//! Prepare [cloud-init][] configuration.
//!
//! The configuration is provided to cloud-init via the "NoCloud"
//! route, using an ISO image file.
//!
//! [cloud-init]: https://cloud-init.io/

use crate::spec::{Specification, SpecificationError};
use crate::sshkeys::{CaKey, KeyError, KeyKind, KeyPair};
use log::debug;
use serde::{Deserialize, Serialize};
use shell_words::quote;
use std::default::Default;
use std::fs::write;
// use std::os::unix::fs::PermissionsExt;
use std::path::Path;
use std::process::Command;
use tempfile::tempdir;

const SCRIPT: &str = r#"
import os
import yaml


def log(msg):
    logfile.write(msg)
    logfile.write("\n")
    logfile.flush()


logfile = open("/tmp/vmadm.script", "w")
log("vmadm cloud-init script starting")

if os.environ.get("VMADM_TESTING"):
    filename = "smoke/user-data"
    etc = "x"
else:
    filename = "/var/lib/cloud/instance/user-data.txt"
    etc = "/etc/ssh"

key_types = ("rsa", "dsa", "ecdsa", "ed25519")

log(f"loading user-data from {filename}")
obj = yaml.safe_load(open(filename))

ssh_keys = obj.get("ssh_keys", {})
# log(f"ssh_keys: {json.dumps(ssh_keys)}")

keys = []
certs = []

for key_type in key_types:
    filename = os.path.join(etc, f"ssh_host_{key_type}_key.pub")
    if os.path.exists(filename):
        log(f"removing {filename}")
        os.remove(filename)
    else:
        log(f"file {filename} does not exist")

for key_type in key_types:
    key = ssh_keys.get(f"{key_type}_private")
    cert = ssh_keys.get(f"{key_type}_certificate")
    log(f"key {key_type} {key}")
    log(f"cert {key_type} {cert }")

    if key:
        filename = os.path.join(etc, f"ssh_host_{key_type}_key")
        log(f"writing key {filename}")
        keys.append(filename)
        with open(filename, "w") as f:
            f.write(key)

    if cert:
        filename = os.path.join(etc, f"ssh_host_{key_type}_key-cert.pub")
        log(f"writing cert {filename}")
        certs.append(filename)
        with open(filename, "w") as f:
            f.write(cert)

config = os.path.join(etc, "sshd_config")
data = ""
if os.path.exists(config):
    data = open(config).read()

log(f"configuring sshd {config}")
log(f"keys {keys}")
log(f"certs {certs}")

with open(config, "w") as f:
    for filename in keys:
        log(f"hostkey {filename}")
        f.write(f"hostkey {filename}\n")
    for filename in certs:
        log(f"hostcert {filename}")
        f.write(f"hostcertificate {filename}\n")
    f.write(data)

log("vmadm cloud-init script ending")
logfile.close()
"#;

/// Errors from this module.
#[derive(Debug, thiserror::Error)]
pub enum CloudInitError {
    /// CA key is not specified.
    #[error("Host certificate requested, but no CA key specified")]
    NoCAKey,

    /// Something went wrong creating ISO image with configuration.
    #[error("failed to create ISO image with genisoimage: {0}")]
    IsoFailed(String),

    /// Error in the specification.
    #[error(transparent)]
    SpecificationError(#[from] SpecificationError),

    /// Error in generating SSH host key or certificate.
    #[error(transparent)]
    KeyError(#[from] KeyError),

    /// Something went wrong doing I/O.
    #[error(transparent)]
    IoError(#[from] std::io::Error),

    /// Something went wrong parsing a string as UTF8.
    #[error(transparent)]
    StringError(#[from] std::string::FromUtf8Error),

    /// Something went wrong parsing or serializing to YAML.
    #[error(transparent)]
    SerdeError(#[from] serde_yaml::Error),
}

#[derive(Clone, Debug, Serialize)]
#[serde(rename_all = "kebab-case")]
struct Metadata {
    local_hostname: String,
}

impl Metadata {
    fn from(spec: &Specification) -> Self {
        Self {
            local_hostname: spec.name.to_string(),
        }
    }

    fn as_yaml(&self) -> Result<String, serde_yaml::Error> {
        let yaml = serde_yaml::to_string(self)?;
        let yaml = cleanup_document(&yaml);
        Ok(format!("# Amazon EC2 style metadata\n{}", &yaml))
    }
}

fn cleanup_document(doc: &str) -> String {
    let doc = doc.strip_prefix("---\n").or(Some(doc)).unwrap();
    let doc = doc.strip_suffix("\n").or(Some(doc)).unwrap();
    doc.to_string()
}

#[derive(Clone, Debug, Serialize)]
struct Userdata {
    ssh_authorized_keys: Vec<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    ssh_keys: Option<Hostkeys>,

    runcmd: Vec<String>,
}

impl Userdata {
    fn from(spec: &Specification) -> Result<Self, CloudInitError> {
        Ok(Self {
            ssh_authorized_keys: spec.ssh_keys.clone(),
            ssh_keys: Hostkeys::from(spec)?,
            runcmd: vec![
                format!("python3 -c {}", quote(SCRIPT)),
                "systemctl reload ssh".to_string(),
            ],
        })
    }

    fn as_yaml(&self) -> Result<String, serde_yaml::Error> {
        let yaml = serde_yaml::to_string(self)?;
        let yaml = cleanup_document(&yaml);
        debug!("userdata self:\n{:#?}", self);
        debug!("userdata yaml:\n{}", yaml);
        Ok(format!("#cloud-config\n{}", &yaml))
    }
}

#[derive(Clone, Debug, Deserialize, Serialize, Default)]
struct Hostkeys {
    #[serde(skip_serializing_if = "Option::is_none")]
    rsa_private: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    rsa_certificate: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    dsa_private: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    dsa_certificate: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    ecdsa_private: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    ecdsa_certificate: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    ed25519_private: Option<String>,

    #[serde(skip_serializing_if = "Option::is_none")]
    ed25519_certificate: Option<String>,
}

impl Hostkeys {
    fn from(spec: &Specification) -> Result<Option<Self>, CloudInitError> {
        let rsa = spec.rsa_host_key.clone();
        let rsa_cert = spec.rsa_host_cert.clone();

        let dsa = spec.dsa_host_key.clone();
        let dsa_cert = spec.dsa_host_cert.clone();

        let ecdsa = spec.ecdsa_host_key.clone();
        let ecdsa_cert = spec.ecdsa_host_cert.clone();

        let ed25519 = spec.ed25519_host_key.clone();
        let ed25519_cert = spec.ed25519_host_cert.clone();

        if rsa.is_some() || dsa.is_some() || ecdsa.is_some() || ed25519.is_some() {
            debug!("At least one host key specified");
            Ok(Some(Self {
                rsa_private: rsa,
                rsa_certificate: rsa_cert,
                dsa_private: dsa,
                dsa_certificate: dsa_cert,
                ecdsa_private: ecdsa,
                ecdsa_certificate: ecdsa_cert,
                ed25519_private: ed25519,
                ed25519_certificate: ed25519_cert,
            }))
        } else if spec.generate_host_certificate {
            if spec.ca_key.is_none() {
                debug!("No CA key specified");
                return Err(CloudInitError::NoCAKey);
            }
            if let Some(filename) = &spec.ca_key {
                debug!("Generating host key and certificate");
                let ca = CaKey::from_file(&filename)?;
                let pair = KeyPair::generate(KeyKind::Ed25519)?;
                let cert = ca.certify_host(&pair, &spec.name)?;
                debug!("generated Ed25519 host certificate {:?}", cert);
                Ok(Some(Self {
                    ed25519_private: Some(pair.private().to_string()),
                    ed25519_certificate: Some(cert),
                    ..Self::default()
                }))
            } else {
                Ok(None)
            }
        } else {
            debug!("No host keys specified, no host certificate wanted");
            Ok(None)
        }
    }
}

/// Full cloud-init configuration.
#[derive(Clone, Debug)]
pub struct CloudInitConfig {
    metadata: Metadata,
    userdata: Userdata,
}

impl CloudInitConfig {
    /// Create from a specification.
    pub fn from(spec: &Specification) -> Result<Self, CloudInitError> {
        let metadata = Metadata::from(spec);
        let userdata = Userdata::from(spec)?;
        Ok(CloudInitConfig { metadata, userdata })
    }

    /// Debugging aid: dump cloud-init to stdout.
    pub fn dump(&self) {
        println!("==== meta-data:\n{}", self.metadata().unwrap());
        println!("==== user-data:\n{}", self.userdata().unwrap());
    }

    fn metadata(&self) -> Result<String, serde_yaml::Error> {
        Ok(self.metadata.as_yaml()?)
    }

    fn userdata(&self) -> Result<String, serde_yaml::Error> {
        Ok(self.userdata.as_yaml()?)
    }

    /// Put cloud-init configuration into a named directory.
    ///
    /// The files `meta-data` and `user-data` will be stored in the
    /// directory. cloud-init reads them on first boot and makes
    /// appropriate changes the host's configuration.
    pub fn create_dir(&self, path: &Path) -> Result<(), CloudInitError> {
        let metadata = path.join("meta-data");
        debug!("writing metadata to {}", metadata.display());
        write(&metadata, self.metadata()?)?;

        let userdata = path.join("user-data");
        debug!("writing userdata to {}", userdata.display());
        write(&userdata, self.userdata()?)?;

        // let scriptsdir = path.join("scripts/per-once");
        // let script = scriptsdir.join("vmadm-configure-sshd");
        // std::fs::create_dir_all(&scriptsdir)?;
        // debug!("writing script to {}", script.display());
        // write(&script, SCRIPT)?;
        // let mut permissions = std::fs::metadata(&script)?.permissions();
        // permissions.set_mode(0o755);
        // debug!("setting permissions on {:?} to {:?}", script, permissions);
        // std::fs::set_permissions(&script, permissions)?;

        Ok(())
    }

    /// Create an ISO disk image file with the cloud-init configuration.
    ///
    /// The image will be attached to the VM when it starts.
    /// cloud-init finds it via the volume ID (file system label).
    pub fn create_iso(&self, filename: &Path) -> Result<(), CloudInitError> {
        let dir = tempdir()?;
        self.create_dir(dir.path())?;

        let r = Command::new("genisoimage")
            .arg("-quiet")
            .arg("-volid")
            .arg("cidata")
            .arg("-joliet")
            .arg("-rock")
            .arg("-output")
            .arg(filename)
            .arg(dir.path())
            .output()?;
        if !r.status.success() {
            let stderr = String::from_utf8(r.stderr)?;
            return Err(CloudInitError::IsoFailed(stderr));
        }
        Ok(())
    }
}