use std::path::PathBuf;

use anyhow::{bail, format_err, Error};
use serde_json::Value;

use proxmox::api::api;
use proxmox::api::cli::{
    ColumnConfig,
    CliCommand,
    CliCommandMap,
    format_and_print_result_full,
    get_output_format,
    OUTPUT_FORMAT,
};
use proxmox::api::router::ReturnType;
use proxmox::sys::linux::tty;
use proxmox::tools::fs::{file_get_contents, replace_file, CreateOptions};

use proxmox_backup::{
    tools::paperkey::{
        PaperkeyFormat,
        generate_paper_key,
    },
    api2::types::{
        PASSWORD_HINT_SCHEMA,
        KeyInfo,
        Kdf,
    },
    backup::{
        rsa_decrypt_key_config,
        KeyConfig,
    },
    tools,
};

pub const DEFAULT_ENCRYPTION_KEY_FILE_NAME: &str = "encryption-key.json";
pub const DEFAULT_MASTER_PUBKEY_FILE_NAME: &str = "master-public.pem";

pub fn find_default_master_pubkey() -> Result<Option<PathBuf>, Error> {
    super::find_xdg_file(DEFAULT_MASTER_PUBKEY_FILE_NAME, "default master public key file")
}

pub fn place_default_master_pubkey() -> Result<PathBuf, Error> {
    super::place_xdg_file(DEFAULT_MASTER_PUBKEY_FILE_NAME, "default master public key file")
}

pub fn find_default_encryption_key() -> Result<Option<PathBuf>, Error> {
    super::find_xdg_file(DEFAULT_ENCRYPTION_KEY_FILE_NAME, "default encryption key file")
}

pub fn place_default_encryption_key() -> Result<PathBuf, Error> {
    super::place_xdg_file(DEFAULT_ENCRYPTION_KEY_FILE_NAME, "default encryption key file")
}

pub fn read_optional_default_encryption_key() -> Result<Option<Vec<u8>>, Error> {
    find_default_encryption_key()?
        .map(file_get_contents)
        .transpose()
}

pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
    // fixme: implement other input methods

    use std::env::VarError::*;
    match std::env::var("PBS_ENCRYPTION_PASSWORD") {
        Ok(p) => return Ok(p.as_bytes().to_vec()),
        Err(NotUnicode(_)) => bail!("PBS_ENCRYPTION_PASSWORD contains bad characters"),
        Err(NotPresent) => {
            // Try another method
        }
    }

    // If we're on a TTY, query the user for a password
    if tty::stdin_isatty() {
        return Ok(tty::read_password("Encryption Key Password: ")?);
    }

    bail!("no password input mechanism available");
}

#[api(
    input: {
        properties: {
            kdf: {
                type: Kdf,
                optional: true,
            },
            path: {
                description:
                    "Output file. Without this the key will become the new default encryption key.",
                optional: true,
            },
            hint: {
                schema: PASSWORD_HINT_SCHEMA,
                optional: true,
            },
        },
    },
)]
/// Create a new encryption key.
fn create(
    kdf: Option<Kdf>,
    path: Option<String>,
    hint: Option<String>
) -> Result<(), Error> {
    let path = match path {
        Some(path) => PathBuf::from(path),
        None => {
            let path = place_default_encryption_key()?;
            println!("creating default key at: {:?}", path);
            path
        }
    };

    let kdf = kdf.unwrap_or_default();

    let mut key = [0u8; 32];
    proxmox::sys::linux::fill_with_random_data(&mut key)?;

    match kdf {
        Kdf::None => {
            if hint.is_some() {
                bail!("password hint not allowed for Kdf::None");
            }

            let key_config = KeyConfig::without_password(key)?;

            key_config.store(path, false)?;
        }
        Kdf::Scrypt | Kdf::PBKDF2 => {
            // always read passphrase from tty
            if !tty::stdin_isatty() {
                bail!("unable to read passphrase - no tty");
            }

            let password = tty::read_and_verify_password("Encryption Key Password: ")?;

            let mut key_config = KeyConfig::with_key(&key, &password, kdf)?;
            key_config.hint = hint;

            key_config.store(&path, false)?;
        }
    }

    Ok(())
}

#[api(
    input: {
        properties: {
            "master-keyfile": {
                description: "(Private) master key to use.",
            },
            "encrypted-keyfile": {
                description: "RSA-encrypted keyfile to import.",
            },
            kdf: {
                type: Kdf,
                optional: true,
            },
            "path": {
                description:
                    "Output file. Without this the key will become the new default encryption key.",
                optional: true,
            },
            hint: {
                schema: PASSWORD_HINT_SCHEMA,
                optional: true,
            },
        },
    },
)]
/// Import an encrypted backup of an encryption key using a (private) master key.
async fn import_with_master_key(
    master_keyfile: String,
    encrypted_keyfile: String,
    kdf: Option<Kdf>,
    path: Option<String>,
    hint: Option<String>,
) -> Result<(), Error> {
    let path = match path {
        Some(path) => PathBuf::from(path),
        None => {
            let path = place_default_encryption_key()?;
            if path.exists() {
                bail!("Please remove default encryption key at {:?} before importing to default location (or choose a non-default one).", path);
            }
            println!("Importing key to default location at: {:?}", path);
            path
        }
    };

    let encrypted_key = file_get_contents(&encrypted_keyfile)?;
    let master_key = file_get_contents(&master_keyfile)?;
    let password = tty::read_password("Master Key Password: ")?;

    let master_key =
        openssl::pkey::PKey::private_key_from_pem_passphrase(&master_key, &password)
        .map_err(|err| format_err!("failed to read PEM-formatted private key - {}", err))?
        .rsa()
        .map_err(|err| format_err!("not a valid private RSA key - {}", err))?;

    let (key, created, _fingerprint) =
        rsa_decrypt_key_config(master_key, &encrypted_key, &get_encryption_key_password)?;

    let kdf = kdf.unwrap_or_default();
    match kdf {
        Kdf::None => {
            if hint.is_some() {
                bail!("password hint not allowed for Kdf::None");
            }

            let mut key_config = KeyConfig::without_password(key)?;
            key_config.created = created; // keep original value

            key_config.store(path, true)?;

        }
        Kdf::Scrypt | Kdf::PBKDF2 => {
            let password = tty::read_and_verify_password("New Password: ")?;

            let mut new_key_config = KeyConfig::with_key(&key, &password, kdf)?;
            new_key_config.created = created; // keep original value
            new_key_config.hint = hint;

            new_key_config.store(path, true)?;
        }
    }

    Ok(())
}

#[api(
    input: {
        properties: {
            kdf: {
                type: Kdf,
                optional: true,
            },
            path: {
                description: "Key file. Without this the default key's password will be changed.",
                optional: true,
            },
            hint: {
                schema: PASSWORD_HINT_SCHEMA,
                optional: true,
            },
        },
    },
)]
/// Change the encryption key's password.
fn change_passphrase(
    kdf: Option<Kdf>,
    path: Option<String>,
    hint: Option<String>,
) -> Result<(), Error> {
    let path = match path {
        Some(path) => PathBuf::from(path),
        None => {
            let path = find_default_encryption_key()?
                .ok_or_else(|| {
                    format_err!("no encryption file provided and no default file found")
                })?;
            println!("updating default key at: {:?}", path);
            path
        }
    };

    let kdf = kdf.unwrap_or_default();

    if !tty::stdin_isatty() {
        bail!("unable to change passphrase - no tty");
    }

    let key_config = KeyConfig::load(&path)?;
    let (key, created, _fingerprint) = key_config.decrypt(&get_encryption_key_password)?;

    match kdf {
        Kdf::None => {
            if hint.is_some() {
                bail!("password hint not allowed for Kdf::None");
            }

            let mut key_config = KeyConfig::without_password(key)?;
            key_config.created =  created; // keep original value

            key_config.store(&path, true)?;
        }
        Kdf::Scrypt | Kdf::PBKDF2 => {
            let password = tty::read_and_verify_password("New Password: ")?;

            let mut new_key_config = KeyConfig::with_key(&key, &password, kdf)?;
            new_key_config.created = created; // keep original value
            new_key_config.hint = hint;

            new_key_config.store(&path, true)?;
        }
    }

    Ok(())
}

#[api(
    input: {
        properties: {
            path: {
                description: "Key file. Without this the default key's metadata will be shown.",
                optional: true,
            },
            "output-format": {
                schema: OUTPUT_FORMAT,
                optional: true,
            },
        },
    },
)]
/// Print the encryption key's metadata.
fn show_key(path: Option<String>, param: Value) -> Result<(), Error> {
    let path = match path {
        Some(path) => PathBuf::from(path),
        None => find_default_encryption_key()?
            .ok_or_else(|| format_err!("no encryption file provided and no default file found"))?,
    };

    let config: KeyConfig = serde_json::from_slice(&file_get_contents(path.clone())?)?;

    let output_format = get_output_format(&param);

    let mut info: KeyInfo = (&config).into();
    info.path = Some(format!("{:?}", path));

    let options = proxmox::api::cli::default_table_format_options()
        .column(ColumnConfig::new("path"))
        .column(ColumnConfig::new("kdf"))
        .column(ColumnConfig::new("created").renderer(tools::format::render_epoch))
        .column(ColumnConfig::new("modified").renderer(tools::format::render_epoch))
        .column(ColumnConfig::new("fingerprint"))
        .column(ColumnConfig::new("hint"));

    let return_type = ReturnType::new(false, &KeyInfo::API_SCHEMA);

    format_and_print_result_full(
        &mut serde_json::to_value(info)?,
        &return_type,
        &output_format,
        &options,
    );

    Ok(())
}

#[api(
    input: {
        properties: {
            path: {
                description: "Path to the PEM formatted RSA public key.",
            },
        },
    },
)]
/// Import an RSA public key used to put an encrypted version of the symmetric backup encryption
/// key onto the backup server along with each backup.
///
/// The imported key will be used as default master key for future invocations by the same local
/// user.
fn import_master_pubkey(path: String) -> Result<(), Error> {
    let pem_data = file_get_contents(&path)?;

    if let Err(err) = openssl::pkey::PKey::public_key_from_pem(&pem_data) {
        bail!("Unable to decode PEM data - {}", err);
    }

    let target_path = place_default_master_pubkey()?;

    replace_file(&target_path, &pem_data, CreateOptions::new())?;

    println!("Imported public master key to {:?}", target_path);

    Ok(())
}

#[api]
/// Create an RSA public/private key pair used to put an encrypted version of the symmetric backup
/// encryption key onto the backup server along with each backup.
fn create_master_key() -> Result<(), Error> {
    // we need a TTY to query the new password
    if !tty::stdin_isatty() {
        bail!("unable to create master key - no tty");
    }

    let rsa = openssl::rsa::Rsa::generate(4096)?;
    let pkey = openssl::pkey::PKey::from_rsa(rsa)?;

    let password = String::from_utf8(tty::read_and_verify_password("Master Key Password: ")?)?;

    let pub_key: Vec<u8> = pkey.public_key_to_pem()?;
    let filename_pub = "master-public.pem";
    println!("Writing public master key to {}", filename_pub);
    replace_file(filename_pub, pub_key.as_slice(), CreateOptions::new())?;

    let cipher = openssl::symm::Cipher::aes_256_cbc();
    let priv_key: Vec<u8> = pkey.private_key_to_pem_pkcs8_passphrase(cipher, password.as_bytes())?;

    let filename_priv = "master-private.pem";
    println!("Writing private master key to {}", filename_priv);
    replace_file(filename_priv, priv_key.as_slice(), CreateOptions::new())?;

    Ok(())
}

#[api(
    input: {
        properties: {
            path: {
                description: "Key file. Without this the default key's will be used.",
                optional: true,
            },
            subject: {
                description: "Include the specified subject as titel text.",
                optional: true,
            },
            "output-format": {
                type: PaperkeyFormat,
                optional: true,
            },
        },
    },
)]
/// Generate a printable, human readable text file containing the encryption key.
///
/// This also includes a scanable QR code for fast key restore.
fn paper_key(
    path: Option<String>,
    subject: Option<String>,
    output_format: Option<PaperkeyFormat>,
) -> Result<(), Error> {
    let path = match path {
        Some(path) => PathBuf::from(path),
        None => find_default_encryption_key()?
            .ok_or_else(|| format_err!("no encryption file provided and no default file found"))?,
    };

    let data = file_get_contents(&path)?;
    let data = String::from_utf8(data)?;

    generate_paper_key(std::io::stdout(), &data, subject, output_format)
}

pub fn cli() -> CliCommandMap {
    let key_create_cmd_def = CliCommand::new(&API_METHOD_CREATE)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    let key_import_with_master_key_cmd_def = CliCommand::new(&API_METHOD_IMPORT_WITH_MASTER_KEY)
        .arg_param(&["master-keyfile"])
        .completion_cb("master-keyfile", tools::complete_file_name)
        .arg_param(&["encrypted-keyfile"])
        .completion_cb("encrypted-keyfile", tools::complete_file_name)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    let key_change_passphrase_cmd_def = CliCommand::new(&API_METHOD_CHANGE_PASSPHRASE)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    let key_create_master_key_cmd_def = CliCommand::new(&API_METHOD_CREATE_MASTER_KEY);
    let key_import_master_pubkey_cmd_def = CliCommand::new(&API_METHOD_IMPORT_MASTER_PUBKEY)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    let key_show_cmd_def = CliCommand::new(&API_METHOD_SHOW_KEY)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    let paper_key_cmd_def = CliCommand::new(&API_METHOD_PAPER_KEY)
        .arg_param(&["path"])
        .completion_cb("path", tools::complete_file_name);

    CliCommandMap::new()
        .insert("create", key_create_cmd_def)
        .insert("import-with-master-key", key_import_with_master_key_cmd_def)
        .insert("create-master-key", key_create_master_key_cmd_def)
        .insert("import-master-pubkey", key_import_master_pubkey_cmd_def)
        .insert("change-passphrase", key_change_passphrase_cmd_def)
        .insert("show", key_show_cmd_def)
        .insert("paperkey", paper_key_cmd_def)
}