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// Copyright (c) 2024, BlockProject 3D
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright notice,
//       this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright notice,
//       this list of conditions and the following disclaimer in the documentation
//       and/or other materials provided with the distribution.
//     * Neither the name of BlockProject 3D nor the names of its contributors
//       may be used to endorse or promote products derived from this software
//       without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use std::fmt::{Display, Formatter};

/// An enum representing the available verbosity levels of the logger.
#[repr(u8)]
#[derive(Clone, PartialEq, Copy, Ord, PartialOrd, Eq, Debug, Hash)]
pub enum LevelFilter {
    /// The "none" level.
    ///
    /// This level is used to disable logging.
    None = 0,

    /// The "trace" level.
    ///
    /// Designates very low priority, often extremely verbose, information.
    Trace = 1,

    /// The "debug" level.
    ///
    /// Designates lower priority information.
    Debug = 2,

    /// The "info" level.
    ///
    /// Designates useful information.
    Info = 3,

    /// The "warn" level.
    ///
    /// Designates hazardous situations.
    Warn = 4,

    /// The "error" level.
    ///
    /// Designates very serious errors.
    // This way these line up with the discriminants for LevelFilter below
    // This works because Rust treats field-less enums the same way as C does:
    // https://doc.rust-lang.org/reference/items/enumerations.html#custom-discriminant-values-for-field-less-enumerations
    Error = 5,
}

impl LevelFilter {
    /// Creates a new [LevelFilter](LevelFilter) from an existing u8 value.
    ///
    /// This returns None if the value could not be found.
    ///
    /// # Arguments
    ///
    /// * `value`: the value to convert from.
    ///
    /// returns: Option<LevelFilter>
    #[allow(clippy::missing_transmute_annotations)]
    pub fn from_u8(value: u8) -> Option<Self> {
        if value > 5 {
            None
        } else {
            // SAFETY: This is safe because LevelFilter is a u8 and we have checked that the variant
            // index is not out of bounds.
            unsafe { std::mem::transmute(value) }
        }
    }
}

/// An enum representing the available verbosity levels for a message.
#[repr(u8)]
#[derive(Clone, PartialEq, Copy, Ord, PartialOrd, Eq, Debug, Hash)]
pub enum Level {
    /// The "trace" level.
    ///
    /// Designates very low priority, often extremely verbose, information.
    Trace = 1,

    /// The "debug" level.
    ///
    /// Designates lower priority information.
    Debug = 2,

    /// The "info" level.
    ///
    /// Designates useful information.
    Info = 3,

    /// The "warn" level.
    ///
    /// Designates hazardous situations.
    Warn = 4,

    /// The "error" level.
    ///
    /// Designates very serious errors.
    // This way these line up with the discriminants for LevelFilter below
    // This works because Rust treats field-less enums the same way as C does:
    // https://doc.rust-lang.org/reference/items/enumerations.html#custom-discriminant-values-for-field-less-enumerations
    Error = 5,
}

static LOG_LEVEL_NAMES: [&str; 6] = ["OFF", "TRACE", "DEBUG", "INFO", "WARNING", "ERROR"];

impl Level {
    /// Returns the string representation of the `Level`.
    ///
    /// This returns the same string as the `fmt::Display` implementation.
    pub fn as_str(&self) -> &'static str {
        LOG_LEVEL_NAMES[*self as usize]
    }

    /// Returns the [LevelFilter](LevelFilter) representation of this log [Level](Level).
    #[allow(clippy::missing_transmute_annotations)]
    pub fn as_level_filter(&self) -> LevelFilter {
        // SAFETY: This is safe because both Level and LevelFilter are u8 values and Level shares
        // the same variants as LevelFilter (with the exception that LevelFilter has one more
        // variant at 0).
        unsafe { std::mem::transmute(*self) }
    }
}

impl Display for Level {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}