// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

//! # Storage layer for Notesmachine
//!
//! This library implements the core functionality of Notesmachine and
//! describes that functionality to a storage layer.  There's a bit of
//! intermingling in here which can't be helped, although it may make
//! sense in the future to separate the decomposition of the note
//! content into a higher layer.
//!
//! Notesmachine storage notes consist of two items: Zettle and Kasten.
//! This distinction is somewhat arbitrary, as structurally these two
//! items are stored in the same table.
//!
//! - Boxes have titles (and date metadata)
//! - Notes have content and a type (and date metadata)
//! - Notes are stored in boxes
//!   - Notes are positioned with respect to other notes.
//!   - There are two positions:
//!     - Siblings, creating lists
//!     - Children, creating trees like this one
//! - Notes may have references (pointers) to other boxes
//! - Notes may be moved around
//! - Notes may be deleted
//! - Boxes may be deleted
//! - When a box is renamed, every reference to that box is auto-edited to
//!   reflect the change. If a box is renamed to match an existing box, the
//!   notes in both boxes are merged.
//!   
//! Note-to-note relationships form trees, and are kept in a SQL database of
//! (`parent_id`, `child_id`, `position`, `relationship_type`). The
//! `position` is a monotonic index on the parent (that is, every pair
//! (`parent_id`, `position`) must be unique).  The `relationship_type` is
//! an enum and can specify that the relationship is *original*,
//! *embedding*, or *referencing*.  An embedded or referenced note may be
//! read/write or read-only with respect to the original, but there is only
//! one original note at any time.
//!
//! Note-to-box relationships form a graph, and are kept in the SQL database
//! as a collection of *edges* from the note to the box (and naturally
//! vice-versa).
//!
//! - Decision: When an original note is deleted, do all references and
//!   embeddings also get deleted, or is the oldest one elevated to be a new
//!   "original"?  Or is that something the user may choose?
//!
//! - Decision: Should the merging issue be handled at this layer, or would
//!   it make sense to move this to a higher layer, and only provide the
//!   hooks for it here?
//!

use crate::errors::NoteStoreError;
use crate::store_private::*;
use crate::structs::*;
use sqlx::sqlite::SqlitePool;
use std::cmp;
use std::collections::HashMap;
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>;

impl NoteStore {
    /// Initializes a new instance of the note store.  Note that the
    /// note store holds an Arc internally; this code is (I think)
    /// safe to Send.
    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_kasten_by_slug(&self, slug: &str) -> NoteResult<Vec<RawZettle>> {
        let page = select_kasten_by_slug(&*self.0, slug).await?;
        Ok(page)
    }
	
}