//! Error types.

use std::error;

use std::fmt;

use cssparser::{BasicParseError, BasicParseErrorKind, ParseErrorKind, ToCss};

use markup5ever::QualName;

#[cfg(doc)]

use crate::RenderingError;

use crate::document::NodeId;

use crate::io::IoError;

use crate::limits;

use crate::node::Node;

/// A short-lived error.

///

/// The lifetime of the error is the same as the `cssparser::ParserInput` that

/// was used to create a `cssparser::Parser`.  That is, it is the lifetime of

/// the string data that is being parsed.

///

/// The code flow will sometimes require preserving this error as a long-lived struct;

/// see the `impl<'i, O> AttributeResultExt<O> for Result<O, ParseError<'i>>` for that

/// purpose.

pub type ParseError<'i> = cssparser::ParseError<'i, ValueErrorKind>;

/// A simple error which refers to an attribute's value

pub enum ValueErrorKind {

    /// A property with the specified name was not found

    UnknownProperty,

    /// The value could not be parsed

    // The value could be parsed, but is invalid

}

impl ValueErrorKind {

}

impl fmt::Display for ValueErrorKind {

        }

}

impl<'a> From<BasicParseError<'a>> for ValueErrorKind {

        };

}

/// A complete error for an attribute and its erroneous value

pub struct ElementError {

}

impl fmt::Display for ElementError {

}

/// Errors returned when looking up a resource by URL reference.

pub enum DefsLookupErrorKind {

    /// Error when parsing the id to lookup.

    InvalidId,

    /// For internal use only.

    ///

    // FIXME: this is returned internally from Handle.lookup_node(), and gets translated

    // to Ok(false).  Don't expose this internal code in the public API.

    NotFound,

}

impl fmt::Display for DefsLookupErrorKind {

        }

}

/// Errors that can happen while rendering or measuring an SVG document.

///

/// This is the internal version of [`crate::api::RenderingError`]; they are the same

/// except that this one has an `InvalidTransform` variant which is only propagated

/// internally.  It is caught during the drawing process, and the element in question

/// is simply not drawn, more or less per <https://www.w3.org/TR/css-transforms-1/#transform-function-lists>

///

///   "If a transform function causes the current transformation matrix of an

///   object to be non-invertible, the object and its content do not get

///   displayed."

pub enum InternalRenderingError {

    /// An error from the rendering backend.

    /// A particular implementation-defined limit was exceeded.

    /// A non-invertible transform was generated.

    ///

    /// This should not be a fatal error; we should catch it and just not render

    /// the problematic element.

    InvalidTransform,

    /// Tried to reference an SVG element that does not exist.

    IdNotFound,

    /// Tried to reference an SVG element from a fragment identifier that is incorrect.

    /// Not enough memory was available for rendering.

    /// The rendering was interrupted via a [`gio::Cancellable`].

    Cancelled,

}

impl From<DefsLookupErrorKind> for InternalRenderingError {

        }

}

impl From<InvalidTransform> for InternalRenderingError {

}

impl fmt::Display for InternalRenderingError {

            }

        }

}

impl From<cairo::Error> for InternalRenderingError {

}

/// Indicates that a transform is not invertible.

///

/// This generally represents an error from [`crate::transform::ValidTransform::try_from`], which is what we use

/// to check affine transforms for validity.

pub struct InvalidTransform;

/// Errors from [`crate::document::AcquiredNodes`].

pub enum AcquireError {

    /// An element with the specified id was not found.

    LinkNotFound(NodeId),

    InvalidLinkType(NodeId),

    /// A circular reference was detected; non-fatal error.

    ///

    /// Callers are expected to treat the offending element as invalid, for example

    /// if a graphic element uses a pattern fill, but the pattern in turn includes

    /// another graphic element that references the same pattern.

    ///

    /// ```xml

    /// <pattern id="foo">

    ///   <rect width="1" height="1" fill="url(#foo)"/>

    /// </pattern>

    /// ```

    CircularReference(Node),

    /// Too many referenced objects were resolved; fatal error.

    ///

    /// Callers are expected to exit as early as possible and return an error to

    /// the public API.  See [`ImplementationLimit::TooManyReferencedElements`] for details.

    MaxReferencesExceeded,

}

impl fmt::Display for AcquireError {

            }

            }

            AcquireError::MaxReferencesExceeded => {

            }

        }

}

/// Helper for converting `Result<O, E>` into `Result<O, ElementError>`

///

/// A `ElementError` requires a `QualName` that corresponds to the attribute to which the

/// error refers, plus the actual `ValueErrorKind` that describes the error.  However,

/// parsing functions for attribute value types will want to return their own kind of

/// error, instead of `ValueErrorKind`.  If that particular error type has an `impl

/// From<FooError> for ValueErrorKind`, then this trait helps assign attribute values in

/// `set_atts()` methods as follows:

///

/// ```

/// # use rsvg::doctest_only::AttributeResultExt;

/// # use rsvg::doctest_only::ValueErrorKind;

/// # use rsvg::doctest_only::ElementError;

/// # use markup5ever::{QualName, Prefix, Namespace, LocalName};

/// # type FooError = ValueErrorKind;

/// fn parse_foo(value: &str) -> Result<(), FooError>

/// # { Err(ValueErrorKind::value_error("test")) }

///

/// // It is assumed that there is an impl From<FooError> for ValueErrorKind

/// # let attr = QualName::new(

/// #     Some(Prefix::from("")),

/// #     Namespace::from(""),

/// #     LocalName::from(""),

/// # );

/// let result = parse_foo("value").attribute(attr);

/// assert!(result.is_err());

/// # Ok::<(), ElementError>(())

/// ```

///

/// The call to `.attribute(attr)` converts the `Result` from `parse_foo()` into a full

/// `ElementError` with the provided `attr`.

pub trait AttributeResultExt<O> {

    fn attribute(self, attr: QualName) -> Result<O, ElementError>;

}

impl<O, E: Into<ValueErrorKind>> AttributeResultExt<O> for Result<O, E> {

}

/// Turns a short-lived `ParseError` into a long-lived `ElementError`

impl<'i, O> AttributeResultExt<O> for Result<O, ParseError<'i>> {

            // FIXME: eventually, here we'll want to preserve the location information

            let ParseError {

                    }

                ParseErrorKind::Basic(_) => {

                    unreachable!("attribute parsers should not return errors for CSS rules")

                }

            }

}

/// Errors returned when resolving an URL

pub enum AllowedUrlError {

    /// parsing error from `Url::parse()`

    /// A base file/uri was not set

    BaseRequired,

    /// Cannot reference a file with a different URI scheme from the base file

    DifferentUriSchemes,

    /// Some scheme we don't allow loading

    DisallowedScheme,

    /// The requested file is not in the same directory as the base file,

    /// or in one directory below the base file.

    NotSiblingOrChildOfBaseFile,

    /// Loaded file:// URLs cannot have a query part, e.g. `file:///foo?blah`

    NoQueriesAllowed,

    /// URLs may not have fragment identifiers at this stage

    NoFragmentIdentifierAllowed,

    /// Error when obtaining the file path or the base file path

    InvalidPath,

    /// The base file cannot be the root of the file system

    BaseIsRoot,

    /// Error when canonicalizing either the file path or the base file path

    CanonicalizationError,

}

impl fmt::Display for AllowedUrlError {

        use AllowedUrlError::*;

        }

}

/// Errors returned when creating a `NodeId` out of a string

pub enum NodeIdError {

    NodeIdRequired,

}

impl From<NodeIdError> for ValueErrorKind {

        match e {

            NodeIdError::NodeIdRequired => {

            }

        }

}

/// Errors that can happen while loading an SVG document.

///

/// All of these codes are for unrecoverable errors that keep an SVG document from being

/// fully loaded and parsed.  Note that SVG is very lenient with respect to document

/// structure and the syntax of CSS property values; most errors there will not lead to a

/// `LoadingError`.  To see those errors, you may want to set the `RSVG_LOG=1` environment

/// variable.

///

/// I/O errors get reported in the `Glib` variant, since librsvg uses GIO internally for

/// all input/output.

#[non_exhaustive]

pub enum LoadingError {

    /// XML syntax error.

    /// Not enough memory to load the document.

    /// A malformed or disallowed URL was used.

    BadUrl,

    /// An invalid stylesheet was used.

    BadCss,

    /// There is no `<svg>` root element in the XML.

    NoSvgRoot,

    /// I/O error.

    /// A particular implementation-defined limit was exceeded.

    /// Catch-all for loading errors.

}

/// Errors for implementation-defined limits, to mitigate malicious SVG documents.

///

/// These get emitted as [`LoadingError::LimitExceeded`] or [`RenderingError::LimitExceeded`].

/// The limits are present to mitigate malicious SVG documents which may try to exhaust

/// all available memory, or which would use large amounts of CPU time.

#[non_exhaustive]

pub enum ImplementationLimit {

    /// Document exceeded the maximum number of times that elements

    /// can be referenced through URL fragments.

    ///

    /// This is a mitigation for malicious documents that attempt to

    /// consume exponential amounts of CPU time by creating millions

    /// of references to SVG elements.  For example, the `<use>` and

    /// `<pattern>` elements allow referencing other elements, which

    /// can in turn reference other elements.  This can be used to

    /// create documents which would require exponential amounts of

    /// CPU time to be rendered.

    ///

    /// Librsvg deals with both cases by placing a limit on how many

    /// references will be resolved during the SVG rendering process,

    /// that is, how many `url(#foo)` will be resolved.

    ///

    /// These malicious documents are similar to the XML

    /// [billion laughs attack], but done with SVG's referencing features.

    ///

    /// See issues

    /// [#323](https://gitlab.gnome.org/GNOME/librsvg/issues/323) and

    /// [#515](https://gitlab.gnome.org/GNOME/librsvg/issues/515) for

    /// examples for the `<use>` and `<pattern>` elements,

    /// respectively.

    ///

    /// [billion laughs attack]: https://bitbucket.org/tiran/defusedxml

    TooManyReferencedElements,

    /// Document exceeded the maximum number of elements that can be loaded.

    ///

    /// This is a mitigation for SVG files which create millions of

    /// elements in an attempt to exhaust memory.  Librsvg does not't

    /// allow loading more than a certain number of elements during

    /// the initial loading process.

    TooManyLoadedElements,

    /// Document exceeded the number of attributes that can be attached to

    /// an element.

    ///

    /// This is here because librsvg uses u16 to address attributes. It should

    /// be essentially impossible to actually hit this limit, because the

    /// number of attributes that the SVG standard ascribes meaning to are

    /// lower than this limit.

    TooManyAttributes,

    /// Document exceeded the maximum nesting level while rendering.

    ///

    /// Rendering is a recursive process, and there is a limit of how deep layers can

    /// nest.  This is to avoid malicious SVGs which try to have layers that are nested

    /// extremely deep, as this could cause stack exhaustion.

    MaximumLayerNestingDepthExceeded,

}

impl error::Error for LoadingError {}

impl fmt::Display for LoadingError {

        }

}

impl From<glib::Error> for LoadingError {

        // FIXME: this is somewhat fishy; not all GError are I/O errors, but in librsvg

        // most GError do come from gio.  Some come from GdkPixbufLoader, though.

}

impl From<IoError> for LoadingError {

        }

}

impl fmt::Display for ImplementationLimit {

                f,

                "exceeded more than {} referenced elements",

                limits::MAX_REFERENCED_ELEMENTS

            ),

                f,

                "cannot load more than {} XML elements",

                limits::MAX_LOADED_ELEMENTS

            ),

                f,

                "cannot load more than {} XML attributes",

                limits::MAX_LOADED_ATTRIBUTES

            ),

                f,

                "maximum depth of {} nested layers has been exceeded",

                limits::MAX_LAYER_NESTING_DEPTH,

            ),

        }

}