use anyhow::{ensure, Context, Result};
use fancy_regex::Regex as FancyRegex;
use regex::Regex;
use serde_json::Value;
use std::fs::File;
use std::hint::black_box;
use std::io::{BufRead, BufReader};
use std::path::PathBuf;
use std::time::Instant;

const SOURCE_TOKEN_PATTERN: &str = r"WEB[-_ ]?DL|WEB[-_ ]?Rip|BDRip|BluRay|BDMV|BD|DVDRip|DVD|TVRip|HDTV|Netflix|NF|AMZN|Baha|CR|ABEMA|DSNP|U[-_ ]?NEXT|Hulu|AT[-_ ]?X|x26[45]|h\.?26[45]|HEVC|AVC|AV1|AAC\d*(?:\.\d+)?|AAC|FLAC|MP3|DTS|Opus|CHS|CHT|GB|BIG5|JPN?|JPSC|JPTC|繁中|简中";
const RESOLUTION_BODY: &str = r"\d{3,4}[pP]|\d[Kk]|\d{3,4}[xX×]\d{3,4}";
const SPECIAL_TAG_PATTERN: &str =
    r"(?i)^(?:檢索|检索|搜索|搜寻|搜尋|别名|別名|alias|search|keyword)\s*[:：].+";
const SPECIAL_CODE_PATTERN: &str =
    r"(?i)^(?:NCOP|NCED|OP|ED|PV|CM)\d*$|^IV\d+$|^(?:OVA|OAD|SP)\d*$";
const EPISODE_CONTEXT_PATTERN: &str = r"(?i)^\s*(?:[-_]\s*(?:\d{1,4}|NCOP|NCED|OP|ED|OVA|OAD|SP|END)\b|#\s*\d{1,4}|[\[\(【《]\s*(?:EP?|#)?\d{1,4})";
const EPISODE_SPAN_PATTERN: &str = r"(?i)(?:[Ss]\d{1,2}[Ee]\d{1,4}(?:v\d+)?|(?:^|[\s._])[-_]\s*\d{1,4}(?:v\d+)?(?=$|[\s._\-\]\)】》\[])|[\[\(【《](?:EP?|#)?\d{1,4}(?:v\d+)?[\]\)】》]|(?:^|[\s._\-\[\(【《#])(?:EP?|第|#)\d{1,4}(?:v\d+)?(?:[话話集])?(?=$|[\s._\-\]\)】》]))";
const READING_MARKER_PATTERN: &str = r"(?i)(?<![A-Za-z0-9])(?P<marker>Ni\s+no\s+(?:Sara|Shou|Sho|Syo|Shō)|San\s+no\s+(?:Sara|Shou|Sho|Syo)|(?:Yon|Shi|Shin)\s+no\s+Sara|(?:Go|Gou)\s+no\s+Sara|Ni\s+Gakki|Sono\s+Ni)(?![A-Za-z0-9])";
const ROMAN_MARKER_PATTERN: &str =
    r"(?<![A-Za-z0-9])(?P<marker>II|III|IV|V|VI|VII|VIII|IX|[ⅡⅢⅣⅤⅥⅦⅧⅨ])(?![A-Za-z0-9])";
const CJK_MARKER_PATTERN: &str = r"(?:[一二三四五六七八九十兩两貳贰弐弍參叁参肆伍陸陆柒捌玖](?:\s*(?:ノ|の|之)\s*(?:章|期|季|部))?|第[一二三四五六七八九十兩两貳贰弐弍參叁参肆伍陸陆柒捌玖\d]+[季期部章])";
const SPECIAL_CONTEXT_PREFIX_PATTERN: &str =
    r"(?i)^(?:[\[\(【《]\s*(?:menu|menus|bdmenu|ncop|nced|op|ed|ova|oad|sp)\s*[\]\)】》]\s*){0,2}";

pub fn run(input: &PathBuf, limit_rows: usize, repeat: usize) -> Result<()> {
    ensure!(repeat > 0, "--regex-benchmark-repeat must be greater than 0");

    let filenames = load_filenames(input, limit_rows)?;
    if filenames.is_empty() {
        anyhow::bail!("no filenames loaded from {}", input.display());
    }

    let selective = SelectivePatterns::new()?;
    let fancy_all = FancyAllPatterns::new()?;

    let (selective_seconds, selective_count) =
        time_repeated(repeat, || run_selective(&filenames, &selective))?;
    let (fancy_seconds, fancy_count) =
        time_repeated(repeat, || run_fancy_all(&filenames, &fancy_all))?;
    ensure!(
        selective_count == fancy_count,
        "selective and fancy-all match counts differ: selective={}, fancy_all={}",
        selective_count,
        fancy_count
    );

    let ratio = if selective_seconds > 0.0 {
        fancy_seconds / selective_seconds
    } else {
        0.0
    };
    println!(
        "{}",
        serde_json::json!({
            "rows": filenames.len(),
            "repeat": repeat,
            "selective_seconds": selective_seconds,
            "fancy_all_seconds": fancy_seconds,
            "ratio": ratio,
            "match_count": selective_count,
        })
    );
    Ok(())
}

fn time_repeated<F>(repeat: usize, mut run_once: F) -> Result<(f64, usize)>
where
    F: FnMut() -> Result<usize>,
{
    let started = Instant::now();
    let mut count = 0usize;
    for _ in 0..repeat {
        count = count.wrapping_add(black_box(run_once()?));
    }
    Ok((started.elapsed().as_secs_f64(), count))
}

struct SelectivePatterns {
    resolution: Regex,
    source: Regex,
    source_tag: Regex,
    special_tag: Regex,
    special_code: Regex,
    episode_context: Regex,
    episode_span: FancyRegex,
    reading_marker: FancyRegex,
    roman_marker: FancyRegex,
    cjk_marker: Regex,
    special_context_prefix: Regex,
}

impl SelectivePatterns {
    fn new() -> Result<Self> {
        Ok(Self {
            resolution: Regex::new(&format!(r"(?i)(?:{RESOLUTION_BODY})"))?,
            source: Regex::new(&format!(r"(?i)(?:{SOURCE_TOKEN_PATTERN})"))?,
            source_tag: Regex::new(&format!(
                r"(?i)^(?:{SOURCE_TOKEN_PATTERN})(?:\s*(?:[&+/,_-]|,\s*)\s*(?:{SOURCE_TOKEN_PATTERN}))*$"
            ))?,
            special_tag: Regex::new(SPECIAL_TAG_PATTERN)?,
            special_code: Regex::new(SPECIAL_CODE_PATTERN)?,
            episode_context: Regex::new(EPISODE_CONTEXT_PATTERN)?,
            episode_span: FancyRegex::new(EPISODE_SPAN_PATTERN)?,
            reading_marker: FancyRegex::new(READING_MARKER_PATTERN)?,
            roman_marker: FancyRegex::new(ROMAN_MARKER_PATTERN)?,
            cjk_marker: Regex::new(CJK_MARKER_PATTERN)?,
            special_context_prefix: Regex::new(SPECIAL_CONTEXT_PREFIX_PATTERN)?,
        })
    }
}

struct FancyAllPatterns {
    resolution: FancyRegex,
    source: FancyRegex,
    source_tag: FancyRegex,
    special_tag: FancyRegex,
    special_code: FancyRegex,
    episode_context: FancyRegex,
    episode_span: FancyRegex,
    reading_marker: FancyRegex,
    roman_marker: FancyRegex,
    cjk_marker: FancyRegex,
    special_context_prefix: FancyRegex,
}

impl FancyAllPatterns {
    fn new() -> Result<Self> {
        Ok(Self {
            resolution: FancyRegex::new(&format!(r"(?i)(?:{RESOLUTION_BODY})"))?,
            source: FancyRegex::new(&format!(r"(?i)(?:{SOURCE_TOKEN_PATTERN})"))?,
            source_tag: FancyRegex::new(&format!(
                r"(?i)^(?:{SOURCE_TOKEN_PATTERN})(?:\s*(?:[&+/,_-]|,\s*)\s*(?:{SOURCE_TOKEN_PATTERN}))*$"
            ))?,
            special_tag: FancyRegex::new(SPECIAL_TAG_PATTERN)?,
            special_code: FancyRegex::new(SPECIAL_CODE_PATTERN)?,
            episode_context: FancyRegex::new(EPISODE_CONTEXT_PATTERN)?,
            episode_span: FancyRegex::new(EPISODE_SPAN_PATTERN)?,
            reading_marker: FancyRegex::new(READING_MARKER_PATTERN)?,
            roman_marker: FancyRegex::new(ROMAN_MARKER_PATTERN)?,
            cjk_marker: FancyRegex::new(CJK_MARKER_PATTERN)?,
            special_context_prefix: FancyRegex::new(SPECIAL_CONTEXT_PREFIX_PATTERN)?,
        })
    }
}

fn run_selective(filenames: &[String], patterns: &SelectivePatterns) -> Result<usize> {
    let mut count = 0usize;
    for filename in filenames {
        count = count.wrapping_add(
            patterns
                .resolution
                .find_iter(filename)
                .filter(|mat| has_ascii_token_boundaries(filename, mat.start(), mat.end()))
                .count(),
        );
        count = count.wrapping_add(
            patterns
                .source
                .find_iter(filename)
                .filter(|mat| has_ascii_token_boundaries(filename, mat.start(), mat.end()))
                .count(),
        );
        count = count.wrapping_add(patterns.episode_context.is_match(filename) as usize);
        count = count.wrapping_add(patterns.cjk_marker.find_iter(filename).count());
        count = count.wrapping_add(fancy_count(&patterns.episode_span, filename)?);
        count = count.wrapping_add(fancy_count(&patterns.reading_marker, filename)?);
        count = count.wrapping_add(fancy_count(&patterns.roman_marker, filename)?);

        for inner in bracket_inners(filename) {
            count = count.wrapping_add(patterns.source_tag.is_match(&inner) as usize);
            count = count.wrapping_add(patterns.special_tag.is_match(&inner) as usize);
            count = count.wrapping_add(patterns.special_code.is_match(&inner) as usize);
            count = count.wrapping_add(patterns.special_context_prefix.is_match(&inner) as usize);
        }
    }
    Ok(count)
}

fn run_fancy_all(filenames: &[String], patterns: &FancyAllPatterns) -> Result<usize> {
    let mut count = 0usize;
    for filename in filenames {
        count = count.wrapping_add(fancy_count_with_boundaries(&patterns.resolution, filename)?);
        count = count.wrapping_add(fancy_count_with_boundaries(&patterns.source, filename)?);
        count = count.wrapping_add(patterns.episode_context.is_match(filename)? as usize);
        count = count.wrapping_add(fancy_count(&patterns.cjk_marker, filename)?);
        count = count.wrapping_add(fancy_count(&patterns.episode_span, filename)?);
        count = count.wrapping_add(fancy_count(&patterns.reading_marker, filename)?);
        count = count.wrapping_add(fancy_count(&patterns.roman_marker, filename)?);

        for inner in bracket_inners(filename) {
            count = count.wrapping_add(patterns.source_tag.is_match(&inner)? as usize);
            count = count.wrapping_add(patterns.special_tag.is_match(&inner)? as usize);
            count = count.wrapping_add(patterns.special_code.is_match(&inner)? as usize);
            count = count.wrapping_add(patterns.special_context_prefix.is_match(&inner)? as usize);
        }
    }
    Ok(count)
}

fn fancy_count(regex: &FancyRegex, text: &str) -> Result<usize> {
    let mut count = 0usize;
    for item in regex.find_iter(text) {
        let _ = item?;
        count += 1;
    }
    Ok(count)
}

fn fancy_count_with_boundaries(regex: &FancyRegex, text: &str) -> Result<usize> {
    let mut count = 0usize;
    for item in regex.find_iter(text) {
        let mat = item?;
        if has_ascii_token_boundaries(text, mat.start(), mat.end()) {
            count += 1;
        }
    }
    Ok(count)
}

fn load_filenames(path: &PathBuf, limit_rows: usize) -> Result<Vec<String>> {
    let file = File::open(path).with_context(|| format!("failed to open {}", path.display()))?;
    let reader = BufReader::new(file);
    let mut filenames = Vec::new();
    for (idx, line) in reader.lines().enumerate() {
        if limit_rows > 0 && filenames.len() >= limit_rows {
            break;
        }
        let raw = line.with_context(|| format!("failed reading line {}", idx + 1))?;
        if raw.trim().is_empty() {
            continue;
        }
        let value: Value = serde_json::from_str(&raw)
            .with_context(|| format!("invalid JSONL line {}", idx + 1))?;
        if let Some(filename) = value.get("filename").and_then(Value::as_str) {
            filenames.push(filename.to_string());
        }
    }
    Ok(filenames)
}

fn bracket_inners(text: &str) -> Vec<String> {
    let chars = text.chars().collect::<Vec<_>>();
    let mut spans = Vec::new();
    let mut idx = 0usize;
    while idx < chars.len() {
        let close = match chars[idx] {
            '[' => ']',
            '(' => ')',
            '【' => '】',
            '《' => '》',
            _ => {
                idx += 1;
                continue;
            }
        };
        if let Some(relative_end) = chars[idx + 1..].iter().position(|ch| *ch == close) {
            let end = idx + 1 + relative_end;
            spans.push(chars[idx + 1..end].iter().collect::<String>());
            idx = end + 1;
        } else {
            idx += 1;
        }
    }
    spans
}

fn has_ascii_token_boundaries(text: &str, start: usize, end: usize) -> bool {
    let previous_ok = text[..start]
        .chars()
        .next_back()
        .map(|ch| !ch.is_ascii_alphanumeric())
        .unwrap_or(true);
    let next_ok = text[end..]
        .chars()
        .next()
        .map(|ch| !ch.is_ascii_alphanumeric())
        .unwrap_or(true);
    previous_ok && next_ok
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn selective_and_fancy_all_count_the_same_matches() -> Result<()> {
        let filenames = vec![
            "[GM-Team][國漫][神印王座][Throne of Seal][2022][200][AVC][GB][1080P].mp4".to_string(),
            "[YYDM&VCB-Studio] Shinsekai Yori II [NCED02][Ma10p_1080p][x265_flac].mkv".to_string(),
            "Witch.Hat.Atelier.S01E07.1080p.NF.WEB-DL.JPN.AAC2.0.H.264.MSubs-ToonsHub".to_string(),
            "[Lilith-Raws] San no Sara - 03 [Baha][WEB-DL][1080p][AVC AAC][CHT].mp4".to_string(),
            "[Test] 搜索: 别名 [OVA01][BDRip][720p]".to_string(),
        ];
        let selective = SelectivePatterns::new()?;
        let fancy_all = FancyAllPatterns::new()?;

        assert_eq!(
            run_selective(&filenames, &selective)?,
            run_fancy_all(&filenames, &fancy_all)?
        );
        Ok(())
    }

    #[test]
    fn bracket_inners_extract_supported_pairs() {
        assert_eq!(bracket_inners("[A](B)【C】《D》"), vec!["A", "B", "C", "D"]);
    }

    #[test]
    fn ascii_token_boundaries_reject_embedded_matches() {
        let text = "ABC1080p 1080p HEVC2 HEVC";
        assert!(!has_ascii_token_boundaries(text, 3, 8));
        assert!(has_ascii_token_boundaries(text, 9, 14));
        assert!(!has_ascii_token_boundaries(text, 15, 19));
        assert!(has_ascii_token_boundaries(text, 21, 25));
    }
}