//! This module contains the matching coordinator
use rayon::ThreadPool;
use std::rc::Rc;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};

use rayon::prelude::*;

use crate::engine::normalized::NormalizedEngineFactory;
use crate::engine::split::SplitMatchEngineFactory;
use crate::item::{ItemPool, MatchedItem, RankBuilder};
use crate::prelude::{AndOrEngineFactory, ExactOrFuzzyEngineFactory, RegexEngineFactory};
use crate::{CaseMatching, MatchEngineFactory, SkimOptions};

//==============================================================================
/// Control handle for a running matcher operation.
///
/// Provides methods to check status, retrieve results, and stop the matcher.
pub struct MatcherControl {
    stopped: Arc<AtomicBool>,
    interrupt: Arc<AtomicBool>,
    processed: Arc<AtomicUsize>,
    matched: Arc<AtomicUsize>,
}

impl Default for MatcherControl {
    fn default() -> Self {
        Self {
            stopped: Arc::new(AtomicBool::new(true)),
            interrupt: Arc::new(AtomicBool::new(false)),
            processed: Default::default(),
            matched: Default::default(),
        }
    }
}

impl MatcherControl {
    /// Returns the number of items that have been processed so far.
    pub fn get_num_processed(&self) -> usize {
        self.processed.load(Ordering::Relaxed)
    }

    /// Returns the number of items that have matched so far.
    pub fn get_num_matched(&self) -> usize {
        self.matched.load(Ordering::Relaxed)
    }

    /// Signals the matcher to stop processing.
    pub fn kill(&mut self) {
        self.interrupt.store(true, Ordering::Relaxed);
    }

    /// Returns true if the matcher has stopped (either completed or killed).
    pub fn stopped(&self) -> bool {
        self.stopped.load(Ordering::Relaxed)
    }
}

impl Drop for MatcherControl {
    fn drop(&mut self) {
        self.kill();
    }
}

//==============================================================================
/// The main matcher that coordinates fuzzy/exact matching of items against a query.
pub struct Matcher {
    engine_factory: Rc<dyn MatchEngineFactory>,
    case_matching: CaseMatching,
}

impl Matcher {
    /// Creates a new Matcher builder with the given engine factory.
    pub fn builder(engine_factory: Rc<dyn MatchEngineFactory>) -> Self {
        Self {
            engine_factory,
            case_matching: CaseMatching::default(),
        }
    }

    /// Sets the case matching mode (smart, ignore, or respect).
    pub fn case(mut self, case_matching: CaseMatching) -> Self {
        self.case_matching = case_matching;
        self
    }

    /// Finalizes the builder and returns the configured Matcher.
    pub fn build(self) -> Self {
        self
    }

    /// Creates a MatchEngineFactory from the given options.
    ///
    /// This is useful when you need the factory directly (e.g., for filter mode)
    /// without creating a full Matcher instance.
    pub fn create_engine_factory(options: &SkimOptions) -> Rc<dyn MatchEngineFactory> {
        if options.regex {
            let regex_factory = RegexEngineFactory::builder();
            if options.normalize {
                Rc::new(NormalizedEngineFactory::new(regex_factory))
            } else {
                Rc::new(regex_factory)
            }
        } else {
            let rank_builder = Arc::new(RankBuilder::new(options.tiebreak.clone()));
            log::debug!("Creating matcher for algo {:?}", options.algorithm);
            let fuzzy_engine_factory = ExactOrFuzzyEngineFactory::builder()
                .fuzzy_algorithm(options.algorithm)
                .exact_mode(options.exact)
                .rank_builder(rank_builder)
                .build();

            // If split_match is enabled, wrap the fuzzy factory with SplitMatchEngineFactory
            // Then wrap with AndOrEngineFactory so that queries like "foo:bar baz:qux" work
            let andor_factory = if let Some(delimiter) = options.split_match {
                let split_factory = SplitMatchEngineFactory::new(fuzzy_engine_factory, delimiter);
                AndOrEngineFactory::new(split_factory)
            } else {
                AndOrEngineFactory::new(fuzzy_engine_factory)
            };

            // Wrap with NormalizedEngineFactory if normalization is requested
            if options.normalize {
                Rc::new(NormalizedEngineFactory::new(andor_factory))
            } else {
                Rc::new(andor_factory)
            }
        }
    }

    /// Creates a Matcher configured from the given SkimOptions.
    pub fn from_options(options: &SkimOptions) -> Self {
        let engine_factory = Self::create_engine_factory(options);
        Matcher::builder(engine_factory).case(options.case).build()
    }

    /// Returns the case matching setting for this matcher.
    pub fn case_matching(&self) -> CaseMatching {
        self.case_matching
    }

    /// Returns a reference to the engine factory.
    pub fn engine_factory(&self) -> &Rc<dyn MatchEngineFactory> {
        &self.engine_factory
    }

    /// Runs the matcher on items from the pool in a background thread.
    ///
    /// The callback is invoked when matching is complete with the matched items.
    /// Returns a MatcherControl that can be used to monitor progress or stop the matcher.
    pub fn run<C>(&self, query: &str, item_pool: Arc<ItemPool>, thread_pool: &ThreadPool, callback: C) -> MatcherControl
    where
        C: Fn(Vec<MatchedItem>) + Send + 'static,
    {
        let matcher_engine = self.engine_factory.create_engine_with_case(query, self.case_matching);
        debug!("engine: {matcher_engine}");
        let stopped = Arc::new(AtomicBool::new(false));
        let stopped_clone = stopped.clone();
        let interrupt = Arc::new(AtomicBool::new(false));
        let interrupt_clone = interrupt.clone();
        let processed = Arc::new(AtomicUsize::new(0));
        let processed_clone = processed.clone();
        let matched = Arc::new(AtomicUsize::new(0));
        let matched_clone = matched.clone();

        // Take items synchronously before spawning to avoid a race condition:
        // if we took items inside the spawned closure, a subsequent restart_matcher()
        // could call kill() + reset() before the old closure runs, causing the old
        // closure to re-take items that should belong to the new matcher.
        let items = item_pool.take();
        trace!("matcher start, total: {}", items.len());

        thread_pool.spawn(move || {
            let matched_items: Vec<MatchedItem> = items
                .into_par_iter()
                .chunks(8196)
                .take_any_while(|_chunk| {
                    if interrupt.load(Ordering::Relaxed) {
                        return false;
                    }

                    true
                })
                .map(|chunk| {
                    processed.fetch_add(chunk.len(), Ordering::Relaxed);

                    let matched_chunk: Vec<MatchedItem> = chunk
                        .into_iter()
                        .filter_map(|item| {
                            matcher_engine.match_item(item.as_ref()).map(|match_result| {
                                // item is Arc but we get &Arc from iterator, so one clone is needed
                                MatchedItem {
                                    item,
                                    rank: match_result.rank,
                                    matched_range: Some(match_result.matched_range),
                                }
                            })
                        })
                        .collect();

                    matched.fetch_add(matched_chunk.len(), Ordering::Relaxed);

                    matched_chunk
                })
                .flatten_iter()
                .collect();

            if !interrupt.load(Ordering::SeqCst) {
                trace!("matcher stop, total matched: {}", matched_items.len());
                callback(matched_items);
            }
            stopped.store(true, Ordering::Relaxed);
        });

        MatcherControl {
            stopped: stopped_clone,
            interrupt: interrupt_clone,
            matched: matched_clone,
            processed: processed_clone,
        }
    }
}
