use crate::frontend::source_registry::{SourcePosition, SourceRegistry, SourceSlice};

#[derive(Debug, Clone)]
pub enum LoxError {
    LexicalError {
        source_slice: SourceSlice,
        message: String,
    },
    RuntimeError {
        source_slice: SourceSlice,
        message: String,
    },
    ParseError {
        source_slice: SourceSlice,
        message: String,
    },
    IoError {
        message: String,
    },
    TypeMismatch {
        source_slice: SourceSlice,
        expected: String,
        found: String,
    },
}

impl LoxError {
    pub fn get_message(&self) -> String {
        match self {
            LoxError::LexicalError { message, .. } => message.clone(),
            LoxError::RuntimeError { message, .. } => message.clone(),
            LoxError::ParseError { message, .. } => message.clone(),
            LoxError::IoError { message } => message.clone(),
            LoxError::TypeMismatch {
                expected, found, ..
            } => {
                format!("expected {}, found {}", expected, found)
            }
        }
    }

    pub fn get_source_slice(&self) -> Option<SourceSlice> {
        match self {
            LoxError::LexicalError { source_slice, .. } => Some(source_slice.clone()),
            LoxError::RuntimeError { source_slice, .. } => Some(source_slice.clone()),
            LoxError::ParseError { source_slice, .. } => Some(source_slice.clone()),
            LoxError::IoError { .. } => None,
            LoxError::TypeMismatch { source_slice, .. } => Some(source_slice.clone()),
        }
    }

    pub fn print_with_context(&self, source_registry: &SourceRegistry) {
        match self.get_source_slice() {
            Some(source_slice) => {
                let source_code = source_registry.get_source_code(&source_slice);
                println!(
                    "\n =============================================== \n DATA:{} \n CODE \n {} | {}",
                    self, source_slice.start_position.line ,source_code
                );
            }
            None => println!("{}", self),
        }
    }
}

fn fetch_source_code(path: &str, start: SourcePosition, end: SourcePosition) -> LoxResult<String> {
    let source_code = std::fs::read_to_string(path).map_err(|e| LoxError::IoError {
        message: format!("Failed to read file: {}", e),
    })?;

    let lines: Vec<&str> = source_code.split('\n').collect();

    // Verifica bounds
    if start.line >= lines.len() || end.line >= lines.len() {
        return Err(LoxError::IoError {
            message: "Line number out of bounds".to_string(),
        });
    }

    let mut result = String::new();

    if start.line == end.line {
        // Caso speciale: stessa riga
        let line = lines[start.line];
        if end.column <= line.len() && start.column <= end.column {
            result.push_str(&line[start.column..end.column]);
        }
    } else {
        // Caso generale: righe multiple

        // Prima riga: da start.column alla fine della riga
        let first_line = lines[start.line];
        if start.column < first_line.len() {
            result.push_str(&first_line[start.column..]);
        }
        result.push('\n');

        // Righe intermedie: complete
        for i in (start.line + 1)..end.line {
            result.push_str(lines[i]);
            result.push('\n');
        }

        // Ultima riga: dall'inizio fino a end.column
        let last_line = lines[end.line];
        if end.column <= last_line.len() {
            result.push_str(&last_line[..end.column]);
        }
    }

    Ok(result)
}

impl std::fmt::Display for LoxError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            LoxError::LexicalError {
                source_slice,
                message,
            } => {
                write!(f, "Lexical error on {:?}: \n {}", source_slice, message)
            }
            LoxError::RuntimeError {
                source_slice,
                message,
            } => {
                write!(f, "Runtime error on {:?}: \n{}", source_slice, message)
            }
            LoxError::ParseError {
                source_slice,
                message,
            } => {
                write!(f, "Parse error on {:?}: \n{}", source_slice, message)
            }
            LoxError::IoError { message } => write!(f, "IO error: {}", message),
            LoxError::TypeMismatch {
                source_slice,
                expected,
                found,
            } => {
                write!(
                    f,
                    "Type mismatch on {:?}: \n expected {}, found {}",
                    source_slice, expected, found
                )
            }
        }
    }
}

impl std::error::Error for LoxError {}

pub type LoxResult<T> = Result<T, LoxError>;