use thiserror::Error;

pub type Result<T> = std::result::Result<T, PakkerError>;

/// Severity level for errors
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum ErrorSeverity {
  /// Fatal error - operation cannot continue
  #[default]
  Error,
  /// Warning - operation can continue but may have issues
  Warning,
  /// Info - informational message
  Info,
}

/// Container for multiple errors that occurred during an operation
#[derive(Debug)]
pub struct MultiError {
  errors: Vec<PakkerError>,
}

impl MultiError {
  pub const fn new() -> Self {
    Self { errors: Vec::new() }
  }

  pub fn push(&mut self, error: PakkerError) {
    self.errors.push(error);
  }

  pub fn extend(&mut self, errors: impl IntoIterator<Item = PakkerError>) {
    self.errors.extend(errors);
  }

  pub const fn is_empty(&self) -> bool {
    self.errors.is_empty()
  }

  pub const fn len(&self) -> usize {
    self.errors.len()
  }

  pub fn into_result<T>(self, success_value: T) -> Result<T> {
    if self.is_empty() {
      Ok(success_value)
    } else {
      Err(PakkerError::Multiple(self.errors))
    }
  }

  pub fn errors(&self) -> &[PakkerError] {
    &self.errors
  }

  pub fn into_errors(self) -> Vec<PakkerError> {
    self.errors
  }
}

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

impl FromIterator<PakkerError> for MultiError {
  fn from_iter<I: IntoIterator<Item = PakkerError>>(iter: I) -> Self {
    Self {
      errors: iter.into_iter().collect(),
    }
  }
}

#[derive(Error, Debug)]
pub enum PakkerError {
  // Network errors
  #[error("Network request failed: {0}")]
  NetworkError(#[from] reqwest::Error),

  #[error("Platform API error: {0}")]
  PlatformApiError(String),

  // Validation errors
  #[error("Invalid lock file: {0}")]
  InvalidLockFile(String),

  #[error("Invalid config file: {0}")]
  InvalidConfigFile(String),

  #[error("Project not found: {0}")]
  ProjectNotFound(String),

  #[error("File selection error: {0}")]
  FileSelectionError(String),

  #[error("File not found: {0}")]
  FileNotFound(String),

  // Conflict errors
  #[error("Circular dependency detected: {0}")]
  CircularDependency(String),

  // File I/O errors
  #[error("IO error: {0}")]
  IoError(#[from] std::io::Error),

  #[error("Serialization error: {0}")]
  SerializationError(#[from] serde_json::Error),

  #[error("Hash mismatch for file {file}: expected {expected}, got {actual}")]
  HashMismatch {
    file:     String,
    expected: String,
    actual:   String,
  },

  #[error("Download failed: {0}")]
  DownloadFailed(String),

  // Export errors
  #[error("Export failed: {0}")]
  ExportFailed(String),

  #[error("Invalid export profile: {0}")]
  InvalidExportProfile(String),

  // General errors
  #[error("Configuration error: {0}")]
  ConfigError(String),

  #[error("Internal error: {0}")]
  InternalError(String),

  #[error("Already exists: {0}")]
  AlreadyExists(String),

  #[error("Invalid input: {0}")]
  InvalidInput(String),

  #[error("Invalid project: {0}")]
  InvalidProject(String),

  #[error("Invalid import file: {0}")]
  InvalidImportFile(String),

  #[error("Zip error: {0}")]
  ZipError(#[from] zip::result::ZipError),

  // Git and Fork errors
  #[error("Git error: {0}")]
  GitError(String),

  #[error("Remote not found: {0}")]
  RemoteNotFound(String),

  #[error("Fork error: {0}")]
  Fork(String),

  #[error("Invalid hash: {0}")]
  InvalidHash(String),

  #[error("Invalid response: {0}")]
  InvalidResponse(String),

  #[error("IPC error: {0}")]
  IpcError(String),

  #[error("{}", format_multiple_errors(.0))]
  Multiple(Vec<Self>),
}

fn format_multiple_errors(errors: &[PakkerError]) -> String {
  if errors.len() == 1 {
    return errors[0].to_string();
  }

  let mut msg = format!("{} errors occurred:\n", errors.len());
  for (idx, error) in errors.iter().enumerate() {
    msg.push_str(&format!("  {}. {}\n", idx + 1, error));
  }
  msg
}

impl From<git2::Error> for PakkerError {
  fn from(err: git2::Error) -> Self {
    Self::GitError(err.to_string())
  }
}

impl From<crate::ipc::IpcError> for PakkerError {
  fn from(err: crate::ipc::IpcError) -> Self {
    Self::IpcError(err.to_string())
  }
}

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

  #[test]
  fn test_multi_error_empty() {
    let multi = MultiError::new();
    assert!(multi.is_empty());
    assert_eq!(multi.len(), 0);
  }

  #[test]
  fn test_multi_error_push() {
    let mut multi = MultiError::new();
    multi.push(PakkerError::ProjectNotFound("mod1".to_string()));
    multi.push(PakkerError::ProjectNotFound("mod2".to_string()));

    assert!(!multi.is_empty());
    assert_eq!(multi.len(), 2);
  }

  #[test]
  fn test_multi_error_into_result_empty() {
    let multi = MultiError::new();
    let result: Result<i32> = multi.into_result(42);
    assert!(result.is_ok());
    assert_eq!(result.unwrap(), 42);
  }

  #[test]
  fn test_multi_error_into_result_with_errors() {
    let mut multi = MultiError::new();
    multi.push(PakkerError::ProjectNotFound("mod1".to_string()));

    let result: Result<i32> = multi.into_result(42);
    assert!(result.is_err());
  }

  #[test]
  fn test_multi_error_from_iterator() {
    let errors = vec![
      PakkerError::ProjectNotFound("mod1".to_string()),
      PakkerError::ProjectNotFound("mod2".to_string()),
    ];
    let multi: MultiError = errors.into_iter().collect();
    assert_eq!(multi.len(), 2);
  }

  #[test]
  fn test_multi_error_extend() {
    let mut multi = MultiError::new();
    multi.push(PakkerError::ProjectNotFound("mod1".to_string()));

    let more_errors = vec![
      PakkerError::ProjectNotFound("mod2".to_string()),
      PakkerError::ProjectNotFound("mod3".to_string()),
    ];
    multi.extend(more_errors);

    assert_eq!(multi.len(), 3);
  }

  #[test]
  fn test_multiple_errors_formatting() {
    let errors = vec![
      PakkerError::ProjectNotFound("mod1".to_string()),
      PakkerError::ProjectNotFound("mod2".to_string()),
    ];
    let error = PakkerError::Multiple(errors);
    let msg = error.to_string();

    assert!(msg.contains("2 errors occurred"));
    assert!(msg.contains("mod1"));
    assert!(msg.contains("mod2"));
  }

  #[test]
  fn test_single_multiple_error_formatting() {
    let errors = vec![PakkerError::ProjectNotFound("mod1".to_string())];
    let error = PakkerError::Multiple(errors);
    let msg = error.to_string();

    // Single error should just display the error itself
    assert!(msg.contains("mod1"));
    assert!(!msg.contains("errors occurred"));
  }

  #[test]
  fn test_error_severity_default() {
    assert_eq!(ErrorSeverity::default(), ErrorSeverity::Error);
  }
}