palate 0.3.9

use fancy_regex::RegexBuilder;
use phf_codegen::Map as PhfMap;
use serde::Deserialize;

/// Convert PCRE2-style `\g<name>` backreferences to fancy-regex `\k<name>` syntax.
fn translate_pcre2_to_fancy_regex(pattern: &str) -> String {
    // Replace \g<name> with \k<name> for fancy-regex compatibility
    pattern.replace(r#"\g<"#, r#"\k<"#)
}

fn validate_fancy_regex(pattern: &str) -> Result<(), fancy_regex::Error> {
    // Runtime matching uses multiline mode; validate patterns with the same semantics
    // to ensure codegen fails fast when Linguist introduces syntax we can't run.
    RegexBuilder::new(&format!("(?m){pattern}"))
        .build()
        .map(|_| ())
}
use std::{
    collections::HashMap,
    fs::{self, File},
    io::{BufWriter, Write},
    iter,
    path::Path,
};

use palate::FileType;

type NamedPatterns = HashMap<String, MaybeMany<String>>;

#[derive(Deserialize)]
struct Heuristics {
    disambiguations: Vec<Disambiguation>,
    named_patterns: NamedPatterns,
}

#[derive(Deserialize)]
struct Disambiguation {
    extensions: Vec<String>,
    rules: Vec<RuleDTO>,
}

impl Disambiguation {
    fn to_domain_object_code(&self, named_patterns: &NamedPatterns) -> String {
        let mut rules = String::new();
        for rule in self.rules.iter() {
            let rule_code = rule.to_domain_object_code(named_patterns);
            // Skip empty rules (languages that don't exist in FileType)
            if !rule_code.is_empty() {
                rules.push_str(format!("{},", rule_code).as_str());
            }
        }
        format!("&[{}]", rules)
    }
}

#[derive(Deserialize)]
struct RuleDTO {
    language: MaybeMany<String>,
    #[serde(flatten)]
    pattern: Option<PatternDTO>,
}

impl RuleDTO {
    fn to_domain_object_code(&self, named_patterns: &NamedPatterns) -> String {
        let languages = match &self.language {
            MaybeMany::Many(values) => values.clone(),
            MaybeMany::One(value) => vec![value.clone()],
        };

        let pattern_code = match &self.pattern {
            Some(pattern) => format!("Some({})", pattern.to_domain_object_code(named_patterns)),
            None => String::from("None"),
        };

        // Convert language names to FileType::Variant format.
        //
        // We intentionally resolve through FileType::from_str (via slugging and
        // other normalizations) so we stay aligned with the canonical tft/Neovim
        // filetypes as generated by scripts/codegen.ts.
        let language_types: Vec<String> = languages
            .iter()
            .filter_map(|lang| filetype_for_language(lang).map(|ft| format!("FileType::{ft:?}")))
            .collect();

        // If all languages in this rule don't exist in FileType, skip the rule
        if language_types.is_empty() {
            return String::new();
        }

        format!(
            "Rule {{ languages: &[{}], pattern: {}}}",
            language_types.join(", "),
            pattern_code
        )
    }
}

#[derive(Clone, Deserialize)]
enum PatternDTO {
    #[serde(rename = "and")]
    And(Vec<PatternDTO>),
    #[serde(rename = "named_pattern")]
    Named(String),
    #[serde(rename = "negative_pattern")]
    Negative(String),
    #[serde(rename = "pattern")]
    Positive(MaybeMany<String>),
}

impl PatternDTO {
    fn to_domain_object_code(&self, named_patterns: &NamedPatterns) -> String {
        match self {
            PatternDTO::Positive(MaybeMany::One(pattern)) => {
                // Translate PCRE2 syntax to fancy-regex syntax
                let pattern = translate_pcre2_to_fancy_regex(pattern);
                // Panic on invalid regex now so we can unwrap in lib
                if let Err(e) = validate_fancy_regex(&pattern) {
                    panic!("Invalid regex pattern: {}\n{}", pattern, e);
                }
                format!("Pattern::Positive({:?})", pattern)
            }
            PatternDTO::Negative(pattern) => {
                // Translate PCRE2 syntax to fancy-regex syntax
                let pattern = translate_pcre2_to_fancy_regex(pattern);
                // Panic on invalid regex now so we can unwrap in lib
                if let Err(e) = validate_fancy_regex(&pattern) {
                    panic!("Invalid regex pattern: {}\n{}", pattern, e);
                }
                format!("Pattern::Negative({:?})", pattern)
            }
            PatternDTO::Positive(MaybeMany::Many(patterns)) => {
                let mut code = String::from("Pattern::Or(&[");
                for pattern in patterns.iter() {
                    let p = PatternDTO::Positive(MaybeMany::One(pattern.clone()));
                    code.push_str(format!("{},", p.to_domain_object_code(named_patterns)).as_str());
                }
                code.push_str("])");
                code
            }
            PatternDTO::And(patterns) => {
                let mut code = String::from("Pattern::And(&[");
                for pattern in patterns.iter() {
                    code.push_str(
                        format!("{},", pattern.to_domain_object_code(named_patterns)).as_str(),
                    );
                }
                code.push_str("])");
                code
            }
            PatternDTO::Named(pattern_name) => {
                if let Some(pattern) = named_patterns.get(pattern_name) {
                    // Assume that all named patterns are positive
                    let pattern = PatternDTO::Positive(pattern.clone());
                    return pattern.to_domain_object_code(named_patterns);
                } else {
                    panic!(
                        "Named pattern: {} not found in named pattern map",
                        pattern_name
                    );
                };
            }
        }
    }
}

#[derive(Clone, Deserialize)]
#[serde(untagged)]
enum MaybeMany<T> {
    Many(Vec<T>),
    One(T),
}

const DISAMBIGUATION_HEURISTICS_FILE: &str = "src/codegen/disambiguation-heuristics-map.rs";
const TOKEN_LOG_PROBABILITY_FILE: &str = "src/codegen/token-log-probabilities.rs";

const HEURISTICS_SOURCE_FILE: &str = "heuristics.yml";

const MAX_TOKEN_BYTES: usize = 32;

fn main() {
    let heuristics: Heuristics =
        serde_norway::from_str(&fs::read_to_string(HEURISTICS_SOURCE_FILE).unwrap()[..]).unwrap();

    // Validate all regex patterns before generating code
    validate_all_patterns(&heuristics);

    create_disambiguation_heuristics_map(heuristics);

    // Only train classifier if samples directory exists
    if Path::new("samples").exists() {
        train_classifier();
    } else {
        println!("Note: Skipping classifier training - 'samples' directory not found");
        println!("      Copy/link samples from hyperpolyglot to enable classifier training");
    }
}

/// Validate all regex patterns in the heuristics file.
/// This ensures all patterns compile with fancy-regex before generating code.
fn validate_all_patterns(heuristics: &Heuristics) {
    let mut pattern_count = 0usize;

    // Validate all disambiguation patterns
    for dis in &heuristics.disambiguations {
        for rule in &dis.rules {
            if let Some(pattern) = &rule.pattern {
                validate_pattern_dto(pattern, &heuristics.named_patterns, &mut pattern_count);
            }
        }
    }

    // Validate all named patterns
    for (name, pattern) in &heuristics.named_patterns {
        match pattern {
            MaybeMany::One(p) => {
                let translated = translate_pcre2_to_fancy_regex(p);
                if let Err(e) = validate_fancy_regex(&translated) {
                    panic!("Invalid named pattern '{}': {}\n{}", name, translated, e);
                }
                pattern_count += 1;
            }
            MaybeMany::Many(patterns) => {
                for p in patterns {
                    let translated = translate_pcre2_to_fancy_regex(p);
                    if let Err(e) = validate_fancy_regex(&translated) {
                        panic!("Invalid named pattern '{}': {}\n{}", name, translated, e);
                    }
                    pattern_count += 1;
                }
            }
        }
    }

    println!("✓ Validated {} regex patterns with fancy-regex", pattern_count);
}

fn validate_pattern_dto(
    pattern: &PatternDTO,
    named_patterns: &NamedPatterns,
    count: &mut usize,
) {
    match pattern {
        PatternDTO::Positive(MaybeMany::One(p)) | PatternDTO::Negative(p) => {
            let translated = translate_pcre2_to_fancy_regex(p);
            if let Err(e) = validate_fancy_regex(&translated) {
                panic!("Invalid regex pattern: {}\n{}", translated, e);
            }
            *count += 1;
        }
        PatternDTO::Positive(MaybeMany::Many(patterns)) => {
            for p in patterns {
                validate_pattern_dto(
                    &PatternDTO::Positive(MaybeMany::One(p.clone())),
                    named_patterns,
                    count,
                );
            }
        }
        PatternDTO::And(patterns) => {
            for p in patterns {
                validate_pattern_dto(p, named_patterns, count);
            }
        }
        PatternDTO::Named(name) => {
            if let Some(pattern) = named_patterns.get(name) {
                let dto = PatternDTO::Positive(pattern.clone());
                validate_pattern_dto(&dto, named_patterns, count);
            } else {
                panic!("Named pattern '{}' not found", name);
            }
        }
    }
}

fn create_disambiguation_heuristics_map(heuristics: Heuristics) {
    let mut file = BufWriter::new(File::create(DISAMBIGUATION_HEURISTICS_FILE).unwrap());

    let mut temp_map: HashMap<String, String> = HashMap::new();
    for mut dis in heuristics.disambiguations.into_iter() {
        for ext in dis.extensions.iter() {
            // Adding a rule to default to C for .h if the Objective C and C++ patterns don't match
            // The classifer was unreliable for distinguishing between C and C++ for .h
            if ext == ".h" {
                dis.rules.push(RuleDTO {
                    language: MaybeMany::One(String::from("C")),
                    pattern: None,
                });
            }
            let extension = ext.clone().to_ascii_lowercase();
            let key = extension;
            let value = dis.to_domain_object_code(&heuristics.named_patterns);
            temp_map.insert(key, value);
        }
    }

    let mut disambiguation_heuristic_map = PhfMap::new();
    for (key, value) in temp_map.iter() {
        disambiguation_heuristic_map.entry(&key[..], &value[..]);
    }

    writeln!(
        &mut file,
        "static DISAMBIGUATIONS: phf::Map<&'static str, &'static [Rule]> =\n{};\n",
        disambiguation_heuristic_map.build()
    )
    .unwrap();
}

fn train_classifier() {
    let mut temp_token_count: HashMap<String, HashMap<String, i32>> = HashMap::new();
    let mut temp_total_tokens_count = HashMap::new();

    fs::read_dir("samples")
        .unwrap()
        .map(|entry| entry.unwrap())
        .filter(|entry| entry.path().is_dir())
        .map(|language_dir| {
            let path = language_dir.path();
            let language = path.file_name().unwrap();
            let language = language.to_string_lossy().into_owned();
            let language = match &language[..] {
                "Fstar" => String::from("F*"),
                _ => language,
            };

            let file_paths = fs::read_dir(language_dir.path())
                .unwrap()
                .map(|entry| entry.unwrap().path())
                .filter(|path| path.is_file());

            let language_iter = iter::repeat(language);
            file_paths.zip(language_iter)
        })
        .flatten()
        .for_each(|(entry, language)| {
            let content = fs::read(entry).unwrap();

            // When tokenizing an invalid utf8 string, just set it to ""
            // Add better error handling here in the future but unure of the best
            // way to handle it now
            let tokens = palate_polyglot_tokenizer::get_key_tokens(
                std::str::from_utf8(&content[..]).unwrap_or(""),
            );

            for token in tokens {
                if token.len() <= MAX_TOKEN_BYTES {
                    let total_tokens = temp_total_tokens_count.entry(language.clone()).or_insert(0);
                    *total_tokens += 1;

                    let tokens_count = temp_token_count
                        .entry(language.clone())
                        .or_insert(HashMap::new());

                    let count = tokens_count.entry(String::from(token)).or_insert(0);
                    *count += 1;
                }
            }
        });

    // Write token log probabilities
    let mut file = BufWriter::new(File::create(TOKEN_LOG_PROBABILITY_FILE).unwrap());
    let mut language_entries: Vec<(String, String)> = Vec::new();
    for (language, token_count_map) in temp_token_count.iter() {
        let total_tokens = *temp_total_tokens_count.get(language).unwrap() as f64;
        let mut token_log_probabilities = PhfMap::new();
        let mut token_entries: Vec<(String, String)> = Vec::new();
        for (token, token_count) in token_count_map.iter() {
            let probability = (*token_count as f64) / (total_tokens);
            let log_probability = probability.ln();
            token_entries.push((token.clone(), format!("{}f64", log_probability)));
        }
        for (token, value) in token_entries.iter() {
            token_log_probabilities.entry(token.as_str(), value.as_str());
        }
        language_entries.push((
            language.clone(),
            token_log_probabilities.build().to_string(),
        ));
    }

    let mut language_token_log_probabilities = PhfMap::new();
    for (language, map) in language_entries.iter() {
        language_token_log_probabilities.entry(language.as_str(), map.as_str());
    }

    writeln!(
        &mut file,
        "static TOKEN_LOG_PROBABILITIES: phf::Map<&'static str, phf::Map<&'static str, f64>> =\n{};\n",
        language_token_log_probabilities.build()
    )
    .unwrap();
}

fn filetype_for_language(language: &str) -> Option<FileType> {
    use std::str::FromStr;

    fn slugify(s: &str) -> String {
        s.trim()
            .to_lowercase()
            .chars()
            .map(|c| if c.is_ascii_alphanumeric() { c } else { '-' })
            .collect::<String>()
            .split('-')
            .filter(|s| !s.is_empty())
            .collect::<Vec<_>>()
            .join("-")
    }

    let raw = language.trim();
    if raw.is_empty() {
        return None;
    }

    // Common symbol-heavy language names.
    let lower = raw.to_lowercase();
    let special = match lower.as_str() {
        "c#" => Some("csharp"),
        "c++" => Some("cpp"),
        "f#" => Some("fsharp"),
        "f*" => Some("fstar"),
        "objective-c" => Some("objc"),
        "objective-c++" => Some("objcpp"),
        _ => None,
    };
    if let Some(s) = special {
        if let Ok(ft) = FileType::from_str(s) {
            return Some(ft);
        }
    }

    let slug = slugify(raw);
    let collapsed = lower.replace([' ', '-', '_'], "");

    for candidate in [lower.as_str(), slug.as_str(), collapsed.as_str()] {
        if let Ok(ft) = FileType::from_str(candidate) {
            return Some(ft);
        }
    }

    None
}