use ruma_identifiers::RoomVersionId;

use crate::{Error, Result};

#[derive(Debug)]
#[allow(clippy::exhaustive_enums)]
pub enum RoomDisposition {
    /// A room version that has a stable specification.
    Stable,
    /// A room version that is not yet fully specified.
    Unstable,
}

#[derive(Debug)]
#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
pub enum EventFormatVersion {
    /// $id:server event id format
    V1,
    /// MSC1659-style $hash event id format: introduced for room v3
    V2,
    /// MSC1884-style $hash format: introduced for room v4
    V3,
}

#[derive(Debug)]
#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
pub enum StateResolutionVersion {
    /// State resolution for rooms at version 1.
    V1,
    /// State resolution for room at version 2 or later.
    V2,
}

#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
pub struct RoomVersion {
    /// The stability of this room.
    pub disposition: RoomDisposition,
    /// The format of the EventId.
    pub event_format: EventFormatVersion,
    /// Which state resolution algorithm is used.
    pub state_res: StateResolutionVersion,
    // FIXME: not sure what this one means?
    pub enforce_key_validity: bool,

    /// `m.room.aliases` had special auth rules and redaction rules
    /// before room version 6.
    ///
    /// before MSC2261/MSC2432,
    pub special_case_aliases_auth: bool,
    /// Strictly enforce canonical json, do not allow:
    /// * Integers outside the range of [-2 ^ 53 + 1, 2 ^ 53 - 1]
    /// * Floats
    /// * NaN, Infinity, -Infinity
    pub strict_canonicaljson: bool,
    /// Verify notifications key while checking m.room.power_levels.
    ///
    /// bool: MSC2209: Check 'notifications'
    pub limit_notifications_power_levels: bool,
    /// Extra rules when verifying redaction events.
    pub extra_redaction_checks: bool,
    /// Allow knocking in event authentication.
    ///
    /// See: <https://spec.matrix.org/v1.1/rooms/v7/> for more information.
    pub allow_knocking: bool,
    /// Adds support for the restricted join rule.
    ///
    /// See: <https://github.com/matrix-org/matrix-doc/pull/3289> for more information.
    pub restricted_join_rules: bool,
}

impl RoomVersion {
    pub const V1: Self = Self {
        disposition: RoomDisposition::Stable,
        event_format: EventFormatVersion::V1,
        state_res: StateResolutionVersion::V1,
        enforce_key_validity: false,
        special_case_aliases_auth: true,
        strict_canonicaljson: false,
        limit_notifications_power_levels: false,
        extra_redaction_checks: false,
        allow_knocking: false,
        restricted_join_rules: false,
    };

    pub const V2: Self = Self { state_res: StateResolutionVersion::V2, ..Self::V1 };

    pub const V3: Self =
        Self { event_format: EventFormatVersion::V2, extra_redaction_checks: true, ..Self::V2 };

    pub const V4: Self = Self { event_format: EventFormatVersion::V3, ..Self::V3 };

    pub const V5: Self = Self { enforce_key_validity: true, ..Self::V4 };

    pub const V6: Self = Self {
        special_case_aliases_auth: false,
        strict_canonicaljson: true,
        limit_notifications_power_levels: true,
        ..Self::V5
    };

    pub const V7: Self = Self {
        // FIXME: once room version 7 is stabilized move this to version 8
        disposition: RoomDisposition::Unstable,
        allow_knocking: true,
        ..Self::V6
    };

    pub const V8: Self = Self { restricted_join_rules: true, ..Self::V7 };

    pub const V9: Self = Self::V8;

    pub fn new(version: &RoomVersionId) -> Result<Self> {
        Ok(match version {
            RoomVersionId::V1 => Self::V1,
            RoomVersionId::V2 => Self::V2,
            RoomVersionId::V3 => Self::V3,
            RoomVersionId::V4 => Self::V4,
            RoomVersionId::V5 => Self::V5,
            RoomVersionId::V6 => Self::V6,
            RoomVersionId::V7 => Self::V7,
            RoomVersionId::V8 => Self::V8,
            RoomVersionId::V9 => Self::V9,
            ver => return Err(Error::Unsupported(format!("found version `{}`", ver.as_str()))),
        })
    }
}