use std::collections::HashSet;

use chrono::{DateTime, Utc};
use diesel::{alias, dsl::not, prelude::*};
use gpodder::AuthErr;

use super::SqliteRepository;
use crate::{
    DbError,
    models::{
        device::{Device, DeviceType, NewDevice},
        sync_group::SyncGroup,
    },
    schema::*,
};

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

impl From<gpodder::DeviceType> for 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::GpodderDeviceStore for SqliteRepository {
    fn devices_for_user(
        &self,
        user: &gpodder::User,
    ) -> Result<Vec<gpodder::Device>, gpodder::AuthErr> {
        (|| {
            Ok::<_, DbError>(
                devices::table
                    .select(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(),
            )
        })()
        .map_err(AuthErr::from)
    }

    fn update_device_info(
        &self,
        user: &gpodder::User,
        device_id: &str,
        patch: gpodder::DevicePatch,
    ) -> Result<(), gpodder::AuthErr> {
        (|| {
            let conn = &mut self.pool.get()?;

            if let Some(mut device) = devices::table
                .select(Device::as_select())
                .filter(
                    devices::user_id
                        .eq(user.id)
                        .and(devices::device_id.eq(device_id)),
                )
                .get_result(conn)
                .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(conn)?;
            } else {
                let device = NewDevice {
                    device_id: device_id.to_string(),
                    user_id: user.id,
                    caption: patch.caption.unwrap_or_default(),
                    type_: patch.r#type.unwrap_or(gpodder::DeviceType::Other).into(),
                };

                diesel::insert_into(devices::table)
                    .values(device)
                    .execute(conn)?;
            }

            Ok::<_, DbError>(())
        })()
        .map_err(AuthErr::from)
    }

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

            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 {
                    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::<_, DbError>(sync_group_id)
            })
        })()
        .map_err(AuthErr::from)
    }

    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::<_, DbError>(())
        })()
        .map_err(AuthErr::from)
    }

    fn synchronize_sync_group(
        &self,
        group_id: i64,
        time_changed: DateTime<Utc>,
    ) -> Result<(), gpodder::AuthErr> {
        (|| {
            let time_changed = time_changed.timestamp();
            let conn = &mut self.pool.get()?;

            conn.transaction(|conn| {
                let device_ids: Vec<i64> = devices::table
                    .filter(devices::sync_group_id.eq(group_id))
                    .select(devices::id)
                    .get_results(conn)?;

                // For each device in the group, we get the list of subscriptions not yet in its own
                // non-deleted list, and add it to the database
                for device_id in device_ids.iter().copied() {
                    let d1 = alias!(device_subscriptions as d1);

                    let own_subscriptions = d1
                        .filter(
                            d1.field(device_subscriptions::device_id)
                                .eq(device_id)
                                .and(d1.field(device_subscriptions::deleted).eq(false)),
                        )
                        .select(d1.field(device_subscriptions::podcast_url));

                    let urls_to_add = device_subscriptions::table
                        .select(device_subscriptions::podcast_url)
                        .filter(
                            device_subscriptions::device_id
                                .eq_any(device_ids.iter())
                                .and(device_subscriptions::deleted.eq(false))
                                .and(not(
                                    device_subscriptions::podcast_url.eq_any(own_subscriptions)
                                )),
                        )
                        .distinct()
                        .load_iter(conn)?
                        .collect::<Result<HashSet<String>, _>>()?;

                    super::subscription::insert_subscriptions_for_single_device(
                        conn,
                        device_id,
                        urls_to_add.iter(),
                        time_changed,
                    )?;
                }

                Ok::<_, DbError>(())
            })
        })()
        .map_err(AuthErr::from)
    }

    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::<_, DbError>((not_synchronized, synchronized))
        })()
        .map_err(AuthErr::from)
    }
}