use super::Str;

/// Error encountered when parsing Box language.
#[derive(Debug, PartialEq, Eq)]
pub enum Error<'a> {
    /// A positional argument appears after a keyword argument.
    ///
    /// This is an error, just like in Python.
    /// The problem is that it's ambiguous which parameter the
    /// positional argument should apply to.
    PositionalArgAfterKeywordArg {
        positional_arg: Str<'a>,
        keyword_arg: Str<'a>,
    },

    /// A function argument has the wrong type.
    IncorrectType {
        wanted_type: &'static str,
        got_type: &'static str,
        got_raw_value: Str<'a>,
        function_name: Str<'a>,
        parameter_name: &'a str,
    },

    /// Too many positional arguments provided.
    TooManyPositionalArgs {
        extra_positional_arg: Str<'a>,
        function_name: Str<'a>,
        max_positional_args: usize,
    },

    /// No such argument to this function.
    NoSuchArgument {
        function_name: Str<'a>,
        argument: Str<'a>,
    },

    /// The same argument was provided multiple times.
    DuplicateArgument {
        parameter_name: &'a str,
        first_assignment: Str<'a>,
        second_assignment: Str<'a>,
    },

    /// The specified function does not exist.
    NoSuchFunction { function_name: Str<'a> },

    /// An opening bracket token '[' or '(' was unmatched.
    UnmatchedOpeningBracket { open: Str<'a> },

    /// A closing bracket token ']' or ')' was unmatched.
    UnmatchedClosingBracket { close: Str<'a> },

    /// An invalid unit was provided for a dimension.
    InvalidDimensionUnit { dimension: Str<'a>, unit: Str<'a> },

    /// An unexpected token was encountered.
    UnexpectedToken {
        want: &'static str,
        got: Str<'a>,
        skipped: Str<'a>,
    },

    /// A function name appeared without any arguments
    MissingArgsForFunction { function_name: Str<'a> },

    /// Mismatched braces - e.g. [) or (].
    MismatchedBraces { open: Str<'a>, close: Str<'a> },

    /// Input ended while parsing a function keyword argument
    IncompleteKeywordArg { keyword: Str<'a> },

    /// A number has multiple decimal points.
    MultipleDecimalPoints { point: Str<'a> },

    /// No units were specified for a number.
    NumberWithoutUnits { number: Str<'a> },

    /// Input contains an invalid character (like a non-ASCII character)
    InvalidCharacter { char: Str<'a> },
}

impl<'a> Error<'a> {
    pub fn message(&self) -> String {
        use Error::*;
        match self {
            PositionalArgAfterKeywordArg { .. } => {
                "A positional argument appears after a keyword argument".into()
            }
            IncorrectType { .. } => "An argument has the wrong type".into(),
            TooManyPositionalArgs { .. } => "Too many positional arguments provided".into(),
            NoSuchArgument { .. } => "No such argument to this function".into(),
            DuplicateArgument { parameter_name, .. } => {
                format!["The `{parameter_name}` argument was provided multiple times"]
            }
            NoSuchFunction { function_name } => {
                format!["Unknown function `{function_name}`"]
            }
            UnmatchedOpeningBracket { .. } => "Unmatched opening bracket".into(),
            UnmatchedClosingBracket { .. } => "Unmatched closing bracket".into(),
            InvalidDimensionUnit { dimension: _, unit } => {
                format!["Dimension has an invalid unit '{unit}'"]
            }
            UnexpectedToken { want, .. } => {
                format!["Unexpected token while looking for {want}"]
            }
            MissingArgsForFunction { function_name } => {
                format!["No arguments provided for '{function_name}'"]
            }
            MismatchedBraces { open, close } => format!["Mismatched braces '{open}' and '{close}'"],
            IncompleteKeywordArg { .. } => "Incomplete keyword argument".into(),
            MultipleDecimalPoints { .. } => "A number has multiple decimal points".into(),
            NumberWithoutUnits { .. } => "No units were provided for this number".into(),
            InvalidCharacter { .. } => "Invalid character in the input".into(),
        }
    }
    pub fn labels(&self) -> Vec<ErrorLabel> {
        use Error::*;
        match self {
            PositionalArgAfterKeywordArg {
                        positional_arg,
                        keyword_arg,
                    } => {
                        vec![
                            ErrorLabel {
                                span: positional_arg.span(),
                                text: "The positional argument appears here".into(),
                            },
                            ErrorLabel {
                                span: keyword_arg.span(),
                                text: "The keyword argument appears here".into(),
                            },
                        ]
                    }
            IncorrectType {
                        wanted_type,
                        got_type: got,
                        got_raw_value,
                        function_name,
                        parameter_name,
                    } => vec![
                        ErrorLabel {
                            span: got_raw_value.span(),
                            text: format!["The provided argument is {got}"],
                        },
                        ErrorLabel {
                            span: function_name.span(),
                            text: format![
                                "The `{parameter_name}` parameter of the `{}` function requires {wanted_type}",
                                function_name.str()
                            ],
                        },
                    ],
            TooManyPositionalArgs { extra_positional_arg, function_name, max_positional_args } => vec![
                        ErrorLabel {
                            span: extra_positional_arg.span(),
                            text: "an extra positional arguments was provided".to_string(),
                        },
                        ErrorLabel {
                            span: function_name.span(),
                            text: format![
                                "The `{}` function accepts up to {max_positional_args} positional arguments",
                                function_name.str()
                            ],
                        },
                    ],
            NoSuchArgument { function_name, argument } => vec![
                        ErrorLabel {
                            span: argument.span(),
                            text: format![
                                "an argument with name `{}` appears here",
                                argument.str(),
                            ],
                        },
                        ErrorLabel {
                            span: function_name.span(),
                            text: format![
                                "The `{}` function does not have a parameter with name `{}`",
                                function_name.str(),
                                argument.str(),
                            ],
                        },
                    ],
            DuplicateArgument { parameter_name: _, first_assignment, second_assignment } => vec![
                        ErrorLabel {
                            span: first_assignment.span(),
                            text: "the first value appears here".to_string(),
                        },
                        ErrorLabel {
                            span: second_assignment.span(),
                            text: "the second value appear here".to_string(),
                        },
                    ],
            NoSuchFunction { function_name } => vec![
                        ErrorLabel {
                            span: function_name.span(),
                            text: "there is no function with this name".to_string(),
                        },
                    ],
            UnmatchedOpeningBracket{ open: close } => vec![
                        ErrorLabel {
                            span: close.span(),
                            text: "this bracket does not correspond to any subsequent closing bracket".to_string(),
                        },
                    ],
            UnmatchedClosingBracket{ close } => vec![
                        ErrorLabel {
                            span: close.span(),
                            text: "this bracket does not correspond to any preceding opening bracket".to_string(),
                        },
                    ],
            InvalidDimensionUnit { dimension: _, unit } => vec![
                        ErrorLabel {
                            span: unit.span(),
                            text: "valid units are the same as TeX".to_string(),
                        },
                    ],
            UnexpectedToken { want: _, got, skipped } => vec![
                        ErrorLabel {
                            span: got.span(),
                            text: "this token was not expected".to_string(),
                        },
                        ErrorLabel {
                            span: skipped.span(),
                            text: "this source code will be skipped".to_string(),
                        },
                    ],
            MissingArgsForFunction { function_name } => vec![
                        ErrorLabel {
                            span: function_name.span(),
                            text: "a function name must be followed by arguments".to_string(),
                        },
                    ],
            MismatchedBraces { open, close } => vec![
                        ErrorLabel {
                            span: open.span(),
                            text: format!["the opening brace is '{open}'"],
                        },
                        ErrorLabel {
                            span: close.span(),
                            text: format!["the closing brace is '{close}'"],
                        },
                    ],
            IncompleteKeywordArg { keyword  } => vec![
                        ErrorLabel {
                            span: keyword.span(),
                            text: "a value was not provided for this keyword".into(),
                        },
                    ],
MultipleDecimalPoints { point } => vec![
    ErrorLabel {
        span: point.span(),
        text: "this is the second or subsequent decimal point".into(),
    },
],
            NumberWithoutUnits { number } =>vec![
    ErrorLabel {
        span: number.span(),
                            text: "valid units are the same as TeX".to_string(),
    },

            ],
            InvalidCharacter { char } => vec![
    ErrorLabel {
        span: char.span(),
        text: "this character is not allowed here".into(),
    },

            ],
        }
    }
    pub fn notes(&self) -> Vec<String> {
        use Error::*;
        match self {
            PositionalArgAfterKeywordArg { .. } => {
                vec![
                    "Positional arguments must be appear before keyword arguments (as in Python)"
                        .to_string(),
                ]
            }
            UnmatchedClosingBracket { .. } | UnmatchedOpeningBracket { .. } => {
                vec!["The token will be ignored".to_string()]
            }
            MismatchedBraces { .. } => {
                vec![
                    "A '(' opening brace must be closed by ')' and similar for '[' and ']'"
                        .to_string(),
                ]
            }
            UnexpectedToken { .. }
            | MissingArgsForFunction { .. }
            | IncorrectType { .. }
            | TooManyPositionalArgs { .. }
            | NoSuchArgument { .. }
            | DuplicateArgument { .. }
            | NoSuchFunction { .. }
            | IncompleteKeywordArg { .. }
            | InvalidDimensionUnit { .. }
            | MultipleDecimalPoints { .. }
            | NumberWithoutUnits { .. }
            | InvalidCharacter { .. } => vec![],
        }
    }
}

/// Label on an error message.
///
/// A label identifies a particular piece of source code and some
/// information about it.
pub struct ErrorLabel {
    pub span: std::ops::Range<usize>,
    pub text: String,
}

impl<'a> Error<'a> {
    #[cfg(feature = "ariadne")]
    pub fn ariadne_report(
        &self,
        file_name: &'a str,
    ) -> ariadne::Report<'static, (&str, std::ops::Range<usize>)> {
        let mut report =
            ariadne::Report::build(ariadne::ReportKind::Error, (file_name, 0..file_name.len()))
                .with_message(self.message());
        let mut color = ariadne::Color::BrightRed;
        for label in self.labels() {
            report = report.with_label(
                ariadne::Label::new((file_name, label.span))
                    .with_message(label.text)
                    .with_color(color),
            );
            color = ariadne::Color::BrightYellow;
        }
        for note in self.notes() {
            report = report.with_note(note);
        }
        report.finish()
    }
}

/// A data structure for accumulating errors.
#[derive(Clone, Debug, Default)]
pub struct ErrorAccumulator<'a> {
    errs: std::rc::Rc<std::cell::RefCell<Vec<Error<'a>>>>,
}

impl<'a> ErrorAccumulator<'a> {
    pub fn add(&self, err: Error<'a>) {
        self.errs.borrow_mut().push(err);
    }
    pub fn len(&self) -> usize {
        self.errs.borrow().len()
    }
    pub fn is_empty(&self) -> bool {
        self.len() == 0
    }
    pub fn check(self) -> Result<(), Vec<Error<'a>>> {
        let errs = self.errs.take();
        if errs.is_empty() {
            Ok(())
        } else {
            Err(errs)
        }
    }
}

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

    pub fn get_unique_err(source: &str) -> Error {
        let mut errs = super::super::parse_horizontal_list(source).unwrap_err();
        assert_eq!(errs.len(), 1, "{:?}", errs);
        errs.pop().unwrap()
    }

    macro_rules! error_tests {
        ( $(
            ($name: ident, $source: expr, $want_variant: ident,),
        )+ ) => {
            $(
            #[test]
            fn $name() {
                let source = $source;
                let err = get_unique_err(source);
                println!["got: {err:?}"];
                assert!(matches!(err, Error::$want_variant {..}), "{:?}", err);
            }
            )+
        };
    }
    error_tests!(
        (invalid_dimension_unit, "glue(0plx)", InvalidDimensionUnit,),
        (invalid_type_positional, r#"text(1pc)"#, IncorrectType,),
        (invalid_type_keyword, r#"text(content=1pc)"#, IncorrectType,),
        (
            too_many_positional_args_1,
            r#"text("Hello", 3, "Mundo")"#,
            TooManyPositionalArgs,
        ),
        (
            too_many_positional_args_2,
            r#"text("Hello", font=3, "Mundo")"#,
            PositionalArgAfterKeywordArg,
        ),
        (
            positional_arg_after_keyword_arg,
            r#"text(font=3, "Hello")"#,
            PositionalArgAfterKeywordArg,
        ),
        (
            duplicate_keyword_args,
            r#"text(content="Hello", content="World")"#,
            DuplicateArgument,
        ),
        (
            duplicate_positional_and_keyword_args,
            r#"text("Hello", content="Mundo")"#,
            DuplicateArgument,
        ),
        (
            invalid_keyword_arg,
            r#"text(random="Hello")"#,
            NoSuchArgument,
        ),
        (invalid_func_name, r#"random()"#, NoSuchFunction,),
        (trailing_closed_square, "text()]", UnmatchedClosingBracket,),
        (trailing_open_square, "text())", UnmatchedClosingBracket,),
        (
            unexpected_token_before_func_name,
            ",text()",
            UnexpectedToken,
        ),
        (unexpected_token_after_func_name, "text,()", UnexpectedToken,),
        (missing_func_name, "()", UnexpectedToken,),
        (
            missing_paren_after_func_name,
            "text",
            MissingArgsForFunction,
        ),
        (incorrect_func_braces, "text[]()", UnexpectedToken,),
        (incorrect_closing_brace_round, "text(]", MismatchedBraces,),
        (
            incorrect_closing_brace_square,
            "hlist(content=[))",
            MismatchedBraces,
        ),
        (
            unmatched_opening_brace_round,
            r#"text("Hello""#,
            UnmatchedOpeningBracket,
        ),
        (
            unexpected_token_in_args_1,
            "glue(,width=1pt)",
            UnexpectedToken,
        ),
        (
            unexpected_token_in_args_2,
            "glue(width,=1pt)",
            UnexpectedToken,
        ),
        (
            unexpected_token_in_args_3,
            "glue(width=,1pt)",
            UnexpectedToken,
        ),
        (unexpected_token_in_args_4, "glue(,1pt)", UnexpectedToken,),
        (end_of_input_in_args_1, "glue(width)", IncompleteKeywordArg,),
        (end_of_input_in_args_2, "glue(width=)", IncompleteKeywordArg,),
        (
            two_decimal_points,
            "glue(width=1.1.1pt)",
            MultipleDecimalPoints,
        ),
        (number_no_unit, "glue(width=1.1)", NumberWithoutUnits,),
        (random_character, "/", InvalidCharacter,),
        (non_ascii_character, "ä", InvalidCharacter,),
    );
}