use crate::app_config::AppConfig;
use crate::crypto::pki;
use crate::devices::device::{Device, DeviceGeneralInfo, DeviceId, DeviceInfo};
use crate::utils::time_utils::time_secs;
use openssl::x509::{X509Req, X509};
use std::collections::HashMap;

#[derive(thiserror::Error, Debug)]
pub enum DevicesListError {
    #[error("Enrollment failed: a device with the same ID was already registered!")]
    EnrollFailedDeviceAlreadyExists,
    #[error("Persist device config failed: the configuration of the device was not found!")]
    PersistFailedDeviceNotFound,
    #[error("Validated device failed: the device does not exists!")]
    ValidateDeviceFailedDeviceNotFound,
    #[error("Validated device failed: the device is already validated!")]
    ValidateDeviceFailedDeviceAlreadyValidated,
    #[error("Update device failed: the device does not exists!")]
    UpdateDeviceFailedDeviceNotFound,
    #[error("Requested device was not found")]
    DeviceNotFound,
    #[error("Requested device is not validated")]
    DeviceNotValidated,
}

pub struct DevicesList(HashMap<DeviceId, Device>);

impl DevicesList {
    /// Load the list of devices. This method should be called only once during the whole execution
    /// of the program
    pub fn load() -> anyhow::Result<Self> {
        let mut list = Self(HashMap::new());

        for f in std::fs::read_dir(AppConfig::get().devices_config_path())? {
            let f = f?.file_name();
            let f = f.to_string_lossy();

            let dev_id = match f.strip_suffix(".conf") {
                Some(s) => DeviceId(s.to_string()),

                // This is not a device configuration file
                None => continue,
            };

            let device_conf = std::fs::read(AppConfig::get().device_config_path(&dev_id))?;

            list.0.insert(dev_id, serde_json::from_slice(&device_conf)?);
        }

        Ok(list)
    }

    /// Check if a device with a given id exists or not
    pub fn exists(&self, id: &DeviceId) -> bool {
        self.0.contains_key(id)
    }

    /// Enroll a new device
    pub fn enroll(
        &mut self,
        id: &DeviceId,
        info: &DeviceInfo,
        csr: &X509Req,
    ) -> anyhow::Result<()> {
        if self.exists(id) {
            return Err(DevicesListError::EnrollFailedDeviceAlreadyExists.into());
        }

        let device = Device {
            id: id.clone(),
            info: info.clone(),
            time_create: time_secs(),
            time_update: time_secs(),
            name: id.0.to_string(),
            description: "".to_string(),
            validated: false,
            enabled: false,
            relays: vec![],
        };

        // First, write CSR
        std::fs::write(AppConfig::get().device_csr_path(id), csr.to_pem()?)?;

        self.0.insert(id.clone(), device);
        self.persist_dev_config(id)?;

        Ok(())
    }

    /// Persist a device configuration on the filesystem
    fn persist_dev_config(&self, id: &DeviceId) -> anyhow::Result<()> {
        let dev = self
            .0
            .get(id)
            .ok_or(DevicesListError::PersistFailedDeviceNotFound)?;

        std::fs::write(
            AppConfig::get().device_config_path(id),
            serde_json::to_string_pretty(dev)?,
        )?;

        Ok(())
    }

    /// Get a copy of the full list of devices
    pub fn full_list(&self) -> Vec<Device> {
        self.0.clone().into_values().collect()
    }

    /// Get the information about a single device
    pub fn get_single(&self, id: &DeviceId) -> Option<Device> {
        self.0.get(id).cloned()
    }

    /// Validate a device
    pub fn validate(&mut self, id: &DeviceId) -> anyhow::Result<()> {
        let dev = self
            .0
            .get_mut(id)
            .ok_or(DevicesListError::ValidateDeviceFailedDeviceNotFound)?;

        if dev.validated {
            return Err(DevicesListError::ValidateDeviceFailedDeviceAlreadyValidated.into());
        }

        // Issue certificate
        let csr = X509Req::from_pem(&std::fs::read(AppConfig::get().device_csr_path(id))?)?;
        let cert = pki::gen_certificate_for_device(&csr)?;
        std::fs::write(AppConfig::get().device_cert_path(id), cert)?;

        // Mark device as validated
        dev.validated = true;
        self.persist_dev_config(id)?;

        Ok(())
    }

    /// Update a device general information
    pub fn update_general_info(
        &mut self,
        id: &DeviceId,
        general_info: DeviceGeneralInfo,
    ) -> anyhow::Result<()> {
        let dev = self
            .0
            .get_mut(id)
            .ok_or(DevicesListError::UpdateDeviceFailedDeviceNotFound)?;

        dev.name = general_info.name;
        dev.description = general_info.description;
        dev.enabled = general_info.enabled;
        dev.time_update = time_secs();

        self.persist_dev_config(id)?;

        Ok(())
    }

    /// Get single certificate information
    fn get_cert(&self, id: &DeviceId) -> anyhow::Result<X509> {
        let dev = self
            .get_single(id)
            .ok_or(DevicesListError::DeviceNotFound)?;
        if !dev.validated {
            return Err(DevicesListError::DeviceNotValidated.into());
        }

        Ok(X509::from_pem(&std::fs::read(
            AppConfig::get().device_cert_path(id),
        )?)?)
    }

    /// Delete a device
    pub fn delete(&mut self, id: &DeviceId) -> anyhow::Result<()> {
        let crt_path = AppConfig::get().device_cert_path(id);
        if crt_path.is_file() {
            let cert = self.get_cert(id)?;
            pki::revoke_device_cert(&cert)?;
        }

        let csr_path = AppConfig::get().device_csr_path(id);
        if csr_path.is_file() {
            std::fs::remove_file(&csr_path)?;
        }

        let conf_path = AppConfig::get().device_config_path(id);
        if conf_path.is_file() {
            std::fs::remove_file(&conf_path)?;
        }

        self.0.remove(id);

        Ok(())
    }
}