// Copyright: Ankitects Pty Ltd and contributors
// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

use std::{
    borrow::Cow,
    path::{Path, PathBuf},
};

use rusqlite::Connection;
use slog::Logger;

use crate::{
    error::Result,
    media::{
        database::{open_or_create, MediaDatabaseContext, MediaEntry},
        files::{add_data_to_folder_uniquely, mtime_as_i64, remove_files, sha1_of_data},
        sync::{MediaSyncProgress, MediaSyncer},
    },
};

pub mod changetracker;
pub mod check;
pub mod database;
pub mod files;
pub mod sync;

pub struct MediaManager {
    db: Connection,
    media_folder: PathBuf,
}

impl MediaManager {
    pub fn new<P, P2>(media_folder: P, media_db: P2) -> Result<Self>
    where
        P: Into<PathBuf>,
        P2: AsRef<Path>,
    {
        let db = open_or_create(media_db.as_ref())?;
        Ok(MediaManager {
            db,
            media_folder: media_folder.into(),
        })
    }

    /// Add a file to the media folder.
    ///
    /// If a file with differing contents already exists, a hash will be
    /// appended to the name.
    ///
    /// Also notes the file in the media database.
    #[allow(clippy::match_like_matches_macro)]
    pub fn add_file<'a>(
        &self,
        ctx: &mut MediaDatabaseContext,
        desired_name: &'a str,
        data: &[u8],
    ) -> Result<Cow<'a, str>> {
        let pre_add_folder_mtime = mtime_as_i64(&self.media_folder)?;

        // add file to folder
        let data_hash = sha1_of_data(data);
        let chosen_fname =
            add_data_to_folder_uniquely(&self.media_folder, desired_name, data, data_hash)?;
        let file_mtime = mtime_as_i64(self.media_folder.join(chosen_fname.as_ref()))?;
        let post_add_folder_mtime = mtime_as_i64(&self.media_folder)?;

        // add to the media DB
        ctx.transact(|ctx| {
            let existing_entry = ctx.get_entry(&chosen_fname)?;
            let new_sha1 = Some(data_hash);

            let entry_update_required = match existing_entry {
                Some(existing) if existing.sha1 == new_sha1 => false,
                _ => true,
            };

            if entry_update_required {
                ctx.set_entry(&MediaEntry {
                    fname: chosen_fname.to_string(),
                    sha1: new_sha1,
                    mtime: file_mtime,
                    sync_required: true,
                })?;
            }

            let mut meta = ctx.get_meta()?;
            if meta.folder_mtime == pre_add_folder_mtime {
                // if media db was in sync with folder prior to this add,
                // we can keep it in sync
                meta.folder_mtime = post_add_folder_mtime;
                ctx.set_meta(&meta)?;
            } else {
                // otherwise, leave it alone so that other pending changes
                // get picked up later
            }

            Ok(())
        })?;

        Ok(chosen_fname)
    }

    pub fn remove_files<S>(&self, ctx: &mut MediaDatabaseContext, filenames: &[S]) -> Result<()>
    where
        S: AsRef<str> + std::fmt::Debug,
    {
        let pre_remove_folder_mtime = mtime_as_i64(&self.media_folder)?;

        remove_files(&self.media_folder, &filenames)?;

        let post_remove_folder_mtime = mtime_as_i64(&self.media_folder)?;

        ctx.transact(|ctx| {
            for fname in filenames {
                if let Some(mut entry) = ctx.get_entry(fname.as_ref())? {
                    entry.sha1 = None;
                    entry.mtime = 0;
                    entry.sync_required = true;
                    ctx.set_entry(&entry)?;
                }
            }

            let mut meta = ctx.get_meta()?;
            if meta.folder_mtime == pre_remove_folder_mtime {
                // if media db was in sync with folder prior to this add,
                // we can keep it in sync
                meta.folder_mtime = post_remove_folder_mtime;
                ctx.set_meta(&meta)?;
            } else {
                // otherwise, leave it alone so that other pending changes
                // get picked up later
            }

            Ok(())
        })
    }

    /// Sync media.
    pub async fn sync_media<'a, F>(
        &'a self,
        progress: F,
        host_number: u32,
        hkey: &'a str,
        log: Logger,
    ) -> Result<()>
    where
        F: FnMut(MediaSyncProgress) -> bool,
    {
        let mut syncer = MediaSyncer::new(self, progress, host_number, log);
        syncer.sync(hkey).await
    }

    pub fn dbctx(&self) -> MediaDatabaseContext {
        MediaDatabaseContext::new(&self.db)
    }
}