use crate::command::command_handle::CommandHandle;
use crate::command::error::Error as CmdError;
use crate::command::error::Error::{
    CommandFailure, CommandNotFound, FailedToReceiveResponse, FailedToSend,
    IncorrectParameterCount, MisingParameter, NoCommandReceiver, WrongParameterType,
};
use anyhow::bail;
use api::data_type::DataType;
use api::data_value::DataValue;
use api::messages::command::{Command, CommandDefinition, CommandResponse};
use api::messages::ResponseMessage;
use chrono::Utc;
use log::error;
use papaya::HashMap;
use std::collections::HashMap as StdHashMap;
use tokio::sync::oneshot;
use tokio::sync::{mpsc, RwLock};
use uuid::Uuid;

#[derive(Clone)]
pub(super) struct RegisteredCommand {
    pub(super) name: String,
    pub(super) definition: CommandDefinition,
    response_uuid: Uuid,
    tx: mpsc::Sender<ResponseMessage>,
}

pub struct CommandManagementService {
    registered_commands: HashMap<String, RegisteredCommand>,
    outstanding_responses: RwLock<StdHashMap<Uuid, oneshot::Sender<CommandResponse>>>,
}

impl CommandManagementService {
    pub fn new() -> Self {
        Self {
            registered_commands: HashMap::new(),
            outstanding_responses: RwLock::new(StdHashMap::new()),
        }
    }

    pub fn get_commands(&self) -> anyhow::Result<Vec<CommandDefinition>> {
        let mut result = vec![];

        let registered_commands = self.registered_commands.pin();
        for registration in registered_commands.values() {
            result.push(registration.clone().into());
        }

        Ok(result)
    }

    pub fn get_command_definition(&self, name: &String) -> Option<CommandDefinition> {
        self.registered_commands
            .pin()
            .get(name)
            .map(|registration| registration.clone().into())
    }

    pub fn register_command(
        &self,
        uuid: Uuid,
        command: CommandDefinition,
        tx: mpsc::Sender<ResponseMessage>,
    ) -> anyhow::Result<CommandHandle> {
        let registered_commands = self.registered_commands.pin();
        // We don't care about the previously registered command
        let name = command.name.clone();
        let _ = registered_commands.insert(
            name.clone(),
            RegisteredCommand {
                response_uuid: uuid,
                name: name.clone(),
                definition: command,
                tx,
            },
        );

        Ok(CommandHandle::new(name, uuid))
    }

    pub async fn send_command(
        &self,
        name: impl Into<String>,
        parameters: serde_json::Map<String, serde_json::Value>,
    ) -> Result<String, CmdError> {
        let timestamp = Utc::now();

        let name = name.into();
        let registered_commands = self.registered_commands.pin();
        let Some(registration) = registered_commands.get(&name) else {
            return Err(CommandNotFound(name));
        };

        if parameters.len() != registration.definition.parameters.len() {
            return Err(IncorrectParameterCount {
                expected: registration.definition.parameters.len(),
                actual: parameters.len(),
            });
        }
        let mut result_parameters = StdHashMap::new();
        for parameter in &registration.definition.parameters {
            let Some(param_value) = parameters.get(&parameter.name) else {
                return Err(MisingParameter(parameter.name.clone()));
            };
            let Some(param_value) = (match parameter.data_type {
                DataType::Float32 => param_value.as_f64().map(|v| DataValue::Float32(v as f32)),
                DataType::Float64 => param_value.as_f64().map(DataValue::Float64),
                DataType::Boolean => param_value.as_bool().map(DataValue::Boolean),
            }) else {
                return Err(WrongParameterType {
                    name: parameter.name.clone(),
                    expected_type: parameter.data_type,
                });
            };
            result_parameters.insert(parameter.name.clone(), param_value);
        }

        // Clone & Drop lets us use a standard pin instead of an owned pin
        let response_uuid = registration.response_uuid;
        let tx = registration.tx.clone();
        drop(registered_commands);

        if tx.is_closed() {
            return Err(NoCommandReceiver);
        }

        let uuid = Uuid::new_v4();
        let (response_tx, response_rx) = oneshot::channel();

        {
            let mut outstanding_responses = self.outstanding_responses.write().await;
            outstanding_responses.insert(uuid, response_tx);
        }

        if let Err(e) = tx
            .send(ResponseMessage {
                uuid,
                response: Some(response_uuid),
                payload: Command {
                    timestamp,
                    parameters: result_parameters,
                }
                .into(),
            })
            .await
        {
            error!("Failed to Send Command {e}");
            return Err(FailedToSend);
        }

        response_rx
            .await
            .map_err(|e| {
                error!("Failed to Receive Command Response: {e}");
                FailedToReceiveResponse
            })
            .and_then(|response| {
                if response.success {
                    Ok(response.response)
                } else {
                    Err(CommandFailure(response.response))
                }
            })
    }

    pub async fn handle_command_response(
        &self,
        uuid: Uuid,
        response: CommandResponse,
    ) -> anyhow::Result<()> {
        let responder = {
            let mut outstanding_responses = self.outstanding_responses.write().await;
            outstanding_responses.remove(&uuid)
        };
        match responder {
            None => bail!("Unexpected Command Response for Command {uuid}"),
            Some(response_tx) => {
                if let Err(e) = response_tx.send(response) {
                    bail!("Failed to send Command Response {e:?}");
                }
            }
        };

        Ok(())
    }

    pub fn unregister(&self, command_handle: CommandHandle) {
        let registered_commands = self.registered_commands.pin();
        // We don't care if this succeeded
        let _ = registered_commands.remove_if(command_handle.name(), |_, registration| {
            registration.response_uuid == *command_handle.uuid()
        });
    }
}