// Copyright (c) 2025 shibedrill
// SPDX-License-Identifier: GPL-3.0-or-later

use core::fmt::Write;

use crate::constants::{LOG_DEFAULT_LEVEL, NEWLINE};
use crate::memory::alloc;
use alloc::boxed::*;
use alloc::string::*;
use alloc::vec::*;
use spin::Mutex;

#[macro_export]
macro_rules! log_info {
    ($($arg:tt)*) => {
        LOGGER.log(LogLevel::Info, &format!($($arg)*), file!(), line!(), column!())
    };
}

#[macro_export]
macro_rules! log_trace {
    ($($arg:tt)*) => {
        LOGGER.log(LogLevel::Trace, &format!($($arg)*), file!(), line!(), column!())
    };
}

#[macro_export]
#[allow(unused_macros)]
macro_rules! log_warning {
    ($($arg:tt)*) => {
        LOGGER.log(LogLevel::Warning, &format!($($arg)*), file!(), line!(), column!())
    };
}

#[macro_export]
#[allow(unused_macros)]
macro_rules! log_error {
    ($($arg:tt)*) => {
        LOGGER.log(LogLevel::Error, &format!($($arg)*), file!(), line!(), column!())
    };
}

#[macro_export]
#[allow(unused_macros)]
macro_rules! log_critical {
    ($($arg:tt)*) => {
        LOGGER.log(LogLevel::Critical, &format!($($arg)*), file!(), line!(), column!())
    };
}

pub struct Logger {
    pub inner: Mutex<LoggerInner>,
}

impl Logger {
    pub fn log(&self, level: LogLevel, msg: &str, file: &'static str, line: u32, column: u32) {
        self.inner.lock().log(level, msg, file, line, column);
    }
    pub fn add_subscriber<T: LogSubscriber + Send + Sync + 'static>(&self, sub: T) {
        self.inner
            .lock()
            .subscriber
            .push(Mutex::new(alloc::boxed::Box::new(sub)));
    }
    pub fn set_level(&self, level: LogLevel) {
        self.inner.lock().level = level;
    }
}

// The logger exists for the entire lifetime of the kernel.
pub static LOGGER: Logger = Logger {
    inner: Mutex::new(LoggerInner::new()),
};

pub struct EnumParseError {}

pub struct LoggerInner {
    pub level: LogLevel,
    pub subscriber: Vec<Mutex<Box<dyn LogSubscriber>>>,
}

pub trait LogSubscriber: Send + Sync {
    fn log_write(&mut self, msg: &str);
}

impl Default for LoggerInner {
    fn default() -> Self {
        Self::new()
    }
}

impl LoggerInner {
    pub const fn new() -> Self {
        LoggerInner {
            level: LOG_DEFAULT_LEVEL,
            subscriber: Vec::new(),
        }
    }

    // Calling log will sequentially acquire lock on all logging subscribers
    // to write to them with a formatted log message.
    pub fn log(&self, level: LogLevel, msg: &str, file: &'static str, line: u32, column: u32) {
        // Nobody is EVER allowed to call log with the Disabled log level. It is a placeholder.
        if level == LogLevel::Disabled {
            // Nothing
        } else if level <= self.level {
            let level_string = String::from(level);
            for sub in &self.subscriber {
                let mut message = String::new();
                write!(
                    &mut message,
                    "[{level_string}] {file}:{line},{column} - {msg}{NEWLINE}"
                )
                .unwrap();
                sub.lock().log_write(&message);
            }
        }
    }
}

#[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Clone, Copy)]
pub enum LogLevel {
    Disabled = 0,
    Critical = 1,
    Error = 2,
    Warning = 3,
    Info = 4,
    Trace = 5,
}

impl TryFrom<u8> for LogLevel {
    type Error = EnumParseError;
    fn try_from(from: u8) -> Result<Self, <crate::log::LogLevel as TryFrom<u8>>::Error> {
        match from {
            0 => Ok(Self::Disabled),
            1 => Ok(Self::Critical),
            2 => Ok(Self::Error),
            3 => Ok(Self::Warning),
            4 => Ok(Self::Info),
            5 => Ok(Self::Trace),
            _ => Err(EnumParseError {}),
        }
    }
}

impl TryFrom<&str> for LogLevel {
    type Error = EnumParseError;
    fn try_from(from: &str) -> Result<Self, <crate::log::LogLevel as TryFrom<u8>>::Error> {
        match from.to_ascii_lowercase().as_ref() {
            "disabled" => Ok(Self::Disabled),
            "critical" => Ok(Self::Critical),
            "error" => Ok(Self::Error),
            "warning" => Ok(Self::Warning),
            "info" => Ok(Self::Info),
            "trace" => Ok(Self::Trace),
            _ => Err(EnumParseError {}),
        }
    }
}

impl From<LogLevel> for String {
    fn from(from: LogLevel) -> String {
        match from {
            LogLevel::Disabled => "Disabled",
            LogLevel::Critical => "CRIT ",
            LogLevel::Error => "ERROR",
            LogLevel::Warning => "WARN ",
            LogLevel::Info => "INFO ",
            LogLevel::Trace => "TRACE",
        }
        .into()
    }
}