use crate::errors::NoteStoreError;
use crate::row_structs::{JustSlugs, NewNote, NewPage, RawNote, RawPage};
use lazy_static::lazy_static;
use regex::Regex;
use slug::slugify;
use sqlx;
use sqlx::{
    sqlite::{Sqlite, SqlitePool},
    Executor,
};
use std::sync::Arc;

/// A handle to our Sqlite database.
#[derive(Clone, Debug)]
pub struct NoteStore(Arc<SqlitePool>);

type NoteResult<T> = core::result::Result<T, NoteStoreError>;
type SqlResult<T> = sqlx::Result<T>;

impl NoteStore {
    pub async fn new(url: &str) -> NoteResult<Self> {
        let pool = SqlitePool::connect(url).await?;
        Ok(NoteStore(Arc::new(pool)))
    }

    // Erase all the data in the database and restore it
    // to its original empty form.  Do not use unless you
    // really, really want that to happen.
    pub async fn reset_database(&self) -> NoteResult<()> {
        reset_database(&*self.0).await.map_err(NoteStoreError::DBError)
    }

    /// Fetch page by slug
    ///
    /// Supports the use case of the user navigating to a known place
    /// via a bookmark or other URL.  Since the title isn't clear from
    /// the slug, the slug is insufficient to generate a new page, so
    /// this use case says that in the event of a failure to find the
    /// requested page, return a basic NotFound.
    pub async fn get_page_by_slug(&self, slug: &str) -> NoteResult<(RawPage, Vec<RawNote>)> {
        //		let select_note_collection_for_root = include_str!("sql/select_note_collection_for_root.sql");
        let mut tx = self.0.begin().await?;
        let page = select_page_by_slug(&mut tx, slug).await?;
        //		let notes = sqlx::query_as(select_note_collection_for_root)
        //			.bind(page.note_id)
        //			.fetch(&tx)
        //			.await?;
        tx.commit().await?;
        Ok((page, vec![]))
    }

    pub async fn get_page_by_title(&self, title: &str) -> NoteResult<(RawPage, Vec<RawNote>)> {
        let mut tx = self.0.begin().await?;
        let page = match select_page_by_title(&mut tx, title).await {
            Ok(page) => page,
            Err(sqlx::Error::RowNotFound) => match create_page_for_title(&mut tx, title).await {
                Ok(page) => page,
                Err(e) => return Err(NoteStoreError::DBError(e))
            },
            Err(e) => return Err(NoteStoreError::DBError(e)),
        };
        // Todo: Replace vec with the results of the CTE
        return Ok((page, vec![]));
    }
}

//  ___     _          _
// | _ \_ _(_)_ ____ _| |_ ___
// |  _/ '_| \ V / _` |  _/ -_)
// |_| |_| |_|\_/\__,_|\__\___|
//

// I'm putting a lot of faith in Rust's ability to inline stuff.  I'm
// sure this is okay.  But really, this lets the API be clean and
// coherent and easily readable, and hides away the gnarliness of some
// of the SQL queries.

async fn select_page_by_slug<'e, E>(executor: E, slug: &str) -> SqlResult<RawPage>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let select_one_page_by_slug_sql = concat!(
        "SELECT id, title, slug, note_id, creation_date, updated_date, ",
        "lastview_date, deleted_date FROM pages WHERE slug=?;"
    );
    Ok(sqlx::query_as(&select_one_page_by_slug_sql)
        .bind(&slug)
        .fetch_one(executor)
        .await?)
}

async fn select_page_by_title<'e, E>(executor: E, title: &str) -> SqlResult<RawPage>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let select_one_page_by_title_sql = concat!(
        "SELECT id, title, slug, note_id, creation_date, updated_date, ",
        "lastview_date, deleted_date FROM pages WHERE title=?;"
    );
    Ok(sqlx::query_as(&select_one_page_by_title_sql)
        .bind(&title)
        .fetch_one(executor)
        .await?)
}

async fn reset_database<'e, E>(executor: E) -> SqlResult<()>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let initialize_sql = include_str!("sql/initialize_database.sql");
    sqlx::query(initialize_sql).execute(executor).await.map(|_| ())
}

async fn get_note_collection_for_root<'e, E>(executor: E, root: i64) -> SqlResult<Vec<RawNote>>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let select_note_collection_for_root = include_str!("sql/select_note_collection_from_root.sql");
    Ok(sqlx::query_as(&select_note_collection_for_root)
	   .bind(&root)
       .fetch_all(executor)
       .await?)
}

async fn insert_one_new_note<'e, E>(executor: E, note: &NewNote) -> SqlResult<i64>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let insert_one_note_sql = concat!(
        "INSERT INTO notes ( ",
        "	   uuid, ",
        "	   content, ",
        "	   notetype, ",
        "	   creation_date, ",
        "	   updated_date, ",
        "	   lastview_date) ",
        "VALUES (?, ?, ?, ?, ?, ?);"
    );

    Ok(sqlx::query(insert_one_note_sql)
        .bind(&note.uuid)
        .bind(&note.content)
        .bind(&note.notetype)
        .bind(&note.creation_date)
        .bind(&note.updated_date)
        .bind(&note.lastview_date)
        .execute(executor)
        .await?
        .last_insert_rowid())
}

fn find_maximal_slug(slugs: &Vec<JustSlugs>) -> Option<u32> {
    lazy_static! {
        static ref RE_CAP_NUM: Regex = Regex::new(r"-(\d+)$").unwrap();
    }

    if slugs.len() == 0 {
        return None;
    }

    let mut slug_counters: Vec<u32> = slugs
        .iter()
        .filter_map(|slug| RE_CAP_NUM.captures(&slug.slug))
        .map(|cap| cap.get(1).unwrap().as_str().parse::<u32>().unwrap())
        .collect();
    slug_counters.sort_unstable();
    slug_counters.pop()
}

// Given an initial string and an existing collection of slugs,
// generate a new slug that does not conflict with the current
// collection.
async fn generate_slug<'e, E>(executor: E, title: &str) -> SqlResult<String>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    lazy_static! {
        static ref RE_STRIP_NUM: Regex = Regex::new(r"-\d+$").unwrap();
    }

    let initial_slug = slugify(title);
    let sample_slug = RE_STRIP_NUM.replace_all(&initial_slug, "");
	let slug_finder_sql = "SELECT slug FROM pages WHERE slug LIKE '?%';";
    let similar_slugs: Vec<JustSlugs> = sqlx::query_as(&slug_finder_sql)
        .bind(&*sample_slug)
        .fetch_all(executor)
        .await?;
    let maximal_slug = find_maximal_slug(&similar_slugs);
    match maximal_slug {
        None => Ok(initial_slug),
        Some(max_slug) => Ok(format!("{}-{}", initial_slug, max_slug + 1)),
    }
}

async fn insert_one_new_page<'e, E>(executor: E, page: &NewPage) -> SqlResult<i64>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    let insert_one_page_sql = concat!(
        "INSERT INTO pages ( ",
        "	   slug, ",
        "	   title, ",
        "	   note_id, ",
        "	   creation_date, ",
        "	   updated_date, ",
        "	   lastview_date) ",
        "VALUES (?, ?, ?, ?, ?, ?);"
    );

    Ok(sqlx::query(insert_one_page_sql)
        .bind(&page.slug)
        .bind(&page.title)
        .bind(&page.note_id)
        .bind(&page.creation_date)
        .bind(&page.updated_date)
        .bind(&page.lastview_date)
        .execute(executor)
        .await?
        .last_insert_rowid())
}

async fn create_page_for_title<'e, E>(_executor: E, _title: &str) -> SqlResult<RawPage>
where
    E: 'e + Executor<'e, Database = Sqlite>,
{
    todo!()
}