use chrono::TimeZone;
use diesel::{
    result::Error as DieselError,
    NotFound,
};
use grate::tracing;
use itertools::Itertools;
use lazy_static::lazy_static;
use serenity::{
    all::{
        GuildId,
        Mentionable,
    },
    futures::{
        StreamExt,
        TryStreamExt,
    },
};
use tap::Pipe;
use timeago::{
    Formatter,
    TimeUnit,
};

use crate::{
    commands::game::get_user_id,
    config::CONFIG,
    db::{
        self,
        connection,
        InvocationRecord,
        Meme,
        Metadata,
    },
    util,
    PoiseContext,
};

lazy_static! {
    static ref TIME_FORMATTER: Formatter = {
        let mut f = Formatter::new();
        f.min_unit(TimeUnit::Minutes);
        f.num_items(2);

        f
    };
}

static CLEAN_DATE_FORMAT: &str = "%b %-e %Y";

/// Print info about the last meme.
#[poise::command(prefix_command, guild_only, category = "memes", aliases("what", "hwaet", "hwæt"))]
pub async fn wat(ctx: PoiseContext<'_>) -> anyhow::Result<()> {
    let guild_id = util::guild_id(ctx)?;

    let mut conn = connection().await?;

    let record = match InvocationRecord::last(&mut conn, guild_id.get()).await {
        Ok(x) => x,
        Err(e) => {
            if let Some(NotFound) = e.downcast_ref::<DieselError>() {
                tracing::info!("found no memes in history");

                util::reply(ctx, "no one has ever memed before").await?;
                return Ok(());
            }

            util::reply(ctx, "BAD MEME BAD MEME").await?;
            return Err(e.into());
        },
    };

    let meme = Meme::find(&mut conn, record.meme_id).await;

    match meme {
        Ok(ref meme) => {
            let metadata = Metadata::find(&mut conn, meme.metadata_id).await?;
            let author = guild_id.member(&ctx, metadata.created_by as u64).await?;

            util::reply(
                ctx,
                &format!(
                    "that was \"{}\" by {} ({})",
                    meme.title,
                    author.mention(),
                    metadata.created.date().format(CLEAN_DATE_FORMAT)
                ),
            )
            .await?;
        },
        Err(e) => {
            if let Some(NotFound) = e.downcast_ref::<DieselError>() {
                tracing::info!("last meme not found in database");

                util::reply(ctx, "heuueueeeeh?").await?;
                return Ok(());
            }

            util::reply(ctx, "do i look like i know what a jpeg is").await?;
            return Err(e.into());
        },
    };

    let _meme = meme?;
    Ok(())
}

/// Print recent memes and who invoked them.
#[poise::command(prefix_command, guild_only, category = "memes", aliases("hist"))]
pub async fn history(ctx: PoiseContext<'_>, n: Option<usize>) -> anyhow::Result<()> {
    let n = n.unwrap_or(CONFIG.default_hist);

    if n > CONFIG.max_hist {
        tracing::debug!(
            MAX_HIST = CONFIG.max_hist,
            "user requested more than MAX_HIST items from history",
        );

        util::reply(ctx, "YER PUSHIN ME OVER THE FUCKIN LINE").await?;
    }

    let n = n.min(CONFIG.max_hist);

    let guild_id = util::guild_id(ctx)?;

    let records = {
        let mut conn = connection().await?;
        InvocationRecord::last_n(&mut conn, n, guild_id.get()).await?
    };

    if records.is_empty() {
        tracing::info!("no memes in history");
        util::reply(ctx, "i don't remember anything :(").await?;

        return Ok(());
    }

    tracing::info!(len = n, "reporting meme history");

    let resp = serenity::futures::stream::iter(records.into_iter().enumerate().rev())
        .then(|(i, rec)| async move {
            let mut conn = connection().await?;

            let dt = chrono::Utc.from_utc_datetime(&rec.time);
            let ago = TIME_FORMATTER.convert((chrono::Utc::now() - dt).to_std().unwrap());

            let rand = if rec.random {
                "R, "
            } else {
                ""
            };

            let meme = match Meme::find(&mut conn, rec.meme_id).await {
                Ok(meme) => Metadata::find(&mut conn, meme.metadata_id)
                    .await
                    .map(|metadata| (metadata, meme)),
                Err(e) => Err(e),
            };

            let invoker_name = guild_id
                .member(&ctx, rec.user_id as u64)
                .await
                .map(|m| m.display_name().to_owned())
                .unwrap_or("???".to_owned());

            let result = match meme {
                Ok((metadata, meme)) => {
                    let author_name = guild_id
                        .member(&ctx, metadata.created_by as u64)
                        .await
                        .map(|m| m.display_name().to_owned())
                        .unwrap_or("???".to_owned());

                    format!(
                        "{}. [{}{}] \"{}\" by {} ({}). invoked by {}.",
                        i + 1,
                        rand,
                        ago,
                        meme.title,
                        author_name,
                        metadata.created.date().format(CLEAN_DATE_FORMAT),
                        invoker_name
                    )
                },
                Err(e) => {
                    if let Some(variant) = e.downcast_ref::<DieselError>() {
                        if *variant != NotFound {
                            tracing::error!(error = %e, "error encountered loading meme history");
                        }
                    }

                    format!("{}. [{}{}] not found. invoked by {}.", i + 1, rand, ago, invoker_name)
                },
            };

            anyhow::Ok(result)
        })
        .try_collect::<Vec<String>>()
        .await?;

    let resp = resp.join("\n");
    util::reply(ctx, resp).await?;

    Ok(())
}

/// Print stats about the meme database.
#[poise::command(prefix_command, guild_only, category = "memes", aliases("stat"))]
pub async fn stats(ctx: PoiseContext<'_>) -> anyhow::Result<()> {
    use db;
    use serenity::model::{
        id::UserId,
        user::User,
    };

    let guild_id = util::guild_id(ctx)?;

    let mut conn = connection().await?;
    let stats = db::stats(&mut conn, guild_id.get()).await?;

    tracing::debug!("reporting stats");

    async fn username(ctx: PoiseContext<'_>, guild_id: GuildId, id: u64) -> anyhow::Result<String> {
        let user: User = UserId::new(id).to_user(&ctx).await?;
        Ok(user.nick_in(&ctx, guild_id).await.unwrap_or(user.name))
    }

    let most_active_day = if let Some(ref most_active_day) = stats.most_active_day {
        let fmt = most_active_day.format(CLEAN_DATE_FORMAT);
        let count = stats.most_active_day_count;

        format!("the most active day was *{fmt}* with **{count}** memes\n")
    } else {
        String::new()
    };
    let loudest_day = if let Some(ref loudest_day) = stats.most_audio_active_day {
        let fmt = loudest_day.format(CLEAN_DATE_FORMAT);
        let count = stats.most_audio_active_count;
        format!("and the loudest day was *{fmt}* with **{count}** audio memes\n")
    } else {
        String::new()
    };

    let rand_user = if let Some(rand_user) = stats.most_random_meme_user {
        let rand_user = username(ctx, guild_id, rand_user).await?;
        format!(
            "**{rand_user}** has invoked the most random memes ({})\n",
            stats.most_random_meme_user_count
        )
    } else {
        String::new()
    };

    let direct_user = if let Some(direct_user) = stats.most_directly_named_meme_user {
        let direct_user = username(ctx, guild_id, direct_user).await?;
        format!(
            "**{direct_user}** has invoked the most memes by name ({})\n",
            stats.most_directly_named_meme_count
        )
    } else {
        String::new()
    };

    let started_recording = if let Some(ref started_recording) = stats.started_recording {
        let fst = started_recording.naive_local().date().format(CLEAN_DATE_FORMAT);
        let snd = TIME_FORMATTER.convert((chrono::Utc::now() - started_recording).to_std()?);

        format!("started recording meme invocations on *{fst}* ({snd})\n")
    } else {
        String::new()
    };

    let most_requested = if let Some(ref most_requested) = stats.most_popular_named_meme {
        format!(
            "*{most_requested}* was the meme specifically requested the most ({})\n",
            stats.most_popular_named_meme_count
        )
    } else {
        String::new()
    };

    let most_random = if let Some(ref most_random) = stats.most_popular_random_meme {
        format!(
            "*{most_random}* was the meme specifically requested the most ({})\n",
            stats.most_popular_random_meme_count
        )
    } else {
        String::new()
    };

    let most_overall = if let Some(ref most_overall) = stats.most_popular_meme_overall {
        format!(
            "*{most_overall}* was the most-memed overall({})\n",
            stats.most_popular_meme_overall_count
        )
    } else {
        String::new()
    };

    let s = format!(
        r#"
**{}** memes stored
**{}** memes with audio ({:0.1}%)
**{}** memes with images ({:0.1}%)

{started_recording}**{}** total meme invocations recorded
**{}** of which were random ({:0.1}%)
and **{}** were audio ({:0.1}%)

{most_active_day}{loudest_day}
{rand_user}{direct_user}
{most_requested}{most_random}{most_overall}"#,
        stats.memes_overall,
        stats.audio_memes,
        (stats.audio_memes as f64) / (stats.memes_overall as f64) * 100.,
        stats.image_memes,
        (stats.image_memes as f64) / (stats.memes_overall as f64) * 100.,
        stats.total_meme_invocations,
        stats.random_meme_invocations,
        (stats.random_meme_invocations as f64) / (stats.total_meme_invocations as f64) * 100.,
        stats.audio_meme_invocations,
        (stats.audio_meme_invocations as f64) / (stats.total_meme_invocations as f64) * 100.,
    );

    util::reply(ctx, s).await?;
    Ok(())
}

/// Print stats about memers.
#[poise::command(prefix_command, guild_only, category = "memes")]
pub async fn memers(ctx: PoiseContext<'_>) -> anyhow::Result<()> {
    use serenity::model::id::UserId;

    let guild_id = util::guild_id(ctx)?;

    let s = db::memers(guild_id.get())
        .await?
        .into_iter()
        .pipe(serenity::futures::stream::iter)
        .then(|info| async move {
            let user = UserId::new(info.user_id).to_user(&ctx).await?;
            let username = user.nick_in(&ctx, guild_id).await.unwrap_or(user.name);

            let res = format!(
                "**{}**: {} total, {} random, {} specific. favorite meme: *{}* ({})",
                username,
                info.random_memes + info.specific_memes,
                info.random_memes,
                info.specific_memes,
                info.most_used_meme,
                info.most_used_meme_count,
            );

            anyhow::Ok(res)
        })
        .try_collect::<Vec<String>>()
        .await?;

    let mut out = String::new();

    for line in s {
        if line.len() >= 2000 {
            anyhow::bail!("singular line too long");
        }

        if out.len() + line.len() >= 2000 {
            let result = out.trim_end_matches('\n');
            util::reply(ctx, &result).await?;
            out.clear();
        }

        out.push_str(&line);
        out.push('\n');
    }

    if !out.is_empty() {
        let result = out.trim_end_matches('\n');
        util::reply(ctx, result).await?;
    } else {
        util::reply(ctx, "no memers :(").await?;
    }

    Ok(())
}

/// Look up a meme by title or content.
///
/// Can pass:
/// - `by=username` or `creator=username` to look up memes created by a specific user.
/// - `age=new` or `age=old` to sort the result by age.
#[poise::command(prefix_command, guild_only, category = "memes")]
pub async fn query(ctx: PoiseContext<'_>, rest: util::RestVec) -> anyhow::Result<()> {
    use regex::Regex;
    use serenity::model::id::UserId;

    use crate::db;

    lazy_static! {
        static ref CREATOR_REGEX: Regex = Regex::new(r"(?i)(?:by|creator)=(.*)").unwrap();
        static ref AGE_REGEX: Regex = Regex::new(r"(?i)(?:age|order)=(.*)").unwrap();
    }

    let guild_id = util::guild_id(ctx)?;

    let mut rest = rest.into_inner();

    let creator: Option<u64> = try {
        let fst = rest.first()?;
        let captures = CREATOR_REGEX.captures(fst)?;
        let creator = captures.get(1)?.as_str().to_owned();

        let guild = ctx.guild()?;
        let user_id = get_user_id(&guild, creator).ok()?.get();
        rest.pop();

        user_id
    };

    let order: Option<String> = try {
        let fst = rest.first()?;
        let captures = AGE_REGEX.captures(fst)?;
        let order = captures.get(1)?.as_str().to_owned();

        order
    };

    let order = order.is_some_and(|o| o.contains("new"));

    let iter = db::query_meme(rest.join(" "), creator, order, guild_id.get()).await?.into_iter();

    let result = iter
        .pipe(serenity::futures::stream::iter)
        .then(|(meme, metadata)| async move {
            let user = UserId::new(metadata.created_by as u64).to_user(&ctx).await?;
            let username = user.nick_in(&ctx, guild_id).await.unwrap_or(user.name);

            Ok(format!(
                "*{}* by **{}** ({}). text length: **{}**, image: **{}**, audio: **{}**",
                meme.title,
                username,
                metadata.created.date().format(CLEAN_DATE_FORMAT),
                meme.content.map_or(0, |s| s.len()),
                meme.image_id.map_or("NO", |_s| "YES"),
                meme.audio_id.map_or("NO", |_s| "YES"),
            )) as anyhow::Result<String>
        })
        .try_collect::<Vec<String>>()
        .await;

    let result = result?
        .into_iter()
        .scan(0, |state, line| {
            *state = *state + line.len() + 1;

            if *state < 2000 {
                Some(line)
            } else {
                None
            }
        })
        .join("\n");

    if result.is_empty() {
        tracing::info!("no memes matched query");

        util::reply(ctx, "no match").await?;
        return Ok(());
    }

    util::reply(ctx, result).await?;
    Ok(())
}