use crate::load_protos;
use crate::{Flag, FlagSource};
use crate::{FlagPermission, FlagValue, ValuePickedFrom};
use aconfigd_protos::{
    ProtoFlagOverrideMessage, ProtoFlagOverrideType, ProtoFlagQueryReturnMessage,
    ProtoListStorageMessage, ProtoListStorageMessageMsg, ProtoRemoveLocalOverrideMessage,
    ProtoRemoveOverrideType, ProtoStorageRequestMessage, ProtoStorageRequestMessageMsg,
    ProtoStorageRequestMessages, ProtoStorageReturnMessage, ProtoStorageReturnMessageMsg,
    ProtoStorageReturnMessages,
};
use anyhow::anyhow;
use anyhow::Result;
use protobuf::Message;
use protobuf::SpecialFields;
use std::collections::HashMap;
use std::io::{Read, Write};
use std::net::Shutdown;
use std::os::unix::net::UnixStream;

pub struct AconfigStorageSource {}

static ACONFIGD_SYSTEM_SOCKET_NAME: &str = "/dev/socket/aconfigd_system";
static ACONFIGD_MAINLINE_SOCKET_NAME: &str = "/dev/socket/aconfigd_mainline";

enum AconfigdSocket {
    System,
    Mainline,
}

impl AconfigdSocket {
    pub fn name(&self) -> &str {
        match self {
            AconfigdSocket::System => ACONFIGD_SYSTEM_SOCKET_NAME,
            AconfigdSocket::Mainline => ACONFIGD_MAINLINE_SOCKET_NAME,
        }
    }
}

fn convert(msg: ProtoFlagQueryReturnMessage, containers: &HashMap<String, String>) -> Result<Flag> {
    let value = FlagValue::try_from(
        msg.boot_flag_value
            .clone()
            .ok_or(anyhow!("no boot flag value for {:?}", msg.flag_name))?
            .as_str(),
    )?;

    let value_picked_from = if msg.has_boot_local_override.unwrap_or(false) {
        ValuePickedFrom::Local
    } else if msg.boot_flag_value == msg.default_flag_value {
        ValuePickedFrom::Default
    } else {
        ValuePickedFrom::Server
    };

    let staged_value = if msg.has_local_override.unwrap_or(false) {
        // If a local override is staged, display it.
        if msg.boot_flag_value == msg.local_flag_value {
            None
        } else {
            Some(FlagValue::try_from(
                msg.local_flag_value.ok_or(anyhow!("no local flag value"))?.as_str(),
            )?)
        }
    } else {
        // Otherwise, display if we're flipping to the default, or a server value.
        let boot_value = msg.boot_flag_value.unwrap_or("".to_string());
        let server_value = msg.server_flag_value.unwrap_or("".to_string());
        let default_value = msg.default_flag_value.unwrap_or("".to_string());

        if boot_value != server_value && server_value != *"" {
            Some(FlagValue::try_from(server_value.as_str())?)
        } else if msg.has_boot_local_override.unwrap_or(false) && boot_value != default_value {
            Some(FlagValue::try_from(default_value.as_str())?)
        } else {
            None
        }
    };

    let permission = match msg.is_readwrite {
        Some(is_readwrite) => {
            if is_readwrite {
                FlagPermission::ReadWrite
            } else {
                FlagPermission::ReadOnly
            }
        }
        None => return Err(anyhow!("missing permission")),
    };

    let name = msg.flag_name.ok_or(anyhow!("missing flag name"))?;
    let package = msg.package_name.ok_or(anyhow!("missing package name"))?;
    let qualified_name = format!("{package}.{name}");
    Ok(Flag {
        name,
        package,
        value,
        permission,
        value_picked_from,
        staged_value,
        container: containers
            .get(&qualified_name)
            .cloned()
            .unwrap_or_else(|| "<no container>".to_string())
            .to_string(),
        // TODO: remove once DeviceConfig is not in the CLI.
        namespace: "-".to_string(),
    })
}

fn write_socket_messages(
    socket: AconfigdSocket,
    messages: ProtoStorageRequestMessages,
) -> Result<ProtoStorageReturnMessages> {
    let mut socket = UnixStream::connect(socket.name())?;

    let message_buffer = messages.write_to_bytes()?;
    let mut message_length_buffer: [u8; 4] = [0; 4];
    let message_size = &message_buffer.len();
    message_length_buffer[0] = (message_size >> 24) as u8;
    message_length_buffer[1] = (message_size >> 16) as u8;
    message_length_buffer[2] = (message_size >> 8) as u8;
    message_length_buffer[3] = *message_size as u8;
    socket.write_all(&message_length_buffer)?;
    socket.write_all(&message_buffer)?;
    socket.shutdown(Shutdown::Write)?;

    let mut response_length_buffer: [u8; 4] = [0; 4];
    socket.read_exact(&mut response_length_buffer)?;
    let response_length = u32::from_be_bytes(response_length_buffer) as usize;
    let mut response_buffer = vec![0; response_length];
    socket.read_exact(&mut response_buffer)?;

    let response: ProtoStorageReturnMessages =
        protobuf::Message::parse_from_bytes(&response_buffer)?;

    Ok(response)
}

fn send_list_flags_command(socket: AconfigdSocket) -> Result<Vec<ProtoFlagQueryReturnMessage>> {
    let messages = ProtoStorageRequestMessages {
        msgs: vec![ProtoStorageRequestMessage {
            msg: Some(ProtoStorageRequestMessageMsg::ListStorageMessage(ProtoListStorageMessage {
                msg: Some(ProtoListStorageMessageMsg::All(true)),
                special_fields: SpecialFields::new(),
            })),
            special_fields: SpecialFields::new(),
        }],
        special_fields: SpecialFields::new(),
    };

    let response = write_socket_messages(socket, messages)?;
    match response.msgs.as_slice() {
        [ProtoStorageReturnMessage {
            msg: Some(ProtoStorageReturnMessageMsg::ListStorageMessage(list_storage_message)),
            ..
        }] => Ok(list_storage_message.flags.clone()),
        _ => Err(anyhow!("unexpected response from aconfigd")),
    }
}

fn send_override_command(
    socket: AconfigdSocket,
    package_name: &str,
    flag_name: &str,
    value: &str,
    immediate: bool,
) -> Result<()> {
    let override_type = if immediate {
        ProtoFlagOverrideType::LOCAL_IMMEDIATE
    } else {
        ProtoFlagOverrideType::LOCAL_ON_REBOOT
    };

    let messages = ProtoStorageRequestMessages {
        msgs: vec![ProtoStorageRequestMessage {
            msg: Some(ProtoStorageRequestMessageMsg::FlagOverrideMessage(
                ProtoFlagOverrideMessage {
                    package_name: Some(package_name.to_string()),
                    flag_name: Some(flag_name.to_string()),
                    flag_value: Some(value.to_string()),
                    override_type: Some(override_type.into()),
                    special_fields: SpecialFields::new(),
                },
            )),
            special_fields: SpecialFields::new(),
        }],
        special_fields: SpecialFields::new(),
    };

    write_socket_messages(socket, messages)?;
    Ok(())
}

impl FlagSource for AconfigStorageSource {
    fn list_flags() -> Result<Vec<Flag>> {
        let flag_defaults = load_protos::load()?;
        let system_messages = send_list_flags_command(AconfigdSocket::System);
        let mainline_messages = send_list_flags_command(AconfigdSocket::Mainline);

        let mut all_messages = vec![];
        if let Ok(system_messages) = system_messages {
            all_messages.extend_from_slice(&system_messages);
        }
        if let Ok(mainline_messages) = mainline_messages {
            all_messages.extend_from_slice(&mainline_messages);
        }

        let container_map: HashMap<String, String> = flag_defaults
            .clone()
            .into_iter()
            .map(|default| (default.qualified_name(), default.container))
            .collect();
        let socket_flags: Vec<Result<Flag>> = all_messages
            .into_iter()
            .map(|query_message| convert(query_message.clone(), &container_map))
            .collect();
        let socket_flags: Result<Vec<Flag>> = socket_flags.into_iter().collect();

        // Load the defaults from the on-device protos.
        // If the sockets are unavailable, just display the proto defaults.
        let mut flags = flag_defaults.clone();
        let name_to_socket_flag: HashMap<String, Flag> =
            socket_flags?.into_iter().map(|p| (p.qualified_name(), p)).collect();
        flags.iter_mut().for_each(|flag| {
            if let Some(socket_flag) = name_to_socket_flag.get(&flag.qualified_name()) {
                *flag = socket_flag.clone();
            }
        });

        Ok(flags)
    }

    fn override_flag(
        _namespace: &str,
        qualified_name: &str,
        value: &str,
        immediate: bool,
    ) -> Result<()> {
        let (package, flag_name) = if let Some(last_dot_index) = qualified_name.rfind('.') {
            (&qualified_name[..last_dot_index], &qualified_name[last_dot_index + 1..])
        } else {
            return Err(anyhow!(format!("invalid flag name: {qualified_name}")));
        };

        let _ = send_override_command(AconfigdSocket::System, package, flag_name, value, immediate);
        let _ =
            send_override_command(AconfigdSocket::Mainline, package, flag_name, value, immediate);
        Ok(())
    }

    fn unset_flag(_namespace: &str, qualified_name: &str, immediate: bool) -> Result<()> {
        let last_period_index = qualified_name.rfind('.').ok_or(anyhow!("No period found"))?;
        let (package, flag_name) = qualified_name.split_at(last_period_index);

        let removal_type = if immediate {
            ProtoRemoveOverrideType::REMOVE_LOCAL_IMMEDIATE
        } else {
            ProtoRemoveOverrideType::REMOVE_LOCAL_ON_REBOOT
        };

        let socket_message = ProtoStorageRequestMessages {
            msgs: vec![ProtoStorageRequestMessage {
                msg: Some(ProtoStorageRequestMessageMsg::RemoveLocalOverrideMessage(
                    ProtoRemoveLocalOverrideMessage {
                        package_name: Some(package.to_string()),
                        flag_name: Some(flag_name[1..].to_string()),
                        remove_all: Some(false),
                        remove_override_type: Some(removal_type.into()),
                        special_fields: SpecialFields::new(),
                    },
                )),
                special_fields: SpecialFields::new(),
            }],
            special_fields: SpecialFields::new(),
        };

        let _ = write_socket_messages(AconfigdSocket::Mainline, socket_message.clone());
        let _ = write_socket_messages(AconfigdSocket::System, socket_message);

        Ok(())
    }
}