//! `lapp` provides a straightforward way to parse command-line
//! arguments, using the _usage text_ as a pattern.
//!
//! # Example
//! ```
//! extern crate lapp;
//!
//! let args = lapp::parse_args("
//!    A test program
//!    -v,--verbose  verbose output
//!    -k         (default 10)
//!    -s, --save (default 'out.txt')
//!    <out>      (default 'stdout')
//! ");
//! assert_eq!(args.get_bool("verbose"),false);
//! assert_eq!(args.get_integer("k"),10);
//! assert_eq!(args.get_string("save"),"out.txt");
//! assert_eq!(args.get_string("out"),"stdout");
//! ```
//!
//! The usage text or _specification_ follows these simple rules:
//! line begining with one of '-short, --long', '--long' or '-short' (flags)
//! or begining with <name> (positional arguments).
//! These may be followed by a type/default specifier (<type>) - otherwise considered a bool flag
//! with default `false`. This specifier can be a type (like '(integer)') or a default,
//! like '(default 10)`. If there's a default, the type is infered from the value - can always
//! use single quotes to insist that the flag value is a string. Otherwise this flag is
//! _required_ and must be present! You can also use a type with default, e.g. "(path default ~/.boo).
//!
//! The currently supported types are 'string','integer','bool','float','infile','outfile' and 'path'.
//! There are corresponding access methods like `get_string("flag")` and so forth.
//! Access methods like `get_string_result("flag")` will _not_ exit the program on error
//! and instead return an error.
//!
//! The flag may be followed by '...' (e.g '-I... (<type>)') and it is then a _multiple_
//! flag; its value will be a vector. This vector may be empty (flag is not required).
//! If the '...' appears inside the type specifier (e.g. '-p (integer...)') then
//! the flag is expecting several space-separated values (like -p '10 20 30'); it is also
//! represented by a vector.
//!
//! Rest of line (or any other kind of line) is ignored.
//!
//! lapp scans command-line arguments using GNU-style short and long flags.
//! Short flags may be combined, and may immediately followed by a value, e.g '-vk5'.
//! As an extension, you can say '--flag=value' or '-f:value'.

use std::process;
use std::env;
use std::io;
use std::io::{Write,Read};
use std::error::Error;
use std::str::FromStr;
use std::fmt::Display;
use std::path::PathBuf;

mod strutil;
mod types;
mod flag;
use types::*;
pub type Result<T> = types::Result<T>;
use flag::Flag;

pub struct Args<'a> {
    flags: Vec<Flag>,
    pos: usize,
    text: &'a str,
    varargs: bool,
    user_types: Vec<String>,
    istart: usize,
}

impl <'a> Args<'a> {
    /// provide a _usage string_ from which we extract flag definitions
    pub fn new(text: &'a str) -> Args {
        Args{flags: Vec::new(), pos: 0, text: text, varargs: false, user_types: Vec::new(), istart: 1}
    }

    /// start offset in program command-line arguments.
    /// This defaults to 1, but e.g. for Cargo subcommands
    /// it would be 2
    pub fn start(mut self, istart: usize) -> Self {
        self.istart = istart;
        self
    }

    /// declare any user-defined types to be used in the spec.
    /// (They will need to implement FromStr)
    pub fn user_types(&mut self, types: &[&str]) {
        let v: Vec<String> = types.iter().map(|s| s.to_string()).collect();
        self.user_types = v;
    }

    /// bail out of program with non-zero return code.
    /// May force this to panic instead with the
    /// LAPP_PANIC environment variable.
    pub fn quit(&self, msg: &str) -> ! {
        let path = env::current_exe().unwrap();
        let exe = path.file_name().unwrap().to_string_lossy();
        let text = format!("{} error: {}\nType {} --help for more information",exe,msg,exe);
        if env::var("LAPP_PANIC").is_ok() {
            panic!(text);
        } else {
            writeln!(&mut io::stderr(),"{}",text).unwrap();
            process::exit(1);
        }
    }

    /// create suggested variable or struct declarations for accessing the flags...
    pub fn declarations(&mut self, struct_name: &str) -> String {
        if let Err(e) = self.parse_spec() {
            self.quit(e.description());
        }
        let mut res = String::new();
        if struct_name.len() > 0 {
            res += &format!("const USAGE: &'static str = \"\n{}\";\n",self.text);
            res += &format!("#[derive(Debug)]\nstruct {} {{\n",struct_name);
            for f in &self.flags {
                res += &format!("\t{}: {},\n",f.rust_name(),f.rust_type());
            }
            res += &format!(
                "}}\n\nimpl {} {{\n\tfn new() -> ({},lapp::Args<'static>) {{\n",
                struct_name,struct_name);
            res += &format!(
                "\t\tlet args = lapp::parse_args(USAGE);\n\t\t({}{{\n",struct_name);
            for f in &self.flags {
                res += &format!("\t\t\t{}: {},\n",f.rust_name(),f.getter_name());
            }
            res += &format!("\t\t}},args)\n\t}}\n}}\n\n");
        } else {
            for f in &self.flags {
                res += &format!("    let {} = {};\n",
                    f.rust_name(),f.getter_name());
            }
        }
        res
    }

    pub fn dump(&mut self) {
        self.parse();
        for f in &self.flags {
            println!("flag '{}' value {:?}",f.long,f.value);
        }
    }

    pub fn parse_env_args(&mut self) -> Result<()> {
        let v: Vec<String> = env::args().skip(self.istart).collect();
        self.parse_command_line(v)
    }

    /// parse the spec and the command-line
    pub fn parse_result(&mut self) -> Result<()> {
        self.parse_spec()?;
        self.parse_env_args()
    }


    /// parse the spec and the command-line, quitting on error.
    pub fn parse(&mut self) {
        if let Err(e) = self.parse_result() {
            self.quit(e.description());
        }
    }

    /// parse the spec and create the flags.
    pub fn parse_spec(&mut self) -> Result<()> {
        for line in self.text.lines() {
            if let Err(e) = self.parse_spec_line(line) {
                return error(format!("{}\nat line: '{}'",e.description(),line));
            }
        }
        if let Err(_) = self.flags_by_long("help") {
            self.parse_spec_line("   -h,--help this help").unwrap();
        }
        Ok(())
    }


    fn parse_spec_line(&mut self, mut slice: &str) -> Result<()> {
        use strutil::*;
        fn flag_error (flag: &Flag,msg: &str) -> Result<()> {
            error(format!("{}: flag '{}'",msg,flag.long))
        }

        if let Some(idx) = slice.find(|c: char| ! c.is_whitespace()) {
            let mut flag: Flag = Default::default();
            let mut is_positional = false;
            slice = &slice[idx..];
            let is_flag = starts_with(&mut slice,"-");
            let mut long_flag = starts_with(&mut slice,"-");
            if is_flag && ! long_flag { // short flag
                flag.short = (&slice[0..1]).chars().next().unwrap();
                flag.long = flag.short.to_string();
                if ! flag.short.is_alphanumeric() {
                    return flag_error(&flag,"not allowed: only letters or digits in short flags");
                }
                slice = &slice[1..];
                if let Some(0) = slice.find(|c: char| c.is_alphanumeric()) {
                   return flag_error(&flag,"short flags should have one character");
                }
                if starts_with(&mut slice,",") {
                    slice = skipws(slice);
                    long_flag = starts_with(&mut slice,"--");
                    if ! long_flag {
                        return flag_error(&flag,"expecting long flag after short flag");
                    }
                }
            }
            if long_flag {
                let idx = slice.find(|c: char| ! (c.is_alphanumeric() || c == '_' || c == '-'))
                    .unwrap_or(slice.len());
                let parts = slice.split_at(idx);
                flag.long = parts.0.to_string();
                slice = parts.1;
                if slice.len() > 0 && ! (slice.starts_with(" ") || slice.starts_with("."))  {
                    return flag_error(&flag,"long flags can only contain letters, numbers, '_' or '-'");
                }
            } else
            if starts_with(&mut slice, "<") { // positional argument
                flag.long = grab_upto(&mut slice, ">")?;
                self.pos = self.pos + 1;
                flag.pos = self.pos;
                is_positional = true;
            }
            if flag.long == "" && flag.short == '\0' {
                // not a significant line, ignore!
                return Ok(());
            }
            if flag.long == "" { // just a short flag
                flag.long = flag.short.to_string();
            }
            slice = skipws(slice);
            if starts_with(&mut slice,"...") {
                flag.is_multiple = true;
                slice = skipws(slice);
            }
            if starts_with(&mut slice,"(") {
                let r = grab_upto(&mut slice, ")")?;
                let mut rest = r.as_str().trim();
                let multable = ends_with(&mut rest,"...");
                if let Some((b1,b2)) = split_with(rest,"..") {
                    // bounds on a number type
                    flag.set_range_constraint(b1,b2)?;
                } else {
                    // default VALUE or TYPE
                    if rest.len() == 0 {
                        return flag_error(&flag,"nothing inside type specifier");
                    }
                    if starts_with(&mut rest,"default ") {
                        rest = skipws(rest);
                        // flag type will be deduced
                        flag.set_default_from_string(rest,true)?;
                    } else {
                        let name = grab_word(&mut rest);
                        // custom types are _internally_ stored as string types,
                        // but we must verify that it is a known type!
                        flag.vtype = if self.user_types.iter().any(|s| s == name.as_str()) {
                            Type::Str
                        } else {
                            Type::from_name(&name)?
                        };
                        if starts_with(&mut rest,"default ") {
                            rest = skipws(rest);
                            // flag already has a definite type
                            flag.set_default_from_string(rest,false)?;
                        }
                    }
                }
                // if type is followed by '...' then the flag is also represented
                // by a vector (e.g. --ports '8080 8081 8082').
                // UNLESS it is a positional argument,
                // where it is considered multiple!
                if multable {
                    flag.defval = Value::empty_array();
                    if is_positional {
                        flag.is_multiple = true;
                        if self.varargs {
                            return flag_error(&flag,"only last argument can occur multiple times");
                        }
                        self.varargs = true;
                    } else { // i.e the flag type is an array of a basic scalar type
                        flag.vtype = flag.vtype.create_empty_array();
                    }
                }
                if flag.is_multiple {
                    flag.value = Value::empty_array();
                }
            } else {
                flag.defval = Value::Bool(false);
                flag.vtype = Type::Bool;
            }
            if slice.len() > 0 {
                flag.help = skipws(slice).to_string();
            }

            // it is an error to specify a flag twice...
            if self.flags_by_long_ref(&flag.long).is_ok() {
                return flag_error(&flag,"already defined");
            }
            self.flags.push(flag);
        }
        Ok(())

    }

    fn flags_by_long(&mut self, s: &str) -> Result<&mut Flag> {
        self.flags.iter_mut()
            .filter(|&ref f| f.long == s)
            .next().ok_or(LappError(format!("no long flag '{}'",s)))
    }

    fn flags_by_long_ref(&self, s: &str) -> Result<&Flag> {
        self.flags.iter()
            .filter(|&f| f.long == s)
            .next().ok_or(LappError(format!("no long flag '{}'",s)))
    }

    fn flags_by_short(&mut self, ch: char) -> Result<&mut Flag> {
        self.flags.iter_mut()
            .filter(|&ref f| f.short == ch)
            .next().ok_or(LappError(format!("no short flag '{}'",ch)))
    }

    fn flags_by_pos(&mut self, pos: usize) -> Result<&mut Flag> {
        self.flags.iter_mut()
            .filter(|&ref f| f.pos == pos)
            .next().ok_or(LappError(format!("no arg #{}",pos)))
    }

    pub fn parse_command_line(&mut self, v: Vec<String>) -> Result<()> {
        use strutil::*;
        let mut iter = v.into_iter();

        fn nextarg(name: &str, ms: Option<String>) -> Result<String> {
            if  ms.is_none() {return error(format!("no value for flag '{}'",name));}
            Ok(ms.unwrap())
        };

        // flags _may_ have the value after a = or : delimiter
        fn extract_flag_value(s: &mut &str) -> String {
            if let Some(idx) = s.find(|c: char| c == '=' || c == ':') {
               let rest = (&s[idx+1..]).to_string();
               *s = &s[0..idx];
               rest
            } else {
               "".to_string()
           }
        }

        let mut parsing = true;
        let mut k = 1;
        while let Some(arg) = iter.next() {
            let mut s = arg.as_str();
             if parsing && starts_with(&mut s, "--") { // long flag
                if s.is_empty() { // plain '--' means 'stop arg processing'
                    parsing = false;
                } else {
                    let mut rest = extract_flag_value(&mut s);
                    let flag = self.flags_by_long(s)?;
                    if flag.vtype != Type::Bool { // then it needs a value....
                        if rest == "" {  // try grab the next arg
                            rest = nextarg(s,iter.next())?;
                        }
                        flag.set_value_from_string(&rest)?;
                    } else {
                        flag.set_value(Value::Bool(true))?;
                    }
                }
            } else
            if parsing && starts_with(&mut s,"-") { // short flag
                // there can be multiple short flags
                // although only the last one can take a value
                let mut chars = s.chars();
                while let Some(ch) = chars.next() {
                    let flag = self.flags_by_short(ch)?;
                    if flag.vtype != Type::Bool {
                        let mut rest: String = chars.collect();
                        if rest == "" {
                            rest = nextarg(&flag.long,iter.next())?;
                        }
                        flag.set_value_from_string(&rest)?;
                        break;
                    } else {
                       flag.set_value(Value::Bool(true))?;
                    }
                }
            } else {  // positional argument
                let flag = self.flags_by_pos(k)?;
                flag.set_value_from_string(s)?;
                // multiple arguments are added to the vector value
                if ! flag.is_multiple {
                    k += 1;
                }

            }
        }


        // display usage if help is requested
        if let Ok(ref flag) = self.flags_by_long_ref("help") {
            if flag.is_set {
                let text = strutil::dedent(self.text);
                println!("{}",text);
                process::exit(0);
            }
        }

        // fill in defaults. If a default isn't available it's
        // a required flag. If not specified the flag value is set to an error
        for flag in &mut self.flags {
            flag.check()?;
        }
        Ok(())
    }

    /// clear used flag state
    pub fn clear_used(&mut self) {
        for flag in &mut self.flags {
            flag.uncheck();
        }
    }

    /// clear all the flags - ready to parse a new command line.
    pub fn clear(&mut self) {
        for flag in &mut self.flags {
            flag.clear();
        }
    }

    fn error_msg(&self, tname: &str, msg: &str, pos: Option<usize>) -> String {
        if let Some(idx) = pos {
            format!("argument #{} '{}': {}",idx,tname,msg)
        } else {
            format!("flag '{}': {}",tname,msg)
        }
    }

    fn bad_flag <T>(&self, tname: &str, msg: &str) -> Result<T> {
        let pos = if let Ok(ref flag) = self.flags_by_long_ref(tname) {
            flag.position()
        } else {
            None
        };
        error(&self.error_msg(tname,msg,pos))
    }

    fn unwrap<T>(&self, res: Result<T>) -> T {
        match res {
            Ok(v) => v,
            Err(e) => self.quit(e.description())
        }
    }

    // there are three bad scenarios here. First, the flag wasn't found.
    // Second, the flag's value was not set. Third, the flag's value was an error.
    fn result_flag_flag (&self, name: &str) -> Result<&Flag> {
        if let Ok(ref flag) = self.flags_by_long_ref(name) {
           if flag.value.is_none() {
                self.bad_flag(name,"is required")
            } else {
                if let Value::Error(ref s) = flag.value {
                   self.bad_flag(name,s)
                } else {
                    Ok(flag)
                }
            }
        } else {
            self.bad_flag(name,"is unknown")
        }
    }

    fn result_flag_value (&self, name: &str) -> Result<&Value> {
        Ok(&(self.result_flag_flag(name)?.value))
    }

    // this extracts the desired value from the Value struct using a closure.
    // This operation may fail, e.g. args.get_float("foo") is an error if the
    // flag type is integer.
    fn result_flag<T, F: Fn(&Value) -> Result<T>> (&self, name: &str, extract: F) -> Result<T> {
        match self.result_flag_value(name) {
            Ok(value) => {
                match extract(value) {
                    Ok(v) => Ok(v),
                    Err(e) => self.bad_flag(name,e.description())
                }
            },
            Err(e) => Err(e)
        }
    }

    /// has this flag been set? Quits if it's an unknown flag
    pub fn flag_present(&self, name: &str) -> bool {
        if let Ok(ref flag) = self.flags_by_long_ref(name) {
           if flag.value.is_none() {
                false
            } else {
                true
            }
        } else {
            self.quit(&format!("'{}' is not a flag",name));
        }
    }


    /// get flag as a string
    pub fn get_string_result(&self, name: &str) -> Result<String> {
        self.result_flag(name,|v| v.as_string())
    }

    /// get flag as an integer
    pub fn get_integer_result(&self, name: &str) -> Result<i32> {
        self.result_flag(name,|v| v.as_int())
    }

    /// get flag as a float
    pub fn get_float_result(&self, name: &str) -> Result<f32> {
        self.result_flag(name,|v| v.as_float())
    }

    /// get flag as boolean
    pub fn get_bool_result(&self, name: &str) -> Result<bool> {
        self.result_flag(name,|v| v.as_bool())
    }

    /// get flag as a file for reading
    pub fn get_infile_result(&self, name: &str) -> Result<Box<Read>> {
        self.result_flag(name,|v| v.as_infile())
    }

    /// get flag as a file for writing
    pub fn get_outfile_result(&self, name: &str) -> Result<Box<Write>> {
        self.result_flag(name,|v| v.as_outfile())
    }

    /// get flag as a path
    pub fn get_path_result(&self, name: &str) -> Result<PathBuf> {
        self.result_flag(name,|v| v.as_path())
    }

    /// get flag always as text, if it's defined
    pub fn get_text_result(&self, name: &str) -> Result<&String> {
        self.result_flag_flag(name).map(|f| &f.strings[0])
    }

    /// get flag as any value which can parsed from a string.
    // The magic here is that Rust needs to be told that
    // the associated Err type can be displayed.
    pub fn get_result<T>(&self, name: &str) -> Result<T>
    where T: FromStr, <T as FromStr>::Err : Display
    {
        match self.get_text_result(name)?.parse::<T>() {
            Ok(v) => Ok(v),
            Err(e) =>  self.bad_flag(name,&e.to_string())
        }
    }

    /// get flag as a string, quitting otherwise.
    pub fn get_string(&self, name: &str) -> String {
        self.unwrap(self.get_string_result(name))
    }

    /// get flag as an integer, quitting otherwise.
    pub fn get_integer(&self, name: &str) -> i32 {
        self.unwrap(self.get_integer_result(name))
    }

    /// get flag as a float, quitting otherwise.
    pub fn get_float(&self, name: &str) -> f32 {
        self.unwrap(self.get_float_result(name))
    }

    /// get flag as a bool, quitting otherwise.
    pub fn get_bool(&self, name: &str) -> bool {
        self.unwrap(self.get_bool_result(name))
    }

    /// get flag as a file for reading, quitting otherwise.
    pub fn get_infile(&self, name: &str) -> Box<Read> {
        self.unwrap(self.get_infile_result(name))
    }

    /// get flag as a file for writing, quitting otherwise.
    pub fn get_outfile(&self, name: &str) -> Box<Write> {
        self.unwrap(self.get_outfile_result(name))
    }

    /// get flag as a path, quitting otherwise.
    pub fn get_path(&self, name: &str) -> PathBuf {
        self.unwrap(self.get_path_result(name))
    }

    /// get flag as any value which can parsed from a string, quitting otherwise.
    pub fn get<T>(&self, name: &str) -> T
    where T: FromStr, <T as FromStr>::Err : Display
    {
        match self.get_result::<T>(name) {
            Ok(v) => v,
            Err(e) => self.quit(&e.to_string())
        }
    }

    fn get_boxed_array(&self, name: &str, kind: &str) -> Result<&Vec<Box<Value>>> {
        let arr = self.result_flag_value(name)?.as_array()?;
        // empty array matches all types
        if arr.len() == 0 { return Ok(arr); }
        // otherwise check the type of the first element
        let ref v = *(arr[0]);
        let tname = v.type_of().short_name();
        if tname == kind {
            Ok(arr)
        } else {
            let msg = format!("wanted array of {}, but is array of {}",kind,tname);
            error(self.error_msg(name,&msg,None))
        }
    }

    fn get_array_result<T,F>(&self, name: &str, kind: &str, extract: F) -> Result<Vec<T>>
    where T: Sized, F: Fn(&Box<Value>)->Result<T> {
        let va = self.get_boxed_array(name,kind)?;
        let mut res = Vec::new();
        for v in va {
            let n = extract(v)?;
            res.push(n);
        }
        Ok(res)
    }

    /// get a multiple flag as an array of strings
    pub fn get_strings_result(&self, name: &str) -> Result<Vec<String>> {
        self.get_array_result(name,"string",|b| b.as_string())
    }

    /// get a multiple flag as an array of integers
    pub fn get_integers_result(&self, name: &str) -> Result<Vec<i32>> {
        self.get_array_result(name,"integer",|b| b.as_int())
    }

    /// get a multiple flag as an array of floats
    pub fn get_floats_result(&self, name: &str) -> Result<Vec<f32>> {
        self.get_array_result(name,"float",|b| b.as_float())
    }

    /// get a multiple flag as an array of any parsable value.
    pub fn get_results<T>(&self, name: &str) -> Result<Vec<T>>
    where T: FromStr, <T as FromStr>::Err : Display
    {
        let flag = self.result_flag_flag(name)?;
        flag.strings.iter()
            .map(|s| s.parse::<T>()) // Result<T,Err>
            .map(|r| { match r { // but we want Result<T,LappError>
                Ok(v) => Ok(v),
                Err(e) => self.bad_flag(name,&e.to_string())
             }})
            .collect()
    }


    /// get a multiple flag as an array of strings, quitting otherwise
    pub fn get_strings(&self, name: &str) -> Vec<String> {
        self.unwrap(self.get_strings_result(name))
    }

    /// get a multiple flag as an array of integers, quitting otherwise
    pub fn get_integers(&self, name: &str) -> Vec<i32> {
        self.unwrap(self.get_integers_result(name))
    }

    /// get a multiple flag as an array of floats, quitting otherwise
    pub fn get_floats(&self, name: &str) -> Vec<f32> {
        self.unwrap(self.get_floats_result(name))
    }

    /// get a multiple flag as an array of any parsable value, quitting otherwise
    pub fn get_array<T>(&self, name: &str) -> Vec<T>
    where T: FromStr, <T as FromStr>::Err : Display
    {
        self.unwrap(self.get_results(name))
    }


}

/// parse the command-line specification and use it
/// to parse the program's command line args.
/// As before, quits on any error.
pub fn parse_args(s: &str) -> Args {
    let mut res = Args::new(s);
    res.parse();
    res
}

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

    const SIMPLE: &'static str = "
        Testing Lapp
          -v, --verbose verbose flag
          -k   arb flag
          -o, --output (default 'stdout')
          -p   (integer...)
          -I, --include... (string)
          <in> (string)
          <out> (string...)
    ";


    fn arg_strings(a: &[&str]) -> Vec<String> {
        a.iter().map(|s| s.to_string()).collect()
    }

    fn empty_strings() -> Vec<String> {
        Vec::new()
    }

    fn parse_args(spec: &'static str, parms: &[&str]) -> Args<'static> {
        let mut args = Args::new(spec);
        args.parse_spec().expect("spec failed");
        args.parse_command_line(arg_strings(parms)).expect("scan failed");
        args
    }


    struct SimpleTest {
        verbose: bool,
        k: bool,
        output: String,
        p: Vec<i32>,
        include: Vec<String>,
        out: Vec<String>
    }

    impl SimpleTest {
        fn new(test_args: &[&str]) -> SimpleTest {
            let args = parse_args(SIMPLE,test_args);
            SimpleTest {
                verbose: args.get_bool("verbose"),
                k: args.get_bool("k"),
                output: args.get_string("output"),
                p: args.get_integers("p"),
                include: args.get_strings("include"),
                out: args.get_strings("out")
            }
        }
    }

    #[test]
    fn test_simple_just_out() {
        let res = SimpleTest::new(&["boo","hello"]);
        assert_eq!(res.verbose,false);
        assert_eq!(res.k,false);
        assert_eq!(res.output,"stdout");
        assert_eq!(res.p,&[]);
        assert_eq!(res.out,&["hello"]);
    }

    #[test]
    fn test_simple_bool_flags() {
        let res = SimpleTest::new(&["boo","-vk","hello"]);
        assert_eq!(res.verbose,true);
        assert_eq!(res.k,true);
        assert_eq!(res.output,"stdout");
        assert_eq!(res.p,&[]);
        assert_eq!(res.out,&["hello"]);
    }

    #[test]
    fn test_simple_array_flag() {
        let res = SimpleTest::new(&["boo","-p","10 20 30","hello"]);
        assert_eq!(res.verbose,false);
        assert_eq!(res.k,false);
        assert_eq!(res.output,"stdout");
        assert_eq!(res.p,&[10,20,30]);
        assert_eq!(res.out,&["hello"]);
    }

    #[test]
    fn test_simple_multiple_positional_args() {
        let res = SimpleTest::new(&["boo","hello","baggins","--","--frodo"]);
        assert_eq!(res.verbose,false);
        assert_eq!(res.k,false);
        assert_eq!(res.output,"stdout");
        assert_eq!(res.p,&[]);
        assert_eq!(res.include,empty_strings());
        assert_eq!(res.out,&["hello","baggins","--frodo"]);
    }

    #[test]
    fn test_simple_multiple_flags() {
        let res = SimpleTest::new(&["boo","-I.","-I..","--include","lib","hello"]);
        assert_eq!(res.verbose,false);
        assert_eq!(res.k,false);
        assert_eq!(res.output,"stdout");
        assert_eq!(res.p,&[]);
        assert_eq!(res.include,&[".","..","lib"]);
        assert_eq!(res.out,&["hello"]);
    }

    fn err<T>(r: Result<T>) -> String {
        r.err().unwrap().description().to_string()
    }

    fn ok<T>(r: Result<T>) -> T {
        r.unwrap()
    }

    static ERRS: &str = "
        testing lapp
        -s,--str (string)
        <frodo> (float)
        <bonzo>... (integer)
    ";

    #[test]
    fn test_errors_result() {
        let aa = parse_args(ERRS,&["1","10","20","30"]);
        assert_eq!(err(aa.get_string_result("str")),"flag \'str\': is required");
        assert_eq!(err(aa.get_string_result("frodo")),"argument #1 \'frodo\': not a string, but float");
        assert_eq!(ok(aa.get_float_result("frodo")),1.0);
        assert_eq!(ok(aa.get_integers_result("bonzo")),[10, 20, 30]);
    }



    const CUSTOM: &str = "
        Custom types need to be given names
        so we accept them as valid:
        --hex (hex)
    ";

    // they need to be user types that implement FromStr
    use std::str::FromStr;
    use std::num::ParseIntError;

    struct Hex {
        value: u64
    }

    impl FromStr for Hex {
        type Err = ParseIntError;

        fn from_str(s: &str) -> ::std::result::Result<Self,Self::Err> {
            let value = u64::from_str_radix(s,16)?;
            Ok(Hex{value: value})
        }
    }


    #[test]
    fn test_custom() {
        let mut args = Args::new(CUSTOM);
        args.user_types(&["hex"]);
        args.parse_spec().expect("spec failed");
        args.parse_command_line(arg_strings(&["--hex","FF"])).expect("scan failed");
        let hex: Hex = args.get("hex");
        assert_eq!(hex.value,0xFF);
    }


}