use chrono::{DateTime, Utc};
use diesel::prelude::*;

use super::SqliteRepository;
use crate::{
    db::{self, schema::*, SyncGroup},
    gpodder,
};

impl From<db::DeviceType> for gpodder::DeviceType {
    fn from(value: db::DeviceType) -> Self {
        match value {
            db::DeviceType::Desktop => Self::Desktop,
            db::DeviceType::Laptop => Self::Laptop,
            db::DeviceType::Mobile => Self::Mobile,
            db::DeviceType::Server => Self::Server,
            db::DeviceType::Other => Self::Other,
        }
    }
}

impl From<gpodder::DeviceType> for db::DeviceType {
    fn from(value: gpodder::DeviceType) -> Self {
        match value {
            gpodder::DeviceType::Desktop => Self::Desktop,
            gpodder::DeviceType::Laptop => Self::Laptop,
            gpodder::DeviceType::Mobile => Self::Mobile,
            gpodder::DeviceType::Server => Self::Server,
            gpodder::DeviceType::Other => Self::Other,
        }
    }
}

impl gpodder::DeviceRepository for SqliteRepository {
    fn devices_for_user(
        &self,
        user: &gpodder::User,
    ) -> Result<Vec<gpodder::Device>, gpodder::AuthErr> {
        Ok(devices::table
            .select(db::Device::as_select())
            .filter(devices::user_id.eq(user.id))
            .get_results(&mut self.pool.get()?)?
            .into_iter()
            .map(|d| gpodder::Device {
                id: d.device_id,
                caption: d.caption,
                r#type: d.type_.into(),
                // TODO implement subscription count
                subscriptions: 0,
            })
            .collect())
    }

    fn update_device_info(
        &self,
        user: &gpodder::User,
        device_id: &str,
        patch: gpodder::DevicePatch,
    ) -> Result<(), gpodder::AuthErr> {
        if let Some(mut device) = devices::table
            .select(db::Device::as_select())
            .filter(
                devices::user_id
                    .eq(user.id)
                    .and(devices::device_id.eq(device_id)),
            )
            .get_result(&mut self.pool.get()?)
            .optional()?
        {
            if let Some(caption) = patch.caption {
                device.caption = caption;
            }

            if let Some(type_) = patch.r#type {
                device.type_ = type_.into();
            }

            diesel::update(devices::table.filter(devices::id.eq(device.id)))
                .set((
                    devices::caption.eq(&device.caption),
                    devices::type_.eq(&device.type_),
                ))
                .execute(&mut self.pool.get()?)?;
        } else {
            let device = db::NewDevice {
                device_id: device_id.to_string(),
                user_id: user.id,
                caption: patch.caption.unwrap_or(String::new()),
                type_: patch.r#type.unwrap_or(gpodder::DeviceType::Other).into(),
            };

            diesel::insert_into(devices::table)
                .values(device)
                .execute(&mut self.pool.get()?)?;
        }

        Ok(())
    }

    fn merge_sync_groups(
        &self,
        user: &gpodder::User,
        device_ids: Vec<&str>,
    ) -> Result<i64, gpodder::AuthErr> {
        let conn = &mut self.pool.get()?;

        Ok(conn.transaction(|conn| {
            let devices: Vec<(i64, Option<i64>)> = devices::table
                .select((devices::id, devices::sync_group_id))
                .filter(
                    devices::user_id
                        .eq(user.id)
                        .and(devices::device_id.eq_any(device_ids)),
                )
                .get_results(conn)?;

            let mut sync_group_ids: Vec<i64> = devices
                .iter()
                .filter_map(|(_, group_id)| *group_id)
                .collect();

            // Remove any duplicates, giving us each sync group ID once
            sync_group_ids.sort();
            sync_group_ids.dedup();

            // If any of the devices are already in a sync group, we reuse the first one we find.
            // Otherwise, we generate a new one.
            let sync_group_id = if let Some(id) = sync_group_ids.pop() {
                id
            } else {
                db::SyncGroup::new(conn)?.id
            };

            // Move all devices in the other sync groups into the new sync group
            diesel::update(
                devices::table.filter(devices::sync_group_id.eq_any(sync_group_ids.iter())),
            )
            .set(devices::sync_group_id.eq(sync_group_id))
            .execute(conn)?;

            // Add the non-synchronized devices into the new sync group
            let unsynced_device_ids =
                devices
                    .iter()
                    .filter_map(|(id, group_id)| if group_id.is_none() { Some(id) } else { None });

            diesel::update(devices::table.filter(devices::id.eq_any(unsynced_device_ids)))
                .set(devices::sync_group_id.eq(sync_group_id))
                .execute(conn)?;

            // Remove the other now unused sync groups
            diesel::delete(sync_groups::table.filter(sync_groups::id.eq_any(sync_group_ids)))
                .execute(conn)?;

            Ok::<_, diesel::result::Error>(sync_group_id)
        })?)
    }

    fn remove_from_sync_group(
        &self,
        user: &gpodder::User,
        device_ids: Vec<&str>,
    ) -> Result<(), gpodder::AuthErr> {
        let conn = &mut self.pool.get()?;

        diesel::update(
            devices::table.filter(
                devices::user_id
                    .eq(user.id)
                    .and(devices::device_id.eq_any(device_ids)),
            ),
        )
        .set(devices::sync_group_id.eq(None::<i64>))
        .execute(conn)?;

        // This is in a different transaction on purpose, as the success of this removal shouldn't
        // fail the entire query
        SyncGroup::remove_unused(conn)?;

        Ok(())
    }

    fn synchronize_sync_group(
        &self,
        group_id: i64,
        time_changed: DateTime<Utc>,
    ) -> Result<(), gpodder::AuthErr> {
        todo!()
    }

    fn devices_by_sync_group(
        &self,
        user: &gpodder::User,
    ) -> Result<(Vec<String>, Vec<Vec<String>>), gpodder::AuthErr> {
        let mut not_synchronized = Vec::new();
        let mut synchronized = Vec::new();

        let conn = &mut self.pool.get()?;
        let mut devices = devices::table
            .select((devices::device_id, devices::sync_group_id))
            .filter(devices::user_id.eq(user.id))
            .order(devices::sync_group_id)
            .load_iter::<(String, Option<i64>), _>(conn)?;

        let mut cur_group = &mut not_synchronized;
        let mut cur_group_id: Option<i64> = None;

        while let Some((device_id, group_id)) = devices.next().transpose()? {
            if group_id != cur_group_id {
                if group_id.is_none() {
                    cur_group = &mut not_synchronized;
                } else {
                    synchronized.push(Vec::new());
                    let index = synchronized.len() - 1;
                    cur_group = &mut synchronized[index];
                }

                cur_group_id = group_id;
            }

            cur_group.push(device_id);
        }

        Ok((not_synchronized, synchronized))
    }
}