//! Docker implementation of the sandbox driver (bollard). Serves local
//! development and the air-gapped compose target; podman works through the
//! same API via `DOCKER_HOST`.

use bollard::exec::{CreateExecOptions, ResizeExecOptions, StartExecResults};
use bollard::models::{ContainerCreateBody, HostConfig, Mount, MountTypeEnum, MountVolumeOptions};
use bollard::query_parameters::{
    CreateContainerOptions, InspectContainerOptions, RemoveContainerOptions, StartContainerOptions,
};
use bollard::Docker;
use futures::StreamExt;

use crate::spec::{ExecResult, ManagedSandbox, PtySession, SandboxHandle, SandboxSpec};
use crate::{SandboxDriver, SandboxError};

/// The seccomp deny profile, embedded so the Docker path needs no file
/// distribution (single source of truth: images/seccomp/agent-profile.json).
const SECCOMP_PROFILE: &str = include_str!("../../../images/seccomp/agent-profile.json");

pub struct DockerDriver {
    docker: Docker,
}

impl DockerDriver {
    pub fn connect() -> Result<DockerDriver, SandboxError> {
        // DOCKER_HOST (set in compose to the allow-listed socket proxy)
        // wins; otherwise the local socket.
        if let Ok(host) = std::env::var("DOCKER_HOST") {
            return DockerDriver::connect_to(&host);
        }
        let docker = Docker::connect_with_local_defaults()
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        Ok(DockerDriver { docker })
    }

    /// Connects to a specific engine endpoint, e.g. the compose
    /// deployment's allow-listed socket proxy (`tcp://socket-proxy:2375`).
    pub fn connect_to(host: &str) -> Result<DockerDriver, SandboxError> {
        let docker = Docker::connect_with_http(host, 30, bollard::API_DEFAULT_VERSION)
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        Ok(DockerDriver { docker })
    }

    /// Removes a container by name if it exists (test/restart hygiene).
    pub async fn destroy_by_name(&self, name: &str) -> Result<(), SandboxError> {
        self.docker
            .remove_container(
                name,
                Some(RemoveContainerOptions {
                    force: true,
                    ..Default::default()
                }),
            )
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))
    }
}

#[async_trait::async_trait]
impl SandboxDriver for DockerDriver {
    async fn provision(&self, spec: &SandboxSpec) -> Result<SandboxHandle, SandboxError> {
        // Hardened tool sandboxes are read-only with a tmpfs home; the Terminal
        // flavour keeps a writable rootfs + home so its baked zsh/oh-my-zsh/p10k
        // config and shell history survive the session. Everything else (non-root,
        // cap-drop ALL, seccomp, no-new-privileges, limits) stays identical.
        let writable = spec.kind.writable_home();
        let tmpfs = if writable {
            None
        } else {
            Some(
                [
                    (
                        "/tmp".to_owned(),
                        "rw,noexec,nosuid,size=67108864".to_owned(),
                    ),
                    // Writable workspace; everything else is read-only.
                    (
                        "/home/agent".to_owned(),
                        "rw,nosuid,size=268435456,uid=10001,gid=10001".to_owned(),
                    ),
                ]
                .into_iter()
                .collect(),
            )
        };
        // Per-agent volume-subpath mounts (the Terminal's Files drives).
        let mounts: Option<Vec<Mount>> = if spec.mounts.is_empty() {
            None
        } else {
            Some(
                spec.mounts
                    .iter()
                    .map(|m| Mount {
                        target: Some(m.target.clone()),
                        source: Some(m.volume.clone()),
                        typ: Some(MountTypeEnum::VOLUME),
                        read_only: Some(m.read_only),
                        // An empty subpath ⇒ mount the whole volume at the target
                        // (the per-agent node-local drive volume, auto-created by
                        // Docker). A non-empty subpath is per-agent isolation within
                        // the shared gateway volume.
                        volume_options: if m.subpath.is_empty() {
                            None
                        } else {
                            Some(MountVolumeOptions {
                                subpath: Some(m.subpath.clone()),
                                ..Default::default()
                            })
                        },
                        ..Default::default()
                    })
                    .collect(),
            )
        };
        // The §15 controls, enforced unconditionally:
        let host_config = HostConfig {
            cap_drop: Some(vec!["ALL".into()]),
            security_opt: Some(vec![
                "no-new-privileges:true".into(),
                format!("seccomp={SECCOMP_PROFILE}"),
            ]),
            readonly_rootfs: Some(!writable),
            tmpfs,
            mounts,
            network_mode: Some(if spec.egress { "bridge" } else { "none" }.into()),
            // Lets browser containers reach host-published test pages on
            // Linux engines; Docker Desktop resolves this name natively.
            extra_hosts: if spec.egress {
                Some(vec!["host.docker.internal:host-gateway".into()])
            } else {
                None
            },
            memory: Some(spec.memory_bytes),
            nano_cpus: Some(spec.nano_cpus),
            pids_limit: Some(spec.pids_limit),
            // Run tini as PID 1 so it reaps re-parented children (Chromium
            // spawns short-lived helper/crashpad processes). `sleep infinity`
            // never wait()s, so without this they accumulate as zombies and
            // eventually exhaust `pids_limit` in long-lived browser sandboxes.
            init: Some(true),
            ..Default::default()
        };
        let body = ContainerCreateBody {
            image: Some(spec.image.clone()),
            user: Some(spec.kind.run_user().into()),
            cmd: Some(vec!["sleep".into(), "infinity".into()]),
            host_config: Some(host_config),
            // Mark every sandbox so the reaper can find orphans after a crash.
            labels: Some(std::collections::HashMap::from([(
                crate::SANDBOX_LABEL.to_string(),
                spec.kind.label().to_string(),
            )])),
            ..Default::default()
        };

        let created = self
            .docker
            .create_container(
                Some(CreateContainerOptions {
                    name: Some(spec.name.clone()),
                    ..Default::default()
                }),
                body,
            )
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        self.docker
            .start_container(&created.id, None::<StartContainerOptions>)
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        Ok(SandboxHandle {
            id: created.id,
            name: spec.name.clone(),
        })
    }

    async fn exec(&self, handle: &SandboxHandle, cmd: &[&str]) -> Result<ExecResult, SandboxError> {
        let exec = self
            .docker
            .create_exec(
                &handle.id,
                CreateExecOptions {
                    cmd: Some(cmd.iter().map(|s| s.to_string()).collect()),
                    attach_stdout: Some(true),
                    attach_stderr: Some(true),
                    ..Default::default()
                },
            )
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;

        let mut stdout = String::new();
        let mut stderr = String::new();
        match self
            .docker
            .start_exec(&exec.id, None)
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?
        {
            StartExecResults::Attached { mut output, .. } => {
                while let Some(chunk) = output.next().await {
                    match chunk.map_err(|e| SandboxError::Engine(e.to_string()))? {
                        bollard::container::LogOutput::StdOut { message } => {
                            stdout.push_str(&String::from_utf8_lossy(&message));
                        }
                        bollard::container::LogOutput::StdErr { message } => {
                            stderr.push_str(&String::from_utf8_lossy(&message));
                        }
                        _ => {}
                    }
                }
            }
            StartExecResults::Detached => {}
        }

        let inspect = self
            .docker
            .inspect_exec(&exec.id)
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        Ok(ExecResult {
            exit_code: inspect.exit_code.unwrap_or(-1),
            stdout,
            stderr,
        })
    }

    async fn attach_pty(
        &self,
        handle: &SandboxHandle,
        cmd: &[&str],
        cols: u16,
        rows: u16,
        env: &[String],
    ) -> Result<PtySession, SandboxError> {
        let exec = self
            .docker
            .create_exec(
                &handle.id,
                CreateExecOptions {
                    cmd: Some(cmd.iter().map(|s| s.to_string()).collect()),
                    env: if env.is_empty() {
                        None
                    } else {
                        Some(env.to_vec())
                    },
                    attach_stdin: Some(true),
                    attach_stdout: Some(true),
                    attach_stderr: Some(true),
                    tty: Some(true),
                    ..Default::default()
                },
            )
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;

        match self
            .docker
            .start_exec(&exec.id, None)
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?
        {
            StartExecResults::Attached { output, input } => {
                // Best-effort initial window size; resize_pty handles later changes.
                let _ = self
                    .docker
                    .resize_exec(
                        &exec.id,
                        ResizeExecOptions {
                            height: rows,
                            width: cols,
                        },
                    )
                    .await;
                let bytes = output.map(|chunk| {
                    chunk
                        .map(|log| log.into_bytes().to_vec())
                        .map_err(|e| SandboxError::Engine(e.to_string()))
                });
                Ok(PtySession {
                    exec_id: exec.id,
                    output: Box::pin(bytes),
                    input,
                })
            }
            StartExecResults::Detached => Err(SandboxError::Engine(
                "pty exec detached unexpectedly".into(),
            )),
        }
    }

    async fn resize_pty(&self, exec_id: &str, cols: u16, rows: u16) -> Result<(), SandboxError> {
        self.docker
            .resize_exec(
                exec_id,
                ResizeExecOptions {
                    height: rows,
                    width: cols,
                },
            )
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))
    }

    async fn destroy(&self, handle: &SandboxHandle) -> Result<(), SandboxError> {
        self.destroy_by_name(&handle.id).await
    }

    async fn health(&self, handle: &SandboxHandle) -> Result<bool, SandboxError> {
        match self
            .docker
            .inspect_container(&handle.id, None::<InspectContainerOptions>)
            .await
        {
            Ok(info) => Ok(info.state.and_then(|s| s.running).unwrap_or(false)),
            Err(bollard::errors::Error::DockerResponseServerError {
                status_code: 404, ..
            }) => Ok(false),
            Err(e) => Err(SandboxError::Engine(e.to_string())),
        }
    }

    async fn list_managed(&self, kind: &str) -> Result<Vec<ManagedSandbox>, SandboxError> {
        use bollard::query_parameters::ListContainersOptions;
        let mut filters = std::collections::HashMap::new();
        filters.insert(
            "label".to_string(),
            vec![format!("{}={}", crate::SANDBOX_LABEL, kind)],
        );
        let opts = ListContainersOptions {
            all: true, // include stopped/exited orphans too
            filters: Some(filters),
            ..Default::default()
        };
        let list = self
            .docker
            .list_containers(Some(opts))
            .await
            .map_err(|e| SandboxError::Engine(e.to_string()))?;
        Ok(list
            .into_iter()
            .filter_map(|c| {
                c.id.map(|id| ManagedSandbox {
                    id,
                    created_unix: c.created.unwrap_or(0),
                })
            })
            .collect())
    }
}