use tempfile::tempdir;

use file_per_thread_logger::{
    allow_uninitialized, initialize, initialize_with_formatter, FormatFn,
};

use log::{debug, error, info, trace, warn};
use std::collections::HashSet;
use std::env;
use std::fs;
use std::io::{self, Write};
use std::thread;

const LOG_PREFIX: &str = "my_log_test-";

/// Returns the names of the log files found in the current directory.
fn log_files(log_prefix: &str) -> io::Result<HashSet<String>> {
    let current_dir = env::current_dir()?;

    let mut logs = HashSet::new();
    for entry in fs::read_dir(current_dir.as_path())? {
        let path = entry?.path();
        if let Some(filename) = path.file_name() {
            let filename = filename.to_string_lossy();
            if filename.starts_with(log_prefix) {
                logs.insert(filename[log_prefix.len()..].to_string());
            }
        }
    }

    Ok(logs)
}

fn read_log(name: &str) -> io::Result<String> {
    fs::read_to_string(format!("{}{}", LOG_PREFIX, name))
}

fn set(names: &[&str]) -> HashSet<String> {
    names.iter().map(|s| s.to_string()).collect()
}

fn flush() {
    log::logger().flush();
}

fn do_log(run_init: bool, formatter: Option<FormatFn>) -> thread::ThreadId {
    trace!("This is a trace entry on the main thread.");
    debug!("This is a debug entry on the main thread.");
    info!("This is an info entry on the main thread.");
    warn!("This is a warn entry on the main thread.");
    error!("This is an error entry on the main thread.");

    let handle = thread::spawn(move || {
        if run_init {
            if let Some(formatter) = formatter {
                initialize_with_formatter(LOG_PREFIX, formatter);
            } else {
                initialize(LOG_PREFIX);
            }
        }
        trace!("This is a trace entry from an unnamed helper thread.");
        debug!("This is a debug entry from an unnamed helper thread.");
        info!("This is an info entry from an unnamed helper thread.");
        warn!("This is a warn entry from an unnamed helper thread.");
        error!("This is an error entry from an unnamed helper thread.");
        flush();
    });

    let unnamed_thread_id = handle.thread().id();
    handle.join().unwrap();

    let handle = thread::Builder::new()
        .name("helper".to_string())
        .spawn(move || {
            if run_init {
                if let Some(formatter) = formatter {
                    initialize_with_formatter(LOG_PREFIX, formatter);
                } else {
                    initialize(LOG_PREFIX);
                }
            }
            trace!("This is a trace entry from a named thread.");
            debug!("This is a debug entry from a named thread.");
            info!("This is an info entry from a named thread.");
            warn!("This is a warn entry from a named thread.");
            error!("This is an error entry from a named thread.");
            flush();
        })
        .unwrap();

    handle.join().unwrap();
    flush();

    unnamed_thread_id
}

#[test]
fn tests() -> io::Result<()> {
    let temp_dir = tempdir()?;
    env::set_current_dir(&temp_dir)?;

    assert_eq!(log_files(LOG_PREFIX)?, set(&[]));

    env::remove_var("RUST_LOG");
    initialize(LOG_PREFIX);

    // Nothing should be logged without something in the RUST_LOG env variable..
    assert_eq!(log_files(LOG_PREFIX)?, set(&[]));
    do_log(false, None);
    assert_eq!(log_files(LOG_PREFIX)?, set(&[]));

    // When the RUST_LOG variable is set, it will create the main thread file even though nothing
    // has been logged yet.
    env::set_var("RUST_LOG", "info");
    initialize(LOG_PREFIX);
    flush();

    let main_log = "tests";
    let named_log = "helper";

    assert_eq!(log_files(LOG_PREFIX)?, set(&[main_log]));
    assert_eq!(
        read_log(main_log)?,
        r#"INFO - Set up logging; filename prefix is my_log_test-
"#
    );

    let unnamed_thread_id = do_log(true, None);
    let unnamed_log = format!("{:?}", unnamed_thread_id);
    let unnamed_log = &unnamed_log
        .chars()
        .filter(|ch| ch.is_alphanumeric() || *ch == '-' || *ch == '_')
        .collect::<String>();

    // It then creates files for each thread with logged contents.
    assert_eq!(
        log_files(LOG_PREFIX)?,
        set(&[main_log, named_log, unnamed_log])
    );
    assert_eq!(
        read_log(main_log)?,
        r#"INFO - Set up logging; filename prefix is my_log_test-
INFO - This is an info entry on the main thread.
WARN - This is a warn entry on the main thread.
ERROR - This is an error entry on the main thread.
"#
    );
    assert_eq!(
        read_log(unnamed_log)?,
        r#"INFO - Set up logging; filename prefix is my_log_test-
INFO - This is an info entry from an unnamed helper thread.
WARN - This is a warn entry from an unnamed helper thread.
ERROR - This is an error entry from an unnamed helper thread.
"#
    );
    assert_eq!(
        read_log(named_log)?,
        r#"INFO - Set up logging; filename prefix is my_log_test-
INFO - This is an info entry from a named thread.
WARN - This is a warn entry from a named thread.
ERROR - This is an error entry from a named thread.
"#
    );

    temp_dir.close()?;
    Ok(())
}

#[test]
fn formatted_logs() -> io::Result<()> {
    let temp_dir = tempdir()?;
    env::set_current_dir(&temp_dir)?;
    let formatter: FormatFn = |get_writer, record| {
        let args = format!("{}", record.args());
        let mut writer = get_writer.get();
        writeln!(
            writer,
            "{} [{}:{}] {}",
            record.level(),
            record.file().unwrap_or_default(),
            record.line().unwrap_or_default(),
            args
        )
    };

    // When the RUST_LOG variable is set, it will create the main thread file even though nothing
    // has been logged yet.
    env::set_var("RUST_LOG", "info");
    initialize_with_formatter(LOG_PREFIX, formatter);
    flush();

    let main_log = "formatted_logs";
    let named_log = "helper";

    assert_eq!(log_files(LOG_PREFIX)?, set(&[main_log]));
    assert_eq!(
        read_log(main_log)?,
        r#"INFO [src/lib.rs:119] Set up logging; filename prefix is my_log_test-
"#
    );

    let unnamed_thread_id = do_log(true, Some(formatter));
    let unnamed_log = format!("{:?}", unnamed_thread_id);
    let unnamed_log = &unnamed_log
        .chars()
        .filter(|ch| ch.is_alphanumeric() || *ch == '-' || *ch == '_')
        .collect::<String>();

    // It then creates files for each thread with logged contents.
    assert_eq!(
        log_files(LOG_PREFIX)?,
        set(&[main_log, named_log, unnamed_log])
    );

    assert_eq!(
        read_log(unnamed_log)?,
        r#"INFO [src/lib.rs:119] Set up logging; filename prefix is my_log_test-
INFO [tests/test.rs:63] This is an info entry from an unnamed helper thread.
WARN [tests/test.rs:64] This is a warn entry from an unnamed helper thread.
ERROR [tests/test.rs:65] This is an error entry from an unnamed helper thread.
"#
    );
    assert_eq!(
        read_log(named_log)?,
        r#"INFO [src/lib.rs:119] Set up logging; filename prefix is my_log_test-
INFO [tests/test.rs:84] This is an info entry from a named thread.
WARN [tests/test.rs:85] This is a warn entry from a named thread.
ERROR [tests/test.rs:86] This is an error entry from a named thread.
"#
    );
    temp_dir.close()?;
    Ok(())
}

#[test]
#[should_panic]
fn uninitialized_threads_should_panic() {
    let temp_dir = tempdir().expect("Cannot create tempdir");
    env::set_current_dir(&temp_dir).expect("Couldn't set current dir");

    env::set_var("RUST_LOG", "info");
    initialize(LOG_PREFIX);
    let handle = thread::spawn(|| {
        log::info!("This is a log from a thread");
    });
    let _ = handle.join().unwrap();
}

#[test]
fn logging_from_uninitialized_threads_allowed() -> io::Result<()> {
    let temp_dir = tempdir()?;
    env::set_current_dir(&temp_dir)?;

    env::set_var("RUST_LOG", "info");
    initialize("");
    flush();
    allow_uninitialized();
    let handle = thread::spawn(|| {
        log::info!("This is a log from a thread");
    });
    flush();
    let unnamed_log = format!("{:?}", handle.thread().id());
    let unnamed_log = &unnamed_log
        .chars()
        .filter(|ch| ch.is_alphanumeric() || *ch == '-' || *ch == '_')
        .collect::<String>();
    let _ = handle.join().unwrap();
    let main_log = "logging_from_uninitialized_threads_allowed";
    assert_eq!(log_files("")?, set(&[main_log, unnamed_log]));
    temp_dir.close()?;
    Ok(())
}

#[test]
fn log_in_log() -> io::Result<()> {
    let temp_dir = tempdir()?;
    env::set_current_dir(&temp_dir)?;

    env::set_var("RUST_LOG", "trace");
    initialize("");
    flush();

    struct Display;

    impl std::fmt::Display for Display {
        fn fmt(&self, _f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            log::info!("log 2");
            Ok(())
        }
    }

    let handle = thread::spawn(|| {
        initialize("");

        log::trace!("log 1");
        let display = Display;
        log::warn!("log 3{display}");
    });
    flush();

    let unnamed_thread_id = handle.thread().id();
    let unnamed_log = format!("{unnamed_thread_id:?}");
    let unnamed_log = &unnamed_log
        .chars()
        .filter(|ch| ch.is_alphanumeric() || *ch == '-' || *ch == '_')
        .collect::<String>();

    let _ = handle.join().unwrap();

    assert_eq!(log_files("")?, set(&["log_in_log", unnamed_log]));

    assert_eq!(
        fs::read_to_string(unnamed_log)?,
        r#"INFO - Set up logging; filename prefix is 
TRACE - log 1
INFO - log 2
WARN - log 3
"#
    );

    temp_dir.close()?;
    Ok(())
}