pub mod followers;

use std::fmt::Display;

use activitypub_federation::{
    activity_queue::queue_activity,
    activity_sending::SendActivityTask,
    config::Data,
    fetch::object_id::ObjectId,
    http_signatures::generate_actor_keypair,
    kinds::actor::{ApplicationType, GroupType, OrganizationType, PersonType, ServiceType},
    protocol::{context::WithContext, public_key::PublicKey},
    traits::{Activity, Actor, Object},
};
use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use sqlx::types::time::OffsetDateTime;
use stack_up::{Environment, Services};
use tracing::trace;
use url::Url;
use uuid::Uuid;

use crate::{error::AppError, state::AppHandle};

#[derive(PartialEq, Clone, Debug)]
pub struct User {
    pub id: String,
    pub username: String,
    pub ap_id: ObjectId<User>,
    pub private_key: Option<String>,
    pub description: Option<String>,
    pub avatar_url: Option<String>,
    pub public_key: String,
    pub inbox: Url,
    pub outbox: Option<Url>,
    pub user_type: UserType,
}

pub struct DbUser {
    pub id: String,
    pub description: Option<String>,
    pub username: String,
    pub ap_id: String,
    pub private_key: Option<String>,
    pub public_key: String,
    pub inbox: String,
    pub outbox: Option<String>,
    pub avatar_url: Option<String>,
    pub local: bool,
    pub updated_at: OffsetDateTime,
    pub created_at: OffsetDateTime,
    pub user_type: UserType,
}

#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
#[serde(rename_all = "PascalCase")]
#[serde(untagged)]
pub enum UserType {
    Person(PersonType),
    Application(ApplicationType),
    Group(GroupType),
    Organization(OrganizationType),
    Service(ServiceType),
}

impl Display for UserType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "{}",
            match self {
                UserType::Person(person) => person.to_string(),
                UserType::Application(application_type) => application_type.to_string(),
                UserType::Group(group_type) => group_type.to_string(),
                UserType::Organization(organization_type) => organization_type.to_string(),
                UserType::Service(service_type) => service_type.to_string(),
            }
            .to_uppercase()
        )
    }
}

impl From<String> for UserType {
    fn from(value: String) -> Self {
        match value.to_lowercase().as_str() {
            "person" => Self::Person(PersonType::Person),
            "application" => Self::Application(ApplicationType::Application),
            "group" => Self::Group(GroupType::Group),
            "organization" => Self::Organization(OrganizationType::Organization),
            "service" => Self::Service(ServiceType::Service),
            _ => unreachable!("{}", value),
        }
    }
}

impl TryFrom<DbUser> for User {
    type Error = AppError;
    fn try_from(value: DbUser) -> Result<Self, Self::Error> {
        Ok(Self {
            id: value.id,
            username: value.username,
            ap_id: Url::parse(&value.ap_id)?.into(),
            private_key: value.private_key,
            public_key: value.public_key,
            inbox: Url::parse(&value.inbox)?,
            outbox: match value.outbox {
                Some(ref url) => Some(Url::parse(url)?),
                None => None,
            },
            description: value.description,
            avatar_url: value.avatar_url,
            user_type: value.user_type,
        })
    }
}

impl User {
    pub async fn new(
        username: &str,
        hostname: &str,
        services: &Services,
        environment: Environment,
    ) -> Result<Self, AppError> {
        trace!(username = ?username, "checking for system user");

        let user = sqlx::query_as!(
            DbUser,
            "select * from account where username = $1 and local = $2",
            username,
            true
        )
        .fetch_optional(&services.postgres)
        .await?;

        if let Some(user) = user {
            trace!(username = ?username, "system user exists");
            return Self::try_from(user);
        } else {
            trace!(username = ?username, "system user does not exist. creating");
        }

        trace!("creating keypair for new user");
        let keys = generate_actor_keypair()?;
        let stub = &format!(
            "{}://{hostname}/users/{username}",
            match environment {
                Environment::Development => "http",
                Environment::Production => "https",
            }
        );
        let id = Uuid::now_v7();

        let kind = UserType::Service(ServiceType::Service);

        trace!(id = ?id, "creating a new user");
        let user = sqlx::query_as!(
            DbUser,
            "insert into account (id, username, ap_id, private_key, public_key, inbox, outbox, local, user_type) values ($1, $2, $3, $4, $5, $6, $7, $8, $9) returning *",
            id,
            username,
            stub,
            keys.private_key,
            keys.public_key,
            &format!("{stub}/inbox"),
            &format!("{stub}/outbox"),
            true,
            kind.to_string(),
        ).fetch_one(&services.postgres).await?;
        Self::try_from(user)
    }

    pub(crate) async fn send<A>(
        &self,
        activity: A,
        recipients: Vec<Url>,
        use_queue: bool,
        data: &Data<AppHandle>,
    ) -> Result<(), AppError>
    where
        A: Activity + Serialize + std::fmt::Debug + Send + Sync,
        <A as Activity>::Error: From<anyhow::Error> + From<serde_json::Error>,
    {
        let activity = WithContext::new_default(activity);
        // Send through queue in some cases and bypass it in others to test both code paths
        if use_queue {
            queue_activity(&activity, self, recipients, data).await?;
        } else {
            let sends = SendActivityTask::prepare(&activity, self, recipients, data).await?;
            for send in sends {
                send.sign_and_send(data).await?;
            }
        }
        Ok(())
    }
}

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct Person {
    #[serde(rename = "type")]
    kind: UserType,
    preferred_username: String,
    id: ObjectId<User>,
    inbox: Url,
    public_key: PublicKey,
    #[serde(skip_serializing_if = "Option::is_none")]
    outbox: Option<Url>,
    followers: Url,
    following: Url,
    #[serde(skip_serializing_if = "Option::is_none")]
    summary: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    image: Option<Url>,
}

#[async_trait]
impl Object for User {
    #[doc = " App data type passed to handlers. Must be identical to"]
    #[doc = " [crate::config::FederationConfigBuilder::app_data] type."]
    type DataType = AppHandle;

    #[doc = " The type of protocol struct which gets sent over network to federate this database struct."]
    type Kind = Person;

    #[doc = " Error type returned by handler methods"]
    type Error = AppError;

    #[doc = " `id` field of the object"]
    fn id(&self) -> &Url {
        self.ap_id.inner()
    }

    #[doc = " Try to read the object with given `id` from local database."]
    #[doc = " Should return `Ok(None)` if not found."]
    async fn read_from_id(
        object_id: Url,
        data: &Data<Self::DataType>,
    ) -> Result<Option<Self>, Self::Error> {
        let id = object_id.as_str();
        let result = sqlx::query_as!(DbUser, "select * from account where ap_id = $1", id)
            .fetch_optional(&data.services.postgres)
            .await?;
        let user = match result {
            Some(user) => Some(User::try_from(user)?),
            None => None,
        };
        Ok(user)
    }

    #[doc = " Convert database type to Activitypub type."]
    #[doc = " Called when a local object gets fetched by another instance over HTTP, or when an object"]
    #[doc = " gets sent in an activity."]
    async fn into_json(self, data: &Data<Self::DataType>) -> Result<Self::Kind, Self::Error> {
        Ok(Person {
            preferred_username: self.username.clone(),
            kind: self.user_type.clone(),
            id: self.ap_id.clone(),
            inbox: self.inbox.clone(),
            public_key: self.public_key(),
            outbox: self.outbox.clone(),
            followers: Url::parse(&format!("{}/followers", self.ap_id))?,
            following: Url::parse(&format!("{}/following", self.ap_id))?,
            summary: self.description,
            image: match self.avatar_url {
                Some(ref v) => Some(Url::parse(v)?),
                None => None,
            },
        })
    }

    #[doc = " Verifies that the received object is valid."]
    #[doc = " You should check here that the domain of id matches `expected_domain`. Additionally you"]
    #[doc = " should perform any application specific checks."]
    #[doc = " It is necessary to use a separate method for this, because it might be used for activities"]
    #[doc = " like `Delete/Note`, which shouldn\'t perform any database write for the inner `Note`."]
    async fn verify(
        json: &Self::Kind,
        expected_domain: &Url,
        data: &Data<Self::DataType>,
    ) -> Result<(), Self::Error> {
        todo!()
    }

    #[doc = " Convert object from ActivityPub type to database type."]
    #[doc = " Called when an object is received from HTTP fetch or as part of an activity. This method"]
    #[doc = " should write the received object to database. Note that there is no distinction between"]
    #[doc = " create and update, so an `upsert` operation should be used."]
    async fn from_json(json: Self::Kind, data: &Data<Self::DataType>) -> Result<Self, Self::Error> {
        Ok(Self {
            id: todo!(),
            username: todo!(),
            ap_id: todo!(),
            private_key: todo!(),
            description: todo!(),
            avatar_url: todo!(),
            public_key: todo!(),
            inbox: todo!(),
            outbox: todo!(),
            user_type: todo!(),
        })
    }
}

impl Actor for User {
    fn public_key_pem(&self) -> &str {
        &self.public_key
    }

    fn private_key_pem(&self) -> Option<String> {
        self.private_key.clone()
    }

    fn inbox(&self) -> Url {
        self.inbox.clone()
    }
}