use std::collections::HashMap;

use drm_sys::drm_mode_modeinfo;
use syscall::{Error, Result, EINVAL};

use crate::GraphicsAdapter;

pub struct DrmObjects<T: GraphicsAdapter> {
    next_id: DrmObjectId,
    objects: HashMap<DrmObjectId, DrmObject<T>>,
}

impl<T: GraphicsAdapter> DrmObjects<T> {
    pub(crate) fn new() -> Self {
        DrmObjects {
            next_id: DrmObjectId(1),
            objects: HashMap::new(),
        }
    }

    pub fn add_connector(&mut self, connector: DrmConnector<T>) -> DrmObjectId {
        let connector_id = self.next_id;
        self.objects.insert(
            connector_id,
            DrmObject {
                kind: DrmObjectKind::Connector(connector),
            },
        );
        self.next_id.0 += 1;

        let encoder_id = self.next_id;
        self.objects.insert(
            encoder_id,
            DrmObject {
                kind: DrmObjectKind::Encoder(DrmEncoder {
                    crtc_id: DrmObjectId::INVALID,
                    possible_crtcs: 0,
                    possible_clones: 0,
                }),
            },
        );
        self.next_id.0 += 1;

        // Attach encoder to connector
        self.get_connector_mut(connector_id).unwrap().encoder_id = encoder_id;

        connector_id
    }

    pub fn connector_ids(&self) -> impl Iterator<Item = DrmObjectId> + use<'_, T> {
        self.objects
            .iter()
            .filter_map(|(&id, object)| match object.kind {
                DrmObjectKind::Connector(_) => Some(id),
                _ => None,
            })
    }

    pub fn connectors(&self) -> impl Iterator<Item = &DrmConnector<T>> + use<'_, T> {
        self.objects
            .values()
            .filter_map(|object| match &object.kind {
                DrmObjectKind::Connector(connector) => Some(connector),
                _ => None,
            })
    }

    pub fn connectors_mut(&mut self) -> impl Iterator<Item = &mut DrmConnector<T>> + use<'_, T> {
        self.objects
            .values_mut()
            .filter_map(|object| match &mut object.kind {
                DrmObjectKind::Connector(connector) => Some(connector),
                _ => None,
            })
    }

    pub fn get_connector(&self, id: DrmObjectId) -> Result<&DrmConnector<T>> {
        let object = self.objects.get(&id).ok_or(Error::new(EINVAL))?;
        match &object.kind {
            DrmObjectKind::Connector(drm_connector) => Ok(drm_connector),
            _ => Err(Error::new(EINVAL)),
        }
    }

    pub fn get_connector_mut(&mut self, id: DrmObjectId) -> Result<&mut DrmConnector<T>> {
        let object = self.objects.get_mut(&id).ok_or(Error::new(EINVAL))?;
        match &mut object.kind {
            DrmObjectKind::Connector(drm_connector) => Ok(drm_connector),
            _ => Err(Error::new(EINVAL)),
        }
    }

    pub fn encoder_ids(&self) -> impl Iterator<Item = DrmObjectId> + use<'_, T> {
        self.objects
            .iter()
            .filter_map(|(&id, object)| match object.kind {
                DrmObjectKind::Encoder(_) => Some(id),
                _ => None,
            })
    }

    pub fn get_encoder(&self, id: DrmObjectId) -> Result<&DrmEncoder> {
        let object = self.objects.get(&id).ok_or(Error::new(EINVAL))?;
        match &object.kind {
            DrmObjectKind::Encoder(drm_encoder) => Ok(drm_encoder),
            _ => Err(Error::new(EINVAL)),
        }
    }

    pub fn get_encoder_mut(&mut self, id: DrmObjectId) -> Result<&mut DrmEncoder> {
        let object = self.objects.get_mut(&id).ok_or(Error::new(EINVAL))?;
        match &mut object.kind {
            DrmObjectKind::Encoder(drm_encoder) => Ok(drm_encoder),
            _ => Err(Error::new(EINVAL)),
        }
    }
}

#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub struct DrmObjectId(pub(crate) u32);

impl DrmObjectId {
    pub const INVALID: DrmObjectId = DrmObjectId(0);
}

struct DrmObject<T: GraphicsAdapter> {
    kind: DrmObjectKind<T>,
}

enum DrmObjectKind<T: GraphicsAdapter> {
    Connector(DrmConnector<T>),
    Encoder(DrmEncoder),
}

pub struct DrmConnector<T: GraphicsAdapter> {
    pub modes: Vec<drm_mode_modeinfo>,
    pub encoder_id: DrmObjectId,
    pub connector_type: u32,
    pub connector_type_id: u32,
    pub connection: DrmConnectorStatus,
    pub mm_width: u32,
    pub mm_height: u32,
    pub subpixel: DrmSubpixelOrder,
    pub driver_data: T::Connector,
}

#[derive(Copy, Clone)]
#[repr(u32)]
pub enum DrmConnectorStatus {
    Disconnected = 0,
    Connected = 1,
    Unknown = 2,
}

#[derive(Copy, Clone)]
#[repr(u32)]
pub enum DrmSubpixelOrder {
    Unknown = 0,
    HorizontalRGB,
    HorizontalBGR,
    VerticalRGB,
    VerticalBGR,
    None,
}

// FIXME can we represent connector and encoder using a single struct?
pub struct DrmEncoder {
    pub crtc_id: DrmObjectId,
    pub possible_crtcs: u32,
    pub possible_clones: u32,
}