use alloc::string::String;
use alloc::vec::Vec;
use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
use embassy_sync::blocking_mutex::Mutex as BlockingMutex;
use log::{LevelFilter, Log, Metadata, Record};

const MAX_LIVE_LOG_ENTRIES: usize = 64;

struct LiveLogBuffer {
    entries: Vec<(u64, String)>,
    next_seq: u64,
}

impl LiveLogBuffer {
    const fn new() -> Self {
        Self {
            entries: Vec::new(),
            next_seq: 0,
        }
    }

    fn push(&mut self, text: String) {
        if self.entries.len() >= MAX_LIVE_LOG_ENTRIES {
            self.entries.remove(0);
        }
        self.entries.push((self.next_seq, text));
        self.next_seq += 1;
    }

    fn get_after(&self, after: Option<u64>) -> (Vec<(u64, String)>, bool, u64) {
        let next_seq = self.next_seq;
        match after {
            None => (self.entries.clone(), false, next_seq),
            Some(after_seq) => {
                let result: Vec<_> = self.entries
                    .iter()
                    .filter(|(seq, _)| *seq > after_seq)
                    .cloned()
                    .collect();

                // Dropped if there are entries that should exist (seq > after_seq) but
                // the oldest retained entry has a higher seq than after_seq + 1.
                let dropped = if next_seq > after_seq.saturating_add(1) {
                    if let Some((oldest_seq, _)) = self.entries.first() {
                        *oldest_seq > after_seq.saturating_add(1)
                    } else {
                        // Buffer empty but entries were written — all dropped
                        true
                    }
                } else {
                    false
                };

                (result, dropped, next_seq)
            }
        }
    }
}

pub struct InterceptorLogger {
    live_log: BlockingMutex<CriticalSectionRawMutex, core::cell::RefCell<LiveLogBuffer>>,
}

impl InterceptorLogger {
    pub const fn new() -> Self {
        Self {
            live_log: BlockingMutex::new(core::cell::RefCell::new(LiveLogBuffer::new())),
        }
    }

    /// Returns (entries_after, dropped, next_seq).
    /// Pass `after = None` to retrieve the entire current buffer.
    /// Pass `after = Some(seq)` to retrieve only entries with seq > that value.
    pub fn get_live_logs(&self, after: Option<u64>) -> (Vec<(u64, String)>, bool, u64) {
        self.live_log.lock(|buf| buf.borrow().get_after(after))
    }

    pub fn init(&'static self) {
        match log::set_logger(self).map(|()| log::set_max_level(LevelFilter::Info)) {
            Ok(()) => {}
            Err(_e) => {
                esp_println::println!("ERROR: Logger already set");
            }
        }
    }
}

impl Log for InterceptorLogger {
    fn enabled(&self, metadata: &Metadata) -> bool {
        metadata.level() <= log::Level::Info
    }

    fn log(&self, record: &Record) {
        if self.enabled(record.metadata()) {
            let message = alloc::format!("{}: {}", record.level(), record.args());

            // Print to serial
            esp_println::println!("{}", message);

            // Store in live log ring buffer
            self.live_log.lock(|buf| {
                buf.borrow_mut().push(message);
            });
        }
    }

    fn flush(&self) {}
}