use std::borrow::Cow;
use std::collections::HashMap;

use actix_session::Session;
use actix_web::{web, HttpResponse, Responder};
use heck::TitleCase;
use itertools::Itertools;
use json_dotpath::DotPaths;
use serde::Serialize;

use yopa::{data, model, Storage, ID};

use yopa::insert::InsertObj;
use yopa::model::{ObjectModel, PropertyModel, RelationModel};
use yopa::update::UpdateObj;

use crate::session_ext::SessionExt;
use crate::tera_ext::TeraExt;
use crate::utils::{redirect, StorageErrorIntoResponseError};
use crate::TERA;
use yopa::helpers::GroupByModel;

// we only need references here, Context serializes everything to Value.
// cloning would be a waste of cycles

#[derive(Debug, Default, Serialize, Clone)]
pub struct Schema<'a> {
    pub obj_models: Vec<&'a model::ObjectModel>,
    pub rel_models: Vec<&'a model::RelationModel>,
    pub prop_models: Vec<&'a model::PropertyModel>,
}

#[derive(Debug, Clone, Serialize)]
pub struct ObjectDisplay<'a> {
    pub id: ID,
    pub model: ID,
    pub name: Cow<'a, str>,
}

#[derive(Serialize, Debug, Clone)]
pub struct ObjectCreateData<'a> {
    pub model_id: ID,
    pub schema: Schema<'a>,
    pub objects: Vec<ObjectDisplay<'a>>,
}

#[get("/object/create/{model_id}")]
pub(crate) async fn create_form(
    model_id: web::Path<ID>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<impl Responder> {
    let mut context = tera::Context::new();
    session.render_flash(&mut context);

    let rg = store.read().await;

    let model = rg
        .get_object_model(*model_id)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such model"))?;

    context.insert("model", model);

    let form_data = prepare_object_create_data(&rg, model.id)?;

    context.insert("form_data", &form_data);

    TERA.build_response("objects/object_create", &context)
}

fn prepare_object_create_data(rg: &Storage, model_id: ID) -> actix_web::Result<ObjectCreateData> {
    let model = rg
        .get_object_model(model_id)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such model"))?;

    let relations: Vec<_> = rg.get_relation_models_for_object_model(model.id).collect();

    let mut prop_object_ids: Vec<ID> = relations.iter().map(|r| r.id).collect();
    prop_object_ids.push(model.id);

    prop_object_ids.sort();
    prop_object_ids.dedup();

    let mut related_ids: Vec<_> = relations.iter().map(|r| r.related).collect();

    related_ids.sort();
    related_ids.dedup();

    let mut models_to_fetch = vec![model_id];
    models_to_fetch.extend(&related_ids);

    Ok(ObjectCreateData {
        model_id: model.id,
        schema: Schema {
            obj_models: rg.get_object_models_by_ids(models_to_fetch).collect(), // TODO get only the ones that matter here
            rel_models: relations,
            prop_models: rg
                .get_property_models_for_parents(prop_object_ids)
                .collect(),
        },
        objects: rg
            .get_objects_of_types(related_ids)
            .map(|o| ObjectDisplay {
                id: o.id,
                model: o.model,
                name: rg.get_object_name(o),
            })
            .collect(),
    })
}

#[post("/object/create")]
pub(crate) async fn create(
    form: web::Json<InsertObj>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<impl Responder> {
    warn!("{:?}", form);

    let mut wg = store.write().await;
    let form = form.into_inner();

    let model_name = wg.get_model_name(form.model).to_owned().to_title_case();

    match wg.insert_object(form) {
        Ok(id) => {
            wg.persist().err_to_500()?;
            let obj_name = wg.get_object_name_by_id(id);
            debug!("Object created, redirecting to root");
            session.flash_success(format!("{} \"{}\" created.", model_name, obj_name));
            Ok(HttpResponse::Ok().finish())
        }
        Err(e) => {
            warn!("Error creating model: {}", e);
            Ok(HttpResponse::BadRequest().body(e.to_string()))
        }
    }
}

#[derive(Debug, Serialize, Clone)]
struct ModelWithObjects<'a> {
    model: &'a ObjectModel,
    objects: Vec<ObjectDisplay<'a>>,
}

#[get("/objects")]
pub(crate) async fn list(
    session: Session,
    store: crate::YopaStoreWrapper,
) -> actix_web::Result<impl Responder> {
    list_inner(session, store).await
}

pub(crate) async fn list_inner(
    session: Session,
    store: crate::YopaStoreWrapper,
) -> actix_web::Result<HttpResponse> {
    let rg = store.read().await;

    let mut objects_by_model = rg.get_grouped_objects();

    let models: Vec<_> = rg
        .get_object_models()
        .sorted_by_key(|m| &m.name)
        .map(|model| {
            let objects = objects_by_model.remove(&model.id).unwrap_or_default();
            let mut objects = objects
                .into_iter()
                .map(|o| {
                    ObjectDisplay {
                        id: o.id,
                        model: o.model,
                        name: rg.get_object_name(o), // TODO optimize
                    }
                })
                .collect_vec();

            objects.sort_by(|a, b| a.name.cmp(&b.name));
            ModelWithObjects { model, objects }
        })
        .collect();

    let mut ctx = tera::Context::new();
    ctx.insert("models", &models);
    session.render_flash(&mut ctx);

    TERA.build_response("objects/index", &ctx)
}

#[derive(Debug, Serialize)]
struct PropertyView<'a> {
    model: &'a PropertyModel,
    values: Vec<&'a yopa::data::Value>,
}

#[derive(Debug, Serialize)]
struct RelationView<'a> {
    model: &'a RelationModel,
    related_name: &'a str,
    instances: Vec<RelationInstanceView<'a>>,
}

#[derive(Debug, Serialize)]
struct RelationInstanceView<'a> {
    related: ObjectDisplay<'a>,
    related_name: Cow<'a, str>,
    properties: Vec<PropertyView<'a>>,
}

#[get("/object/detail/{id}")]
pub(crate) async fn detail(
    id: web::Path<ID>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<impl Responder> {
    let object_id = *id;

    let mut context = tera::Context::new();
    session.render_flash(&mut context);

    let rg = store.read().await;

    let object = rg
        .get_object(object_id)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such object"))?;

    let model = rg
        .get_object_model(object.model)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such model"))?;

    context.insert(
        "object",
        &ObjectDisplay {
            id: object_id,
            model: object.model,
            name: rg.get_object_name(object),
        },
    );
    context.insert("model", model);
    context.insert("kind", &rg.get_model_name(object.model));

    let relations = rg.get_relations_for_object(object_id).collect_vec();
    let reci_relations = rg
        .get_reciprocal_relations_for_object(object_id)
        .collect_vec();

    // values by parent ID
    let mut ids_to_get_values_for = relations.iter().map(|r| r.id).collect_vec();
    ids_to_get_values_for.extend(reci_relations.iter().map(|r| r.id));
    ids_to_get_values_for.push(object_id);

    let mut grouped_values = rg.get_grouped_values_for_objects(ids_to_get_values_for);

    // object's own properties
    {
        let object_values_by_model = grouped_values
            .remove(&object_id)
            .unwrap_or_default()
            .group_by_model();

        let mut view_object_properties = vec![];
        for (prop_model_id, values) in object_values_by_model {
            view_object_properties.push(PropertyView {
                model: rg.get_property_model(prop_model_id).unwrap(),
                values,
            })
        }

        view_object_properties.sort_by_key(|p| &p.model.name);

        context.insert("properties", &view_object_properties);
    }

    // go through relations
    {
        let grouped_relations = relations
            .iter()
            .group_by_model();

        let mut relation_views = vec![];
        for (model_id, relations) in grouped_relations {
            let mut instances = vec![];

            for rel in relations {
                let related_obj = match rg.get_object(rel.related) {
                    None => continue,
                    Some(obj) => obj,
                };

                let rel_values_by_model = grouped_values
                    .remove(&rel.id)
                    .unwrap_or_default()
                    .group_by_model();

                let mut view_rel_properties = vec![];
                for (prop_model_id, values) in rel_values_by_model {
                    view_rel_properties.push(PropertyView {
                        model: rg.get_property_model(prop_model_id).unwrap(),
                        values,
                    })
                }

                view_rel_properties.sort_by_key(|p| &p.model.name);

                let related_name = rg.get_object_name(related_obj);

                instances.push(RelationInstanceView {
                    related: ObjectDisplay {
                        id: related_obj.id,
                        model: related_obj.model,
                        name: rg.get_object_name(related_obj),
                    },
                    related_name,
                    properties: view_rel_properties,
                })
            }

            instances.sort_by(|a, b| a.related_name.cmp(&b.related_name));

            relation_views.push(RelationView {
                model: rg.get_relation_model(model_id).unwrap(),
                related_name: rg.get_model_name(model_id),
                instances,
            })
        }

        relation_views.sort_by_key(|r| &r.model.name);

        context.insert("relations", &relation_views);
    }

    // near-copypasta for reciprocal
    {
        let grouped_relations = reci_relations
            .iter()
            .group_by_model();

        let mut relation_views = vec![];
        for (model_id, relations) in grouped_relations {
            let mut instances = vec![];

            for rel in relations {
                let related_obj = match rg.get_object(rel.object) {
                    None => continue,
                    Some(obj) => obj,
                };

                let rel_values_by_model = grouped_values
                    .remove(&rel.id)
                    .unwrap_or_default()
                    .group_by_model();

                let mut view_rel_properties = vec![];
                for (prop_model_id, values) in rel_values_by_model {
                    view_rel_properties.push(PropertyView {
                        model: rg.get_property_model(prop_model_id).unwrap(),
                        values,
                    })
                }

                view_rel_properties.sort_by_key(|p| &p.model.name);

                let related_name = rg.get_object_name(related_obj);

                instances.push(RelationInstanceView {
                    related: ObjectDisplay {
                        id: related_obj.id,
                        model: related_obj.model,
                        name: rg.get_object_name(related_obj),
                    },
                    related_name,
                    properties: view_rel_properties,
                })
            }

            // sort_by_key is not possible because rust is still stupid about lifetimes
            instances.sort_by(|a, b| a.related_name.cmp(&b.related_name));

            relation_views.push(RelationView {
                model: rg.get_relation_model(model_id).unwrap(),
                related_name: rg.get_model_name(model_id),
                instances,
            })
        }

        relation_views.sort_by_key(|r| &r.model.reciprocal_name);

        context.insert("reciprocal_relations", &relation_views);
    }

    TERA.build_response("objects/object_detail", &context)
}

#[derive(Serialize, Debug, Clone)]
struct EnrichedObject<'a> {
    id: ID,
    model: ID,
    name: Cow<'a, str>,
    values: HashMap<
        String, /* ID but as string so serde will stop exploding */
        Vec<&'a data::Value>,
    >,
    relations: HashMap<String /* ID */, Vec<EnrichedRelation<'a>>>,
}

#[derive(Serialize, Debug, Clone)]
struct EnrichedRelation<'a> {
    id: ID,
    object: ID,
    model: ID,
    related: ID,
    values: HashMap<String /* ID */, Vec<&'a data::Value>>,
}

#[get("/object/update/{id}")]
pub(crate) async fn update_form(
    id: web::Path<ID>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<impl Responder> {
    let mut context = tera::Context::new();
    session.render_flash(&mut context);

    let rg = store.read().await;

    let object = rg
        .get_object(*id)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such object"))?;

    let model = rg
        .get_object_model(object.model)
        .ok_or_else(|| actix_web::error::ErrorNotFound("Object has no model"))?;

    // maybe its useful,idk
    context.insert("model", &model);
    context.insert(
        "object",
        &ObjectDisplay {
            id: object.id,
            model: object.model,
            name: rg.get_object_name(object),
        },
    );

    let create_data = prepare_object_create_data(&rg, model.id)?;

    let mut value_map = HashMap::new();
    let mut relation_map = HashMap::new();

    // Some properties may have no values, so we first check what IDs to expect
    let prop_ids = create_data
        .schema
        .prop_models
        .iter()
        .filter(|p| p.object == model.id)
        .map(|p| p.id)
        .collect_vec();

    let mut values_grouped = rg.get_values_for_object(*id)
        .group_by_model();

    prop_ids.into_iter().for_each(|id| {
        value_map.insert(
            id.to_string(),
            values_grouped.remove(&id).unwrap_or_default(),
        );
    });

    {
        // Some properties may have no values, so we first check what IDs to expect
        let relation_model_ids = create_data
            .schema
            .rel_models
            .iter()
            .filter(|p| p.object == model.id)
            .map(|p| p.id)
            .collect_vec();

        let relations = rg.get_relations_for_object(*id).collect_vec();
        let relation_ids = relations.iter().map(|r| r.id).collect_vec();

        let mut relations_grouped_by_model = relations
            .iter()
            .group_by_model();

        let mut property_models_grouped_by_parent =
            rg.get_grouped_prop_models_for_parents(relation_model_ids.clone());

        let mut relation_values_grouped_by_instance =
            rg.get_grouped_values_for_objects(relation_ids);

        for rel_model_id in relation_model_ids {
            let relations = relations_grouped_by_model
                .remove(&rel_model_id)
                .unwrap_or_default();

            let mut instances = vec![];
            let prop_models_for_relation = property_models_grouped_by_parent
                .remove(&rel_model_id)
                .unwrap_or_default();

            for rel in relations {
                let mut relation_values_map = HashMap::new();

                // values keyed by model
                let mut rel_values = relation_values_grouped_by_instance
                    .remove(&rel.id)
                    .unwrap_or_default()
                    .group_by_model();

                prop_models_for_relation.iter().for_each(|prop_model| {
                    relation_values_map.insert(
                        prop_model.id.to_string(),
                        rel_values.remove(&prop_model.id).unwrap_or_default(),
                    );
                });

                instances.push(EnrichedRelation {
                    id: rel.id,
                    object: rel.object,
                    model: rel.model,
                    related: rel.related,
                    values: relation_values_map,
                });
            }

            relation_map.insert(rel_model_id.to_string(), instances);
        }
    }

    let mut form = serde_json::to_value(create_data)?;

    let object = EnrichedObject {
        id: object.id,
        model: object.model,
        name: rg.get_object_name(object),
        values: value_map,
        relations: relation_map,
    };

    form.dot_remove("model_id").unwrap();
    form.dot_set("object", object).unwrap();
    context.insert("form_data", &form);

    TERA.build_response("objects/object_update", &context)
}

#[post("/object/update/{id}")]
pub(crate) async fn update(
    id: web::Path<ID>,
    form: web::Json<UpdateObj>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<HttpResponse> {
    let mut wg = store.write().await;
    let form = form.into_inner();

    let object = wg
        .get_object(*id)
        .ok_or_else(|| actix_web::error::ErrorNotFound("No such object"))?;

    let model_name = wg.get_model_name(object.model).to_owned().to_title_case();
    let id = object.id;

    match wg.update_object(form) {
        Ok(_id) => {
            wg.persist().err_to_500()?;
            debug!("Object created, redirecting to root");
            session.flash_success(format!(
                "{} \"{}\" updated.",
                model_name,
                wg.get_object_name_by_id(id)
            ));
            Ok(HttpResponse::Ok().finish())
        }
        Err(e) => {
            warn!("Error updating model: {}", e);
            Ok(HttpResponse::BadRequest().body(e.to_string()))
        }
    }
}

#[get("/object/delete/{id}")]
pub(crate) async fn delete(
    id: web::Path<ID>,
    store: crate::YopaStoreWrapper,
    session: Session,
) -> actix_web::Result<impl Responder> {
    let mut wg = store.write().await;

    let name = wg.get_object_name_by_id(*id).to_string();

    match wg.delete_object(*id) {
        Ok(_obj) => {
            wg.persist().err_to_500()?;
            debug!("Object deleted, redirecting to root");
            session.flash_success(format!("Object \"{}\" deleted.", name));
            redirect("/")
        }
        Err(e) => {
            warn!("Error deleting object: {}", e);
            session.flash_error(e.to_string());
            redirect("/") // back?
        }
    }
}