use crate::*;


/// Compiles multiple source code files into one.
pub struct Compiler {
    pub source_path: PathBuf,
    pub resolver: Resolver,
}

impl Compiler {
    pub fn from_string<P: AsRef<Path>>(source_code: String, path: P) -> Self {
        let source_unit = SourceUnit::from_string(source_code, &path, parse_symbols);
        Self {
            source_path: path.as_ref().to_path_buf(),
            resolver: Resolver::new(source_unit)
        }
    }

    pub fn from_path<P: AsRef<Path>>(path: P) -> Result<Self, FileError> {
        let source_unit = SourceUnit::from_path(&path, None, parse_symbols)?;
        Ok(Self {
            source_path: path.as_ref().to_path_buf(),
            resolver: Resolver::new(source_unit)
        })
    }

    /// Find library files descending from the parent directory.
    pub fn include_libs_from_parent(&mut self, ext: &str) {
        if let Some(parent_path) = self.source_path.parent() {
            let parent_path = parent_path.to_owned();
            self.include_libs_from_path(&parent_path, ext);
        }
    }

    /// Find library files at or descending from a path.
    pub fn include_libs_from_path(&mut self, path: &Path, ext: &str) {
        let libraries = gather_from_path(path, Some(ext), parse_symbols);
        self.resolver.add_library_source_units(libraries);
        self.resolver.resolve();
    }

    /// Find library files from a PATH-style environment variable.
    pub fn include_libs_from_path_variable(&mut self, name: &str, ext: &str) {
        let libraries = gather_from_path_variable(name, Some(ext), parse_symbols);
        self.resolver.add_library_source_units(libraries);
        self.resolver.resolve();
    }

    pub fn error(&self) -> Option<ResolverError> {
        self.resolver.error()
    }

    pub fn get_compiled_source(&self) -> Result<String, MergeError> {
        self.resolver.get_merged_source_code(push_source_code)
    }
}


/// Parse all symbols from a source code string.
fn parse_symbols(source_code: &str, path: Option<&Path>) -> Vec<Symbol> {
    use SyntacticTokenVariant as SynVar;
    let mut symbols = Vec::new();
    for token in SyntacticParser::from_source_code(&source_code, path) {
        let source = token.source;
        let (name, role) = match token.variant {
            SynVar::LabelDefinition(name) =>
                (name, SymbolRole::Definition(DefinitionType::CanFollowReference)),
            SynVar::MacroDefinition(name) =>
                (name, SymbolRole::Definition(DefinitionType::MustPrecedeReference)),
            SynVar::Symbol(name) =>
                (name, SymbolRole::Reference),
            _ => continue,
        };
        symbols.push(Symbol { name, source, role });
    }
    return symbols;
}

/// Push source code to a source compilation string.
fn push_source_code(compilation: &mut String, source_file: &SourceFile) {
    // Skip blank files.
    let source_code = &source_file.source_code;
    if source_code.chars().all(|c| c.is_whitespace()) { return; }
    // Ensure that the previous section is followed by two newline characters.
    if !compilation.is_empty() {
        if !compilation.ends_with('\n') { compilation.push('\n'); }
        if !compilation.ends_with("\n\n") { compilation.push('\n'); }
    }
    // Push a path comment and the source code.
    let path_str = source_file.path.as_os_str().to_string_lossy();
    let path_comment = format!("(: {path_str} )\n");
    compilation.push_str(&path_comment);
    compilation.push_str(&source_code);
}