use std::path::Path;

use ignore::WalkBuilder;

use archlens_domain::{
    AnalysisConfig, DomainError, FilePath, Language, SourceFile, ports::FileDiscovery,
};

pub struct WalkdirDiscovery;

impl Default for WalkdirDiscovery {
    fn default() -> Self {
        Self::new()
    }
}

impl WalkdirDiscovery {
    pub fn new() -> Self {
        Self
    }

    fn detect_language(path: &Path) -> Option<Language> {
        match path.extension()?.to_str()? {
            "rs" => Some(Language::Rust),
            "py" => Some(Language::Python),
            "cs" => Some(Language::CSharp),
            _ => None,
        }
    }

    fn is_excluded(path: &Path, root: &Path, excludes: &[String]) -> bool {
        let relative = path.strip_prefix(root).unwrap_or(path);
        let relative_str = relative.to_string_lossy();

        for component in relative.components() {
            let name = component.as_os_str().to_string_lossy();
            if AnalysisConfig::is_standard_excluded(&name) {
                return true;
            }
        }

        excludes
            .iter()
            .any(|exclude| relative_str.contains(exclude.trim_end_matches('/')))
    }
}

impl FileDiscovery for WalkdirDiscovery {
    fn discover(
        &self,
        root: &Path,
        config: &AnalysisConfig,
    ) -> Result<Vec<SourceFile>, DomainError> {
        let mut files = Vec::new();

        let walker = WalkBuilder::new(root).hidden(true).git_ignore(true).build();

        for entry in walker.filter_map(|e| e.ok()) {
            let path = entry.path();

            if !path.is_file() {
                continue;
            }

            if Self::is_excluded(path, root, config.excludes()) {
                continue;
            }

            if let Some(scope) = config.scope() {
                let relative = path.strip_prefix(root).unwrap_or(path);
                if !relative.starts_with(scope) {
                    continue;
                }
            }

            if let Some(language) = Self::detect_language(path) {
                if !config.include_tests() && language.is_test_file(path) {
                    continue;
                }
                if let Some(changed) = config.changed_files() {
                    let relative = path.strip_prefix(root).unwrap_or(path).to_string_lossy();
                    if !changed
                        .iter()
                        .any(|c| relative.ends_with(c.as_str()) || c.ends_with(relative.as_ref()))
                    {
                        continue;
                    }
                }
                let absolute = path.canonicalize().unwrap_or_else(|_| path.to_path_buf());
                let file_path = FilePath::new(&absolute.to_string_lossy())
                    .map_err(|e| DomainError::IoError(e.to_string()))?;
                files.push(SourceFile::new(file_path, language));
            }
        }

        Ok(files)
    }
}