//! Client de l'API du daemon de containers et opérations de cycle de vie.

use std::{collections::HashMap, path::Path, time::Duration};

use bollard::{
    Docker, body_try_stream,
    container::LogOutput,
    errors::Error as BollardError,
    exec::{CreateExecOptions, StartExecOptions, StartExecResults},
    models::{BuildInfo, ContainerCreateBody, NetworkCreateRequest, NetworkDisconnectRequest},
    query_parameters::{
        BuildImageOptions, CreateContainerOptions, RemoveContainerOptions, RemoveImageOptions,
        StartContainerOptions, StopContainerOptions, UploadToContainerOptions,
    },
};
use futures_util::StreamExt;

use crate::{
    consts::{DEFAULT_COMMAND_TIMEOUT, DEFAULT_ENDPOINT, EXIT_CODE_ATTEMPTS, EXIT_CODE_DELAY},
    context::tar_directory_stream,
    errors::ContainerError,
    exec::ExecOutput,
};

/// Un client de l'API du daemon de containers.
#[derive(Debug, Clone)]
pub struct ContainerRuntime {
    docker: Docker,
    endpoint: String,
    timeout: Duration,
}

impl ContainerRuntime {
    /// Se connecte au daemon désigné par `DOCKER_HOST`, ou au socket local par défaut.
    pub fn connect() -> Result<Self, ContainerError> {
        let endpoint =
            std::env::var("DOCKER_HOST").unwrap_or_else(|_| String::from(DEFAULT_ENDPOINT));

        Ok(Self {
            docker: Docker::connect_with_defaults()?,
            endpoint,
            timeout: DEFAULT_COMMAND_TIMEOUT,
        })
    }

    /// Remplace le timeout appliqué aux opérations de build/run/stop/remove.
    pub fn with_timeout(mut self, timeout: Duration) -> Self {
        self.timeout = timeout;
        self
    }

    /// Endpoint du daemon, pour les logs.
    pub fn endpoint(&self) -> &str {
        &self.endpoint
    }

    pub fn timeout(&self) -> Duration {
        self.timeout
    }

    /// Vérifie que le daemon est joignable et répond.
    pub async fn available(&self) -> bool {
        self.docker.ping().await.is_ok()
    }

    /// Exécute une requête du daemon en appliquant le timeout des commandes.
    async fn request<T>(
        &self,
        operation: &str,
        request: impl Future<Output = Result<T, BollardError>>,
    ) -> Result<T, ContainerError> {
        match tokio::time::timeout(self.timeout, request).await {
            Ok(Ok(value)) => Ok(value),
            Ok(Err(source)) => Err(ContainerError::Request { source }),
            Err(_) => Err(ContainerError::Timeout {
                operation: String::from(operation),
                timeout: self.timeout,
            }),
        }
    }

    /// Construit l'image `tag` depuis le contexte `context_dir`.
    pub(crate) async fn build_image(
        &self,
        context_dir: &Path,
        dockerfile: &str,
        tag: &str,
        build_args: &HashMap<String, String>,
    ) -> Result<(), ContainerError> {
        let options = BuildImageOptions {
            dockerfile: String::from(dockerfile),
            t: Some(String::from(tag)),
            buildargs: Some(build_args.clone()),
            rm: true,
            ..Default::default()
        };

        let context = tar_directory_stream(context_dir);
        let mut stream = self
            .docker
            .build_image(options, None, Some(body_try_stream(context)));

        // Le flux porte la progression du build : la dernière erreur signalée par le
        // daemon fait échouer l'opération.
        let consume = async {
            let mut failure = None;

            while let Some(info) = stream.next().await {
                let info: BuildInfo = info?;

                if let Some(message) = info.error_detail.and_then(|detail| detail.message) {
                    failure = Some(message);
                }
            }

            Ok::<_, BollardError>(failure)
        };

        let failure = match tokio::time::timeout(self.timeout, consume).await {
            Ok(Ok(failure)) => failure,
            Ok(Err(source)) => return Err(ContainerError::Request { source }),
            Err(_) => {
                return Err(ContainerError::Timeout {
                    operation: format!("build image `{tag}`"),
                    timeout: self.timeout,
                });
            }
        };

        match failure {
            Some(message) => Err(ContainerError::Build { message }),
            None => Ok(()),
        }
    }

    /// Crée un container, sans le démarrer.
    pub(crate) async fn create_container(
        &self,
        name: &str,
        body: ContainerCreateBody,
    ) -> Result<(), ContainerError> {
        let options = CreateContainerOptions {
            name: Some(String::from(name)),
            ..Default::default()
        };

        self.request(
            "create container",
            self.docker.create_container(Some(options), body),
        )
        .await?;

        Ok(())
    }

    pub(crate) async fn upload_directory(
        &self,
        container: &str,
        destination: &str,
        directory: &Path,
    ) -> Result<(), ContainerError> {
        let options = UploadToContainerOptions {
            path: String::from(destination),
            ..Default::default()
        };

        self.request(
            "upload workspace",
            self.docker.upload_to_container(
                container,
                Some(options),
                body_try_stream(tar_directory_stream(directory)),
            ),
        )
        .await?;

        Ok(())
    }

    pub(crate) async fn start_container(&self, name: &str) -> Result<(), ContainerError> {
        self.request(
            "start container",
            self.docker
                .start_container(name, None::<StartContainerOptions>),
        )
        .await?;

        Ok(())
    }

    /// Exécute une commande dans un container et renvoie sa sortie.
    pub(crate) async fn exec(
        &self,
        container: &str,
        cmd: &[&str],
        user: Option<&str>,
        timeout: Duration,
    ) -> Result<ExecOutput, ContainerError> {
        let config = CreateExecOptions {
            cmd: Some(cmd.iter().map(|arg| String::from(*arg)).collect()),
            user: user.map(String::from),
            attach_stdout: Some(true),
            attach_stderr: Some(true),
            ..Default::default()
        };

        let created = self
            .request("create exec", self.docker.create_exec(container, config))
            .await?;

        let started = self
            .request(
                "start exec",
                self.docker
                    .start_exec(&created.id, None::<StartExecOptions>),
            )
            .await?;

        let StartExecResults::Attached { mut output, .. } = started else {
            return Err(ContainerError::Unexpected(String::from(
                "the daemon detached an exec that was not requested as detached",
            )));
        };

        let mut stdout = String::new();
        let mut stderr = String::new();

        // Le timeout couvre l'exécution de la commande elle-même, pas seulement sa
        // mise en place.
        let collect = async {
            while let Some(message) = output.next().await {
                match message? {
                    LogOutput::StdOut { message } | LogOutput::Console { message } => {
                        stdout.push_str(&String::from_utf8_lossy(&message));
                    }
                    LogOutput::StdErr { message } => {
                        stderr.push_str(&String::from_utf8_lossy(&message));
                    }
                    LogOutput::StdIn { .. } => {}
                }
            }

            Ok::<_, BollardError>(())
        };

        match tokio::time::timeout(timeout, collect).await {
            Ok(Ok(())) => {}
            Ok(Err(source)) => return Err(ContainerError::Request { source }),
            Err(_) => {
                // Le processus continue de tourner dans le container : sans arrêt, il
                // consommerait CPU et mémoire et pourrait encore modifier le workspace
                // pendant toute la durée de vie de la sandbox. L'API n'offre pas de
                // moyen de tuer un exec, on arrête donc le container qui le porte.
                let _ = self.stop_container(container).await;

                return Err(ContainerError::Timeout {
                    operation: format!("exec {}", cmd.join(" ")),
                    timeout,
                });
            }
        }

        // Le code de sortie n'est pas forcément publié au moment où le flux se ferme :
        // on laisse au daemon le temps de le renseigner, sans bloquer indéfiniment.
        // Sans cela, une commande réussie peut être rapportée en échec (code -1) et
        // l'outil renvoie une erreur au modèle à la place du contenu.
        let mut inspected = self
            .request("inspect exec", self.docker.inspect_exec(&created.id))
            .await?;

        for _ in 0..EXIT_CODE_ATTEMPTS {
            if !inspected.running.unwrap_or(false) {
                break;
            }

            tokio::time::sleep(EXIT_CODE_DELAY).await;

            inspected = self
                .request("inspect exec", self.docker.inspect_exec(&created.id))
                .await?;
        }

        Ok(ExecOutput {
            status: inspected.exit_code.unwrap_or(-1) as i32,
            stdout,
            stderr,
        })
    }

    pub(crate) async fn stop_container(&self, name: &str) -> Result<(), ContainerError> {
        let options = StopContainerOptions {
            t: Some(1),
            ..Default::default()
        };

        self.request(
            "stop container",
            self.docker.stop_container(name, Some(options)),
        )
        .await?;

        Ok(())
    }

    /// Supprime un container, ses volumes anonymes et le processus qui y tourne.
    pub(crate) async fn remove_container(&self, name: &str) -> Result<(), ContainerError> {
        let options = RemoveContainerOptions {
            force: true,
            v: true,
            ..Default::default()
        };

        self.request(
            "remove container",
            self.docker.remove_container(name, Some(options)),
        )
        .await?;

        Ok(())
    }

    pub(crate) async fn remove_image(&self, tag: &str) -> Result<(), ContainerError> {
        let options = RemoveImageOptions {
            force: true,
            ..Default::default()
        };

        self.request(
            "remove image",
            self.docker.remove_image(tag, Some(options), None),
        )
        .await?;

        Ok(())
    }

    /// Crée le réseau dédié d'une sandbox.
    pub(crate) async fn create_network(&self, name: &str) -> Result<(), ContainerError> {
        let request = NetworkCreateRequest {
            name: String::from(name),
            ..Default::default()
        };

        self.request("create network", self.docker.create_network(request))
            .await?;

        Ok(())
    }

    /// Détache un container d'un réseau, ce qui coupe sa connectivité.
    pub(crate) async fn disconnect_network(
        &self,
        network: &str,
        container: &str,
    ) -> Result<(), ContainerError> {
        let request = NetworkDisconnectRequest {
            container: String::from(container),
            ..Default::default()
        };

        self.request(
            "disconnect network",
            self.docker.disconnect_network(network, request),
        )
        .await?;

        Ok(())
    }

    pub(crate) async fn remove_network(&self, name: &str) -> Result<(), ContainerError> {
        self.request("remove network", self.docker.remove_network(name))
            .await?;

        Ok(())
    }
}