * Replace only Party field.
     */

    const fields =
        oldEmbed.fields.map(
            field => {

                if (
                    field.name !==
                    "Party"
                ) {
                    return {
                        name:
                            field.name,

                        value:
                            field.value,

                        inline:
                            field.inline
                    };
                }


                return {
                    name:
                        "Party",

                    value:
                        buildPartyField(
                            duty,
                            counts,
                            uniqueParticipants
                        ),

                    inline:
                        false
                };
            }
        );


    updatedEmbed.setFields(
        fields
    );


    /*
     * Update message.
     */

    await message.edit({
        embeds: [
            updatedEmbed
        ]
    });
}


/*
 * BUILD PARTY FIELD
 */

function buildPartyField(
    duty,
    counts,
    uniqueParticipants
) {
    return (
        `${RAID_EMOJIS.Tank.display} Tank **(${counts.Tank}/${duty.Party.Tanks})**\n` +
        `${RAID_EMOJIS.Healer.display} Healer **(${counts.Healer}/${duty.Party.Healers})**\n` +
        `${RAID_EMOJIS.DPS.display} DPS **(${counts.DPS}/${duty.Party.DPS})**\n` +
        `${RAID_EMOJIS.Flex.display} Flex **(${counts.Flex})**\n\n` +
        `**Participants: ${uniqueParticipants}/${duty.Party.Size}**`
    );
}


/*
 * EMOJI -> ROLE
 */

function getRoleFromEmoji(
    emoji
) {

    if (
        emoji.id ===
        RAID_EMOJIS.Tank.id
    ) {
        return "Tank";
    }


    if (
        emoji.id ===
        RAID_EMOJIS.Healer.id
    ) {
        return "Healer";
    }


    if (
        emoji.id ===
        RAID_EMOJIS.DPS.id
    ) {
        return "DPS";
    }


    if (
        emoji.id ===
        RAID_EMOJIS.Flex.id
    ) {
        return "Flex";
    }


    return null;
}


module.exports = {
    handleRaidReaction,
    updateRaidPlanner
};