use actix_web::{web, HttpRequest, HttpResponse};
use meilisearch_lib::tasks::task::{TaskContent, TaskEvent, TaskId};
use meilisearch_lib::tasks::TaskFilter;
use meilisearch_lib::MeiliSearch;
use meilisearch_types::error::ResponseError;
use meilisearch_types::index_uid::IndexUid;
use serde::Deserialize;
use serde_cs::vec::CS;
use serde_json::json;

use crate::analytics::Analytics;
use crate::extractors::authentication::{policies::*, GuardedData};
use crate::extractors::sequential_extractor::SeqHandler;
use crate::task::{TaskListView, TaskStatus, TaskType, TaskView};

use super::{fold_star_or, StarOr};

const DEFAULT_LIMIT: fn() -> usize = || 20;

pub fn configure(cfg: &mut web::ServiceConfig) {
    cfg.service(web::resource("").route(web::get().to(SeqHandler(get_tasks))))
        .service(web::resource("/{task_id}").route(web::get().to(SeqHandler(get_task))));
}

#[derive(Deserialize, Debug)]
#[serde(rename_all = "camelCase", deny_unknown_fields)]
pub struct TaskFilterQuery {
    #[serde(rename = "type")]
    type_: Option<CS<StarOr<TaskType>>>,
    status: Option<CS<StarOr<TaskStatus>>>,
    index_uid: Option<CS<StarOr<IndexUid>>>,
    #[serde(default = "DEFAULT_LIMIT")]
    limit: usize,
    from: Option<TaskId>,
}

#[rustfmt::skip]
fn task_type_matches_content(type_: &TaskType, content: &TaskContent) -> bool {
    matches!((type_, content),
          (TaskType::IndexCreation, TaskContent::IndexCreation { .. })
        | (TaskType::IndexUpdate, TaskContent::IndexUpdate { .. })
        | (TaskType::IndexDeletion, TaskContent::IndexDeletion { .. })
        | (TaskType::DocumentAdditionOrUpdate, TaskContent::DocumentAddition { .. })
        | (TaskType::DocumentDeletion, TaskContent::DocumentDeletion{ .. })
        | (TaskType::SettingsUpdate, TaskContent::SettingsUpdate { .. })
    )
}

#[rustfmt::skip]
fn task_status_matches_events(status: &TaskStatus, events: &[TaskEvent]) -> bool {
    events.last().map_or(false, |event| {
        matches!((status, event),
              (TaskStatus::Enqueued, TaskEvent::Created(_))
            | (TaskStatus::Processing, TaskEvent::Processing(_) | TaskEvent::Batched { .. })
            | (TaskStatus::Succeeded, TaskEvent::Succeeded { .. })
            | (TaskStatus::Failed, TaskEvent::Failed { .. }),
        )
    })
}

async fn get_tasks(
    meilisearch: GuardedData<ActionPolicy<{ actions::TASKS_GET }>, MeiliSearch>,
    params: web::Query<TaskFilterQuery>,
    req: HttpRequest,
    analytics: web::Data<dyn Analytics>,
) -> Result<HttpResponse, ResponseError> {
    analytics.publish(
        "Tasks Seen".to_string(),
        json!({ "per_task_uid": false }),
        Some(&req),
    );

    let TaskFilterQuery {
        type_,
        status,
        index_uid,
        limit,
        from,
    } = params.into_inner();

    let search_rules = &meilisearch.filters().search_rules;

    // We first transform a potential indexUid=* into a "not specified indexUid filter"
    // for every one of the filters: type, status, and indexUid.
    let type_: Option<Vec<_>> = type_.and_then(fold_star_or);
    let status: Option<Vec<_>> = status.and_then(fold_star_or);
    let index_uid: Option<Vec<_>> = index_uid.and_then(fold_star_or);

    // Then we filter on potential indexes and make sure that the search filter
    // restrictions are also applied.
    let indexes_filters = match index_uid {
        Some(indexes) => {
            let mut filters = TaskFilter::default();
            for name in indexes {
                if search_rules.is_index_authorized(&name) {
                    filters.filter_index(name.to_string());
                }
            }
            Some(filters)
        }
        None => {
            if search_rules.is_index_authorized("*") {
                None
            } else {
                let mut filters = TaskFilter::default();
                for (index, _policy) in search_rules.clone() {
                    filters.filter_index(index);
                }
                Some(filters)
            }
        }
    };

    // Then we complete the task filter with other potential status and types filters.
    let filters = if type_.is_some() || status.is_some() {
        let mut filters = indexes_filters.unwrap_or_default();
        filters.filter_fn(move |task| {
            let matches_type = match &type_ {
                Some(types) => types
                    .iter()
                    .any(|t| task_type_matches_content(t, &task.content)),
                None => true,
            };

            let matches_status = match &status {
                Some(statuses) => statuses
                    .iter()
                    .any(|t| task_status_matches_events(t, &task.events)),
                None => true,
            };

            matches_type && matches_status
        });
        Some(filters)
    } else {
        indexes_filters
    };

    // We +1 just to know if there is more after this "page" or not.
    let limit = limit.saturating_add(1);

    let mut tasks_results: Vec<_> = meilisearch
        .list_tasks(filters, Some(limit), from)
        .await?
        .into_iter()
        .map(TaskView::from)
        .collect();

    // If we were able to fetch the number +1 tasks we asked
    // it means that there is more to come.
    let next = if tasks_results.len() == limit {
        tasks_results.pop().map(|t| t.uid)
    } else {
        None
    };

    let from = tasks_results.first().map(|t| t.uid);

    let tasks = TaskListView {
        results: tasks_results,
        limit: limit.saturating_sub(1),
        from,
        next,
    };

    Ok(HttpResponse::Ok().json(tasks))
}

async fn get_task(
    meilisearch: GuardedData<ActionPolicy<{ actions::TASKS_GET }>, MeiliSearch>,
    task_id: web::Path<TaskId>,
    req: HttpRequest,
    analytics: web::Data<dyn Analytics>,
) -> Result<HttpResponse, ResponseError> {
    analytics.publish(
        "Tasks Seen".to_string(),
        json!({ "per_task_uid": true }),
        Some(&req),
    );

    let search_rules = &meilisearch.filters().search_rules;
    let filters = if search_rules.is_index_authorized("*") {
        None
    } else {
        let mut filters = TaskFilter::default();
        for (index, _policy) in search_rules.clone() {
            filters.filter_index(index);
        }
        Some(filters)
    };

    let task: TaskView = meilisearch
        .get_task(task_id.into_inner(), filters)
        .await?
        .into();

    Ok(HttpResponse::Ok().json(task))
}