// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
//! This mod provides DenoError to unify errors across Deno.
use crate::colors;
use crate::source_maps::apply_source_map;
use crate::source_maps::SourceMapGetter;
use deno_core::ErrBox;
use deno_core::JSStackFrame;
use std::error::Error;
use std::fmt;
use std::ops::Deref;

const SOURCE_ABBREV_THRESHOLD: usize = 150;

/// A trait which specifies parts of a diagnostic like item needs to be able to
/// generate to conform its display to other diagnostic like items
pub trait DisplayFormatter {
  fn format_category_and_code(&self) -> String;
  fn format_message(&self, level: usize) -> String;
  fn format_related_info(&self) -> String;
  fn format_source_line(&self, level: usize) -> String;
  fn format_source_name(&self) -> String;
}

fn format_source_name(
  script_name: String,
  line_number: i64,
  column: i64,
  is_internal: bool,
) -> String {
  let line_number = line_number + 1;
  let column = column + 1;
  if is_internal {
    format!("{}:{}:{}", script_name, line_number, column)
  } else {
    let script_name_c = colors::cyan(script_name);
    let line_c = colors::yellow(line_number.to_string());
    let column_c = colors::yellow(column.to_string());
    format!("{}:{}:{}", script_name_c, line_c, column_c)
  }
}

/// Formats optional source, line number and column into a single string.
pub fn format_maybe_source_name(
  script_name: Option<String>,
  line_number: Option<i64>,
  column: Option<i64>,
) -> String {
  if script_name.is_none() {
    return "".to_string();
  }

  assert!(line_number.is_some());
  assert!(column.is_some());
  format_source_name(
    script_name.unwrap(),
    line_number.unwrap(),
    column.unwrap(),
    false,
  )
}

/// Take an optional source line and associated information to format it into
/// a pretty printed version of that line.
pub fn format_maybe_source_line(
  source_line: Option<String>,
  line_number: Option<i64>,
  start_column: Option<i64>,
  end_column: Option<i64>,
  is_error: bool,
  level: usize,
) -> String {
  if source_line.is_none() || line_number.is_none() {
    return "".to_string();
  }

  let source_line = source_line.as_ref().unwrap();
  // sometimes source_line gets set with an empty string, which then outputs
  // an empty source line when displayed, so need just short circuit here.
  // Also short-circuit on error line too long.
  if source_line.is_empty() || source_line.len() > SOURCE_ABBREV_THRESHOLD {
    return "".to_string();
  }

  assert!(start_column.is_some());
  assert!(end_column.is_some());
  let line_number = (1 + line_number.unwrap()).to_string();
  let line_color = colors::black_on_white(line_number.to_string());
  let line_number_len = line_number.len();
  let line_padding =
    colors::black_on_white(format!("{:indent$}", "", indent = line_number_len))
      .to_string();
  let mut s = String::new();
  let start_column = start_column.unwrap();
  let end_column = end_column.unwrap();
  // TypeScript uses `~` always, but V8 would utilise `^` always, even when
  // doing ranges, so here, if we only have one marker (very common with V8
  // errors) we will use `^` instead.
  let underline_char = if (end_column - start_column) <= 1 {
    '^'
  } else {
    '~'
  };
  for i in 0..end_column {
    if i >= start_column {
      s.push(underline_char);
    } else {
      s.push(' ');
    }
  }
  let color_underline = if is_error {
    colors::red(s).to_string()
  } else {
    colors::cyan(s).to_string()
  };

  let indent = format!("{:indent$}", "", indent = level);

  format!(
    "\n\n{}{} {}\n{}{} {}\n",
    indent, line_color, source_line, indent, line_padding, color_underline
  )
}

/// Format a message to preface with `error: ` with ansi codes for red.
pub fn format_error_message(msg: String) -> String {
  let preamble = colors::red("error:".to_string());
  format!("{} {}", preamble, msg)
}

fn format_stack_frame(frame: &JSStackFrame, is_internal_frame: bool) -> String {
  // Note when we print to string, we change from 0-indexed to 1-indexed.
  let function_name = if is_internal_frame {
    colors::italic_bold_gray(frame.function_name.clone()).to_string()
  } else {
    colors::italic_bold(frame.function_name.clone()).to_string()
  };
  let mut source_loc = format_source_name(
    frame.script_name.clone(),
    frame.line_number,
    frame.column,
    is_internal_frame,
  );

  // Each chunk of styled text is auto-resetted on end,
  // which make nesting not working.
  // Explicitly specify color for each section.
  let mut at_prefix = "    at".to_owned();
  if is_internal_frame {
    at_prefix = colors::gray(at_prefix).to_string();
  }
  if !frame.function_name.is_empty() || frame.is_eval {
    source_loc = format!("({})", source_loc); // wrap then style
  }
  if is_internal_frame {
    source_loc = colors::gray(source_loc).to_string();
  }
  if !frame.function_name.is_empty() {
    format!("{} {} {}", at_prefix, function_name, source_loc)
  } else if frame.is_eval {
    format!("{} eval {}", at_prefix, source_loc)
  } else {
    format!("{} {}", at_prefix, source_loc)
  }
}

/// Wrapper around deno_core::JSError which provides color to_string.
#[derive(Debug)]
pub struct JSError(deno_core::JSError);

impl JSError {
  pub fn create(
    core_js_error: deno_core::JSError,
    source_map_getter: &impl SourceMapGetter,
  ) -> ErrBox {
    let core_js_error = apply_source_map(&core_js_error, source_map_getter);
    let js_error = Self(core_js_error);
    ErrBox::from(js_error)
  }
}

impl Deref for JSError {
  type Target = deno_core::JSError;
  fn deref(&self) -> &Self::Target {
    &self.0
  }
}

impl DisplayFormatter for JSError {
  fn format_category_and_code(&self) -> String {
    "".to_string()
  }

  fn format_message(&self, _level: usize) -> String {
    format!(
      "{}{}",
      colors::red_bold("error: ".to_string()),
      self.0.message.clone()
    )
  }

  fn format_related_info(&self) -> String {
    "".to_string()
  }

  fn format_source_line(&self, level: usize) -> String {
    format_maybe_source_line(
      self.0.source_line.clone(),
      self.0.line_number,
      self.0.start_column,
      self.0.end_column,
      true,
      level,
    )
  }

  fn format_source_name(&self) -> String {
    let e = &self.0;
    if e.script_resource_name.is_none() {
      return "".to_string();
    }

    format!(
      "\n► {}",
      format_maybe_source_name(
        e.script_resource_name.clone(),
        e.line_number,
        e.start_column,
      )
    )
  }
}

impl fmt::Display for JSError {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    write!(
      f,
      "{}{}{}",
      self.format_message(0),
      self.format_source_name(),
      self.format_source_line(0),
    )?;

    for frame in &self.0.frames {
      let is_internal_frame = frame.script_name.starts_with("$deno$");
      write!(f, "\n{}", format_stack_frame(&frame, is_internal_frame))?;
    }
    Ok(())
  }
}

impl Error for JSError {}

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

  #[test]
  fn js_error_to_string() {
    let core_js_error = deno_core::JSError {
      message: "Error: foo bar".to_string(),
      source_line: None,
      script_resource_name: None,
      line_number: None,
      start_column: None,
      end_column: None,
      frames: vec![
        JSStackFrame {
          line_number: 4,
          column: 16,
          script_name: "foo_bar.ts".to_string(),
          function_name: "foo".to_string(),
          is_eval: false,
          is_constructor: false,
        },
        JSStackFrame {
          line_number: 5,
          column: 20,
          script_name: "bar_baz.ts".to_string(),
          function_name: "qat".to_string(),
          is_eval: false,
          is_constructor: false,
        },
        JSStackFrame {
          line_number: 1,
          column: 1,
          script_name: "deno_main.js".to_string(),
          function_name: "".to_string(),
          is_eval: false,
          is_constructor: false,
        },
      ],
    };
    let formatted_error = JSError(core_js_error).to_string();
    let actual = strip_ansi_codes(&formatted_error);
    let expected = "error: Error: foo bar\n    at foo (foo_bar.ts:5:17)\n    at qat (bar_baz.ts:6:21)\n    at deno_main.js:2:2";
    assert_eq!(actual, expected);
  }

  #[test]
  fn test_format_none_source_name() {
    let actual = format_maybe_source_name(None, None, None);
    assert_eq!(actual, "");
  }

  #[test]
  fn test_format_some_source_name() {
    let actual = format_maybe_source_name(
      Some("file://foo/bar.ts".to_string()),
      Some(1),
      Some(2),
    );
    assert_eq!(strip_ansi_codes(&actual), "file://foo/bar.ts:2:3");
  }

  #[test]
  fn test_format_none_source_line() {
    let actual = format_maybe_source_line(None, None, None, None, false, 0);
    assert_eq!(actual, "");
  }

  #[test]
  fn test_format_some_source_line() {
    let actual = format_maybe_source_line(
      Some("console.log('foo');".to_string()),
      Some(8),
      Some(8),
      Some(11),
      true,
      0,
    );
    assert_eq!(
      strip_ansi_codes(&actual),
      "\n\n9 console.log(\'foo\');\n          ~~~\n"
    );
  }

  #[test]
  fn test_format_error_message() {
    let actual = format_error_message("foo".to_string());
    assert_eq!(strip_ansi_codes(&actual), "error: foo");
  }
}