use maud::{Markup, PreEscaped};
use regex::Regex;
use sqlx::QueryBuilder;
use sqlx::sqlite::SqlitePool;
use std::collections::HashSet;

use crate::AppError;
use crate::db::DbId;

pub struct Switchboard {
    trie: radix_trie::Trie<String, String>,
}

struct Mentionable {
    text: String,
    uri: String,
}

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct Mention {
    pub entity_id: DbId,
    pub entity_type: DbId,
    pub url: String,
    pub input_text: String,
    pub byte_range_start: DbId,
    pub byte_range_end: DbId,
}

// must match the constants in trigger definitions in
// migrations/each_user/0010_more-mentions.sql (or future migrations)
#[derive(Copy, Clone)]
pub enum MentionHostType {
    JournalEntry,
    ContactTextBody,
    ContactLivesWith,
}

#[derive(Copy, Clone)]
pub struct MentionHost<'a> {
    pub entity_id: DbId,
    pub entity_type: DbId,
    pub input: &'a String,
}

impl MentionHost<'_> {
    pub fn format<'a>(
        self: &Self,
        mentions: impl IntoIterator<Item = &'a Mention>,
    ) -> Result<Markup, AppError> {
        let mut out = self.input.clone();
        for mention in mentions.into_iter() {
            out.replace_range(
                (mention.byte_range_start as usize)..(mention.byte_range_end as usize),
                &format!("[{}]({})", mention.input_text, mention.url),
            );
        }

        Ok(PreEscaped(markdown::to_html(&out)))
    }
    pub async fn format_pool(self: &Self, pool: &SqlitePool) -> Result<Markup, AppError> {
        let mentions = sqlx::query_as!(
            Mention,
            "select * from mentions
            where entity_id = $1 and entity_type = $2
            order by byte_range_start desc",
            self.entity_id,
            self.entity_type
        )
        .fetch_all(pool)
        .await?;

        self.format(&mentions)
    }
}

impl Switchboard {
    pub async fn new(pool: &SqlitePool) -> Result<Self, AppError> {
        let mut trie = radix_trie::Trie::new();

        let mentionables = sqlx::query_as!(
            Mentionable,
            "select name as text, '/contact/'||contact_id as uri from (
                select contact_id, name, count(name) as ct from names group by name
            ) where ct = 1
            union
            select distinct name as text, '/group/'||slug as uri from groups",
        )
        .fetch_all(pool)
        .await?;

        for mentionable in mentionables {
            trie.insert(mentionable.text, mentionable.uri);
        }

        Ok(Switchboard { trie })
    }

    pub fn remove(self: &mut Self, text: &String) {
        self.trie.remove(text);
    }

    pub fn add_mentionable(self: &mut Self, text: String, uri: String) {
        self.trie.insert(text, uri);
    }

    pub fn extract_mentions<'a>(&self, host: impl Into<MentionHost<'a>>) -> HashSet<Mention> {
        let host: MentionHost = host.into();
        let name_re = Regex::new(r"\[\[(.+?)\]\]").unwrap();
        name_re
            .captures_iter(host.input)
            .map(|caps| {
                let range = caps.get_match().range();
                self.trie.get(&caps[1]).map(|url| Mention {
                    entity_id: host.entity_id,
                    entity_type: host.entity_type,
                    url: url.to_string(),
                    input_text: caps[1].to_string(),
                    byte_range_start: DbId::try_from(range.start).unwrap(),
                    byte_range_end: DbId::try_from(range.end).unwrap(),
                })
            })
            .filter(|o| o.is_some())
            .map(|o| o.unwrap())
            .collect()
    }
}

pub async fn insert_mentions<'a>(
    mentions: impl IntoIterator<Item = &'a Mention>,
    pool: &SqlitePool,
) -> Result<(), AppError> {
    let mut mentions = mentions.into_iter().peekable();
    if mentions.peek().is_some() {
        let mut qb = QueryBuilder::<sqlx::Sqlite>::new(
            "insert into mentions (
                entity_id, entity_type, url, input_text,
                byte_range_start, byte_range_end) ",
        );
        qb.push_values(mentions, |mut b, mention| {
            b.push_bind(mention.entity_id)
                .push_bind(mention.entity_type)
                .push_bind(&mention.url)
                .push_bind(&mention.input_text)
                .push_bind(mention.byte_range_start)
                .push_bind(mention.byte_range_end);
        });
        qb.build().execute(pool).await?;
    }
    Ok(())
}