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    use std::fmt;
    use std::mem;
    use std::os::raw::c_void;
    use std::path::{Path, PathBuf};

    use {trace, resolve, SymbolName};

    /// Representation of an owned and self-contained backtrace.
    ///
    /// This structure can be used to capture a backtrace at various points in a
    /// program and later used to inspect what the backtrace was at that time.
    #[derive(Clone)]
    #[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
    #[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
    pub struct Backtrace {
        frames: Vec<BacktraceFrame>,
    }

    /// Captured version of a frame in a backtrace.
    ///
    /// This type is returned as a list from `Backtrace::frames` and represents one
    /// stack frame in a captured backtrace.
    #[derive(Clone)]
    #[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
    #[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
    pub struct BacktraceFrame {
        ip: usize,
        symbol_address: usize,
        symbols: Option<Vec<BacktraceSymbol>>,
    }

    /// Captured version of a symbol in a backtrace.
    ///
    /// This type is returned as a list from `BacktraceFrame::symbols` and
    /// represents the metadata for a symbol in a backtrace.
    #[derive(Clone)]
    #[cfg_attr(feature = "serialize-rustc", derive(RustcDecodable, RustcEncodable))]
    #[cfg_attr(feature = "serialize-serde", derive(Deserialize, Serialize))]
    pub struct BacktraceSymbol {
        name: Option<Vec<u8>>,
        addr: Option<usize>,
        filename: Option<PathBuf>,
        lineno: Option<u32>,
    }

    impl Backtrace {
        /// Captures a backtrace at the callsite of this function, returning an
        /// owned representation.
        ///
        /// This function is useful for representing a backtrace as an object in
        /// Rust. This returned value can be sent across threads and printed
        /// elsewhere, and the purpose of this value is to be entirely self
        /// contained.
        ///
        /// # Examples
        ///
        /// ```
        /// use backtrace::Backtrace;
        ///
        /// let current_backtrace = Backtrace::new();
        /// ```
        pub fn new() -> Backtrace {
            let mut bt = Backtrace::new_unresolved();
            bt.resolve();
            return bt
        }

        /// Similar to `new` except that this does not resolve any symbols, this
        /// simply captures the backtrace as a list of addresses.
        ///
        /// At a later time the `resolve` function can be called to resolve this
        /// backtrace's symbols into readable names. This function exists because
        /// the resolution process can sometimes take a significant amount of time
        /// whereas any one backtrace may only be rarely printed.
        ///
        /// # Examples
        ///
        /// ```
        /// use backtrace::Backtrace;
        ///
        /// let mut current_backtrace = Backtrace::new_unresolved();
        /// println!("{:?}", current_backtrace); // no symbol names
        /// current_backtrace.resolve();
        /// println!("{:?}", current_backtrace); // symbol names now present
        /// ```
        pub fn new_unresolved() -> Backtrace {
            let mut frames = Vec::new();
            trace(|frame| {
                frames.push(BacktraceFrame {
                    ip: frame.ip() as usize,
                    symbol_address: frame.symbol_address() as usize,
                    symbols: None,
                });
                true
            });

            Backtrace { frames: frames }
        }

        /// Returns the frames from when this backtrace was captured.
        ///
        /// The first entry of this slice is likely the function `Backtrace::new`,
        /// and the last frame is likely something about how this thread or the main
        /// function started.
        pub fn frames(&self) -> &[BacktraceFrame] {
            &self.frames
        }

        /// If this backtrace was created from `new_unresolved` then this function
        /// will resolve all addresses in the backtrace to their symbolic names.
        ///
        /// If this backtrace has been previously resolved or was created through
        /// `new`, this function does nothing.
        pub fn resolve(&mut self) {
            for frame in self.frames.iter_mut().filter(|f| f.symbols.is_none()) {
                let mut symbols = Vec::new();
                resolve(frame.ip as *mut _, |symbol| {
                    symbols.push(BacktraceSymbol {
                        name: symbol.name().map(|m| m.as_bytes().to_vec()),
                        addr: symbol.addr().map(|a| a as usize),
                        filename: symbol.filename().map(|m| m.to_path_buf()),
                        lineno: symbol.lineno(),
                    });
                });
                frame.symbols = Some(symbols);
            }
        }
    }

    impl From<Vec<BacktraceFrame>> for Backtrace {
        fn from(frames: Vec<BacktraceFrame>) -> Self {
            Backtrace {
                frames: frames
            }
        }
    }

    impl Into<Vec<BacktraceFrame>> for Backtrace {
        fn into(self) -> Vec<BacktraceFrame> {
            self.frames
        }
    }

    impl BacktraceFrame {
        /// Same as `Frame::ip`
        pub fn ip(&self) -> *mut c_void {
            self.ip as *mut c_void
        }

        /// Same as `Frame::symbol_address`
        pub fn symbol_address(&self) -> *mut c_void {
            self.symbol_address as *mut c_void
        }

        /// Returns the list of symbols that this frame corresponds to.
        ///
        /// Normally there is only one symbol per frame, but sometimes if a number
        /// of functions are inlined into one frame then multiple symbols will be
        /// returned. The first symbol listed is the "innermost function", whereas
        /// the last symbol is the outermost (last caller).
        ///
        /// Note that if this frame came from an unresolved backtrace then this will
        /// return an empty list.
        pub fn symbols(&self) -> &[BacktraceSymbol] {
            self.symbols.as_ref().map(|s| &s[..]).unwrap_or(&[])
        }
    }

    impl BacktraceSymbol {
        /// Same as `Symbol::name`
        pub fn name(&self) -> Option<SymbolName> {
            self.name.as_ref().map(|s| SymbolName::new(s))
        }

        /// Same as `Symbol::addr`
        pub fn addr(&self) -> Option<*mut c_void> {
            self.addr.map(|s| s as *mut c_void)
        }

        /// Same as `Symbol::filename`
        pub fn filename(&self) -> Option<&Path> {
            self.filename.as_ref().map(|p| &**p)
        }

        /// Same as `Symbol::lineno`
        pub fn lineno(&self) -> Option<u32> {
            self.lineno
        }
    }

    impl fmt::Debug for Backtrace {
        fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
            let hex_width = mem::size_of::<usize>() * 2 + 2;

            try!(write!(fmt, "stack backtrace:"));

            for (idx, frame) in self.frames().iter().enumerate() {
                let ip = frame.ip();
                try!(write!(fmt, "\n{:4}: {:2$?}", idx, ip, hex_width));

                let symbols = match frame.symbols {
                    Some(ref s) => s,
                    None => {
                        try!(write!(fmt, " - <unresolved>"));
                        continue
                    }
                };
                if symbols.len() == 0 {
                    try!(write!(fmt, " - <no info>"));
                }

                for (idx, symbol) in symbols.iter().enumerate() {
                    if idx != 0 {
                        try!(write!(fmt, "\n      {:1$}", "", hex_width));
                    }

                    if let Some(name) = symbol.name() {
                        try!(write!(fmt, " - {}", name));
                    } else {
                        try!(write!(fmt, " - <unknown>"));
                    }

                    if let (Some(file), Some(line)) = (symbol.filename(), symbol.lineno()) {
                        try!(write!(fmt, "\n      {:3$}at {}:{}", "", file.display(), line, hex_width));
                    }
                }
            }

            Ok(())
        }
    }

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

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