use crate::entities::{GroupPB, GroupViewChangesetPB};
use crate::services::group::{default_group_configuration, make_no_status_group, GeneratedGroupConfig, Group};
use flowy_error::{FlowyError, FlowyResult};
use flowy_grid_data_model::revision::{
    FieldRevision, FieldTypeRevision, GroupConfigurationContentSerde, GroupConfigurationRevision, GroupRevision,
};
use indexmap::IndexMap;
use lib_infra::future::AFFuture;
use std::collections::HashMap;
use std::fmt::Formatter;
use std::marker::PhantomData;
use std::sync::Arc;

pub trait GroupConfigurationReader: Send + Sync + 'static {
    fn get_configuration(&self) -> AFFuture<Option<Arc<GroupConfigurationRevision>>>;
}

pub trait GroupConfigurationWriter: Send + Sync + 'static {
    fn save_configuration(
        &self,
        field_id: &str,
        field_type: FieldTypeRevision,
        group_configuration: GroupConfigurationRevision,
    ) -> AFFuture<FlowyResult<()>>;
}

impl<T> std::fmt::Display for GroupContext<T> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        self.groups_map.iter().for_each(|(_, group)| {
            let _ = f.write_fmt(format_args!("Group:{} has {} rows \n", group.id, group.rows.len()));
        });

        Ok(())
    }
}

/// A [GroupContext] represents as the groups memory cache
/// Each [GenericGroupController] has its own [GroupContext], the `context` has its own configuration
/// that is restored from the disk.
///
/// The `context` contains a list of [Group]s and the grouping [FieldRevision]
pub struct GroupContext<C> {
    pub view_id: String,
    /// The group configuration restored from the disk.
    ///
    /// Uses the [GroupConfigurationReader] to read the configuration data from disk
    configuration: Arc<GroupConfigurationRevision>,
    configuration_phantom: PhantomData<C>,

    /// The grouping field
    field_rev: Arc<FieldRevision>,

    /// Cache all the groups
    groups_map: IndexMap<String, Group>,

    /// A writer that implement the [GroupConfigurationWriter] trait is used to save the
    /// configuration to disk  
    ///
    writer: Arc<dyn GroupConfigurationWriter>,
}

impl<C> GroupContext<C>
where
    C: GroupConfigurationContentSerde,
{
    #[tracing::instrument(level = "trace", skip_all, err)]
    pub async fn new(
        view_id: String,
        field_rev: Arc<FieldRevision>,
        reader: Arc<dyn GroupConfigurationReader>,
        writer: Arc<dyn GroupConfigurationWriter>,
    ) -> FlowyResult<Self> {
        let configuration = match reader.get_configuration().await {
            None => {
                let default_configuration = default_group_configuration(&field_rev);
                writer
                    .save_configuration(&field_rev.id, field_rev.ty, default_configuration.clone())
                    .await?;
                Arc::new(default_configuration)
            }
            Some(configuration) => configuration,
        };

        Ok(Self {
            view_id,
            field_rev,
            groups_map: IndexMap::new(),
            writer,
            configuration,
            configuration_phantom: PhantomData,
        })
    }

    /// Returns the no `status` group
    ///
    /// We take the `id` of the `field` as the default group id
    pub(crate) fn get_no_status_group(&self) -> Option<&Group> {
        self.groups_map.get(&self.field_rev.id)
    }

    pub(crate) fn get_mut_no_status_group(&mut self) -> Option<&mut Group> {
        self.groups_map.get_mut(&self.field_rev.id)
    }

    pub(crate) fn groups(&self) -> Vec<&Group> {
        self.groups_map.values().collect()
    }

    pub(crate) fn get_mut_group(&mut self, group_id: &str) -> Option<&mut Group> {
        self.groups_map.get_mut(group_id)
    }

    // Returns the index and group specified by the group_id
    pub(crate) fn get_group(&self, group_id: &str) -> Option<(usize, &Group)> {
        match (self.groups_map.get_index_of(group_id), self.groups_map.get(group_id)) {
            (Some(index), Some(group)) => Some((index, group)),
            _ => None,
        }
    }

    /// Iterate mut the groups. The default group will be the last one that get mutated.
    pub(crate) fn iter_mut_all_groups(&mut self, mut each: impl FnMut(&mut Group)) {
        self.groups_map.iter_mut().for_each(|(_, group)| {
            each(group);
        });
    }

    pub(crate) fn move_group(&mut self, from_id: &str, to_id: &str) -> FlowyResult<()> {
        let from_index = self.groups_map.get_index_of(from_id);
        let to_index = self.groups_map.get_index_of(to_id);
        match (from_index, to_index) {
            (Some(from_index), Some(to_index)) => {
                self.groups_map.move_index(from_index, to_index);

                self.mut_configuration(|configuration| {
                    let from_index = configuration.groups.iter().position(|group| group.id == from_id);
                    let to_index = configuration.groups.iter().position(|group| group.id == to_id);
                    if let (Some(from), Some(to)) = &(from_index, to_index) {
                        tracing::trace!("Move group from index:{:?} to index:{:?}", from_index, to_index);
                        let group = configuration.groups.remove(*from);
                        configuration.groups.insert(*to, group);
                    }
                    tracing::debug!(
                        "Group order: {:?} ",
                        configuration
                            .groups
                            .iter()
                            .map(|group| group.name.clone())
                            .collect::<Vec<String>>()
                            .join(",")
                    );

                    from_index.is_some() && to_index.is_some()
                })?;
                Ok(())
            }
            _ => Err(FlowyError::record_not_found().context("Moving group failed. Groups are not exist")),
        }
    }

    ///  Reset the memory cache of the groups and update the group configuration
    ///
    /// # Arguments
    ///
    /// * `generated_group_configs`: the generated groups contains a list of [GeneratedGroupConfig].
    ///
    /// Each [FieldType] can implement the [GroupGenerator] trait in order to generate different
    /// groups. For example, the FieldType::Checkbox has the [CheckboxGroupGenerator] that implements
    /// the [GroupGenerator] trait.
    ///
    /// Consider the passed-in generated_group_configs as new groups, the groups in the current
    /// [GroupConfigurationRevision] as old groups. The old groups and the new groups will be merged
    /// while keeping the order of the old groups.
    ///
    #[tracing::instrument(level = "trace", skip(self, generated_group_configs), err)]
    pub(crate) fn init_groups(
        &mut self,
        generated_group_configs: Vec<GeneratedGroupConfig>,
    ) -> FlowyResult<Option<GroupViewChangesetPB>> {
        let mut new_groups = vec![];
        let mut filter_content_map = HashMap::new();
        generated_group_configs.into_iter().for_each(|generate_group| {
            filter_content_map.insert(generate_group.group_rev.id.clone(), generate_group.filter_content);
            new_groups.push(generate_group.group_rev);
        });

        let mut old_groups = self.configuration.groups.clone();
        if !old_groups.iter().any(|group| group.id == self.field_rev.id) {
            old_groups.push(make_no_status_group(&self.field_rev));
        }

        // The `all_group_revs` represents as the combination of the new groups and old groups
        let MergeGroupResult {
            mut all_group_revs,
            new_group_revs,
            updated_group_revs: _,
            deleted_group_revs,
        } = merge_groups(old_groups, new_groups);

        let deleted_group_ids = deleted_group_revs
            .into_iter()
            .map(|group_rev| group_rev.id)
            .collect::<Vec<String>>();

        // Delete/Insert the group in the current configuration
        self.mut_configuration(|configuration| {
            let mut is_changed = false;
            if !deleted_group_ids.is_empty() {
                configuration
                    .groups
                    .retain(|group| !deleted_group_ids.contains(&group.id));
                is_changed = true;
            }
            for group_rev in &mut all_group_revs {
                match configuration
                    .groups
                    .iter()
                    .position(|old_group_rev| old_group_rev.id == group_rev.id)
                {
                    None => {
                        // Push the group to the end of the list if it doesn't exist in the group
                        configuration.groups.push(group_rev.clone());
                        is_changed = true;
                    }
                    Some(pos) => {
                        let mut old_group = configuration.groups.remove(pos);

                        // Take the old group setting
                        group_rev.update_with_other(&old_group);
                        if !is_changed {
                            is_changed = is_group_changed(group_rev, &old_group);
                        }

                        // Consider the the name of the `group_rev` as the newest.
                        old_group.name = group_rev.name.clone();
                        configuration.groups.insert(pos, old_group);
                    }
                }
            }
            is_changed
        })?;

        // Update the memory cache of the groups
        all_group_revs.into_iter().for_each(|group_rev| {
            let filter_content = filter_content_map
                .get(&group_rev.id)
                .cloned()
                .unwrap_or_else(|| "".to_owned());
            let group = Group::new(group_rev.id, self.field_rev.id.clone(), group_rev.name, filter_content);
            self.groups_map.insert(group.id.clone(), group);
        });

        let new_groups = new_group_revs
            .into_iter()
            .flat_map(|group_rev| {
                let filter_content = filter_content_map.get(&group_rev.id)?;
                let group = Group::new(
                    group_rev.id,
                    self.field_rev.id.clone(),
                    group_rev.name,
                    filter_content.clone(),
                );
                Some(GroupPB::from(group))
            })
            .collect();

        let changeset = GroupViewChangesetPB {
            view_id: self.view_id.clone(),
            new_groups,
            deleted_groups: deleted_group_ids,
            update_groups: vec![],
            inserted_groups: vec![],
        };
        tracing::trace!("Group changeset: {:?}", changeset);
        if changeset.is_empty() {
            Ok(None)
        } else {
            Ok(Some(changeset))
        }
    }

    #[allow(dead_code)]
    pub(crate) async fn hide_group(&mut self, group_id: &str) -> FlowyResult<()> {
        self.mut_group_rev(group_id, |group_rev| {
            group_rev.visible = false;
        })?;
        Ok(())
    }

    #[allow(dead_code)]
    pub(crate) async fn show_group(&mut self, group_id: &str) -> FlowyResult<()> {
        self.mut_group_rev(group_id, |group_rev| {
            group_rev.visible = true;
        })?;
        Ok(())
    }

    fn mut_configuration(
        &mut self,
        mut_configuration_fn: impl FnOnce(&mut GroupConfigurationRevision) -> bool,
    ) -> FlowyResult<()> {
        let configuration = Arc::make_mut(&mut self.configuration);
        let is_changed = mut_configuration_fn(configuration);
        if is_changed {
            let configuration = (&*self.configuration).clone();
            let writer = self.writer.clone();
            let field_id = self.field_rev.id.clone();
            let field_type = self.field_rev.ty;
            tokio::spawn(async move {
                match writer.save_configuration(&field_id, field_type, configuration).await {
                    Ok(_) => {}
                    Err(e) => {
                        tracing::error!("Save group configuration failed: {}", e);
                    }
                }
            });
        }
        Ok(())
    }

    fn mut_group_rev(&mut self, group_id: &str, mut_groups_fn: impl Fn(&mut GroupRevision)) -> FlowyResult<()> {
        self.mut_configuration(|configuration| {
            match configuration.groups.iter_mut().find(|group| group.id == group_id) {
                None => false,
                Some(group_rev) => {
                    mut_groups_fn(group_rev);
                    true
                }
            }
        })
    }
}

fn merge_groups(old_groups: Vec<GroupRevision>, new_groups: Vec<GroupRevision>) -> MergeGroupResult {
    let mut merge_result = MergeGroupResult::new();
    // group_map is a helper map is used to filter out the new groups.
    let mut new_group_map: IndexMap<String, GroupRevision> = IndexMap::new();
    new_groups.into_iter().for_each(|group_rev| {
        new_group_map.insert(group_rev.id.clone(), group_rev);
    });

    // The group is ordered in old groups. Add them before adding the new groups
    for old in old_groups {
        if let Some(new) = new_group_map.remove(&old.id) {
            merge_result.all_group_revs.push(new.clone());
            if is_group_changed(&new, &old) {
                merge_result.updated_group_revs.push(new);
            }
        } else {
            merge_result.all_group_revs.push(old);
        }
    }

    // Find out the new groups
    new_group_map.reverse();
    let new_groups = new_group_map.into_values();
    for (_, group) in new_groups.into_iter().enumerate() {
        merge_result.all_group_revs.insert(0, group.clone());
        merge_result.new_group_revs.insert(0, group);
    }
    merge_result
}

fn is_group_changed(new: &GroupRevision, old: &GroupRevision) -> bool {
    if new.name != old.name {
        return true;
    }

    false
}

struct MergeGroupResult {
    // Contains the new groups and the updated groups
    all_group_revs: Vec<GroupRevision>,
    new_group_revs: Vec<GroupRevision>,
    updated_group_revs: Vec<GroupRevision>,
    deleted_group_revs: Vec<GroupRevision>,
}

impl MergeGroupResult {
    fn new() -> Self {
        Self {
            all_group_revs: vec![],
            new_group_revs: vec![],
            updated_group_revs: vec![],
            deleted_group_revs: vec![],
        }
    }
}